Acid-iron waste disposal and the summer distribution of standing crops in the New York bight

Water Research Pergamon Press 1972. Vol. 6, pp. 231-256. Printed in Great Britain

ACID-IRON WASTE DISPOSAL A N D THE SUMMER DISTRIBUTION OF S T A N D I N G CROPS IN THE NEW Y O R K BIGHT* RALPH F. VACCARO, GEORGE D . GRICE, GILBERT T. ROWE a n d PETER H . WIEBE Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, U.S.A. (Received 29 November 1971) Abstract--Ecological consequences arising from the disposal of 50 million tons of acid-iron industrial waste in the coastal waters off New York over the past 22 yr were assessed. Most of the data were obtained at two identical grids of stations which enabled comparisons of hydrographic, chemical and biological conditions within the acid-iron disposal area with similar parameters in a nearby control area. Supplementary information on benthos and sediment was obtained at other locations peripheral to the two station grids and in Hudson Gorge, and these were used to construct a synoptic picture of the physio--cbemical conditions and standing crops in the New York Bight. At each grid station the hydrographic measurements made were temperature, salinity and light penetration; chemical observations consisted of dissolved oxygen, dissolved and suspended iron, total inorganic nitrogen and phosphate; while chlorophyll a, zooplankton and benthos biomass provided a measure of the abundance of standing crops. Trace metal spectra (Fe, Zn, Co, Cu, Pb, Cr, Ni and Cd) were determined on selected zooplankton, benthos and sediment samples. LaboratoIy toxicity studies were conducted on phytoplankton and zooplankton species at several concentrations of acid-iron waste in seawater. The maximum concentration of iron in the water column (832 ~g 1-1) occurred as suspended material within a restricted area of the acid grid. In terms of raw acid-iron etttuent this suggests a maximum in situ concentration of 1 part waste in 39,000 parts of seawater thereby providing a useful guide for the design of laboratory toxicity studies. Despite the abundance of suspended iron in the overlying water of the acid-grid the average concentrations of iron in the sediments of both the acid and control grids were remarkably similar, while sediments from the nearby Hudson Gorge were notably richer in iron. However, a comparison of previous measurements in the study area dating back to 1948 indicates that there has been no accumulation of iron within the sediments below the disposal area or Hudson Gorge over the past 22 yr. The phytoplankton toxicity experiment conducted with an acid-iron waste concentration four times greater than that observed in the field showed no adverse effect on phytoplankton growth or diversity. Similar experiments with copepods caused either failure of these organisms to reproduce or a delay in the time required to transform eggs into adults. Although the average zooplankton abundance within the control grid exoeeded that of the acid grid by about 30 per cent, the range of values describing zooplankton abundance in the two areas was similar. This difference was attributed to a transitory large scale patchiness in the area and not to toxicity of acid-iron waste. A positive correlation was found between F e : C in zooplankton and the amount of particulate iron present in the seawater. The average number of benthic animals on the bottom of the acid grid area was significantly less than in the sediment of the control grid but there was no difference in biomass or species diversity between the two areas. As was the case with zooplankton the higher Fe: C in the benthos corresponded to the higher iron in the sediment of Hudson Gorge and acidgrid. The heavy metal content of zooplankton, benthos and sediment showed that samples from the acid grid were significantly richer in these elements than the comparable control area samples. However, a broader comparison showed that samples from Hudson Gorge contained the maximum amounts of lead and chromium in benthos as well as the maximum concentrations of all eight metals in the sediment. These data are consistent with the possibility that entrapment in the gorge sediments may be the ultimate fate of the heavy metal enrichment * Contribution No. 2697 from the Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543. This study was supported in part by the National Science Foundation Grants G B 16539, G A 27405, the Atomic Energy Commission Contract AT(30-1)-3862 (Ref. No. NYO3862-45) and N L Industries. 231

232

R A L e H F. V A C C A R O , GEORGE D . GRICE, GILBERT T . R O W ~ a n d PETER H . W [ E e E

in the New York Bight area and that sources of heavy metals other than acid-iron waste may be substantial. The remaining data reviewed in this study did not demonstrate any adverse in situ effects of acid-iron waste on the distribution of such parameters as dissolved oxygen, chlorophyll a and plant nutrients. Present indications are that the disposal of acid-iron waste in the New York Bight a p p e a r s to influence standing crops in minor ways considering the magnitude and nature of the waste material involved.

INTRODUCTION

THE COASTAL waters adjacent to New York and northern New Jersey, which form the New York Bight, are a repository for massive quantities of waste materials generated from one of the world's most densely populated and highly industrialized areas. Currently about l0 million tons of dredge spoils, construction debris, sewage sludge and industrial wastes are being disposed of within a sea surface area of 250 km 2, the annual rate of increase being about 4 per cent (G~oss, 1970). The effects of sewage sludge and dredge spoils on the benthic fauna immediately underlying the deposition sites have been recently described by PEARCE (1970). His and other observations (KING, 1970; TRAIN et el., 1970) regarding ocean dumping are indicative of increasing concern over the effects of waste disposal in the marine environment. The Titanium Division of NL Industries discharges acid-iron waste at a location. known as the "acid grounds", approximately 22 km off the New Jersey coast (RG. 1), This industrial residual is derived from the production of titanium dioxide, a pigment used principally in the manufacture of paint, paper, plastic and ceramics. Titanium, which occurs in an ore that is mined in northern New York, contains various complexes of titanium and iron oxides as well as trace quantities of other metallic elements.

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Distribution of Standing Crops in the New York Bight

233

In processing the ore, a sulfuric acid residue ( ~ 10per cent) containing soluble iron (3 per cent), metallic salts and insoluble material such as silica and undissolved titanium dioxide, accumulates as waste. The mixture is transported in a barge of 5400 tons capacity and in recent years an average of 1.5 trips to the discharge site have been made every 24 h. The original disposal site, which was established in 1948, was located over the Hudson Gorge but in April, 1949 the discharge site was moved to its present location (FIG. 1). Since 1948 about 50 million tons of mixed, acid wastes have been deposited within this relatively limited area of the New York Bight. The acid waste is released into the sea beneath the surface through specially designed exit ports. Solids are dispersed by gravity from separate aerated conical tanks. Throughout the operation, way is maintained and dumping is continuous over a 7.24-km hairpin-shaped route. Summer and winter tracks are alternately used to help avoid waste accumulation and to assist in initial mixing. A more detailed description of the disposal operations has been published by PESCHn~RAand FREmERR, 1968).

HYDROGRAPHIC CONSIDERATIONS The principal hydrographic factors and currents which govern the dispersal of pollutants in the New York Bight have been described by KETCHUMet al. (1951), REOFIELDand WALFORD(1951) and BUMPUS(1969). Their studies indicate that significant changes in the winter and summer circulation patterns are influenced by the prevailing wind system in conjunction with the amount of fresh water input from the Hudson River. During winter, persistent northwesterly winds often impose an offshore component to a net southerly set along the New Jersey coast. In summer, the onset of southwesterly winds, following spring freshening and stratification of the surface layer, can lead to current reversals whereby surface water moves in a northeasterly direction toward the southern coast of Long Island. The residual drift of bottom water in the region between Cape Cod and Delaware Bay has been studied by BuMPUS (1965) and in the New York Bight by PEARCE (1969). Based on results obtained from sea-bed drifters, the former investigator reported a definite residual movement of bottom water towards the mouths of estuaries. This on-shore movement was more pronounced in depths less than 60 in. Preliminary studies by PEARCE(1969) show that bottom currents in the New York Bight are strong and flow inshore towards Long Island throughout much of the year. More detailed current studies are needed before confident predictions can be made concerning the transport and fate of waste materials that are deposited on the sea bottom in the New York Bight. An on-site study of the acid dispersal procedure by KETCI-IUMand FORD (1952) has provided a basis for evaluating the dispersal of soluble waste substances discharged at sea from a moving barge. In general, the distribution of the waste components in the wake of the barge was shown to be a function of the rate of discharge and of the overall horizontal mixing coefficient, a term which includes the effects of turbulence in the wake of a barge moving across the sea surface. In practice, predictions of waste concentrations under such circumstances are also sensitive to delayed chemical or biological transformations which significantly alter the solubility or mobility of specific waste components. w.R. 6 / 3 ~ a

