Paleolimnological evidence of variations in deposition of atmosphere-borne Polycyclic Aromatic Hydrocarbons (PAHs) in Ireland

Chemosphere 77 (2009) 1374–1380

Contents lists available at ScienceDirect

Chemosphere journal homepage: www.elsevier.com/locate/chemosphere

Paleolimnological evidence of variations in deposition of atmosphere-borne Polycyclic Aromatic Hydrocarbons (PAHs) in Ireland B. O’Dwyer *, D. Taylor Geography, School of Natural Sciences, Trinity College, University of Dublin, Dublin, Ireland

a r t i c l e

i n f o

Article history: Received 25 May 2009 Received in revised form 11 September 2009 Accepted 14 September 2009 Available online 12 October 2009 Keywords: Atmospheric contamination Fossil fuels Lake sediments Pollution

a b s t r a c t Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous in the environment and are produced by both natural and anthropogenic processes, principally from the incomplete combustion of organic matter. Levels of emissions of PAHs from the combustion of fossil fuels have increased rapidly over the last ca. 200 years. As PAHs have detrimental environmental and human health impacts, assessing spatial and temporal variations in environmental loadings has become a pressing issue in many industrialised and industrialising countries. The current paper reports spatial and temporal variations in levels of atmospheric deposition of PAHs recorded in sediment cores from three lakes in Ireland, the locations of which were selected on the basis of known geographic differences in the deposition of atmospheric pollutants. Thirteen PAH compounds were analysed for in samples of lake sediment that were assumed to represent contemporary/recent and historical (possibly reference) levels of deposition. A third sample was selected from each core on the basis of measured levels of spheroidal carbonaceous particles, which are regarded as a direct indicator of depositions from the industrial-level combustion of fossil fuels. Chronological control was provided by the 210Pb dating technique which also allowed for the calculation of PAH flux. For the most part, and when compared with the limited published data, measured levels of PAH depositions were relatively low. However, levels of deposition of PAHs in the west of Ireland are higher now than previously, which is in contrast to a general trend of decreasing levels in Europe. Ó 2009 Elsevier Ltd. All rights reserved.

1. Introduction The combustion of fossil fuels is a major source of environmental contaminants, including Polycyclic Aromatic Hydrocarbons (PAHs) (Hites et al., 1977; Srogi, 2007) which are of particular concern for aquatic ecosystems due to their persistence, toxicity and bioavailability (Fernandez et al., 2003). Polycyclic Aromatic Hydrocarbons can accumulate in living tissue and therefore pose a health risk to humans (Burton Jr, 2002). Pyrolytic PAHs are those produced during the combustion of fossil fuels at high-temperature. Once emitted, pyrolytic PAHs may occur in the gas phase or in association with atmospheric particulate matter, mainly in the sub-micron fraction, and can therefore be transported over large distances (Fernandez et al., 2003). PAHs can therefore potentially impact relatively remote sites, far from industrial or urban sources. Because of the potential for detrimental environmental and human impacts over large areas, the European Union recently issued a Directive (2004/107/EC) aimed at decreasing emissions of PAHs. However, there is little empirical evidence upon which to compare current ambient levels with past amounts of PAHs because the

* Corresponding author. Tel.: +353 861679840. E-mail address: [email protected] (B. O’Dwyer). 0045-6535/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2009.09.023

monitoring of PAHs has to date been poor (European Communities, 2001; Breivik et al., 2006). Evidence from cores of undisturbed and dated lake sediments has the potential to supplement existing information on spatial and temporal variations in the occurrence of PAHs and related atmospheric contaminants, such as heavy metals and Spheroidal Carbonaceous Particles (SCPs) (Gevao et al., 1998), linked to the combustion of fossil fuels. Once deposited in a lake, most PAHs are associated with the particulate phase, due to their sorptive properties (Fernandez et al., 1999), and have a short residence time before being incorporated in sediments (Wong et al., 1995). Once incorporated in the sediments, PAHs can persist, relatively unchanged chemically, for long periods of time (Punning et al., 2008). Moreover, owing to their nature of formation and similar physicochemical properties, groups of pyrolytic PAHs tend to co-occur in sediments and mixtures of pyrolytic PAHs deposited at sites are often remarkably constant in composition (Stout et al., 2001). Relatively little environmental monitoring had been carried out in Ireland until the early 1980s. This is particularly the case for atmospheric contaminants, and currently there is no programme for monitoring PAHs in ambient air. This paper describes palaeolimnological (i.e. lake sediment-based) data on spatial and temporal variations in depositions of PAHs in Ireland. The data allow the

