- Email: [email protected]
Degree of pollution of several major streams entering Tolo Harbour, Hong Kong
Marine Pollution Bulletin
The Tarpenbek incident also showed the n~-~xi for immediate analysis of the type of oil on a stricken ship. In the Eleni V incident, off East Anglia, which led to the setting-up of the pollution unit, the leaking oil failed to respond to detergents intended to break it up, and it was later found that the escaping oil was engine oil and not light-grade fuel oil.
Round-the-World News The island of Madagascar has been identified by the World Wildlife Fund as a top international conservation priority and M. Barthelemi Vaohita has been appointed as director of WWF operations there. Most of the pressure on the island's unique collection of wildlife is caused by its rapidly expanding human population which now exceeds 8 million. Urgent action is required to reduce the strain on land and forestry resources and to halt the destruction of naturalhabitatsof a wide range of species.
Lreland A full-scale anti-pollutionexercise took place in Bantry Bay, Southern Ireland, last month, when the midships section of the French tanker Betelgeuse was raised to the watcl"'S SUrfag¢.
The sections were the Nos. 4, 5 and 6 tanks of the vessel.
The Beteigeuse sank lastJanuary after a fireand explosion
resulting in the loss of 50 lives. The section will eventually be towed to Rotterdam, Holland, for scrapping. China Major offshore oil exploration could get underway in the South China Sea and the southern Yellow Sea in 1981. The Chinese government, which has allowed 16 British, American and French companies to carry out seismic testing in these areas, is expected to invite tenders for drilling later this year.
USA A collision with a barge under tow ruptured the hull of the, tanker P/ha and caused a spillof 168000 gallons of crude oil into the Mississippi river at New Orleans, Louisiana. The tug, travelling downstream, was towing two barges, and the tanker was carrying 2.4 million gallons of crude oil to an upstream refn~-ry. The crews abandoned both vessels immediately and casualties were avoided, but oil began spilling from a 20 x 4 m gash in the tanker's bow. It ignited and began to burn, but the fire was quickly brought under control. Oil continued to spill, reaching about 60 km downstream, and drinking water pumps were shut off to avoid risk of contamination. Air Oil Inc. were brought in by the US Coast Guard to dean up the oil, and a boom was used along the Mississippi river, which deflected the oil to river banks for eventual recovery by land based vacuum trucks.
Mm,i~Polhaion~d~tm, Vot. I I , pp. 36-.40 Pe~ Pre~, Ltd. 19~0. Printed in Grgat Britain.
Degree of Pollution of SeveralMajor Stre EntermgTolo Harbour, HongKong MING-HUNG WONG, KIN-CHUNG HO and TIM-TAK KWOK
Department of Biology, Chinese University of Hong Kong, Shatin, Hong Kong Untreated domestic and industrial wastes are discharged into Tolo Harbour via several major streams entering the harbour. Tlm~ untreated wastes will cause a harmful effect because Tolo I-larbour is a land-locked sea with only a narrow outlet and an ever-decreusing volume caused by the construction of Plover Cove Reservoir and the reclamation of Slmtin New Town. In order to study the effect of polluted water discharged into the harbour, water samples and sedimants ~ the mouths of the major rivers were collected. The analysis of the total organic carbon, total nitrogen, and water soluble phosphate contents of the samples showed that Lain Tsuen River, Tai Po Kau River, and Shing Mou River were grossly polluted by organic and inorganic wastes. Blue Snake River which passes through
36
the iron ore tallings accumulated high contents of metal contaminants. Tolo Harbour is a land-locked sea with only a narrow outlet, ToM Channel (Fig. 1). The untreated domestic and industrial wastes discharged into the Harbour via several major streams are expected to dilute and flush away by tidal waves. However, the dilution is low because the volume of the Harbour has been decreasing due to various developments, e.g. construction of the Plover Cove Reservoir and the Race Course, the reclamation of Shatin New Town and Tai Po industrial estate (Fig. 2). The Harbour has become shallow, with the greatest part no deeper than 10m.
Volume 11/Number 2/February 1980
/
p,.. ~
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~
Km
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CHINA
/
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PERAL ~ ,,,/~ RIVERj~vC~#~; ~J~J
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Fig. 1 Map of H o n g Kong showing the position o f Tolo Harbour.
The major agricultural land is situated in New Territories. The streams entering Tolo Harbour pass through large areas of farms interspersed with industrial districts (Fig. 2). The untreated organic and inorganic wastes are discharged from the villages, agricultural areas (including pig and poultry farms) and various factories (e.g. slaughter houses, textile and electroplating factories). Agricultural waste is the most important cause of pollution in the New Territories and pig and poultry manure contributes more than two-thirds of the total quantity of readily degradable matter entering streams. The total industrial toxic metal load was estimated to be about 2000 kg day-;, and 92°70 of this originated in the textile and wig industries and a further 7070 from electroplating (Environmental Resources Ltd., 1975). Table 1 shows the types of pollutants entering streams in New Territories (Bine & Partners, 1974). In view of the critical situation of Tolo Harbour, the aim of'the present investigation is to study the degree of water
pollution of several major streams entering the Harbour in order to verify the exact sources of various ponutants.
Description of the Study Sites The hydrology of Hong Kong is affected by two major factors. 1. The heavy rainfall of 2200 rmn dilutes the seawater to certain degree from May to September every year. 2. A large spate of freshwater issuing from the Pearl River dilutes the seawater of western coast of Hong Kong (Morton & Wu, 1975). The eastern and north-eastern coast of Hong Kong are virtually unaffected by the freshwater draining, and the salinity is typical of ocean conditions. However, Tolo Harbour receives freshwater from several rivers and therefore would have a lower salinity. Eight major rivers entering Tolo Harbour are chosen for the present study. The site descriptions are listed in Table 2.
TABLE 2 TABLE 1
S u m m a r y o f site d e s c r i p t i o n s .