234

RALPHF. VACCARO,GEORGED. GRICE,GILBERTT. ROWEand PETERH. WEBE

The present study is an attempt to evaluate the effects of the disposal of acid-iron wastes on the ecology of the acid grounds by means of intensive synoptic sampling of selected biological, physical, and chemical components of the disposal area and an adjacent control area, and by means of a limited series of laboratory experiments. METHODS Sampling strategy To detect possible relationships between physical-chemical data and standing crops of resident zooplankton and benthic populations in the vicinity of the acid grounds, two grids of eight locations each were sampled intensively over the period 25-29 June, 1970 aboard the R/V Gosnold. One grid was placed so as to cover the acid grounds. The other, a replicate or control grid, was placed 20 km to the northeast, where the bottom topography was similar to that of the acid grounds (FIG. 1). Station locations were selected to provide maximum geographic coverage of the two areas. Each grid location was occupied twice, once during the day and once at night (stations 1-16 on acid grounds; stations 21-37 on control area). Additional stations (17-20 and 38-43) were taken around the periphery of the acid-iron and control areas and in Hudson Gorge. Scuba observations were made of the water column and bottom at a single location on the acid grounds.

Physical-chemical observations At stations 1-8, 30-37, water samples were routinely collected with a PVC Niskin bottle (~ 26-1. capacity) from two depths, 1 and 20 m, for hydrographic and chemical measurements above and below the thermocline. The properties measured were salinity, dissolved oxygen, dissolved and suspended carbon, dissolved and suspended iron, chlorophyll, phosphate, nitrate, and ammonia. At these stations, surface to bottom temperature profiles were obtained with a bathythermograph and the relative penetration of light beneath the sea surface was estimated with a white secchi disc (30-cm dia.). Salinity was determined with a conductivity bridge (SCHLEICHERand BRADSHAW, 1956) and dissolved oxygen by Winkler titration using a biniodate standard (CARRIT and CARPENTER, 1966). Dissolved and suspended carbon (suspended particles greater than 0.80 t~m in diameter) were nleasured independently by the infra-red absorption of CO2 following oxidative combustion of the filterable and unfilterable organic fractions (MENZELand VACCARO,1964). Biologically reactive iron in solution and in suspension as well as that associated with zooplankton, benthos and the sediments were measured according to the various, colorimetric tests for iron described by STPaCKLANDand PARSONS(1968). Chlorophyll, used to evaluate the magnitude of the standing crop of phytoplankton, was measured by the method of Richards with THOMPSON(1952) using a membrane filter to concentrate the phytoplankton cells as recommended by CRErrz and RICHARDS (1955). Ammonia-nitrogen was determined colorimetrically using the method described by SOL6RZONA(1969). Phosphorus as phosphate and nitrogen as nitrate were also determined colorimetrically by the respective methods of MURPHYand RXLEY(1962) and by WOOD et al. (1967). Based on the composition of acid-iron waste, the distribution of eight metallic

Distribution of Standing Crops in the New York Bight

235

components was measured by atomic absorption in selected zooplankton, benthic, and inert sediment material from the study area and also in a seawater precipitate prepared with acid-iron liquor in the laboratory. The elements measured were Fe, Zn, Co, Cu, Pb, Cr, Ni, and Cd. Weighed zooplankton and benthic samples were totally digested in a mixture of HF, HNO3, and HCIO4 and the presence of abundant elements such as Fe, Na, K, Ca, and Mg was checked in order to establish matrix conditions. Metals from the inert sediment samples were leached with hot HC1 and the residues clarified by filtration. Matrices of these samples were also used to prepare standard reference solutions applicable to the analysis of the individual metals. The precision of the atomic absorption techniques was :k 10 per cent, although the error associated with colorimetric vs. atomic absorption iron analyses was somewhat greater.

Zooplankton Each station of the acid and control grids was sampled twice for zooplankton, once during the day and once at night giving a total of 32 collections. On July 6 an additional zooplankton haul was made at a remote station located off Martha's Vineyard Island, approximately 226 km northeast of the acid grounds. All collections were obtained with a 70-cm dia. conical net (mesh size 0.239 mm aperture) equipped with a flowmeter which was used in surface to bottom oblique tows taken at a ship's speed of 1.0-2.5 kt. The average duration of a tow was 6.4 min and the average volume filtered was 119 m s. Upon completion of each tow, the net was thoroughly washed and prior to preservation the wet displacement volume was determined using the method described by AHI_Sa'aOMand Trm~KILL(1963). The sample was then divided with a Folsom plankton splitter (McEw~'N et al., 1954) and one-half was preserved in 10 per cent buffered formalin for analysis of species composition, and the other half frozen in a chest freezer and ultimately dried at 60°C to constant weight for chemical analyses.

Benthos Two replicate van Veen grab samples (1/25 m 2) were obtained from the bottom at stations in the acid grounds (stations 1-8) and in the control area (stations 30-37). Additional grab samples were obtained from the area adjacent to the acid grounds and control area and in Hudson Gorge (stations 17-21, 38--42). Two 5-cm cores were taken with a 3.5-cm dia. plastic core liner from the first grab sample collected at each station. These cores were frozen for subsequent analyses of iron and organic material. The remainder of the first grab sample was gently washed through 1 mm sieving screens and the animals preserved in 10 per cent buffered formalin for identification and enumeration. The diversity of species in the acid grounds and control area was calculated using the Shannon-Wiener information formula (SHANNON and WEAVER, 1964) :

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~ pllog2pi i~l

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236

RALPHF. VACCARO,GEORGED. GRICE,GILBERTT. ROWEand PETERH. WtEBE

were removed by sieving the sediment through a 1 mm screen. Dry weights were determined and aliquots of this material were combusted at 500°C. The organic carbon content o f the animals has been considered as 50 per cent o f the weight loss on ignition.

Phytoplankton and copepod laboratory studies A laboratory study was conducted to determine the effects o f acid-iron waste (obtained from the N L Industries plant at Sayreville, New Jersey) on the growth and development of a wild phytoplankton population o f coastal origin. The test organisms originated from a sample collected in Vineyard Sound in which the dominant species were Nitzschia closterium, Skeletonema costatum, Chaetocerous decipiens and Licmohpora lyngbyei. The experiment was conducted in continuous culture apparatus (DUNSTAN and MENZZL, in press) to stabilize media composition throughout the test period. The culture medium, 1/10 strength medium f (GUILLARD and RYTHER, 1962), Was prepared in seawater both with and without the addition o f a 1 : 10,000 dilution o f filtered acid-iron waste. Subsequent to inoculation, growth, examined over a 12-day period at 26°C, was recorded in terms o f cell numbers and by changes in the concentration o f chlorophyll a and particulate carbon. The combination o f cell numbers and the number o f species represented was used to evaluate diversity. Pseudodiaptomus coronatus, an estuarine and coastal species o f copepod, was used for making preliminary experiments on the effects o f acid waste on reproduction and survival. This species carries from 25 to 30 eggs and its life history is known (GRXCE, 1969). Ovigerous specimens o f P. coronatus were isolated from plankton collected in Woods Hole Harbor in July and August, 1970, and transferred directly to various concentrations o f unfiltered and filtered acid waste which was prepared from an original dilution of 1 : 10,000 with Woods Hole Harbor seawater. In the initial experiment 2 ovigerous females were placed in two series o f acid waste concentrations: one series consisted of concentrations of l0 -'~, l0 -s, l0 -~ by volume of unfiltered acidwaste and the other series consisted of the same concentrations o f filtered acid-waste. For filtration a 0.8 ~m membrane filter was used. Control animals were kept in seawater from Woods Hole Harbor. A second experiment was undertaken using two ovigerous P. coronatus in each o f 4 culture dishes containing 10 -4 concentration of filtered acidwaste. The cultures were maintained at 18°C and fed lsocrysis galbana and Cyclotella nana daily. They were examined generally every day and the condition o f the adults recorded, the presence o f nauplii and copepodids noted and their number estimated. RESULTS

Hydrography and primary production measurements The dominant hydrographic feature in the area was a very intense thermocline which was maintained by an upper layer of brackish warm water and a lower layer of more saline cold water. The transition zonewas located between 9 and 15 m. The surface waters in the acid grounds were slightly lower in salinity (28.73-30.14 per cent) than those in the control area (29.99-30.82 per cent). At a depth of 20 m the water was more saline and less variable (30.14-31.44 per cent) (TABLE 1). Horizontally, the maximum variations in termperature in acid and control areas amounted to 3°C at the surface (17-20°C) and only 2 degrees (7-9°C) at the 20-m level (TABLE l).