1375

B. O’Dwyer, D. Taylor / Chemosphere 77 (2009) 1374–1380

comparison of current/recent levels of deposition with those that existed prior to increased levels of industrialisation, power generation in particular, and improved environmental legislation at three lakes in Ireland, and a basis for comparisons with other sites in Europe.

areas of both well-established deciduous woodland and conifer plantations (Quirke, 2001; Leira et al., 2006). The lake is ecologically important and supports populations of Salvelinus alpinus (Arctic char), which is otherwise rare in Ireland (Igoe et al., 2003). Proximate LPSs include those located on the Shannon estuary, ca. 70 km to the north, and, downwind of the site, Marina powerstation, ca. 85 km to the east. The cities of Cork (to the east) and Limerick (to the north) are within a radius of ca. 80–85 km, while the town of Killarney is ca. 15 km to the north.

2. Study sites The palaeolimnological research that underpins this paper focused on three oligotrophic (low nutrient status) lakes in Ireland (Fig. 1). The sites were selected for study on the basis of previously published research on the atmospheric loading of pollutants in Ireland (Bowman and Harlock, 1998; Aherne and Farrell, 2002; O’Dwyer, 2009) and the relatively undisturbed nature of their catchments. Kelly’s Lough is a small, humic lake located in the granitic Wicklow Mountains of eastern Ireland. The catchment for the lake largely comprises blanket bog and bare rock surfaces (Leira et al., 2007). An extensive conifer plantation extends to ca. 2 km from the western shoreline of the lake. The closest Large Point Sources (LPSs) of atmospheric pollutants are located in Dublin, ca. 45 km to the north. Furthermore, the air-shed for Kelly’s Lough extends eastwards to include sources of transboundary pollutant emissions located in western Britain. Basement rocks in the catchment for Lough Maumwee are also granitic and covered largely with shallow stony soils or blanket peat (Flower et al., 1994). The nearest major LPSs are located upwind of the site, ca. 90 km to the southeast on the Shannon, while also to the southeast are the cities of Galway (ca. 30 km) and Limerick (ca. 110 km). Upper Killarney Lough is the largest of the three study sites considered here. The catchment for the lake, far larger than for the two other study sites, is underlain by sandstones: blanket bog is extensive, and there are

3. Methods 3.1. Field-based methods Two sediment cores were collected from the deepest part of each lake, following an extensive bathymetric survey, using a prototype Renberg gravity corer fitted with either a 0.5 or 1 m-long coring tube (Renberg and Hansson, 2008) in January 2005 (Kelly’s Lough), March 2005 (Lough Maumwee) and May 2006 (Upper Killarney Lough). Sediment cores collected from Kelly’s Lough, Lough Maumwee and Upper Killarney Lough extended to depths of, respectively, 31, 32 and 30 cm. Sediment cores were sampled in the field immediately following collection, with samples wrapped in tin-foil pre-rinsed with acetone, sealed in zip-lock bags, and stored at low temperature. 3.2. Laboratory-based methods 3.2.1. Chronological control 3.2.1.1. 210Pb, 226Ra, 137Cs and SCP analysis. Sediment accumulation rates and geochronologies for the sediment cores were determined by 210Pb and 226Ra analyses, while 137Cs analysis was also under-

Wind direction frequency (Claremorris)

Wind direction frequency(Dublin Airport) North 15% Northwest

10%

55

Northeast

North 20%

5% West

0%

Northwest

East

Northeast 10%

Southwest

Southeast

West

0%

East

South

Southwest

WAPDR

Southeast

54

South

Lough Maumwee

EAPDR Galway

Dublin urban area

Wind direction frequency (Valentia)

53

Shannon-based industries Kelly’s Lough

North Northwest

10%

Northeast

Limerick

5% West

0%

Southwest

Long-range transport of pollutants originating from Britain and mainland Europe

East

Southeast

Upper Killarney Lough

Cork

52

South

SWAPDR Marina

51 0

10

09

08

85

07

170

06

340 Kilometers

05

Fig. 1. Map of Ireland showing the locations of the three study sites and local prevailing wind direction. Major urban and industrial areas and the regions previously identified as being in receipt of atmospheric deposition of pollutants from differing sources and of differing levels are also shown: EAPDR = eastern atmospheric pollutant deposition region; WAPDR = western atmospheric pollutant deposition region and SWAPDR = southwestern atmospheric pollutant deposition region.

