The chemical response of particle-associated contaminants in aquatic sediments to urbanization in New England, U.S.A

Relations between urbanization and particle-associated contaminants in New England were evaluated using a combination of samples from sediment cores, streambed sediments, and suspended stream sediments. Concentrations of PAHs, PCBs, DDT, and seven trace metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) were correlated strongly with urbanization, with the strongest relations to percentage commercial, industrial, and transportation (CIT) land use. Average PAH and metal concentrations in the most urbanized watersheds were approximately 30 and 6 times the reference concentrations, respectively, in remote, undeveloped watersheds. One-quarter to one-half of sampling sites had concentrations of PAHs, Cu, Pb, or Zn above the probable effects concentration, a set of sediment quality guidelines for adverse effects to aquatic biota, and sediments were predicted to be toxic, on average, when CIT land use exceeded about 10%. Trends in metals in cores from urban watersheds were dominantly downward, whereas trends in PAHs in a suburban watershed were upward. A regional atmospheric-fallout gradient was indicated by as much as order-of-magnitude-greater concentrations and accumulation rates of contaminants in cores from an undeveloped reference lake in Boston compared to those from remote reference watersheds. Contaminant accumulation rates in the lakes with urbanization in their watersheds, however, were 1-3 orders of magnitude greater than those of reference lakes, which indicate the dominance of local sources and fluvial transport of contaminants to urban lakes. These analyses demonstrate the magnitude of urban contamination of aquatic systems and air sheds, and suggest that, despite reductions in contaminant emissions in urban settings, streams and lakes will decline in quality as urbanization of their watersheds takes place.     

Contamination in sediments, bivalves and sponges of McMurdo Sound, Antarctica

This study examined the concentrations of total hydrocarbons (THC), polychlorinated biphenyls (PCB), polyaromatic hydrocarbons (PAH), and trace metals (Cu, Zn, Cd, Pb, Hg and As) in marine sediments off Scott Base (NZ) and compared them with sediments near the highly polluted McMurdo Station (US) as well as less impacted sites including Turtle Rock and Cape Evans. The Antarctic mollusc, Laternula elliptica and three common sponge species were also analysed for trace metals. The mean THC concentration in sediments from Scott Base was 3 fold higher than the pristine site, Turtle Rock, but 10 fold lower than samples from McMurdo Station. McMurdo Station sediments also contained the highest concentrations of PAHs, PCBs and the trace metals, Cu, Zn, Pb, Cd and Hg. Copper was significantly higher in bivalves from McMurdo Station than other sites. Trace metal concentrations in sponges were generally consistent within sites but no spatial patterns were apparent.     

Mussel-based monitoring of trace metal and organic contaminants along the east coast of China using Perna viridis and Mytilus edulis

Green lipped mussels, Perna viridis, and blue mussels, Mytilus edulis, were collected from seven locations along the east coast of China in September and October 2001. The mussel tissues were analyzed for metals (Ag, As, Cd, Cr, Ni, Pb, Se, Zn, Cu, Fe and Hg), and trace organic contaminants including organochlorine compounds (OCs), polycyclic aromatic hydrocarbons (PAHs; based on 24 individual PAHs), polychlorinated biphenyls (PCBs) and petroleum hydrocarbons (PHCs). Maximum concentrations of Ag, As, Cd, Cr, Ni, Pb, Se, Zn, Cu, Fe and Hg in the mussel tissues were 0.14, 26.76, 5.31, 15.72, 4.78, 2.93, 7.40, 231.0, 54.17, 1002 and 317.3 microg/g dry weight respectively. Levels of DDTs, PAHs, PCBs and PHCs in the mussel samples were 14-640, 456-3495, 1-13 ng/g and 621-2863 microg/g dry weight, respectively. Results of this study indicated that contaminant levels were, in general, higher or at least comparable to those reported in other local or regional studies. Mussel samples collected in Chongming Dao in Shanghai and Jiao Zhou Wan in Qingdao had significantly higher levels of metal and trace organic contaminants among the seven sampling stations. Examination of the contaminant profiles suggests that PHCs originated from petrogenic sources, while both petrogenic and pyrolytic sources were important for PAHs. The generally high levels of metals and organochlorine compounds are probably the result of increasingly intense industrial activities along the east coast of China. An assessment of potential risks to human health due to consumption of the mussels was undertaken for the metals, PCBs, DDTs and chlordanes, and the results indicated that all metals, except Ni, could pose a health risk to heavy seafood consumers, while Hg appears to be of concern even for low level consumers.     