Distribution of Standing Crops in the New York Bight TABLE 1. HYDRO(3RAPHIC AND PARTICULATE IRON DATA. STATIONS GROUNDS; 22-37, CONTROL AREA

Station No. 1

237

1-16, ACID

Depth Temperature Salinity Dissolved Oz Particulate Fe (m) (°C) (~'oo) (ml 1-1) (/~g 1-1)

1 18.8 29.07 20 7.7 30.99 2 1 19.5 30.07 20 8.1 31.23 3 1 17.6 28.73 20 7.6 31.44 4 l 20.1 29.73 20 8.0 31.33 5 1 20.2 30.12 20 8.5 31.13 6 1 19.9 30.14 20 9.2 31.02 7 1 20.0 29.69 20 8.0 31.15 8 1 20. l 29.33 20 7.8 31.06 15 l 20.3 29.87 20 8.4 31.05 16 1 20.1 29.96 20 8.2 31.01 22 1 18.5 29.99 20 9.0 31.20 23 1 19.0 29.99 20 9.3 31.17 30 1 16.5 30.35 20 9.0 31.08 31 I 17.2 30. 82 20 9.9 30.14 32 1 16.9 30.27 20 10.9 30.82 33 1 17.8 30.15 20 9.3 30.56 34 1 17.5 30.28 20 9.0 31.22 35 1 17.7 30.27 20 8.1 31.08 36 1 18.3 30.09 20 8.4 31.12 37 1 19.0 29.99 20 7.7 30.98 Sample of opportunity, red surface water

7.13 5.38 5.88 6.12 7.30 5.68 6.00 5.97 5.61 5.99 5.74 6.36 5.98 6.04 6.02 6.71 5.85 6.73 5.79 6.71 5.90 5.58 5.88 4.90 5.98 7.00 5.86 5.31 5.95 5.35 5.81 5.63 5.85 5.38 5.89 5.82 5.77 5.29 5.78 5.72

30 53 11 22 32 68 13 26 10 18 21 4 14 17 16 9 21 14 12 7 13 13 14 26 15 21 16 19 12 31 15 12 11 28 9 10 22 20 20 17 832

T w o divers m a d e in situ o b s e r v a t i o n s o f the water c o l u m n a n d the b o t t o m at station 3 (Fro. 1) at a b o u t 1800 h o n 28 June. The surface o f the 23 m water c o l u m n was colored light b r o w n a n d provided a visibility o f a b o u t 3 m. A m u r k y green layer, 1 - ! . 5 m in thickness, e n c o u n t e r e d at 9 m, restricted lateral visibility to a b o u t 1 m. I m m e d i a t e l y below 9 m the water b e c a m e b r o w n again a n d the visibility i m p r o v e d slightly. A t a depth o f 15 m there was n o visible light p e n e t r a t i o n yet the water was quite t r a n s p a r e n t a n d the visibility range, m e a s u r e d h o r i z o n t a l l y b y flashlight, reached 4.5-6.0 m. A t the diving site the t e m p e r a t u r e s were 17°C at the surface, 15°C

238

RALPH F. VACCARO, GEORGE D. GRIC~, GILBERTT. Row~ and PETER H. WIEBE

at the top of the discontinuity layer at about 9 m, and 9°C between 9.5 m and the bottom. The location of the murky green layer at a depth of 9 m is thought to be due to an accumulation of incompletely oxidized metal hydroxides, the sinking of which was being retarded by a rapidly changing density structure. A limited laboratory study showed that the high degree of stratification, characteristic of summer shelf water in the New York Bight is capable of retarding the sinking of small but settleabl¢ particles such as precipitated iron floc. The divers also reported that the bottom was fine sand and silt, and above it was a flocculent, brown particulate material which also collected in the troughs of bottom sediment ripples. Although no bottom current was observed, the asymmetry of the ripple marks indicated that currents when active flowed to the north.

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FIG. 2 A - D . Distribution of oxygen, chlorophyll a, particulate iron and zooplankton in the New York Bight, 25-29 June, 1970. A. Surface oxygen; B. Mean of surface and 20 m values; C. Mean of surface and 20 m values, except for single surface sample at station of opportunity which exceeded 800/~g l-Z; D. Mean of combined day and night values.

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Distribution of Standing Crops in the New York Bight

239

The oxygen content of the surface water in terms of per cent saturation is shown in FIG. 2 A. Values in excess of 100 per cent are characteristic throughout the area with a maximum value of 130 per cent in the vicinity of stations 1 and 3. Except for a single observation (station 30, control grid), the water at 20 m was undersaturated with respect to oxygen but in no instance did any value fall below the 74 per cent recorded for station 23 in the control grid. Horizontally the surface distribution of oxygen showed a strong positive gradient which was generally oriented in a northerly direction across the acid disposal area. The surface distribution of chlorophyll a (FIG. 2 B) suggests that a dense phytoplankton population (as high as 80 mg chlorophyll a m -a) was centered northwest of the disposal area near the head of Hudson Gorge. Apparently, an unusually high rate of photosynthetic activity by the resident plant population was primarily responsible for the oxygen saturation pattern observed in and around the disposal area. The maintenance of a given population of planktonic algae depends upon a favorable balance between their nutrient requirements and the rate at which essential elements become available. To evaluate the status of plant nutrient reserves, the residual concentrations of available nitrogen and phosphorus were also measured. The results showed that neither of these elements was limiting plant growth at the time of sampling since they were present in adequate concentrations. The available nitrogen (combined as ammonia, nitrite, and nitrate) ranged from 28 to 70/zg N 1-1 and phosphorus (as phosphate) ranged from 9.3 to 24.8/~g P l -I. The original hydrographic and chemical data have been deposited in the Woods Hole Oceanographic Institution Reference Library and copies are available from the authors.