1376

B. O’Dwyer, D. Taylor / Chemosphere 77 (2009) 1374–1380

taken on selected subsamples from the Kelly’s Lough core. Lough Maumwee and Upper Killarney Lough sediments were analysed for 210Pb indirectly through the determination of 210Po, a granddaughter isotope of 210Pb, as outlined by Eakins and Morrison (1978); analysis was conducted using Ortec ‘Ortet’ alpha spectrometry. For Kelly’s Lough samples, the activities of 210Pb, 226Ra and 137 Cs were determined by low-energy photon spectrometry, as outlined by Joshi (1987). The reliability of the 210Pb estimated chronologies and accumulation rates was assessed through reference to the activity profile of 137Cs for sediments from Kelly’s Lough, and with reference to precisely dated profiles of SCP variations from other lake sites in Ireland (Rose et al., 1995). Up-core variations in the relative proportions of inorganic and organic matter were used to extend chronological control to the other cores from the same site (Carol et al., 1998; Brancelj et al., 2002) and to highlight sediment in wash as a result of catchment instability. They were established following the gravimetric method outlined in Dean (1974) for 0.5 cm-thick contiguous slices of sediment for the uppermost 10 cm of each of the total of six cores analysed and for 1 cm-thick slices thereafter.

was reduced under a vacuum (<30 °C) to ca. 1 mL and transferred to a pre-cleaned vial. Aliquots (1.0 ll) of selected aromatic fractions of sediment, dissolved in dichloromethane, were analysed by GC–MS using a Perkin Elmer Turbomass Gold mass spectrometer with Turbomass version 4.4 data system. The injector was splitless at 325 °C and the column used was a 30 m  0.32 mm id. X0.25 lm d.f J & W DB5MS. The temperature program was 35 °C (1 min)-100 °C at 45 °C min 1, 100–325 °C at 8 °C min 1, 325 °C (10 min) and helium was the carrier gas (1.5 mL min 1). The following mass range was used for identification: 128.1, 136.1, 142.1, 152.1, 154.1, 156.1, 166.1, 170.1, 178.1, 184.1, 188.1, 192.1, 198.1, 202.2, 206.2, 212.2, 220.2, 226.2, 228.2, 252.2, 276.2 and 278.2 (dwell time of 0.03 s; inter-scan delay of 0.001 s). Quantification of the PAHs was performed against the appropriate deuterated internal standard and procedural blanks were analysed in parallel. To facilitate intra- and inter-site comparisons, and to account for variations in sediment accumulation rate, PAH data are expressed as individual and total amounts of pyrolytic compounds in accumulation (influx) form (Geschwend and Hites, 1981; Fernandez et al., 2000; Quiroz et al., 2005).

3.3. PAH analysis 4. Results Samples were analysed for 13 parent PAH compounds (naphthalene, phenanthrene, fluorene, anthracene, flouranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, dibenzo(a,h) anthracene, benzo(ghi)perylene). sourced predominately from processes of fossil fuel combustion (Fernandez et al., 2002). Analysis was undertaken at M-Scan Ltd., Berkshire, United Kingdom following extraction using ultra-sonication (Zhou and Maskaoui, 2003). Three samples of sediment were analysed per lake site (nine samples in total): surface and basal sediment core samples were analysed in order to determine, respectively, contemporary/recent and historical (possibly reference) levels. The third sample was selected at each site on the basis of the depth of occurrence of maximum measured abundances of SCPs, a direct by-product of the industrial-scale combustion of fossil fuels (O’Dwyer, 2009), which occurred at sample depths of 14–15 cm, 10–11 cm and 15–16 cm for sediments collected from, respectively, Kelly’s Lough, Lough Maumwee and Upper Killarney Lough. Prior to extraction, 8 lg each of heptamethylnonane, chloro-octadene and squalene and 2 lg each of d8-naphthalene, d10-anthracene and d10-pyrene were added as internal standards. 80 mL of isoproponal and 20 mL of hexane were added to the sample, which was then extracted using ultra-sonication (2  5 min, stirring in between) and then centrifuged at 1500 rpm for 10 min. The extract was then decanted, and partitioned between water and pentane (2:3 v/v 120 mL). The organic layer was collected in a pre-cleaned, 500 mL round-bottom flask. A further 100 mL isopropanol/hexane (4:1) was added to the sediment, and the extraction procedure was repeated, omitting addition of the internal standards. The organic layers were combined, and washed. The extract was reduced to 5–10 mL under a vacuum (<30 °C, Büchi Rotovap R110). The total organic extract was saponified by adding ca. 1 mL of aqueous potassium hydroxide (60% w/v) and ca. 5 mL of ethanol, followed by incubation at room temperature for 24 h. The mixture containing PAHs was extracted by water partitioning. The pentane layer was separated and reduced by rotary-evaporation to ca. 2 mL. The resulting total neutral fraction was fractionated by column chromatography. Pentane (40 mL) was used to elute the aliphatic fraction, followed by 50 mL of dichloromethane to elute the aromatic fraction. The fractions were collected in pre-cleaned 100 mL round-bottom flasks. The solvent