T h e m a i n s o u r c e s o f p o l l u t a n t s in N e w T e r r i t o r i e s ( f r o m Bine & P a r t n e r s , 1974). (I) L i q u i d W a s t e s : D o m e s t i c s e w a g e , sullage a n d n i g h t soil Industrial effluent A g r i c u l t u r a l e f f l u e n t f r o m pig f a r m s (II) Solid W a s t e s : D o m e s t i c refuse I n d u s t r i a l solid wastes A g r i c u l t u r a l solid wastes - p o u l t r y d r o p p i n g s
River
10.2 (°70) 21.7 54.2
0.4 0.I 13.4 Total I 0 0 . 0 ( % )
Population
Agriculture
I. Blue S n a k e
+
-
2. S h i n g M o n
+++
+++
Industries + + +
+++
3. F o T a n
+
+
+++
4. K a u T o
+
+
+
5. C h e n g S h u e T a n
+
+
-
+ +
+ +
+
+ + +
+ + +
+ + +
+++
+++
+++
6. Tai P o K a u 7. Y u e n C h a u Tsai 8. L a m T s u e n + +-,- = i m p o r t a n t ;
+ ~- = m o d e r a t e ; + = m i l d ; - = n o effect.
37
Marine Pollution Bulletin
CHINA
.~" ~'~.
N I
I
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~
T
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5
HorDour Tolo
.~
6_
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w
t
O
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,
STUDY SITES t Blue Snoke 2 Shing Mon 3 FoTan 4 Kau To 5 Cheun9 Shue Ton 6 Tai Po Kau 7 Yuen Chau Tsoi S tam Tsuen 4 I 2 $
~
51
J
Km
Fig. 2 Enlarged m a p o f Tolo Harbour showing the study sites and the reclaimed areas (dotted lines).
Numbers are designated for each river throughout the text for the sake of convenience.
Materials and Methods Water and sediment samples were collected near the mouths of the streams at low tides. The values of dissolved oxygen was determined at the study sites immediately by dissolved oxygen meter. Additional water samples were transferred into the laboratory for the measurement of pH. The water samples were then concentrated by Alloay's reagent (Allen et aL, 1974) and analysed for the following items: total nitrogen content fmicro Kjeldahl's distillation method), total phosphate test (ammonium molybdate colorimetric method), and the contents of cadmium, copper, iron, manganese, lead and zinc (atomic absorption spectrophotometer after f'dtering through Whatman No. 42 filter papers). The sediment samples were sealed in polythene bags and transferred to the laboratory. They were then dried at 105°C overnight and passed through a 2 mm mesh sieve before conducting the following analyses: total organic carbon (loss on ignition), total nitrogen (concentrated acid digestion followed by Kjeldahl's distillation method), total phosphate (acid digestion followed by ammonium molybdate colorimetric method). The sediments were ashed at 800°C using the method described by Allen et al. (1974) before measuring the contents of cadmium, zinc, iron, copper, lead and manganese (atomic absorption spectrophotometer). 38
Results and Discussion Organic pollution Table 3 shows the contents of pH, dissolved oxygen, total nitrogen and total phosphate of the water samples. Fo Tan (3) exhibited the lowest pH value (6.0), indicating a certain degree of industrial pollution in the river. Most of the rivers had values between 6.8 and 7.8. The extremely high pH (8.1) of Blue Snake (1) was caused by the iron ore tailings which originated from the magnesium limestone deposit (Davies, 1964). The value of dissolved oxygen may serve as an indicator of the microbial activity of water. The extremely low value (5.8--6.1 ppm) of Shing Mon (2), Tai Po Kau (6), Yuen Chau Tsai (~, Lain Tsuen (8) indicated that these rivers were TABLE 3 Results of the water analysis - pH, dissolved oxygen, total nitrogen and :oral phosphate in the water samples. Study sites
pH
Blue Snake 8.13+0.2 Shing Mon 7.5±0.5 FoTan 6.0±0.5 KauTo 6.9±0.5 Cheung Shue Tan 7.8±0.5 Tai Po Kau 7.8 = 0 , 6 Yuen C h a u Tsai 7.5 ±0.5 Lain Tsuen 6.8+0.5 T.A. = trace amount.
Dissolved oxygen (ppm)
Total nitrogen (ppm)
Total phosphate (ppm)
8.7 5.8 6.0 8.8 8.9 6.1 5.8 5.8
0.35+0.05 1.10±0.05 0.90±0.05 0.60±0.05 1.05±0.15 1.20±0.10 1.25 ±0.15 1.32:t:0.05
T.A. T.A. T.A. T.A. T.A. T.A. " T.A. T.A.
Volume I l/Number 2/February 1980 TABLE 4
TABLE S Heavy metal content of the water samples.