Soluble and particulate iron distribution As one of the more prominent and traceable chemical components of the acid-iron liquor, iron provides a useful means of determining the fate of this material within the study area. Only about 10-20 per cent of the iron measured in the New York Bight was in true solution or occurred as panicles less than 1 /~m in diameter while the remaining iron fraction was in the form of particulate matter. The amount of iron at 20 m was generally higher than at the surface although at both depths the relative horizontal changes in concentration were similar (TAaLr 1). We have used average total iron concentrations for our surface and 20 m analyses to give a synoptic picture of the iron distribution observed during the daylight hours of 26--28 June (FIG. 2 C). Exclusive of the sample of opportunity, the two highest iron concentrations (53, 68 ~g 1-1) on the acid grounds were measured at stations 1 and 3. These stations are located about 5 km north of the summer dispersal area. From here the concentrations of iron decreased both in a southerly and easterly direction so that at a distance of 10-20 km from the center of dispersal the iron concentrations were uniformily less than 25/zg 1-1. The maximum particulate iron concentration measured during this study (a sample of opportunity) was actually 832/~g 1-1 near the northeast edge of the acid plume where large amounts of brown flocculent material were visible. Apparently this discoloration developed after the release of waste material from a dispersal operation on June 28. A comparison of the above value with the iron concentration (3.3 per cent) which was measured in a sample of concentrated acid-iron liquor from the titanium

335,000 83 520 120 140 190 55 3

6800 970 31---0 47 110 780 53 17

22,000 240 390 ! 2--O 120 120 __ 69 2. I

2900 230 150 29 35 52 i6 __ 2.6

Ashed benthos Control Acid-iron grid grid Sta. 2 Sta. 3 Sta. 35

52,500 < 0.5 25 5 5 7 4 --

5600 2 !0 160 170 130 25 34 3.2

Hudson Gorge Sta. 19

830 49 560 2--6 I-T 12 -9 3.8

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3100 I. 5 10 3 6 0.6 1.3 0.2

Sta. 2

867 5--2.3 377 20 103 9.3 9 2.1

Acid-iron grid Sta. 3++

12,500 15 41 37 34 5.5 8.2 1.3

130 19 210 7 6 6 5 1.6

Control grid Sta. 33 260 39 352 7 8 6 7 2.7

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5900 4.7 12 8 8 1.5 2.2 0.2

8400 4.2 93 6 10 1.8 3.6 0.2

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2200 3.0 9 2 5 0.6 ! .2 0. !

3200 0.7 5 13 6 0.7 1.3 0.3

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Sediment ash (HCI leachable)

380 40 380 10 12 ~ 9 1.6

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120 42 290 8 7 12 1-2" 1.4

Sta. 10

Dried zooplankton

* The machine precision of each value was less than or equal to 10 per cent. t Prepared by adding raw effluent to seawater and filtering and drying the resulting precipitate. ++These are mean values of 3 separate analyses performed on the sample from Station 3. § The oceanic zooplankton sample was collected on Atlantis II, Cruise 52, Station 1541 (37 ° 02' N) 74 ° 27' W).

Fe Cu Zn Pb Cr Co Ni Cd

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Fe Cu Zn Pb Cr Co Ni Cd

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Acid-iron waste Raw Seawatert effluent ppt. dried

31)300 ~83 170 1 !--'O 130 17 ! _1 2.__ 3

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730 20 180 13 6 9 10 2.1

Oceanic§ Sta. 1541

TABLE 2. TRACE METAL CONCENTRATIONS IN ACID WASTE) SEAWATER PRECIPITATE, ZOOPLANKTON, BENTHOS, AND SEDIMENT IN p p m . THE MAXIMUM VALUE IN EACH SEPARATE DATA SET i.e., ZOOPLANKTON) BENTHOS, AND SEDIMENT, IS UNDERLINED

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Distribution of Standing Crops in the New York Bight

241

plant in Sayreville gave a dilution of 1:39,000 for the mixture of acid waste with seawater. Iron and other trace metals in the biota and sediment

When acid-iron waste mixes with seawater there is a selective precipitation of metals which is related to the solubility of individual metals at the resulting oxidation potential and hydrogen iron concentration (TABLE 2). Essentially all of the added iron precipitates and there is an additional enrichment of the seawater precipitate with respect to lead, copper, zinc, chromium, cobalt, nickel, and cadmium. The Fe that precipitates in the discharge area (up to 832 t~g 1-1) appears to affect the iron concentration of zooplankton less than that of benthos and sediment (TABLE2). Our sample of zooplankton from the slope water (collected from 120 km south of the acid grounds on Atlantis H Cruise 52, 37° 02' N 74 ° 27' W) contained about the same amount of Fe as two of the three samples from the acid grounds. Of the remaining seven metals, Cu, Zn, Pb, Cr, and Co were higher in the zooplankton of the acid grounds (TABLE2). The benthos of the acid grounds appeared to be higher in all eight metals as compared to the control area. In relation to the control area the benthos of the Hudson Gorge was richer in all metals excepting Co. Acid grounds sediment as compared to that of the control was particularly high in Fe, Zn, Cr, and Ni but all eight elements were much more highly concentrated in the sediments of the Hudson Gorge than in either of the other two areas. Comparing maximum values, the metal concentrations measured in zooplankton, benthos and sediment from the acid grounds exceeded those in the control area in every instance excepting one (Cr in zooplankton from the control area). When samples of benthos and sediment from the Hudson Gorge are included, maximum concentrations of Pb and Cr were found in benthos from the Gorge, but highest values for all eight trace metals were in the Hudson Gorge sediment. Zooplankton

Displacement volumes, dry weights and Fe: C ratios measured for each zooplankton haul from the acid and control grid stations are given in TABLE3. The distribution of mean day-night zooplankton dry weights are shown in FIG. 2 D. The range of dry weights in the acid grounds was 0.08-0.32 g m -a and the range in the control area was 0.09-0.33 g m -a. A two-way analysis of variance was used to test the difference in mean zooplankton biomass between the two areas and the difference between the mean day and night observations (TABLE4). The average zooplankton abundance at the control grid stations significantly exceeded that of the acid grid stations by about 30 per cent, both in terms of dry weight (p < 0.05) and displacement volume (0.10 > p > 0.05). The overall average daytime concentration of zooplankton did not differ significantly from the average night-time concentration (p > 0.10). However, the average night-time biomass (dry wt.) on the acid ground was 43 per cent greater than the average day value, while the control area showed a night-time increase of only 7 per cent. Apparently the larger relative increase in zooplankton abundance at night within the acid area played an important role in minimizing the difference in overall biomass between the two areas. The dry weight (0.10 g m -a) of the zooplankton collection obtained off Martha's

242

RALPH F. VACCARO,GEORGE D. GRICE, GILBERT T. ROWE and PETER H. WIEBE TABLE 3. ZOOPLANKTONDATAFROMSURFACETO BOTTOMOBLIQUE NET HAULS. STATIONS 1-16, ACID GROUNDS, 22--37, CONTROL AREA

Displ. vol. (cm3m -3)

Dry wt. ( g m -3)

F e : C ratio

1150 1233 1500 1635 1740 1855 1948 2030 2215 2305 2345 0026 0115 0155 0305 0400 2135 2240 2312 2348 0046 0120 0200 0250 0820 0945 1120 1224 1350 1445 1532 1635

0.673 1.030 0,860 0.849 0.571 0.730 0.585 1.062 2.094 1.397 1.529 1.142 0,830 0.673 1.303 0.658 0.677 0.812 0.991 1.084 1.159 2.062 1.669 1.694 0.924 1.531 1.341 1.021 0.894 0.729 1.491 2.532

0.22 0.12 0.12 0,11 0,11 0,11 0,08 0,15 0.32 0,23 0.22 0.17 0.12 0.10 0.20 0.08 0.09 0.14 0.17 0.18 0.25 0.33 0.29 0.25 O.15 0.24 0.22 0.16 0.15 0.16 0.20 0.32

0,0010 0.0009 0.0004 0.0004 0.0004 0.0004 0.0003 0.0004 0.0006 0.0007 0,0013 0.0005 0.0004 0.0002 0.0004 0.0003 0.0004 0.0003 0.0006 0.0004 0.0004 0.0005 0.0004 0.0006 0.0003 0.0003 0.0004 0.0002 0.0003 0.0002 0.0004 0.0004

1400

--

0.10

Station Timeofday 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

Martha's Vineyard

0.0005

Vineyard Island, an area removed from waste disposal activities, was less than the average values of either the acid grounds or the control areas, but was within the range of values found at each of these locations. The ratio of iron to carbon (Fe:C) in dried zooplankton has been used to evaluate the relative amount of iron present in each zooplankton haul. A contour plot showing the average distribution of Fe: C from combined day and night samples is shown in FXG. 3 A. The highest values (both day and night data), observed at the northern most stations of the acid grounds (stations I, 2, 9, 10, 11), differed from the minimum observed Fe:C value by as much as a factor of 6.5. In other instances, the iron content of acid grid zooplankton did not exceed that found in the control area or the Martha's Vineyard sample. Significantly, however, the locations where the plankton were richest in iron were closest to the track of a barge observed discharging wastes while

Distribution of Standing Crops in the New York Bight TABLE4.