4.1. Chronological control 4.1.1. 210Pb, 226Ra, 137Cs and SCP analysis For all three sites, measured levels of excess 210Pb show an exponential decline with depth indicating that at all three sites sediment accumulation rate has been relatively constant and that catchment disturbance has been minimal. Levels of excess 210Pb suggest a relatively uniform sediment accumulation rate of 0.034 g cm 2 y 1 at Kelly’s Lough. With greater variation evident at Lough Maumwee (0.012–0.028 g cm 2 y 1) and Upper Killaroverall, but 0.031– ney Lough (0.0437 g cm 2 y 1 2 1 in the uppermost 12 cm of the core) (and see 0.053 g cm y O’Dwyer (2009) for more information). Based on these rates, the estimated ages of the basal sample of each core examined are ca. 1945, 1900/pre-1900 and ca. 1920, for Kelly’s Lough, Lough Maumwee, and Upper Killarney Lough, respectively. The sediment accumulation rates were also used to estimate the age of sediment samples analysed for their content of PAHs. 4.2. PAH analysis 4.2.1. Total PAH Levels of total PAHs are highest at each site in the sample from Lough Maumwee dated ca. 2002, Kellys Lough ca. 1980 and Upper Killarney ca. 1920 (Table 1). Highest levels were measured in the sample from Kellys Lough (9972 ng g 1; 339 ng cm 2 y 1), while highest levels measured at Upper Killarney and Lough Maumwee were lower (respectively, 3732 ng g 1, 141 ng cm 2 y 1 and 3576 ng g 1, 58 ng cm 2 y 1). In addition, for Kelly’s Lough and Lough Maumwee samples, highest measured levels of PAHs coincided with those of SCPs. The highest value for contemporary/recent deposition was measured at Lough Maumwee (2897 ng g 1; 47 ng cm 2 y 1), while the lowest was observed for Upper Killarney Lough (548.1 ng g 1; 27 ng cm 2 y 1). 4.3. Individual PAH compounds Inter-sample differences in levels of individual PAHs at the three study sites are in agreement with those of total PAH, which is suggestive of a common source.

1377

B. O’Dwyer, D. Taylor / Chemosphere 77 (2009) 1374–1380 Table 1 Concentration and accumulation rate data for levels of total PAH measured in samples of sediment from the three study sites. Measured levels of total PAH Concentration (ng g

1

)

Accumulation rate (ng cm 2 y

Kelly’s Lough ca. 2005 (0–1 cm) ca. 1980 (14–15 cm) ca. 1945 (30–31 cm) Lough Maumwee

3000 5900 1100

33 200 105

ca. 2002 (0–1 cm) ca. 1977 (10–11 cm) ca. 1900 (30–31 cm)

2910 532 150

47 8 4

Upper Killarney Lough ca. 2006 (0–1 cm) ca. 1969 (15–16 cm) ca. 1920 (30–31 cm)

550 1240 1850

27 43 71

the sample dated ca. 1920 and lowest in the sample dated ca. 2006. Fluorene shows the opposite profile. 5. Discussion

1

)

The majority of PAHs measured in material from Kelly’s Lough are higher in the sample dated ca. 1980 than those dated ca. 1945 and ca. 2005 (Table 2). Fluorene and phenanthrene show exception to this, showing highest levels in the sample dated ca. 1945. At Lough Maumwee, levels of all PAHs are lowest in the sample dated pre-1900 and highest in the sample relating to contemporary/recent conditions (ca. 2002 in this case). Fluorene was not detected in the sample dated pre-1900, but was found to be present in minute amounts (0.0232 ng g 1) in the sample dated ca. 1980. The absence of fluorene could reflect the limit of detection (0.01 ng g 1) associated with the technique. In contrast, at Upper Killarney Lough levels of all PAHs, except fluorene, are highest in

Inter-site differences in the measured contemporary/recent depositions of PAHs reflect geographic differences in both atmospheric pollution loads and sources repeated in other sedimentbased proxies (O’Dwyer, 2009). At Kelly’s Lough, highest levels of all PAHs analysed, with the exception of fluorene and phenanthrene, date to ca. 1980. Fluorene and phenanthrene are low molecular weight (LMW) PAHs and may therefore be particularly susceptible to post-depositional processing, remobilisation and bio-geochemical recycling (Gevao et al., 1998). In addition, temperature is the main controlling factor on the deposition fluxes of LMW PAHs (Fowler and Batterbee, 2005). Eastern Ireland receives pollutants originating in Britain and continental Europe (Bowman and Harlock, 1998; Aherne and Farrell, 2002; O’Dwyer, 2009) and these transboundary sources are a likely source of some of the PAHs deposited at Kelly’s Lough. This is particularly the case in the sample dated ca. 1945, when industrial activity in Ireland was at a low level relative to areas to the east. Moreover, relatively high levels of PAHs in the sample dated ca. 1980 coincide with the European SO2 emissions peak (1980), according to Mylona (1993). Reduced PAHs have been detected in lake sediments post-1980 across Europe, as a result of legislative measures, changes in the types of fuel combusted, and the introduction of new technologies aimed at decreasing pollutant emissions (Gevao et al., 1998; Muri et al., 2006). Lower contemporary/recent levels when compared to those of ca. 1980 are also evident at Kelly’s Lough. Levels of PAHs recorded at Lough Maumwee, pre-1900 and ca. 1980 are slightly higher than those considered as background for