Content of total organic carbon, total nitrogen and total phosphate in sediments. Study sites Blue Snake Shing Mon Fo Tan Kau To Cheung Shue Tan Tai Po Kau Yuen Chau Tsai Lain Tsuen
Organic carbon (%) 1.06 ± 0.07 4.80 ± 0.30 4.40 ± 0.20 3.20 ± 0.11 2.84 ± 0.03 4.42 ± 0 29 10.70 ± 0.39 12.31 ± 0.15
Total nitrogen Wpm) 280 ± 5 1480 + 10 1180 ± 10 320 4- 5 690 ± 5 1430 + 10 1250 + 5 3090 ± 10
Total
phosphate (ppm) 0.26 0.41 0.28 0.22 0.54 0.59 0.62 0.55
bacteriologically active and contaminated by organic wastes. The relatively high contems (8.7-8.9 ppm) of Kau To (4), Blue Snake (11 and Cheung Shue Tan (5) showed that they had a low content of organic nutrients and microbial activities. I.am Tsuen (81, Yuen Chau Tsal (7) and Tai Po Kau (6) accumulated the highest levels of total nitrogen (1.2-1.3 ppm). Nitrogen may also serve as one of the primary indicators of water pollution because it is the essential element required virtually by all living organisms. The high levels of total nitrogen of these rivers may imply that they received high loadings of organic discharges from the nearby villages and agricultural farms. Kau To (4) and Blue Snake (11 had relatively low levels (0,6 and 0.3 ppm, respectively) due to the comparatively small mumber of inhibitants and agricultural establishments. Shing Mon (2), Fo Tan (3) and Cheung Shue Tan (5) had moderate levels (0.9-1.1 ppm). Only a trace amount of phosphate was detected in all the water samples. The contents of organic carbon, total nitrogen and total phosphate of the sediment are shown in Table~4. Total organic carbon is frequently used as a primary indicator of water pollution. The various organic matters, discharged from different types of agricultural farms, industries and domestic sewage, seriously impared the water usage by causing bad taste and odour, toxicity and loss of dissolved oxygen. Lain Tsuen (8) and Yuan Chau Tsai (7) accumulated the highest level of organic carbon in the sediment (12.3 and 10.7 ppm, respectively), whereas Shing Mon (2), Tai Po Kau (6) and Fo Tan (3) had moderate values (4.4-4.8 ppm). Blue Snake (1), Cheung Shue Tan (5) and Kau To (4) had relatively low levels (1-3.2 ppm). Lain Tsuen (8) also accumulated the highest content of total nitrogen in the sediment (3090 ppm). The figures of Cheung Shue Tan (5), Kau To (4) and Blue Snake (11 were relatively low (320-690 ppm) and the rest were in between (1180-1480 ppm). Lain Tsuen (9), Yuen Chau Tsai (7), Tai Po Kau (6) and Cheung Shue Tan (5) had a similarly high level of total phosphate (over 0.5a ppm), whereas Blue Snake (11. Kau To (4) and Cheung Shue Tan (5) had a low level (below 0.3 ppm). Shing Mon (2) had a moderate level (0.4 ppm). The main sources of organic matter originated from agricultural wastes (mainly pig and poultry manure), domestic and industrial sewage. The latter included wastes discharged from food processing factories, textile factories and slaughter houses. The wastes are accumulated in the sediment mostly in a
ppm Study sites Blue Snake Shing Mort Fo Tan Kau To Cheung Sheu Tan Tai Po Kau Yuen Chau Tsai Lam Tsuen
Zn
Fe
Mn
Cd
Cu
Pb
0.166 0.087 0.1 50 0.018 0.016 0.085 0.102 0.133
0.350 0.388 0.264 0.264 0.243 0.332 0.323 0.305
0.150 0.041 0.079 0.016 0.038 0.089 0.135 0.087
0.053 0.041 0.019 0.006 0.005 0.035 0.050 0.053
0.042 0.006 0.014 0:~3 0.007 0.010 0.013 0.008
0.12! 0.014 0.011 0.005 0.009 0.010 0.01! 0.011
solid and unavailable form. They may be decomposed slowly by microorganisms and available nutrients or soluble nutrients would be released and become available for living organisms. The high nutrient load in Lain Tsuen (8) and Yuen Chau Tsai (7) indicates alarming organic pollution. The result was in line with the assessment of organic pollution of Lain Tsuen River using bacteriological tests. The water was heavily polluted and the number of bacteria per 100 ml of water exceeded the upper limit of drinking and bathing set by World Health Organization (Mark & Wan, 19761. Clams collected from Tal Po and Shatin which received agricultural effluent from Lain Tsuen (8) and Siting Mon (2) had a high content of coliform bacteria according to an earlier investigation (Wong et al., 1977). A range of pathogenic bacteria was also isolated from clams collected from the shore of Tolo Harbour (Kueh & Trott, 19741. Other studies have also shown that Tolo Harbour is already organically polluted although no indication as to the exact source of contamination has been given (Trott, 197,2; Trott &Fung, 1973; Jueh &Chan, 19751.
Inorganic pollution Table 5 shows the heavy metal content of the water samples. Blue Snake River (1) which passes through the iron ore tailings contained the highest value of cadmium, copper, iron, lead, manganese and zinc. Some of the rivers also possessed a high level of certain heavy metals possibly due to the types of industries which discharged their untreated wastes into the water, e.g. Fo Tan (3) had a rather high TABLE 6 The upper limit of various heavy metals and their possible origins. Substance Cadmium
Copper
Upper limit (ppm) 0.05 "t
i .0"
Possible sources of the pollutants Electroplating, ceramics, pigments, insecticides, textile printing Corrosion ol copper tubing, algicides, textile, pigmentation, tanning, electroplating, engraving
Lead
0.1 ~r
Textile dyes, glass, electroplating, printing, vehicles waste gas
Iron
0.3*
Iron ore tailing, steel alloy, electroplating
Manganese
0. I *
Steel alloy, dry cell batteries, glass, ceramics, paints, ink, dyes, fireworks, agriculture
Zinc
5.0*
Galvanizing, alloy, printing plates, dyes. painting, pigmentation, cosmetics and insecticides
*International Standards for Drinking-water, WHO. Geneva (1958). * From European Standards for Drinking-wate:. WHO. Geneva (1961).