243

M E A N VALUES OF Z O O P L A N K T O N BIOMASS CALCULATED FOR AREAS A N D TIME o r DAY, AND BENTHOS NUMBERS AND BIOMASS CALCULATED FOR AREAS

Biomass estimate Zooplankton : Displacement volume (crna m -a) Dry weight (g m -a) Acid grounds Control area Benthos: Numbers of benthonts m- 2 Ash-free dry weight (g m-2) With large echinoderms Without large echinoderms

Acid grounds vs. control*

0.999-1.288t 0.155-0.206+~

Day vs. night Day vs. night (both areas, 16 (separate areas, 8 samples/mean) samples/mean)

1.051-1.236 0.163-0.198 0.128-0.182t 0.199-0.213

1694-2984** 11.4-16.8 1.4-1.6

* Zooplankton: combined day and night samples, 16 samples per mean. Benthos: 8 samples per mean. t Probability of difference between means 0.10 > p > 0.05. $ Probability of difference between means p < 0.05. the survey was underway and moreover the water was greener and more opaque than at other stations. A regression analysis o f the daytime Fe: C vs. particulate iron in the surrounding seawater shows that a positive relationship exists between these two variables (0.10 > p > 0.05). This relation accounts for the general similarity between the distribution patterns describing particulate iron (Fro. 2 C) and that describing the F e : C values (FIG. 3 A). We do not know whether this trend reflects true biological uptake or the fortuitous adherence o f iron particles on the external body covering, spines, and setae o f zooplankton.

Benthos The average number o f animals on the b o t t o m of the control area was significantly higher (p < 0.05) than on the acid grounds (TABLES 4 and 5). However, the biomass expressed as ash-free dry weight (TABLE 5 and Fro. 3 B), was essentially the same on the two areas regardless o f whether the total biomass was compared with or without large echinoderms which were the dominant element in terms of biomass contribution at a number o f stations. In addition there was little difference in species diversity, as measured by the Shannon-Wiener index, between the acid grounds [H(s) = 2.08] and control area [ H ( s ) = 2.13]. The average ratio of iron to carbon (FIG. 3 C) in the benthos was greater in the acid grounds (0.018) than in the control (0.011), although both o f these were far below the average (0.060 o f the two Hudson Gorge samples (stations 19 and 39) or the single value from the sewage sludge dumping ground (0.0967). The high value, however, located near the sludge area (station 1504), m a y not be strictly comparable to the others because the animals were large epibenthic species taken with a b o t t o m trawl, rather than the relatively small, infaunal species taken with the grab at all of the other locations.

244

RALPHF. VACCARO,GEORGED. GRICE,GILBERTT. ROWEand PETERH. WIEBE

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Comparison of Fo: C in benthos with total iron in the sediment (TABLE 5, FIGS. 3 C and 3 D) indicates that a strong positive relationship (which is greatly influenced by stations 3, 19, and 39) exists between the two. The higher the concentration of iron in the sediments, the more is incorporated into the animal. It is unlikely that this relationship represents the fortuitous adherence o f iron floc to the organisms as was mentioned for zooplankton because the benthic animals were sieved and individually picked from the sediment. Presumably any adhered iron would have been removed by such handling. At the three stations cited above where high Fe: C ratios and high iron concentrations in the sediment occurred, there was no indication o f adverse effects on the benthic populations. The density o f organisms and the biomass at these stations were high.

Distribution of Standing Crops in the New York Bight

245

TABLE 5. DATA FOR BENTHOS AND SEDIMENT. STATIONS 1-8, ACID GROUNDS; 30-37, CONTROL AREA. SEE FIG. 1 FOR OTHER STATION LOCATIONS

Fe:C ratio

Sediment organic matter % loss on combustion

2.1

0.0026

0.50

0.175

0.18

2.5 -2.1 1.7 2.2 1.9 -2.1

0.44 1.21 0.75 0.52 0.92 0.56 1.42 1.48

0.108 0.422 0.182 0.126 0.058 0.116 0.124 0.330

0.11 0.42 0.18 0.13 0.06 0.12 0.12 0.30

--

0.0075 0.0490 0.0090 0.0199 0.0240 0.0260 0.0056 -(0.0100)* --

0.63

0.136

0.10

1.8

0.0049

3.28

0.119

0.10

1.9 2.1 2.0

0.0079 0.0045 0.0252

0.33 0.58 0.35

0.204 0.071 0.047

0.20 0.07 0.05

0.0022 0.0215 m 0.0820

0.68 1.06 32.26 26.44 0.90 . 5.54 1.96 0.52 3.65 . 3.05 --

0.214 0.113 0.947 0.832 0.217

0.21 0.11 0.64 0.61 0.22

0.181 0.127 0.209

0.32 0.18 0.13 0.20

Biomass ash-free Density dry wt. Diversity Station (No m - 2 ) (g m - 2) [H(s)]

1

1100

2 3 4 5 6 7 8 30

1425 3025 2100 1025 1625 2275 975 2574

31

2425

32

3975

33 34 35

1500 2775 5050

80.38 (0.63)* 1.48 3.25 2.60 0.60 0.68 1.38 0.50 15.1 (1.5)* 8.63 (1.63)* 9.63 (2.18)* 0.88 1.75 94.35

Fe % Fe % dry wt. of dry ash sediment

(0.48)* 36 37 18 19 20t 21 39 17 38 40 41 42 1504~

2200 3375 4650 59,450

2.95 1.50 -15.67

2.9 m m ~

65,800 14,625 17505 900 1225 2700 160,750 704

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0.20

* Parenthetical values are less large echinoderms. t Wall of canyon, sand and gravel substrate. ** An estimate for the first grab sample was 103,000 animals m -2. § Sample collected on Atlantis II, Cruise 52, September 9, 1969. II Estimate from trawl sample.

Phytoplankton and copepod laboratory studies The phytoplankton development experiment failed to demonstrate any significant effect o n p h y t o p l a n k t o n g r o w t h b y a 1 : 10,000 d i l u t i o n o f a c i d w a s t e . A f t e r 12 d a y s b o t h t h e a c i d w a s t e c u l t u r e a n d t h e c o n t r o l s h o w e d a n i n c r e a s e i n cell n u m b e r s w h i c h approximated one order of magnitude with no apparent change in species diversity. The changes in chlorophyll a and particulate carbon are consistent with the above r e s u l t s a n d a r e s h o w n i n FIG. 4.

246

RALPHF. VACCARO,GEORGED. GRICE,GILBERTT. ROWEand P~rERH. WIEBE

I x 10 5

I

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I

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Cellular

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I ~ 10 4

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acid waste in seawater. There appeared to be no effect on survival of the eggs or development of the copepod Pseudodiaptomus coronatus in cultures with acid waste concentrations of 10 -5 and 10 -~ by volume. At these concentrations the developmental period from egg to adult in unfiltered and filtered waste was 13-14 days and in the seawater control (Woods Hole Harbor water) it was 13 days. In the same experiment but in a 10-4 concentration the eggs failed to hatch, there was high mortality of nauplii, or the development time from eggs to adult was prolonged relative to the control. Because nauplii and adults were observed to have accumulations of iron floc on their exoskeletons and appendages, filtered acid waste was used in another series of experiments in which mortality and development time was compared in each of four 10-4 concentrations of acid waste and a control (TAaL~. 6). In two of these cultures (A, B) no copepods reached the adult stage and in the other two (C, D) development time was prolonged from 3 to 7 days relative to the time required to reach comparable stages in Woods Hole Harbour control. DISCUSSION To isolate the effects of a particular type of pollutant is difficult when substantial quantities of industrial and domestic wastes are deposited in close proximity to one another as illustrated in FIG. 1. In addition to barged wastes, the Hudson River also brings large quantities of iron (Kzrcntr~ et al., 1951) and nutrients (partially treated domestic sewage) into the New York Bight (RYTHERand DUNSTAN, 1971). The flushing time of the New York Bight is of primary importance in influencing the distribution and particularly the concentrations of water-borne pollutants. This time can be expected to vary seasonally since river discharge, tidal currents, non-tidal drift and wind induced turbulence can all affect the movement and mixing of shelf water and sediment, especially in winter when these waters may not be so strongly stratified as they are in summer. The flushing time has been estimated for the New York