Table 2 Concentration and accumulation rate data for measured levels of the 13 individual PAH compounds analysed for all samples of sediment from all three study sites. Conc = concentration data (ng g 1); Accum = accumulation rate data (ng cm 2 y 1). Kelly’s Lough

Lough Maumwee

Upper Killarney Lough

ca. 2005

ca. 1980

ca.1945

ca. 2002

ca. 1977

ca. 1900

ca. 2006

ca. 1969

ca. 1920

Phenathrene

Conc Accum

1.61 97

3.23 370

5.23 520

0.78 120

0.22 24

0.07 12

0.74 25

0.91 50

2.54 330

Fluorene

Conc Accum

0.12 4.1

0.45 13

0.49 14

0.06 3.9

0.02 1.6

0.00 0

0.25 5

0.08 2.4

0.09 2.4

Anthracene

Conc Accum

0.00 0

0.18 5.2

0.11 3.2

0.08 4.7

0.02 1.1

0.02 0.71

0.07 1.4

0.10 2.8

0.28 7.3

Fluoranthene

Conc Accum

4.56 150

29.52 860

20.22 580

3.24 200

0.75 52

0.20 7.5

2.26 46

4.20 120

7.70 200

Pyrene

Conc Accum

2.37 78

16.47 480

12.90 370

3.08 190

0.57 39

0.26 10

1.82 37

2.84 81

6.93 180

Benzo(a)anthracene

Conc Accum

0.40 13

5.15 150

3.49 100

0.78 48

0.14 9.9

0.05 1.8

0.49 10

1.09 31

3.31 86

Chrysene

Conc Accum

4.87 160

37.75 1100

15.69 450

5.99 370

0.90 62

0.63 24

1.53 31

5.25 150

6.93 180

Benzo(b)fluoranthene

Conc Accum

10.34 340

54.92 1600

23.70 680

15.39 950

2.47 170

1.41 54

4.92 100

12.95 370

15.40 400

Benzo(k)fluoranthene

Conc Accum

1.61 53

12.70 370

4.88 140

2.27 140

0.28 19

0.15 5.8

0.84 17

2.56 73

3.73 97

Benzo(a)pyrene

Conc Accum

0.58 19

6.86 200

2.96 85

1.41 87

0.29 20

0.10 4

0.84 17

1.75 50

4.62 120

Indeno(1,2,3-cd)pyrene

Conc Accum

3.01 99

17.16 500

7.67 220

7.61 470

1.10 76

0.39 15

1.97 40

6.30 180

10.01 260

Dibenzo(a,h)anthracene

Conc Accum

0.30 10

2.78 81

0.70 20

0.63 39

0.09 6.2

0.04 1.7

0.23 4.7

0.56 16

1.12 29

Benzo(ghi)perylene

Conc Accum

2.31 76

12.70 370

6.97 200

5.51 340

0.84 58

0.31 12

1.67 34

4.55 130

8.09 210

1378

B. O’Dwyer, D. Taylor / Chemosphere 77 (2009) 1374–1380

Europe (20–100 ng g 1) (Fernandez et al., 2000; Muri et al., 2006). Much higher levels measured in the sample dated ca. 2002 could be a result of either increased levels of atmospheric deposition or peat erosion. PAHs show a high affinity for organic matter and catchment soils provide a good environmental compartment for the storage of atmospherically deposited PAHs (Grimalt et al., 2004). Therefore, increased levels of catchment peat erosion can result in the increased delivery of PAHs to lake sediments (Muri et al., 2006). However, in this case, increased levels of atmospheric deposition would seem more likely as evidence from the results of 210 Pb analysis indicate that sediment accumulation has remained relatively constant at the site, indicating little increase in levels of peat erosion. Moreover, maximum measured levels of PAHs are coincident with enhanced levels of SCPs (O’Dwyer, 2009). Increasing industrialisation of the Shannon estuary has occurred over the last two decades and represents a possible source of both SCPs and PAHs to the site. For example, PAHs are formed when coal is burned to generate power (Neff, 1979; Donahue et al., 2006). Moneypoint coal-fired power station, Ireland’s largest point source emitter, was commissioned on the Shannon estuary in the early 1980s. The lowest measured levels of PAHs in the surficial sediment sample for Upper Killarney Lough, when compared with sediment