39
Marine Pollution Bulletin TABLE 7
Heavy metal content (ppm) of the sediment. ppm Study sites BlueSnake Shing Mon FoTan KauTo Cheung ShueTan Tai Po Kau Yuen Chau Tsai Lain Tsuen
Zn
ICe
93.81 ± 1 . 7 2 52.35±5.37 81.59±7.2~ 41.17 ~: 1.21 37.74+a.63 53.18±3.22 65.36±12.13 82.78+0.51
2422±20 2276±70 1272+50 1073 ±93 1022-'11 1438:t:70 1382±40 1503±48
Mn 288.93 ± 2.94 60.50.~ 14.37 !71.8 --27.34 43.66___9.37 54.88±0.97 129.01±40.7 73.56±6.48 109.8 & 11.5
content of copper (0.014 ppm), manganese (0.08 ppm) and zinc (0.15 ppm); Yuen Chau Tsai (7), cadmium (0.05 ppm), copper (0.013 ppm), iron (0.323 ppm) and zinc (0. l0 ppm) and Lain Tsuen (8) cadmium (0.05 ppm) and zinc (0.133 ppm). Table 6 reveals the lxxssible sources of the metal pollutants as well as the standards set by World Health Organization (WHO, 1958, 1961). The level of four of the metals, cadmium, iron, manganese and lead in the water sample collected from Blue Snake River (1) exceeded the upper safety limit. Water samples fi'om other sites also exceeded the limit; Shing Mon (2) - iron; Fo Tan (3) - cadmium; Kau To (4) - manganese; Tai Po Kau (6) - iron; Yuen Chau Tsai (7) - iron, manganese and cadmium; Lain Tsuen (8) - iron and cadmium. However, it must be borne in mind that the limits were set for drinking water. According to Table 7, sediment collected from Blue Snake (1) showed the highest levels of various heavy metals with the sole exception of cadmium. Sediments from other sites also exhibited a high level of certain metals, e.g. Lam Tsuen (8) had rather high level of cadmium (6.78 ppm) and zinc (82.78 ppm); Fo Tan (3) copper (107.2 ppm), and zinc (81.6 ppm); Yuen Chau Tsai (7) cadmium (6.12 ppm) and lead (77.23 ppm) and Shing Mon (2) iron (2276 ppm). The metal contents of the sediment were related to the metal content of the water samples. Untreated discharges from various industries accounted for the high levels of these metals. Although the metal accumulates in the sediment, it exists largely in an unavailable form. The effect of the rather high. heavy metals contained in the iron ore tailings has been studied extensively, it was revealed that lfigher plants, Neyraudia reynaudiana (grass), Enteromorpha crinita and Chaetomorpha brychagona (green algae) growing on the tailings showed a high uptake of various heavy metals, Paphta sp. (clam) and Scopimera intermedia (crab) collected from the tailings also had elevated levels of various metals in their tissues (Wong & Li, 1977; Wong & Tam, 1977; Wong et al., 1978, in press). There is a lack of data as to the heavy metal contents in living organisms in other areas although a high level of several heavy metals (cadmium, iron and zinc) was recorded from water samples collected at Tai Po and Shatin which received water from Lain Tsuen River (8) and Shing Mon River (2) (Chart et al., 1974). In view of this, the analysis of heavy metal contents in the sea lettuce, Ulva latuca (green alga) collected from different sites within as well as outside ToM Harbour has been carried out, the results will be given in another paper.
40
Cd 6.17±0.98 5.32±0.88 3,43± 1 , 4 3 2.87±0.33 2.63±0.74 5.93±1.81 6.12 4-0 38 6,78+0.59
Cu
Pb
231.32& 13.1 187.31±27.3 68.44± 9.72 43.83±2.72 107.2+ 1.03 44.11±2.98 6.83 ± 1.07 20.21±3.94 16,94±2.53 32.62±2.32 29.51±0.84 50.28±3.94 52.40±1.21 77.23±9.31 61.45:t: 1.98 66.28±5.93
Conclusion According to the present investigation, it can be concluded that Lam Tsuen (8), Yuen Chau Tsai (7) and Shing Mon (2) were grossly polluted by both organic and inorganic contaminants. The iron ore railings also possessed a high level of various heavy metals in the sedument as well as the water. The rapid development of the satellite cities around Tolo Harbour, e.g. Tai Po, Shatin introduces the possibility of further deterioration of this delicate environment. A large reclamation scheme has been carried out at Tai Po for the development of a heavy industrial estate. Other industrial areas have also been developed and expanded. Although the treatment plant will remos, e nitrogen (but not phosphates) the large volume of domestic effluent will undoubtedly contribute a heavy nutrient load to the harbour, especially with the reduction in volume of the inlet as a result of extensive reclamation. Furthermore, no ultimate solution has been given as to the disposal of pig and poultry manure. No legislation has been set up to prevent the discharge of untreated wastes from the various industries. Beside strong legislations, a careful planning and management of the industrial areas and agricultural farms is equally important in the future town planning or rural development.
Allen, S. E., Grimshaw, H. M., Parkinson, J. A. & Quarmby, C. d974). ChemicalAnalysis of Ecological.h4aterial& Halsted Press, New York. Binne & Partners (1974). A Study of the Stream Pollution in New Terri,or/es. H.K. Hong Kong Government Press. Chen, J. P., Cheung, M. T. & Li, F. P. (1974). Mar. Pollut. Bull., 5, 171174. Environmental Resources Ltd. (1975). Control of the Environment in Hong Kong. Stage l Report. Secretary of the Environment, Hong Kong Government. Kueh, C. S. W. & Chart, K. Y. (1975). In Proc. PacificSci. Ass. Special Syrup. on Marine Sci., Hong Kong, pp. 95-99. Kueh, C. S. W. &Trott, L. B. (1974). Chung ChiJ., 12, 79-84. Mark, K. K. & Wan, S. L. (1975). J. Chinese Univ. Hong Kong, 2, 527534. Morton, B. & Wu, S. S. (1975). Envir. Res., tO, 319-349. Trott, L. B. & Fung, Y. C. (1971). Mar. Pollut. Bull., 4, 13-15. Wong, M. H. & Li, M. W. (1977,').Hydrobiology, 56,265-272. Wong, M. H. & Tam, F. Y. (1977). Envir. Pollut., 14, 24! -254. Wong, M. H., Young, Y. F., Wong, F. S. & Leung, K. N. (1977). Hydrobiology, 54, 141-143. Wong, M. H., Chan. K. C: & Choy, C. K. (1978). Envir. Res.. 15,342356. Wong, M. H., Chan, K. Y., Kwan, S. H. & Mo, C. F. (1979). Mar. Poilul. Bull., 10, 56-59. World Health Organization. (1958). International Standards for Drinking- water. Geneva. World Hezdth Organization. ( ]961 ). European Standards for Drinkingwaler. Geneva.