Distribution of Standing Crops in the New York Bight

247

TABLE 6. DEVELOPMENT TIMES FOR Pseudodioptomus coronatus IN WOODS HOLE HARBOR WATER WITH AND WITHOUT A 1:10,000 DILUTION OF FILTERED ACID-IRON WASTE. TEMPERATURE, 1 8 ° C , p H = 7.6

(1:10,000); 7.9 (HARBORWATER) Duration of exposure, days Acid-iron waste cultures Stage of development Eggs to copepodid Eggs to adult Eggs to second generation nauplii Experiment terminated

A > 21" >21" >21" 21

B 13 >21" >21" 21

C

D

Harbor water controlt

8 15 17 21

11 18 21 21

9 11-13 14-15 15

* Naupliar stages failed to reach copepodid stages or copepodid stages failed to reach adult. 1"Based on 7 experiments, not run concurrently.

Bight by KETCHUM et al. (1951) and by REDFIELD and WALFORD (1951) as 6-10 days based on the measured accumulation o f river water and as 8-14 days based on the measured accumulation o f iron in the greater New York Bight area in relation to iron contribution from river discharge. The variety o f waste sources which enter the New York Bight and the uncertainty regarding the relative importance o f the processes affecting their distribution complicate the interpretation o f our biological survey results in several ways. F o r example, high nutrient contributions f r o m one area may be reflected in large phytoplankton and zooplankton populations in areas distantly removed from the site o f nutrient enrichment. Since plankton populations are transitory their advection through polluted areas may be so swift that they are little affected by local toxic conditions or the effects are not manifested until populations are away from the site. Benthic animals on the other hand are less motile and thus m a y be seriously affected by extensive waste disposal in restricted areas as has been discussed by PEARCE (1970) for animals in the sewage sludge and dredge spoil areas o f the New Y o r k Bight. The addition o f large quantities of sulfuric acid and iron wastes in the form of ferrous and non-ferrous metals into a restricted area o f the New York Bight, the acid grounds, may be expected to have measurable local effects on the ecology o f the area. Our synoptic sampling was planned to detect alterations in the biota of the acid grounds which could be attributable to the discharge of approximately 50 million tons o f acid waste over a period of 22 yr. We have been unable to detect major effects of acid-iron waste on the sediment and biotas o f the region~ although we have indications in our observations o f possible minor effects o f this waste. Iron accumulation in sediment

In 1950 the daily discharge o f iron at the disposal site amounted to 150 metric tons. There was an additional 50 tons per day entering the New York Bight from adjacent river systems. According to RF~FIELD and WALFORD (1951), 2 yr after the inception of offshore barging in 1948 the iron concentration in the Raritan River decreased from 2000 to 150/~g 1-1. At that time it was recognized that the success o f barging as a

RALPh F. VACCARO,GEORGE D. GgICE, GILBERT T. ROWE and P~ER H. W~BE

248

pollution control technique depended upon the extent of the concomitant changes in the quality of the offshore receiving waters and sediments. Addressing themselves to this question, the above authors concluded that by 1950 there had been no undue accumulation of iron in the water column or sediments and that the amount of iron present corresponded to the combined contributions from barging and riverflow over an 8-14 day period. A later study by CORWINand KETCHUM(1956) corroborated these results insofar as they too were unable to correlate iron enrichment of the sediments with iron disposal at the surface. Industrial expansion has now led to a 60 per cent increase in the rate of barging activity as compared with 1950. Assuming no significant change in river input, the total flux of iron from these two sources entering the Bight is about 300 tons per day. Once again, however, there is no clear indication that enhanced disposal activity has caused a significant built-up of iron within the sediments immediately below the acid grounds. When the results of our present study (TABLE7) are compared with those of REDFIELDand WALFORD(1951) and COgWlN and K~cmyM (1956) it would appear that iron concentrations may have declined slightly during the past 14 yr. However, as is often true, comparisons of absolute values on a chronological basis can be influenced from differences in analytical techniques (see footnotes, TABLE7). At the same time a general relative agreement within these studies is apparent since the highest concentrations of iron consistently occur in the soft sediments of the Hudson Gorge which TXel~ 7. IRON CONTENT IN COMBUSTED SEDIMENT SAMPLF~ COLLECTED FROM THE NEW YORK BIGHT

Date

Place

October 1956 Acid grounds

No. samples

Iron content as Fe, % ash Max. Min. Avg.

18"

0.38

0.21

0.38

Acid grounds Control area Hudson Gorge

8 8 2

0.42 0.33 0.95

0.06 0.05 0.62

0.16 0.15 0.78

October 1956 Hudson Gorge

2

2.15

0.82

1.48

June 1970

2

0.95

0.83

0.89

June 1970 June 1970 May 1948

Reference CORW~ AND ICs'rCHUM (1956)1" This study** This study++ REDFIELDand WALFORD

(1951)t Hudson Gorge

CORWZNand K~xcmnu (1956)I" This study++

* Excludes one diver collected sample of black ooze (Fe concentration of 3.13 per cent). t Used multiple extractions in 6 N HCI at room temperature. ++Used single extraction with 5 N HCI at 100°C for 15 rain.

contain about 10 times more organic material than the coarser sediments of the acid and control grid areas. Thus the distribution of iron on the seabottom still appears to be regulated by natural phenomena. These favor an accumulation of fine sediments in the gorge which in this case are notably rich in organic carbon as well as iron. Failure to measure a marked difference of iron accumulation in the disposal area from that reported by R~DnELD and WALFORD(1951) and CORWIN and KETCHUM(1956) indicates the flushing times cited earlier in this discussion have not changed appreciably.

Distribution of Standing Crops in the New York Bight

249

Affects of acid wastes on biotas The oxygen required to oxidize ferrous to ferric iron in seawater was investigated by KETCHUMand FORD(1948) and found to be negligible. Actually, our data show that the dissolved oxygen concentration of the water of the acid grounds is higher than that of the control area (FIG. 2 A). Surface waters were supersaturated throughout the survey area and the saturation of the water at 20 m was not less than 74 per cent. Likewise there was little difference observed in the distribution of available nitrogen and phosphorus on the acid and control area, and our overall impression is that the concentration levels of these elements were actually somewhat higher than the typical summer concentrations over the Atlantic continental shelf (VACCARO,1963). There were distinctly greater concentrations of chlorophyll a in the northern portion of the acid ground than elsewhere in the area (FIG. 2 B). It appears that significant amounts of available nitrogen and phosphorus, probably from a nearby source, were responsible for the high level ofphytoplankton activity. A laboratory toxicity test failed to demonstrate adverse effects of acid-iron waste on phytoplankton at a concentration four times greater than the highest concentration measured on the acid grounds (FIG. 4). The smaller average zooplankton concentration on the acid grounds as compared to the control area is not readily explained (FIG. 2 D). Although the laboratory toxicity studies indicated the acid-iron wastes when highly concentrated could prolong or inhibit copepod development if the exposure time was sufficient (TABLE6), concentrations of 10-* usually exist only immediately behind the discharging barge and then for short periods of time (KETCHUM and FORD, 1952). The possibility that the raw acid waste with a pH of 1.5-2.0 could cause an instantaneous mortality of a variety of zooplankton as it enters seawater from the discharge barge was investigated by REDFXELDand WALFORD(1951) and found to be negligible. Even if there was substantial mortality of preadult copepods it would not be evident in our biomass data as the net mesh size used did not quantitatively sample the smaller developmental stages of copepods. Adult copepods were volumetrically the most important element of the zooplankton. Thus, the present evidence suggests there is no direct link between the lower biomass on the acid grounds and the discharge of acid wastes. We have considered two alternate explanations. First, the observed 30 per cent difference in biomass between these two areas may be a transitory manifestation of a large scale patchiness in the New York Bight arising from natural processes or from agents introduced elsewhere. In fact lower zooplankton volumes were measured in the southern section of the acid grounds several km from the observed area of active waste discharge (Fro. 2 D). A second, but we feel less likely alternative is that the difference is due to sampling error. While the error associated with a single haul may be as high as a factor of 5 (WIEBE and HOLLAND, 1968), the trend is based on 16 tows from each area and the probability is small that a cumulative sampling error is the cause.