samples dating to the late 1960s and early 20th century are in keeping with evidence from many European lake sites. For example, highest PAH concentrations were observed at lakes in Gredos, Sierra Estrella, Mid-Norway, and north west Scotland in the period 1919–1932 (Fernandez et al., 2000; Rose and Rippey, 2002) and could reflect widespread and substantial increases in deposition of PAHs at the turn of the 20th century linked to industrialisation and weak pollution control (Rose and Rippey, 2002). In the case of Upper Killarney Lough, however, relatively high depositions of PAHs may reflect the past occurrence of fires. Woodland management practices in southwestern Ireland have frequently involved the use of fire and this is particularly the case for the area surrounding Upper Killarney Lough (Mitchell, 1988, 1990). Biomass burning can represent a significant source of PAHs (Mandalakis et al., 2005). The different patterns of temporal variations in depositions of PAHs at the three study sites suggest broadly different LPSs. The situation at Kelly’s Lough reflects European trends in levels of atmospheric PAH contamination, suggesting that eastern Ireland receives PAHs from a combination of local and transboundary sources. In the west, PAH data indicate that Upper Killarney Lough, and perhaps southwestern Ireland more generally, has remained relatively un-impacted by any specific and identifiable source of

Fig. 2. Accumulation rates of PAHs measured in surficial sediment samples from the three study sites. Published levels of PAH accumulation measured in samples of surficial lake sediments from a range of sites throughout Europe, as reported by Fernandez et al. (1999), are also shown. The accumulation rate measured for surface sediment samples from Lake Arresjøen (Svalbard) is also included as an inset.

B. O’Dwyer, D. Taylor / Chemosphere 77 (2009) 1374–1380

emission, with measured levels of PAHs in the three sediment samples analysed similar to background. Lough Maumwee, by comparison, may have been relatively un-impacted by PAHs until increased industrialisation centred on the Shannon estuary from the early 1980s. The atmospheric pollution effects may not be evident at Upper Killarney to the southwest because the prevailing wind direction disperses pollutants from the Shannon estuary in a northerly direction. PAH analysis has only been undertaken at one other lake site in Ireland (Lough Maam, northwestern Ireland) where surficial concentrations of total PAH were measured at 2900 ng g 1 (150 ng cm 2 y 1) (Fernandez et al., 1999). All lake sites examined in this study exhibit lower surficial total PAH deposition fluxes: Lough Maumwee (2897 ng g 1; 46.82 ng cm 2 y 1); Upper Killarney (548 ng g 1; 28 ng cm 2 y 1); and Kellys Lough (1097 ng g 1; 37 ng cm 2 y 1). Furthermore, and as illustrated in Fig. 2, although comparisons can be complicated by the different analytical methods used and PAHs quantified, levels of PAHs determined in the current study are relatively low when compared with the results of similar studies from elsewhere in Europe. For example, the lowest recorded contemporary total PAH flux is reported in Lake Arresjoen on Svalbard (6.9 ng cm 2 y 1), while lakes in west and central Europe exhibit average total PAH deposition fluxes of 76 ng cm 2 y 1 (Fernandez et al., 1999).

6. Conclusion This study provides the first results on spatial and temporal variations in depositions of PAHs in Ireland. The palaeolimnological approach has previously been utilised in North America (Lima et al., 2003; Van Metre and Mahler, 2005; Donahue et al., 2006) and Europe (Fernandez et al., 1999, 2000, 2002; Muri et al., 2006) to reconstruct past levels of atmospheric depositions of PAHs. This study therefore provides further support for the potential of palaeolimnological approaches to complement and supplement data acquired from traditional environmental monitoring programmes, and reveals important differences in the history of depositions of PAHs in Ireland. Acknowledgements The research presented here would not have been possible without the generous support of the EPA, and the authors would like to thank in particular Jim Bowman, Alice Wemaere, Paul Toner and Shane Colgan. Thanks are also due to Manel Leira, Richard McFaul, Pete Rodgers, Elaine Treacy, Phil Jordan, Catherine Dalton and Conor Quinlan for help with fieldwork. Barry O’Dwyer received financial support from the EPA through a PhD scholarship (2004PHD4-2-M1). References Aherne, J., Farrell, E.P., 2002. Deposition of sulphur, nitrogen and acidity in precipitation over Ireland: chemistry, spatial distribution and long-term trends. Atmos. Environ. 36, 1379–1389. Bowman, J.J., Harlock, S., 1998. The spatial distribution of characterised fly-ash particles and trace metals in lake sediments and catchment mosses: Ireland. Water Air Soil Pollut. 106, 263–286. Brancelj, A., Sisko, M., Muri, G., Appleby, P., Lami, A., Shilland, E., Rose, N.L., Kamenik, C., Brooks, S.J., Dearing, J.A., 2002. Lake Jezero v Ledvici (NW Slovenia) – changes in sediment records over the last two centuries. J. Paleolimnol. 28, 47–58. Breivik, K., Vestreng, V., Rozovskaya, O., Pacyna, J.M., 2006. Atmospheric emissions of some POPs in Europe: a discussion of existing inventories and data needs. Environ. Sci. Policy 9, 663–674. Burton Jr, G.A., 2002. Sediment quality criteria in use around the world. Limnology 3, 65–75. Carol, D., Dearing, J., Roberts, R., 1998. Land-use history and sediment flux in a lowland lake catchment: Groby Pool, Leicestershire, UK. Holocene 8, 383–394.