The Tarpenbek incident also showed the n~-~xi for immediate analysis of the type of oil on a stricken ship. In the Eleni V incident, off East Anglia, which led to the setting-up of the pollution unit, the leaking oil failed to respond to detergents intended to break it up, and it was later found that the escaping oil was engine oil and not light-grade fuel oil.
Round-the-World News The island of Madagascar has been identified by the World Wildlife Fund as a top international conservation priority and M. Barthelemi Vaohita has been appointed as director of WWF operations there. Most of the pressure on the island's unique collection of wildlife is caused by its rapidly expanding human population which now exceeds 8 million. Urgent action is required to reduce the strain on land and forestry resources and to halt the destruction of naturalhabitatsof a wide range of species.
Lreland A full-scale anti-pollutionexercise took place in Bantry Bay, Southern Ireland, last month, when the midships section of the French tanker Betelgeuse was raised to the watcl"'S SUrfag¢.
The sections were the Nos. 4, 5 and 6 tanks of the vessel.
The Beteigeuse sank lastJanuary after a fireand explosion
resulting in the loss of 50 lives. The section will eventually be towed to Rotterdam, Holland, for scrapping. China Major offshore oil exploration could get underway in the South China Sea and the southern Yellow Sea in 1981. The Chinese government, which has allowed 16 British, American and French companies to carry out seismic testing in these areas, is expected to invite tenders for drilling later this year.
USA A collision with a barge under tow ruptured the hull of the, tanker P/ha and caused a spillof 168000 gallons of crude oil into the Mississippi river at New Orleans, Louisiana. The tug, travelling downstream, was towing two barges, and the tanker was carrying 2.4 million gallons of crude oil to an upstream refn~-ry. The crews abandoned both vessels immediately and casualties were avoided, but oil began spilling from a 20 x 4 m gash in the tanker's bow. It ignited and began to burn, but the fire was quickly brought under control. Oil continued to spill, reaching about 60 km downstream, and drinking water pumps were shut off to avoid risk of contamination. Air Oil Inc. were brought in by the US Coast Guard to dean up the oil, and a boom was used along the Mississippi river, which deflected the oil to river banks for eventual recovery by land based vacuum trucks.
Mm,i~Polhaion~d~tm, Vot. I I , pp. 36-.40 Pe~ Pre~, Ltd. 19~0. Printed in Grgat Britain.
Degree of Pollution of SeveralMajor Stre EntermgTolo Harbour, HongKong MING-HUNG WONG, KIN-CHUNG HO and TIM-TAK KWOK
Department of Biology, Chinese University of Hong Kong, Shatin, Hong Kong Untreated domestic and industrial wastes are discharged into Tolo Harbour via several major streams entering the harbour. Tlm~ untreated wastes will cause a harmful effect because Tolo I-larbour is a land-locked sea with only a narrow outlet and an ever-decreusing volume caused by the construction of Plover Cove Reservoir and the reclamation of Slmtin New Town. In order to study the effect of polluted water discharged into the harbour, water samples and sedimants ~ the mouths of the major rivers were collected. The analysis of the total organic carbon, total nitrogen, and water soluble phosphate contents of the samples showed that Lain Tsuen River, Tai Po Kau River, and Shing Mou River were grossly polluted by organic and inorganic wastes. Blue Snake River which passes through
36
the iron ore tallings accumulated high contents of metal contaminants. Tolo Harbour is a land-locked sea with only a narrow outlet, ToM Channel (Fig. 1). The untreated domestic and industrial wastes discharged into the Harbour via several major streams are expected to dilute and flush away by tidal waves. However, the dilution is low because the volume of the Harbour has been decreasing due to various developments, e.g. construction of the Plover Cove Reservoir and the Race Course, the reclamation of Shatin New Town and Tai Po industrial estate (Fig. 2). The Harbour has become shallow, with the greatest part no deeper than 10m.
Volume 11/Number 2/February 1980
/
p,.. ~
CHN IA
%
N ? ~
f . ~<""P''~'"5""~" / . , - v "TAI" P % Tolo"v OLOHARBOUtR NEWTERRT IORE IS SHATIN E
%
HONGKONG LT'•__
~
Km
~,,,~:,~
CHINA
/
[
I
PERAL ~ ,,,/~ RIVERj~vC~#~; ~J~J
\ C
~C
HK C'~
Fig. 1 Map of H o n g Kong showing the position o f Tolo Harbour.
The major agricultural land is situated in New Territories. The streams entering Tolo Harbour pass through large areas of farms interspersed with industrial districts (Fig. 2). The untreated organic and inorganic wastes are discharged from the villages, agricultural areas (including pig and poultry farms) and various factories (e.g. slaughter houses, textile and electroplating factories). Agricultural waste is the most important cause of pollution in the New Territories and pig and poultry manure contributes more than two-thirds of the total quantity of readily degradable matter entering streams. The total industrial toxic metal load was estimated to be about 2000 kg day-;, and 92°70 of this originated in the textile and wig industries and a further 7070 from electroplating (Environmental Resources Ltd., 1975). Table 1 shows the types of pollutants entering streams in New Territories (Bine & Partners, 1974). In view of the critical situation of Tolo Harbour, the aim of'the present investigation is to study the degree of water
pollution of several major streams entering the Harbour in order to verify the exact sources of various ponutants.
Description of the Study Sites The hydrology of Hong Kong is affected by two major factors. 1. The heavy rainfall of 2200 rmn dilutes the seawater to certain degree from May to September every year. 2. A large spate of freshwater issuing from the Pearl River dilutes the seawater of western coast of Hong Kong (Morton & Wu, 1975). The eastern and north-eastern coast of Hong Kong are virtually unaffected by the freshwater draining, and the salinity is typical of ocean conditions. However, Tolo Harbour receives freshwater from several rivers and therefore would have a lower salinity. Eight major rivers entering Tolo Harbour are chosen for the present study. The site descriptions are listed in Table 2.
TABLE 2 TABLE 1
S u m m a r y o f site d e s c r i p t i o n s .