Although the numerical abundance of benthic animals was measurably lower in the acid ground than in the control area, we have no evidence that this difference is related to acid waste discharge. Actually the benthic fauna of the acid grounds is far from being depauperate, and the fact that no significant differences in biomass (TABLE 4) or species diversity (TABLE 5) were detected suggests that the effects of acid waste on numerical abundance, if any, are minimal. We realize that the larger epibenthic organisms have not been adequately sampled or their abundances properly estimated, W.R.6/3---<:

250

RALPHF. VACCARO,GEOROED. G~CE, GILBERTT. ROWEand PETERH. WmsE

a situation that is common to most benthic investigations. In their attempt to make estimates of the larger components of the benthic fauna on the acid grounds and an adjacent area, ARNOLD and ROYCE (1950) used bottom photography. These authors also collected grab samples and from these made estimates of the density of the smaller organisms in the acid grounds. They were unable to detect effects which could be related to the discharge of acid waste. Unfortunately, we are unable to compare our estimates of abundance with theirs because they did not state the sieve size through which the sediment was washed. A parallel relationship is evident in the incorporation of iron (based on colorimetric analyses) onto or in the zooplankton and benthos as reflected in the iron to carbon ratio. Both biotas showed highest ratios where iron in the environment was highest. In the case of zooplankton, highest particulate iron in seawater and Fe: C in zooplankton occurred at stations located in the northern section of the acid grounds, an area where the discharge of acid-iron waste was observed during the study. High iron concentrations in the benthos and sediment were also measured at the northern part of the acid grounds, but the highest concentrations occurred in the Hudson Gorge. Significantly, the Fe: C ratios in benthos (TABLE5) were on the average 40 times greater than in zooplankton (TABLE3), a fact that may reflect the relatively rapid movement of zooplankton populations through the area. We are aware of the lack of agreement between the iron concentrations measured by colorimetry (TABLE 5) and by atomic absorption (FIG. 2). This is in part due to methodology and in part to the different extraction procedures used to leach soluble iron.

Heavy metal distributions Besides iron, the distribution ofCu, Zn, Pb, Cr, Co. Ni and Cd was also measured in a limited number of zooplankton, benthic and sediment samples (TABLE 2). For zooplankton, only data on the acid ground and the control grid populations were collected in the New York Bight, but for the benthic and sediment samples, an expanded comparison involving Hudson Gorge material is possible. As previously noted, the comparison of acid grid with control grid zooplankton has shown that with the exception of Cr the highest concentrations of these metals consistently occurred in the acid ground population. A similar comparison of the metal content of benthic organisms from the same two areas showed that all eight metals also attained maximum concentrations in the acid ground fauna. When the benthic data from Hudson Gorge are also included, six of the eight metals were again more abundant in organisms from the acid grounds, with only Pb and Cr being more concentrated in the benthos of the gorge. However, Hudson Gorge sediment was by far the richest in all seven metals when compared with the other two areas. This suggests that the relatively higher organic fraction in the gorge sediment may cause chemical binding of metallic elements in a manner which limits or retards the entry of metals into the biochemical cycle. It should also be emphasized that although the zooplankton, benthos and sediment of the acid grounds tend to have higher concentrations of Fe and other heavy metals, the observed difference is hardly dramatic. The largest individual difference is no more than a factor of 5 and in some instances no difference or even a reverse trend is evident. Organisms react in a variety of ways to heavy metals in the environment, frequently accumulating them within the body tissues. Useful generalizations on the relationships

Distribution of Standing Crops in the New York Bight

251

are rarely possible because of a lack of definitive background information (BRYAN, 1971). On the basis of our data, we have endeavored to determine whether the concentrations of various heavy metals vary systematically with respect to the amount of Fe present in various samples. For this comparison, we have expressed the data as atomic ratios relative to Fe, which is arbitrarily set at a 100 atoms in each sample. These ratios are presented in TABLE 8, which shows the total Fe content and the atomic abundance relative to Fe of other metals in various possible sources and in samples of zooplankton, benthos and sediment from the New York Bight. The possible sources of Fe and other heavy metals in TAnLE 8 include a dried seawater precipitate of the acid-iron waste, an analysis of the acid-iron waste (raw effluent), dried sewage sludge, settled sewage supernatant, and seawater. The acid-iron waste, as would be expected, contains the greatest absolute abundance of Fe. As a consequence, the relative abundance of the other heavy metals is very low when compared to any of the other possible sources, including seawater. Although the acid-iron waste disposal unquestionably contributes the greatest amount of Fe to this area, the contribution of other metals from sewage sludge, which is dumped within a few miles of the acid-iron grid (FIG. 1), or from sewer effluents which reach the area via the Hudson estuary may be more important than their addition in the acid-iron waste. Comparison of the analyses of organisms and sediments collected in the acid-iron grid with those collected in the control area can be used to give a first approximation of the combined effects of (a) various sources of heavy metals and (b) of different responses of the organisms or sediments to their presence. Two simplifying assumptions, representing extreme cases, can be made in order to evaluate, in a qualitative way, the importance of these two effects. One assumption is that Fe is the only significant heavy metal added to the environment in the acid-iron grid area. The other assumption is that the heavy metal pollution of both the acid-iron grid and the control area are o f different amounts but of identical relative composition. If it is assumed that Fe is the only addition to the acid-iron grid environment, all other metals would remain constant; hence their abundance relative to Fe would decrease. If the acid-iron waste were the only source of heavy metal pollution, the addition of other metals would be negligible, since this waste contributes less than 1 atom of Mn for every 100 atoms of Fe, and for all of the other heavy metals measured, less than 1 atom of the metal for every 2000 atoms of iron. Samples collected in the acid-iron area typically contained higher amounts of Fe than comparable samples collected in the control area (TABL~ 2 and 8). The Fe ratios vary from about 3 for zooplankton or sediment samples to about 7.5 for benthos in these two areas. On the basis of the above assumption, these increases in Fe would result in a relative dilution of the other heavy metal atoms. Thus, increasing the Fe content in the acid-iron grid by a factor of 3 when compared to the control area, as was found for zooplankton or sediments, would give an expected ratio for the other heavy metals of 1/3 in the acid-grid area. For the zooplankton data, only Cr gives the expected ratio of 0.33; the other ratios range from 0.38 for Zn to 0.75 for Pb. Thus, with the exception of Cr, the other elements must either have been contributed to the environment from other sources or accumulated by the organism at high levels relative to iron. The sequence of the ratios comparing atomic abundances in zooplankton in the acid-iron grid and the control areas was: Fe > Pb > Co > Cu > Ni > Zn > Cd > Cr.