Evaluating the size distribution characteristics and sources of atmospheric trace elements at two mountain sites: comparison of the clean and polluted regions in China

Size-resolved trace metal concentrations at two background sites were assessed during a 1-year observation campaign, with the measurements performed in parallel at two mountain sites, where Mt. Dinghu (DHS) located in the rural region of Pearl River Delta (PRD) and Mt. Gongga (GGS) located in the Tibetan Plateau region. In total, 15 selected trace elements (Mg, Al, K, V, Mn, Fe, Cu, Zn, As, Mo, Ag, Cd, Ba, Tl, and Pb) in aerosol samples were determined using inductively coupled plasma mass spectrometry (ICPMS). The major metals in these two mountain sites were Fe, K, Mg, and Ca with concentrations ranging between 241 and 1452 ng/m³, 428 and 1351 ng/m³, 334 and 875 ng/m³, and 376 and 870 ng/m³, respectively, while the trace metals with the lowest concentrations were Mo, Ag, Cd, and Tl with concentrations lower than 4 ng/m³ in DHS and 2 ng/m³ in GGS. The pronounced seasonal variability in the trace elements was observed in DHS, with lower concentrations in spring and summer and relatively high in winter and autumn, whereas seasonal variance of trace elements is hardly observed in Mt. Gongga. The size distribution pattern of crustal elements of Al, Mg, K, Ba, and Fe was quite similar in DHS and GGS, which were mainly found in coarse particles peaked at 4.7–5.8 μm. In addition, V, Mo, Ag, and Tl were also concentrated in coarse particles, although the high enrichment factor (EF?>?100) of which suggested anthropogenic origin, whereas trace metals of Cd, Mn, Zn, As, Cu, and Pb concentrated in fine mode particles. Specifically, these trace metals peak at approximately 1.5 μm in DHS, while those in GGS peaked at diameter smaller than 0.3 μm, indicating the responsible for long-range transport from the far urban and industrialized areas. Multivariate receptor model combined with the enrichment factor results demonstrated that the trace elemental components at these two background sites were largely contributed from the fossil fuel combustion (55.4% in DHS and 44.0% in GGS) and industrial emissions factors (20.1% vs. 26.5%), which are associated with long distance transport from the coastal area of Southeast China and the Northwestern India, respectively, as suggested by the backward air mass trajectory analysis. Local sources from soil dust contributed a minor variance for trace elements in DHS (9.7%) and GGS (13.8%), respectively.

     

Specific accumulation of 20 trace elements in great cormorants (Phalacrocorax carbo) from Japan

This study is to elucidate the specific accumulation of 20 trace elements in tissues/organs of great cormorants from two different colonies (Lake Biwa and Mie) in Japan. In the body distribution of trace elements, some elements revealed tissue-specific accumulation such as most of the burden of Mo, Ag and Cd in liver, Tl and Cd in kidney, Cu, Rb and Cs in muscle, and V, Sr and Ba in bone. Gender-related variation was not observed in both populations for most of the trace elements, except for higher hepatic Sr in males from Lake Biwa. Hepatic V, muscular Hg and Tl, and Cd in liver, kidney and muscle increased with growth. Comparison of trace element levels in tissues between the two colonies showed that Cr, Rb, Sr, Cd, Cs, Ba and Tl levels were higher in Lake Biwa than in Mie, whereas Zn, Co and Hg in Mie samples were greater than Lake Biwa. Variations of elemental levels in stomach contents also showed similar patterns, thus, showing that dietary sources tended to be the main factor for these regional variations. Toxic Hg and Cd concentrations in the liver of cormorants from the two colonies were lower than those from other areas, implying relatively low exposure to these metals in the present study sites. Concentrations of V, Co, Ag, Cd, Cs, Hg, Tl, Pb and Bi in liver remained more or less at the same level between 1993 and 2003, while hepatic Cr, Mn, Cu, Zn, Se, Rb, Sr and Ba showed apparent decrease, which might be related to the biological factors.     