T h e m a i n s o u r c e s o f p o l l u t a n t s in N e w T e r r i t o r i e s ( f r o m Bine & P a r t n e r s , 1974). (I) L i q u i d W a s t e s : D o m e s t i c s e w a g e , sullage a n d n i g h t soil Industrial effluent A g r i c u l t u r a l e f f l u e n t f r o m pig f a r m s (II) Solid W a s t e s : D o m e s t i c refuse I n d u s t r i a l solid wastes A g r i c u l t u r a l solid wastes - p o u l t r y d r o p p i n g s
River
10.2 (°70) 21.7 54.2
0.4 0.I 13.4 Total I 0 0 . 0 ( % )
Population
Agriculture
I. Blue S n a k e
+
-
2. S h i n g M o n
+++
+++
Industries + + +
+++
3. F o T a n
+
+
+++
4. K a u T o
+
+
+
5. C h e n g S h u e T a n
+
+
-
+ +
+ +
+
+ + +
+ + +
+ + +
+++
+++
+++
6. Tai P o K a u 7. Y u e n C h a u Tsai 8. L a m T s u e n + +-,- = i m p o r t a n t ;
+ ~- = m o d e r a t e ; + = m i l d ; - = n o effect.
37
Marine Pollution Bulletin
CHINA
.~" ~'~.
N I
I
/
~
T
F., ~" .f
5
HorDour Tolo
.~
6_
~
w
t
O
O
N
~
,
STUDY SITES t Blue Snoke 2 Shing Mon 3 FoTan 4 Kau To 5 Cheun9 Shue Ton 6 Tai Po Kau 7 Yuen Chau Tsoi S tam Tsuen 4 I 2 $
~
51
J
Km
Fig. 2 Enlarged m a p o f Tolo Harbour showing the study sites and the reclaimed areas (dotted lines).
Numbers are designated for each river throughout the text for the sake of convenience.
Materials and Methods Water and sediment samples were collected near the mouths of the streams at low tides. The values of dissolved oxygen was determined at the study sites immediately by dissolved oxygen meter. Additional water samples were transferred into the laboratory for the measurement of pH. The water samples were then concentrated by Alloay's reagent (Allen et aL, 1974) and analysed for the following items: total nitrogen content fmicro Kjeldahl's distillation method), total phosphate test (ammonium molybdate colorimetric method), and the contents of cadmium, copper, iron, manganese, lead and zinc (atomic absorption spectrophotometer after f'dtering through Whatman No. 42 filter papers). The sediment samples were sealed in polythene bags and transferred to the laboratory. They were then dried at 105°C overnight and passed through a 2 mm mesh sieve before conducting the following analyses: total organic carbon (loss on ignition), total nitrogen (concentrated acid digestion followed by Kjeldahl's distillation method), total phosphate (acid digestion followed by ammonium molybdate colorimetric method). The sediments were ashed at 800°C using the method described by Allen et al. (1974) before measuring the contents of cadmium, zinc, iron, copper, lead and manganese (atomic absorption spectrophotometer). 38
Results and Discussion Organic pollution Table 3 shows the contents of pH, dissolved oxygen, total nitrogen and total phosphate of the water samples. Fo Tan (3) exhibited the lowest pH value (6.0), indicating a certain degree of industrial pollution in the river. Most of the rivers had values between 6.8 and 7.8. The extremely high pH (8.1) of Blue Snake (1) was caused by the iron ore tailings which originated from the magnesium limestone deposit (Davies, 1964). The value of dissolved oxygen may serve as an indicator of the microbial activity of water. The extremely low value (5.8--6.1 ppm) of Shing Mon (2), Tai Po Kau (6), Yuen Chau Tsai (~, Lain Tsuen (8) indicated that these rivers were TABLE 3 Results of the water analysis - pH, dissolved oxygen, total nitrogen and :oral phosphate in the water samples. Study sites
pH
Blue Snake 8.13+0.2 Shing Mon 7.5±0.5 FoTan 6.0±0.5 KauTo 6.9±0.5 Cheung Shue Tan 7.8±0.5 Tai Po Kau 7.8 = 0 , 6 Yuen C h a u Tsai 7.5 ±0.5 Lain Tsuen 6.8+0.5 T.A. = trace amount.
Dissolved oxygen (ppm)
Total nitrogen (ppm)
Total phosphate (ppm)
8.7 5.8 6.0 8.8 8.9 6.1 5.8 5.8
0.35+0.05 1.10±0.05 0.90±0.05 0.60±0.05 1.05±0.15 1.20±0.10 1.25 ±0.15 1.32:t:0.05
T.A. T.A. T.A. T.A. T.A. T.A. " T.A. T.A.
Volume I l/Number 2/February 1980 TABLE 4
TABLE S Heavy metal content of the water samples.