7450

2700 31,300

Sediment Acid-iron grid*

Centre lgrid* Hudson Gorge

100 100

100

100 100 100

100

100 100

100

100

100

100 100

Fe

---

--

----

--

m --

25.0

46.7

6.66

0.99 --

Mn

0.076 0.096

0.052

0.146 0.272 0.825

0.480

0.632 0.844

0.271

m

2.71

0.004 0.010

Pb

0.023 0.052

0.030

0.519 1.710 0.426

1.17

1.11 2.23

4.76

11.2

--

0.021 0.054

Co

0.225 0.461

0.449

1.53 447 2.48

21.2

40.6 105.4

54.1

241 .I

70.0

0.067 0.137

Zn

0.216 0.449

0.205

0.59 1.30 2.50

0.88

1.26 3.78

27.0

16.2

24.3

0.016 0.045

Cr

7.14

0.011 0.015

Ni

0.039 0.033

0.048

0.298 0.520 0.580

1.30

! .11 2.59

59.5

23.8

* Means of samples from indicated stations. 3"Oceanic zooplankton sample collected on Atlantis H, Cruise 52, Station 1541 (37 ° 02' N, 74 ° 27" W).

22,000 2900 5600

730

848 257

0.008

18,600

Benthos Acid-iron grid Control grid Hudson Gorge

Oceanict

Zooplankton Acid-iron grid* Control grid*

Seawater

Dried sludge

0.80

32,500 335,000

Acid-iron waste Raw effluent Seawater precipitate

Sewage Supernatant

Fe ppm

Sample source

Elementary composition by atoms when Fe ---- 100 atoms

0.061 0.236

0.075

0.96 6.98 3.28

2.39

5.02 1! .20

32.8

113.2

21.9

< 0.002 0.022

Cu

0.0037 0.0035

0.0038

0.0045 0.1444 0.0286

0.1440

0.1370 0.3900

0.6250

--

--

-0.0004

Cd

Source

This study, Sta. 2, 3, 5, 7 This study, Sta. 33, 35 This study, Sta. 19

This study, Sta. 3 This study, Sta. 35 This study, Sta. 19

This study, Sta. 2, 3 This study, Sta. 29, 33, 37 This study, Sta. 1541

PAINTERand VINEY (1959) THOMPSON(1964). Mean, 12 plant effluents CHow (1968)

This study This study

TABLE 8. M E T A L SPECTRUM FOR IRON AND OTHER METALS 1N SAMPLE MATERIAL RELATING TO THE ]N~EW Y O R K B I G H T

= I:h

.,--1

r-

m

.~ C~

~:

O

<

Lh t,J

Distribution of Standing Crops in the New York Bight

253

For the benthic populations, the Fe content in samples taken on the acid-iron grid was 7.5 times greater than samples from the control area. On the same assumption made above, the ratio for the other heavy metal elements in these two areas should equal 0.13 if there were no other source of supply and organisms reacted in the same way to all of the metals. Only one element, Cu, gave a ratio of this magnitude, 0.135. In these samples, Cd gave a ratio of 0.03 indicating a greater effect than mere dilution by the Fe, presumably exclusion from the organisms. The other ratios ranged from 0.30 for Co to 0.57 for Ni. The sequence of these ratios for the benthic organisms was Fe > Ni > Pb > Zn > Co > Cu > Cr. In both sets of biological samples the ratios indicated, in most cases, enrichment above what would be expected if Fe alone had been added to the system. In no case, however, did the enrichment of other heavy metals in the organisms equal the proportional increase in Fe content. Quite different results are obtained, however, when comparing the sediments from the two areas in which the expected ratio as a result of simple Fe dilution would be 0.36. Several of the ratios in sediments comparing the acid-iron grid with the control area are greater than 1, namely Zn, Co, Ni and Cu. The ratio for Cd is 1 and for Cr 0.95. The sequence for decreasing ratios in the sediments is as follows: Zn > Co > Ni > Cu > Cd = Fe > Cr > Pb. The sediments in the Hudson Gorge are even more enriched (TXBLE2) than those in the acidiron grid, containing about 4 times as much Fe, and all of the other heavy metals except Ni are greatly enriched in the Hudson Gorge samples when compared to the acid-iron grid samples. This suggests that the entrapment in the Gorge sediments may be the ultimate fate of the heavy metal enrichment of the New York Bight area. Another assumption which can be made in evaluating these data is that the atomic ratio relative to Fe of each element added to the environment is the same for all areas investigated. This assumes that the pollution reaching the control area has the same composition as pollution reaching the acid-iron grid. On the basis of this assumption, a ratio of unity for the comparison of each element in the two areas would indicate that the organisms or the sediment are responding in the same way to that element that they are responding to Fe. For both the zooplankton and the benthic organisms the ratios are all less than unity. Only in the sediments, as discussed above, are they equal to or greater than unity. The sequence of the ratios as listed above remains, of course, the same. These results imply that neither assumption is correct and that the truth probably lies somewhere between. On the basis of the analyses of organisms, the implication is that most of the heavy metal contamination of the New York Bight, other than the Fe, is derived from sources other than the acid-iron dump. The results on the sediments suggest that these other sources of heavy metal pollution may be substantial, since they indicate that five of the heavy metals were present at ratios equal to or greater than that for Fe. The relative enrichment of heavy metals in the sediments is emphasized by the results on the Hudson Gorge where enrichment of all metals, except Ni, was equal to or greater than that of the acid-iron dump area. It has been shown by GROSS (1971), that both the sewage sludge and dredging spoils which are dumped close to this area in the New York Bight have high concentrations of these heavy metals and these pollutants seem a probable source for the excess amounts of various heavy metals we have found in the area.

254

RALPH F. VACC~O, GF.OROE D. G~CE, GILBERT T. Rowe and PETER H. WmBE CONCLUSIONS

1. The m a x i m u m persistent particulate iron concentration on the acid grounds was 832/~g l - i a value which corresponds to a minimum dilution o f the acid wastes in the disposal area o f 1 : 39,000. 2. There is no indication of an increase in iron in sediments of the acid grounds over the past 14 yr. 3. Although the standing crop o f zooplankton and numbers o f benthic animals were less on the acid grounds than the control area, we have been unable to attribute these differences to acid waste. 4. A phytoplankton toxicity experiment carried out in a culture containing a l0 -~ concentration of acid-waste in seawater, a concentration four times greater than that observed in the field, had no effect on phytoplankton growth. 5. Similar toxicity experiments were performed using copepods in seawater cultures containing acid-waste at concentrations o f l0 -4, l0 - s and l0 -~. The copepods o f 10 -4 concentration either failed to reproduce or their development was prolonged. N o adverse effects were noted in l0 -5 and l0 -~ concentrations. 6. A comparison between the acid and control area indicates that the highest value for the concentration o f eight trace metals (Fe, Cu, Zn, Pb, Cr, Co, Ni, Cd) in zooplankton, benthos and sediment were found in the acid grounds with but one exception, Cr, which was more concentrated in one zooplankton sample from the control area. When benthos from the Hudson Gorge are included in the comparisons, highest single values for the concentrations o f the eight metals excepting Pb and Cr, were also present in the acid grounds, but when sediments are included the maximum concentrations of all eight trace metals were present in Hudson Gorge. The origin o f the metals in the sediment o f the gorge has not been determined by the possibility that they are being derived from sewage sludge and dredging spoils cannot be discounted. 7. N o major effects o f acid-iron waste on the sediment and biota of the region have been detected AcknowledgementsmThe authors are grateful to: Mr. GEORGE HAMI'SON and Mr. JOHN MOODY for their assistance on shipboard; Mr. NAT~ANmL CoRwrN and Miss Mn~I KoEm. for their valuable technical assistance with hydrographic and chemical measurements; Dr. Wn.Lt~M DUNSTAN for

his study of the effects of acid-iron waste on marine phytoplankton; Drs. PETERBREWERand HERBERT WINDOM for the atomic absorption analyses of the heavy metal spectra; Mr. TASOR HAND, Mr. JAMESSALZER,Miss AtacE WERTHEtMERand Mrs. JtmrrrI ROWEfor assistance in sorting the benthic samples; Mrs. PAMELAPOLLONIfor identifying many of the benthic invertebrates; and Dr. BOSTWtCK H. K~TCHUMfor review of the manuscript and for suggestions which led to its improvement.

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Distribution of Standing Crops in the New York Bight

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