Ambient concentrations and source apportionment of PCBs and trace elements around an industrial area in Izmir, Turkey

Atmospheric concentrations of polychlorinated biphenyls (PCBs) and trace elements were measured at two sites (Industrial and Urban) located around the Aliaga industrial region, Izmir, Turkey. Average sigma 36PCB concentrations were 3136+/-824 and 1371+/-642 pg m(-3) for summer and winter periods, respectively in the Industrial site and they were 314+/-129 and 847+/-610 pg m(-3) in the Urban site. The elemental content showed that the PM(10) measured at the Industrial site was dominated by terrestrial elements and trace elements emitted by the iron-steel plants (Fe, Zn and Pb). The elemental profile at the Urban site was typical for Aegean Region that was dominated by terrestrial elements (Ca, Al, Mg) and sea salt (Na). Sources of particle-phase PCBs and trace elements were identified using factor analysis (FA) and were apportioned by chemical mass balance (CMB) model. FA suggested that the steel industry, fuel oil combustion, or the nearby vinyl chloride process in the petrochemical plant, and soil were significant PCB sources. CMB results showed that at the Industrial site, the contribution of steel industry and soil to particle-phase PCBs were 71% and 22%, respectively, while at the Urban site, the contributions were 33% and 49%, respectively. Steel industry was also the dominant contributor for trace elements around the site. Fugacity calculations in air and soil showed that the soil acts as a secondary source to the atmosphere for low molecular weight PCBs especially in summer and as a sink for the higher molecular weight ones.     

Determination of cadmium, zinc, copper, chromium and arsenic in crude oil cargoes

One of the sources of trace heavy metal elements in air is emission by the oil industry, either directly through stack emissions from refineries or indirectly from emissions of combustion of hydrocarbons. Emission estimates are based mainly on the trace metal content of the crude oil processed. From a literature study carried out at the beginning of the 1990s it became clear that data on the trace metal content of crudes were scarce and showed a very large scatter. For this reason a measurement programme to assess the occurrence and concentrations of a number of trace metals, i.e. Cadmium (Cd), Zinc (Zn), Copper (Cu), Chromium (Cr), and arsenic (As), in crudes which are regularly processed in the Netherlands, was set up. By drafting strict sampling protocols and by constructing a special sampling device, as many as possible of the additional contamination sources were avoided. The study suggests that sample contamination may explain a significant amount of the scatter and some of the high concentrations reported in the literature for certain metals. The measured variation in the concentrations of Cd, Zn, and Cu is thought to be due to associated water and/or sediment particles from the producing wells or that picked up during transport. The greater consistency in our measurements for Cr and As suggests that these metals are predominantly associated with the hydrocarbon matrix. Based on the results of this work, it can be concluded that emissions of Cd, Zn, Cu, Cr, and As by the oil industry in the Netherlands are most probably significantly lower than hitherto assumed.     

Principal component analysis of trace substance concentrations in rainwater samples

A total of 197 bulk precipitation samples from different rural and suburban stations in Bavaria, F.R.G., were analysed for the following trace substance concentrations: PAH (fluoranthen, benzo-ghiperylene, benzo-a-pyrene), chlorinated hydrocarbons (α- and γ-BHC, HCB, PCB) and trace metals (Zn, Cd, Pb, Cu, Fe). Data analysis was carried out with multivariate principal component analysis separately for suburban and rural sites, and for summer and winter events. The resulting principal component loadings matrices are characterized by typical patterns indicating differences of the emission of the single pollutants in their temporal and spatial distribution. PAH and Pb are concentrations parameters for the interpretation of the data structure of suburban sites. While Pb concentrations are elevated in the rainwater samples of these stations during all seasons, PAH indicate space-heating by showing elevated levels during winter. Rural sites are characterized by a lower interrelation between the various parameters and chlorinated BHC pesticides as further pollution variables. These substances are highly enriched in rainwater samples from spring and summer events.     