Content of total organic carbon, total nitrogen and total phosphate in sediments. Study sites Blue Snake Shing Mon Fo Tan Kau To Cheung Shue Tan Tai Po Kau Yuen Chau Tsai Lain Tsuen
Organic carbon (%) 1.06 ± 0.07 4.80 ± 0.30 4.40 ± 0.20 3.20 ± 0.11 2.84 ± 0.03 4.42 ± 0 29 10.70 ± 0.39 12.31 ± 0.15
Total nitrogen Wpm) 280 ± 5 1480 + 10 1180 ± 10 320 4- 5 690 ± 5 1430 + 10 1250 + 5 3090 ± 10
Total
phosphate (ppm) 0.26 0.41 0.28 0.22 0.54 0.59 0.62 0.55
bacteriologically active and contaminated by organic wastes. The relatively high contems (8.7-8.9 ppm) of Kau To (4), Blue Snake (11 and Cheung Shue Tan (5) showed that they had a low content of organic nutrients and microbial activities. I.am Tsuen (81, Yuen Chau Tsal (7) and Tai Po Kau (6) accumulated the highest levels of total nitrogen (1.2-1.3 ppm). Nitrogen may also serve as one of the primary indicators of water pollution because it is the essential element required virtually by all living organisms. The high levels of total nitrogen of these rivers may imply that they received high loadings of organic discharges from the nearby villages and agricultural farms. Kau To (4) and Blue Snake (11 had relatively low levels (0,6 and 0.3 ppm, respectively) due to the comparatively small mumber of inhibitants and agricultural establishments. Shing Mon (2), Fo Tan (3) and Cheung Shue Tan (5) had moderate levels (0.9-1.1 ppm). Only a trace amount of phosphate was detected in all the water samples. The contents of organic carbon, total nitrogen and total phosphate of the sediment are shown in Table~4. Total organic carbon is frequently used as a primary indicator of water pollution. The various organic matters, discharged from different types of agricultural farms, industries and domestic sewage, seriously impared the water usage by causing bad taste and odour, toxicity and loss of dissolved oxygen. Lain Tsuen (8) and Yuan Chau Tsai (7) accumulated the highest level of organic carbon in the sediment (12.3 and 10.7 ppm, respectively), whereas Shing Mon (2), Tai Po Kau (6) and Fo Tan (3) had moderate values (4.4-4.8 ppm). Blue Snake (1), Cheung Shue Tan (5) and Kau To (4) had relatively low levels (1-3.2 ppm). Lain Tsuen (8) also accumulated the highest content of total nitrogen in the sediment (3090 ppm). The figures of Cheung Shue Tan (5), Kau To (4) and Blue Snake (11 were relatively low (320-690 ppm) and the rest were in between (1180-1480 ppm). Lain Tsuen (9), Yuen Chau Tsai (7), Tai Po Kau (6) and Cheung Shue Tan (5) had a similarly high level of total phosphate (over 0.5a ppm), whereas Blue Snake (11. Kau To (4) and Cheung Shue Tan (5) had a low level (below 0.3 ppm). Shing Mon (2) had a moderate level (0.4 ppm). The main sources of organic matter originated from agricultural wastes (mainly pig and poultry manure), domestic and industrial sewage. The latter included wastes discharged from food processing factories, textile factories and slaughter houses. The wastes are accumulated in the sediment mostly in a
ppm Study sites Blue Snake Shing Mort Fo Tan Kau To Cheung Sheu Tan Tai Po Kau Yuen Chau Tsai Lam Tsuen
Zn
Fe
Mn
Cd
Cu
Pb
0.166 0.087 0.1 50 0.018 0.016 0.085 0.102 0.133
0.350 0.388 0.264 0.264 0.243 0.332 0.323 0.305
0.150 0.041 0.079 0.016 0.038 0.089 0.135 0.087
0.053 0.041 0.019 0.006 0.005 0.035 0.050 0.053
0.042 0.006 0.014 0:~3 0.007 0.010 0.013 0.008
0.12! 0.014 0.011 0.005 0.009 0.010 0.01! 0.011
solid and unavailable form. They may be decomposed slowly by microorganisms and available nutrients or soluble nutrients would be released and become available for living organisms. The high nutrient load in Lain Tsuen (8) and Yuen Chau Tsai (7) indicates alarming organic pollution. The result was in line with the assessment of organic pollution of Lain Tsuen River using bacteriological tests. The water was heavily polluted and the number of bacteria per 100 ml of water exceeded the upper limit of drinking and bathing set by World Health Organization (Mark & Wan, 19761. Clams collected from Tal Po and Shatin which received agricultural effluent from Lain Tsuen (8) and Siting Mon (2) had a high content of coliform bacteria according to an earlier investigation (Wong et al., 1977). A range of pathogenic bacteria was also isolated from clams collected from the shore of Tolo Harbour (Kueh & Trott, 19741. Other studies have also shown that Tolo Harbour is already organically polluted although no indication as to the exact source of contamination has been given (Trott, 197,2; Trott &Fung, 1973; Jueh &Chan, 19751.
Inorganic pollution Table 5 shows the heavy metal content of the water samples. Blue Snake River (1) which passes through the iron ore tailings contained the highest value of cadmium, copper, iron, lead, manganese and zinc. Some of the rivers also possessed a high level of certain heavy metals possibly due to the types of industries which discharged their untreated wastes into the water, e.g. Fo Tan (3) had a rather high TABLE 6 The upper limit of various heavy metals and their possible origins. Substance Cadmium
Copper
Upper limit (ppm) 0.05 "t
i .0"
Possible sources of the pollutants Electroplating, ceramics, pigments, insecticides, textile printing Corrosion ol copper tubing, algicides, textile, pigmentation, tanning, electroplating, engraving
Lead
0.1 ~r
Textile dyes, glass, electroplating, printing, vehicles waste gas
Iron
0.3*
Iron ore tailing, steel alloy, electroplating
Manganese
0. I *
Steel alloy, dry cell batteries, glass, ceramics, paints, ink, dyes, fireworks, agriculture
Zinc
5.0*
Galvanizing, alloy, printing plates, dyes. painting, pigmentation, cosmetics and insecticides
*International Standards for Drinking-water, WHO. Geneva (1958). * From European Standards for Drinking-wate:. WHO. Geneva (1961).