1379

Dean, W.E., 1974. Determination of carbonate and organic matter in calcareous sediments and sedimentary rocks by loss on ignition: comparison with other methods. J. Sediment. Petrol. 44, 242–248. Donahue, W.F., Allen, E.W., Schindler, D.W., 2006. Impacts of coal-fired powerplants on trace metals and polycyclicaromatic hydrocarbons (PAHs) in lake sediments in central Alberta, Canada. J. Paleolimnol. 35, 111–128. Eakins, J.D., Morrison, R.T., 1978. A new procedure for the determination of lead-210 in lake and marine sediments. Int. J. Appl. Radiat. Isotopes 29, 531–536. European Communities, 2001. Ambient Air Pollution by Polycyclic Aromatic Hydrocarbons (PAHs): Position Paper. Luxembourg, 44 p. Fernandez, P., Villanova, R.M., Grimalt, J.O., 1999. Sediment fluxes of polycyclic aromatic hydrocarbons in European high altitude mountain lakes. Environ. Sci. Technol. 33, 3719–3722. Fernandez, P., Vilanova, R.M., Martinez, C., Appleby, P., Grimalt, J.O., 2000. The historical record of atmospheric pyrolytic pollution over Europe registered in the sedimentary PAH from remote mountain lakes. Environ. Sci. Technol. 34, 1906–1913. Fernandez, P., Rose, N.L., Villanova, R.M., Grimalt, J.O., 2002. Spatial and temporal comparison of polycyclic aromatic hydrocarbons and spheroidal carbonaceous particles in remote European mountain lakes. Water Air Soil Pollut. Focus 2, 261–274. Fernandez, P., Carrera, G., Grimalt, J.O., 2003. Factors governing the atmospheric deposition of polycyclic aromatic hydrocarbons to remote areas. Environ. Sci. Technol. 37, 3261–3267. Flower, R.J., Rippey, B., Rose, N.L., Appleby, P.G., Battarbee, R.W., 1994. Palaeolimnological evidence for the acidification of lakes by atmospheric pollution in western Ireland. J. Ecol. 82, 581–596. Fowler, D., Battarbee, R., 2005. Climate change and pollution in the mountains: the nature of change. In: Thompson, D.B.A., Price, M.F. (Eds.), Galbraith Mountains of Europe: Conservation Management, People and Nature. TSO Scotland, Edinburgh, pp. 71–88. Geschwend, P.M., Hites, R.A., 1981. Fluxes of the polycyclic aromatic compounds to marine and lacustrine sediments in the northeastern United States. Geochim. Cosmochim. Acta 45, 2359–2367. Gevao, B., Jones, K.C., Hamilton-Taylor, J., 1998. Polycyclic aromatic hydrocarbon (PAH) deposition to and processing in a small rural lake, Cumbria, UK. Sci. Total Environ. 215, 231–242. Grimalt, J.O., van Drooge, B.L., Ribes, A., Fernández, P., Appleby, P., 2004. Polycyclic aromatic hydrocarbon compositions in soils and sediments of high altitude lakes. Environ. Pollut. 131, 13–24. Hites, R.A., Laflamme, R.E., Farrington, J.W., 1977. Sedimentary polycyclic aromatic hydrocarbons: The historical record. Science 198, 829–831. Igoe, F., O’Grady, D., Tierney, D., Fitzmaurice, P., 2003. Arctic Char Salvelinus alpinus (L.) in Ireland – a millennium review of its distribution and status with conservation recommendations. Proc. Roy. Irish Acad. B 103, 9–22. Joshi, S.R., 1987. Nondestructive determination of lead-210 and radium-226 in sediments by direct photon analysis. J. Radioanal. Nucl. Chem. 116, 169– 182. Leira, M., Jordan, P., Taylor, D., Dalton, C., Bennion, H., Rose, N., Irvine, K., 2006. Assessing the ecological status of candidate reference lakes in Ireland using palaeolimnology. J. Appl. Ecol. 43, 816–827. Leira, M., Cole, E.E., Mitchell, F.J.G., 2007. Peat erosion and atmospheric deposition on an oligotrophic lake in eastern Ireland. J. Paleolimnol. 38, 49–71. Lima, A.L.C., Eglinton, T.I., Reddy, C.M., 2003. High-resolution record of pyrogenic polycyclic aromatic hydrocarbon deposition during the 20th century. Environ. Sci. Technol. 37, 53–61. Mandalakis, M., Gustafsson, Ö., Alsberg, T., Egebä, A.-L., Reddy, C.M., XU, L., Klanove, J., Holoubek, I., Euripides, G.S., 2005. Contribution of biomass burning to atmospheric polycyclic aromatic hydrocarbons at three European background sites. Environ. Sci. Technol. 39, 2976–2982. Mitchell, F.J.G., 1988. The vegetational history of the Killarney oakwoods, SW Ireland: evidence from fine spatial resolution pollen analysis. J. Ecol. 76, 415– 436. Mitchell, F.J.G., 1990. The impact of grazing and human disturbance on the dynamics of woodland in SW Ireland. J. Veg. Sci. 1, 245–254. Muri, G., Wakeham, S.G., Rose, N.L., 2006. Records of atmospheric delivery of pyrolysis-derived pollutants in recent mountain lake sediments of the Julian Alps (NW Slovenia). Environ. Pollut. 139, 461–468. Mylona, S., 1993. Trends of Sulphur Dioxide Emissions, Air Concentrations and Depositions of Sulphur in Europe Since 1880. EMEP/MSC-W 2/93. EMEP. Neff, J.M., 1979. Polycyclic Aromatic Hydrocarbons in the Aquatic Environment: Sources, Fates and Biological Effects. Applied Science Publishers, London. O’Dwyer, B., 2009. Lake sediment-based reconstructions of variations in levels of deposition of atmospheric pollutants from the industrial-scale combustion of fossil fuels and ecosystem response at three Irish lake sites. Unpublished PhD thesis, Trinity College Dublin. Punning, J.-M., Terasmaa, J., Vaasma, T., Kapanen, G., 2008. Historical changes in the concentrations of polycyclic aromatic hydrocarbons (PAHs) in Lake Peipsi sediments. Environ. Monitor Assess. 144, 131–141. Quirke, B., 2001. Killarney National Park: A Place to Treasure. The Collins Press, Cork. Quiroz, R., Popp, P., Urrutia, R., Bauer, C., Araneda, A., Treutler, H.-C., Barra, R., 2005. PAH fluxes in the Laja Lake of south central Chile Andes over the last 50 years: evidence from a dated sediment core. Sci. Total Environ. 349, 150– 160. Renberg, I., Hansson, H., 2008. The HTH sediment corer. J. Paleolimnol. 40, 655–659.