Comprehensive assessment of toxic metals in urban and suburban street deposited sediments (SDSs) in the biggest metropolitan area of China

A set of toxic metals, i.e. As, Hg, Pb, Cd, Cu, Zn, Ni and Cr, in urban and suburban SDSs were investigated comparatively in the biggest metropolitan area of China, Shanghai. Results showed that all of the metals except As were accumulated greatly, much higher than background values. Geo-accumulation index indicated that metal contamination in urban SDSs was generally heavier than that in suburban SDSs. Potential ecological risk index demonstrated that overall risks caused by metals were considerable. Cd contributed 52% to the overall risk. Multivariate statistical analysis revealed that in urban SDSs, Zn, Ni, Cd, Pb, Cu and Cr were related to traffic and industry; coal combustion led to elevated levels of Hg; soil parent materials controlled As contents. In suburban SDSs, Pb, Cu, As and Cd largely originated from traffic pollution; Zn, Ni and Cr were associated with industrial contaminants; Hg was mainly from domestic solid waste.     

Levels and distribution of heavy metals in atmospheric particular matters over the northern South China Sea

Oceans play a significant role in the cycling of trace metals and persistent organic pollutants. In this study, aerosol samples covering the whole northern South China Sea (SCS) were collected in 2005 and 2007, respectively, for analysis of trace metals and major elements. The levels of trace metals detected ranged from 0.514 to 119 ng/m³ in 2005 and from 0.130 to 24.2 ng/m³ in 2007, respectively. Cu, Zn, and Pb were the three predominant metals with high enrichment factors (>10), indicating the strong anthropogenic inputs. The trace metals over SCS were comparable to the values in suburban and background sites of South China, but generally higher than those over other seas and oceans. Considering the fact that they were influenced by their proximity to source regions and air mass origins, the elevated metals in 2005 were probably attributed to the strong wind and long-range atmospheric transport driven by Asian monsoon.     

Comparison of trace element accumulation in Baikal seals (Pusa sibirica), Caspian seals (Pusa caspica) and northern fur seals (Callorhinus ursinus)

Concentrations of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Zr, Mo, Ag, Cd, Sb, Cs, Hg, Tl and Pb) were determined in liver, kidney, muscle and hair of Baikal seals, Caspian seals and northern fur seals. All the three species showed the highest concentrations of Hg, V, Mn, Se and Ag in liver, Cd, Co and Tl in kidney, and Cs in muscle among the soft tissues examined. The highest burdens of Zn, Rb and Cs were observed in muscle, Mo and Ag in liver, and Sb and Pb in hair in all the three species. Concentrations of non-essential elements, Rb, Cd, Cs and Hg, showed significant positive correlations among liver, kidney and muscle, whereas correlation coefficients for essential elements, Mn, Co, Cu, Zn and Se, between the three tissues were generally low for all the species, suggesting that homeostasis controls the concentrations of essential elements but not the non-essential elements in the tissues of these animals. Significant age-dependent increase was found in the concentrations of V, Se and Ag in liver and Hg in liver and kidney of all the three species. Hair concentrations showed significant positive correlations with Zn levels in liver and kidney and Hg in muscle for Caspian seals, Hg in liver and kidney for Baikal seals, and Pb in liver for northern fur seals. Furthermore, regression analysis using the data in the present study and in the literature showed significant positive correlations between Hg levels in hair, and liver, kidney and muscle for various species of pinnipeds. These results indicate the possibility of using hair samples for monitoring these trace elements in pinnipeds.     

Occurrence,spatial distribution,sources, and risks of polychlorinated biphenyls and heavy metals in surface sediments from a large eutrophic Chinese lake (Lake Chaohu)