39
Marine Pollution Bulletin TABLE 7
Heavy metal content (ppm) of the sediment. ppm Study sites BlueSnake Shing Mon FoTan KauTo Cheung ShueTan Tai Po Kau Yuen Chau Tsai Lain Tsuen
Zn
ICe
93.81 ± 1 . 7 2 52.35±5.37 81.59±7.2~ 41.17 ~: 1.21 37.74+a.63 53.18±3.22 65.36±12.13 82.78+0.51
2422±20 2276±70 1272+50 1073 ±93 1022-'11 1438:t:70 1382±40 1503±48
Mn 288.93 ± 2.94 60.50.~ 14.37 !71.8 --27.34 43.66___9.37 54.88±0.97 129.01±40.7 73.56±6.48 109.8 & 11.5
content of copper (0.014 ppm), manganese (0.08 ppm) and zinc (0.15 ppm); Yuen Chau Tsai (7), cadmium (0.05 ppm), copper (0.013 ppm), iron (0.323 ppm) and zinc (0. l0 ppm) and Lain Tsuen (8) cadmium (0.05 ppm) and zinc (0.133 ppm). Table 6 reveals the lxxssible sources of the metal pollutants as well as the standards set by World Health Organization (WHO, 1958, 1961). The level of four of the metals, cadmium, iron, manganese and lead in the water sample collected from Blue Snake River (1) exceeded the upper safety limit. Water samples fi'om other sites also exceeded the limit; Shing Mon (2) - iron; Fo Tan (3) - cadmium; Kau To (4) - manganese; Tai Po Kau (6) - iron; Yuen Chau Tsai (7) - iron, manganese and cadmium; Lain Tsuen (8) - iron and cadmium. However, it must be borne in mind that the limits were set for drinking water. According to Table 7, sediment collected from Blue Snake (1) showed the highest levels of various heavy metals with the sole exception of cadmium. Sediments from other sites also exhibited a high level of certain metals, e.g. Lam Tsuen (8) had rather high level of cadmium (6.78 ppm) and zinc (82.78 ppm); Fo Tan (3) copper (107.2 ppm), and zinc (81.6 ppm); Yuen Chau Tsai (7) cadmium (6.12 ppm) and lead (77.23 ppm) and Shing Mon (2) iron (2276 ppm). The metal contents of the sediment were related to the metal content of the water samples. Untreated discharges from various industries accounted for the high levels of these metals. Although the metal accumulates in the sediment, it exists largely in an unavailable form. The effect of the rather high. heavy metals contained in the iron ore tailings has been studied extensively, it was revealed that lfigher plants, Neyraudia reynaudiana (grass), Enteromorpha crinita and Chaetomorpha brychagona (green algae) growing on the tailings showed a high uptake of various heavy metals, Paphta sp. (clam) and Scopimera intermedia (crab) collected from the tailings also had elevated levels of various metals in their tissues (Wong & Li, 1977; Wong & Tam, 1977; Wong et al., 1978, in press). There is a lack of data as to the heavy metal contents in living organisms in other areas although a high level of several heavy metals (cadmium, iron and zinc) was recorded from water samples collected at Tai Po and Shatin which received water from Lain Tsuen River (8) and Shing Mon River (2) (Chart et al., 1974). In view of this, the analysis of heavy metal contents in the sea lettuce, Ulva latuca (green alga) collected from different sites within as well as outside ToM Harbour has been carried out, the results will be given in another paper.
40
Cd 6.17±0.98 5.32±0.88 3,43± 1 , 4 3 2.87±0.33 2.63±0.74 5.93±1.81 6.12 4-0 38 6,78+0.59
Cu
Pb
231.32& 13.1 187.31±27.3 68.44± 9.72 43.83±2.72 107.2+ 1.03 44.11±2.98 6.83 ± 1.07 20.21±3.94 16,94±2.53 32.62±2.32 29.51±0.84 50.28±3.94 52.40±1.21 77.23±9.31 61.45:t: 1.98 66.28±5.93
Conclusion According to the present investigation, it can be concluded that Lam Tsuen (8), Yuen Chau Tsai (7) and Shing Mon (2) were grossly polluted by both organic and inorganic contaminants. The iron ore railings also possessed a high level of various heavy metals in the sedument as well as the water. The rapid development of the satellite cities around Tolo Harbour, e.g. Tai Po, Shatin introduces the possibility of further deterioration of this delicate environment. A large reclamation scheme has been carried out at Tai Po for the development of a heavy industrial estate. Other industrial areas have also been developed and expanded. Although the treatment plant will remos, e nitrogen (but not phosphates) the large volume of domestic effluent will undoubtedly contribute a heavy nutrient load to the harbour, especially with the reduction in volume of the inlet as a result of extensive reclamation. Furthermore, no ultimate solution has been given as to the disposal of pig and poultry manure. No legislation has been set up to prevent the discharge of untreated wastes from the various industries. Beside strong legislations, a careful planning and management of the industrial areas and agricultural farms is equally important in the future town planning or rural development.
Allen, S. E., Grimshaw, H. M., Parkinson, J. A. & Quarmby, C. d974). ChemicalAnalysis of Ecological.h4aterial& Halsted Press, New York. Binne & Partners (1974). A Study of the Stream Pollution in New Terri,or/es. H.K. Hong Kong Government Press. Chen, J. P., Cheung, M. T. & Li, F. P. (1974). Mar. Pollut. Bull., 5, 171174. Environmental Resources Ltd. (1975). Control of the Environment in Hong Kong. Stage l Report. Secretary of the Environment, Hong Kong Government. Kueh, C. S. W. & Chart, K. Y. (1975). In Proc. PacificSci. Ass. Special Syrup. on Marine Sci., Hong Kong, pp. 95-99. Kueh, C. S. W. &Trott, L. B. (1974). Chung ChiJ., 12, 79-84. Mark, K. K. & Wan, S. L. (1975). J. Chinese Univ. Hong Kong, 2, 527534. Morton, B. & Wu, S. S. (1975). Envir. Res., tO, 319-349. Trott, L. B. & Fung, Y. C. (1971). Mar. Pollut. Bull., 4, 13-15. Wong, M. H. & Li, M. W. (1977,').Hydrobiology, 56,265-272. Wong, M. H. & Tam, F. Y. (1977). Envir. Pollut., 14, 24! -254. Wong, M. H., Young, Y. F., Wong, F. S. & Leung, K. N. (1977). Hydrobiology, 54, 141-143. Wong, M. H., Chan. K. C: & Choy, C. K. (1978). Envir. Res.. 15,342356. Wong, M. H., Chan, K. Y., Kwan, S. H. & Mo, C. F. (1979). Mar. Poilul. Bull., 10, 56-59. World Health Organization. (1958). International Standards for Drinking- water. Geneva. World Hezdth Organization. ( ]961 ). European Standards for Drinkingwaler. Geneva.