1380

B. O’Dwyer, D. Taylor / Chemosphere 77 (2009) 1374–1380

Rose, N.L., Harlock, S., Appleby, P.G., Battarbee, R.W., 1995. Dating of recent lake sediments in the United Kingdom and Ireland using spheroidal carbonaceous particle (SCP) concentration profiles. Holocene 5, 328–335. Rose, N.L., Rippey, B., 2002. The historical record of PAH, PCB, trace metal and flyash particle deposition at a remote lake site in north-west Scotland. Environ. Pollut. 117, 121–132. Srogi, K., 2007. Modelling of environmental exposure to polycyclic aromatic hydrocarbons: a review. Environ. Chem. Lett. 5, 169–195. Stout, S.A., Uhler, A.D., Boehm, P.D., 2001. Recognition of and allocation among multiple sources of PAH in urban sediments. Environ. Claim. J. 13, 141–158.

Van Metre, P.C., Mahler, B.J., 2005. Trends in hydrophobic organic contaminants in urban and reference lake sediments across the United States, 1970–2001. Environ. Sci. Technol. 39, 5567–5574. Wong, C.S., Sanders, G., Engstrom, D.R., Long, D.T., Swackhamer, D.L., Eisenreich, S.J., 1995. Accumulation, inventory and diagenesis of chlorinated hydrocarbons in Lake Ontario sediments. Environ. Sci. Technol. 29, 2661–2672. Zhou, J.L., Maskaoui, K., 2003. Distribution of polycyclic aromatic hydrocarbons in water and surface sediments from Daya Bay, China. Environ. Pollut. 121, 269– 281.