Surface sediment from large and eutrophic Lake Chaohu was investigated to determine the occurrence, spatial distribution, sources, and risks of polychlorinated biphenyls (PCBs) and heavy metals in one of the five biggest freshwater lakes in China. Total concentration of PCBs (Σ₃₄PCBs) in Lake Chaohu was 672 pg g^?1 dry weight (dw), with a range of 7 to 3999 pg g^?1 dw, which was lower than other water bodies worldwide. The majority of heavy metals were detected at all sampling locations, except for Sr, B, and In. Concentrations of Al, Fe, Ca, Mn, Sr, Co, Zn, Cd, Pb, and Hg were similar to that reported for other lakes globally. Concentrations of K, Mg, Na, Li, Ga, and Ag were greater than the average, whereas those of Cr, Ni, and Cu were lower. Cluster analysis (CA) and positive matrix factorization (PMF) yielded accordant results for the source apportionment of PCBs. The technical PCBs and microbial degradation accounted for 34.2 % and 65.8 % of total PCBs using PMF, and PMF revealed that natural and anthropogenic sources of heavy metals accounted for 38.1 % and 61.8 %, respectively. CA indicated that some toxic heavy metals (e.g., Cd, In, Tl, and Hg) were associated with Ca–Na–Mg minerals rather than Fe–Mn minerals. The uncorrelated results between organic matter revealed by pyrolysis technology and heavy metals might be caused by the existence of competitive adsorption between organic matter and minerals. PCBs and heavy metals were coupling discharge without organochlorine pesticides (OCPs), but with polycyclic aromatic hydrocarbons (PAHs) and polybrominated diphenyl ethers (PBDEs). No sediment sample exceeded the toxic threshold for dioxin-like PCBs (dl-PCBs) set at 20 pg toxicity equivalency quantity (TEQ)?g^?1, (max dl-PCBs, 10.9 pg TEQ g^?1). However, concentrations of Ag, Cd, and Hg were at levels of environmental concern. The sediment in the drinking water source area (DWSA) was threatened by heavy metals from other areas, and some fundamental solutions were proposed to protect the DWSA.     

Annual input fluxes and source identification of trace elements in atmospheric deposition in Shanxi Basin: the largest coal base in China

Industrialization and urbanization have led to a great deterioration of air quality and provoked some serious environmental concerns. One hundred and five samples of atmospheric deposition were analyzed for their concentrations of 13 trace elements (As, Cd, Cu, Fe, Al, Co, Cr, Hg, Mn, Mo, Pb, Se, and Zn) in Shanxi Basin, which includes six isolate basins. The input fluxes of the trace elements in atmospheric deposition were observed and evaluated. Geostatistical analysis (EF, PCA, and CA ) were conducted to determine the spatial distribution, possible sources, and enrichment degrees of trace elements in atmospheric deposition. Fe/Al and K/Al also contribute to identify the sources of atmospheric deposition. The distribution of trace elements in atmospheric deposition was proved to be geographically restricted. The results show that As, Cd, Pb, Zn, and Se mainly come from coal combustion. Fe, Cu, Mn, Hg, and Co originate mainly from interactions between local polluted soils and blowing dust from other places, while the main source of Al, Cr, and Mo are the soil parent materials without pollution. This work provides baseline information to develop policies to control and reduce trace elements, especially toxic elements, from atmospheric deposition. Some exploratory analytical methods applied in this work are also worth considering in similar researches.     

Emissions from simulated deep-seated fires in domestic waste

The emissions from deep-seated fires in domestic waste have been investigated. The gas phase yields of PAH, PCDD/F, PCB, HCB, particles, and metals associated to the particulate matter were analysed during a series of simulated deep-seated fires. The method of extinguishment was varied and in cases where water was used for extinguishment, the runoff water was analysed for PAH, PCDD/F, PCB, hexachlorobenzene, and metals. In total six tests were performed. In four of the tests, samples of the fire residue were analysed for PCDD/F, PCBs, and chlorobenzenes.     

Modification of trace metal accumulation in the green mussel Perna viridis by exposure to Ag, Cu, and Zn

To examine the Cd, Hg, Ag, and Zn accumulation in the green mussel Perna viridis affected by previous exposure to Cu, Ag, or Zn, the dietary metal assimilation efficiency (AE) and the uptake rate from the dissolved phase were quantified. The mussel's filtration rate, metallothionein (MT) concentration, and metal tissue burden as well as the metal subcellular partitioning were also determined to illustrate the potential mechanisms underlying the influences caused by one metal pre-exposure on the bioaccumulation of the other metals. The green mussels were pre-exposed to Cu, Ag, or Zn for different periods (1-5 weeks) and the bioaccumulation of Cd, Hg, Ag, and Zn were concurrently determined. Pre-exposure to the three metals did not result in any significant increase in MT concentration in the green mussels. Ag concentration in the insoluble fraction increased with increasing Ag exposure period and Ag ambient concentration. Our data indicated that Cd assimilation were not influenced by the mussel's pre-exposure to the three metals (Cu, Ag, and Zn), but its dissolved uptake was depressed by Ag and Zn exposure. Although Hg assimilation from food was not affected by the metal pre-exposure, its influx rate from solution was generally inhibited by the exposure to Cu, Ag, and Zn. Ag bioaccumulation was affected the most obviously, in which its AE increased with increasing Ag tissue concentration, and its dissolved uptake decreased with increasing tissue concentrations of Ag and Cu. As an essential metal, Zn bioaccumulation remained relatively stable following the metal pre-exposure, suggesting the regulatory ability of Zn uptake in the mussels. Zn AE was not affected by metal pre-exposure, but its dissolved uptake was depressed by Ag and Zn pre-exposure. All these results indicated that the influences of one metal pre-exposure on the bioaccumulation of other metals were metal-specific due to the differential binding and toxicity of metals to the mussels. Such factors should be considered in using metal concentrations in mussel's soft tissues to evaluate the metal pollution in coastal waters.     

Biomonitoring of air quality in the Cologne Conurbation using pine needles as a passive sampler – Part III: Major and trace elements

We here report complementary trace element (Fe, Pb, Cd, Zn, Cr, Cu, Ni and sulfur) concentrations and ratios in pine needles collected in the urban area of Cologne, Germany. Potential element sources are discussed in conjunction with enviromagnetic and PAH data to evaluate air quality. Foliar trace element concentrations of Zn, Cr, Cu, Ni and sulfur are close to essential nutrient levels. Median concentrations of foliar Fe, Pb and Cd in Cologne are 132, 1.1, and 0.06 μg g^?1, respectively. Thus these elements are enhanced over biogenic background levels and show significant accumulation with needle exposure time. Foliar sulfur concentrations vary between 868 and 2076 μg g^?1 with a median value of 1409 μg g^?1, except for two locations where 2370 and 2379 μg g^?1 were observed. Cadmium serves as an indicator for local industrial emissions with short transport distances of only a few kilometres in Cologne City. Elevated Fe, Pb and Zn concentrations mark areas with higher traffic loads and agree with enhanced PAH burdens and magnetic susceptibility intensities of pine needles. Isopleths mapping and source differentiation of atmospheric pollutants using foliar trace elements is feasible. For temporal or spatial high-resolution studies more cost-effective environmental magnetics is recommended, which may guide in design of detailed studies aiming at identification and allocation of emission sources. Hereby, a combination of organic tracers (PAH), magnetic properties, and trace metals is considered most reliable.     

Risk assessment of trace elements in the stomach contents of Indo-Pacific Humpback Dolphins and Finless Porpoises in Hong Kong waters

The potential health risks due to inorganic substances, mainly metals, was evaluated for the two resident marine mammals in Hong Kong, the Indo-Pacific Humpback Dolphin (Sousa chinensis) and the Finless Porpoise (Neophocaena phocaenoides). The stomachs from the carcasses of twelve stranded dolphins and fifteen stranded porpoises were collected and the contents examined. Concentrations of thirteen trace elements (Ag, As, Cd, Co, Cr, Cs, Cu, Hg, Mn, Ni, Se, V and Zn) were determined by inductively coupled plasma mass spectrometer (ICP-MS). An assessment of risks of adverse effects was undertaken using two toxicity guideline values, namely the Reference Dose (RfD), commonly used in human health risk assessment, and the Toxicity Reference Value (TRV), based on terrestrial mammal data. The levels of trace metals in stomach contents of dolphins and porpoises were found to be similar. Risk quotients (RQ) calculated for the trace elements showed that risks to the dolphins and porpoises were generally low and within safe limits using the values based on the TRV, which are less conservative than those based on the RfD values. Using the RfD-based values the risks associated with arsenic, cadmium, chromium, copper, nickel and mercury were comparatively higher. The highest RQ was associated with arsenic, however, most of the arsenic in marine organisms should be in the non-toxic organic form, and thus the calculated risk is likely to be overestimated.     

A high-resolution historical sediment record of nutrients,trace elements and organochlorines (DDT and PCB) deposition in a drinking water reservoir (Lake Brêt,Switzerland) points at local and regional pollutant sources

The ¹³⁷Cs and ²¹⁰Pb dating of a 61-cm long sediment core retrieved from a drinking water reservoir (Lake Brêt) located in Switzerland revealed a linear and relatively high sedimentation rate (～1 cm year^?1) over the last decades. The continuous centimeter scale measurement of physical (porewater and granulometry), organic (C_org, P, N, HI and OI indexes) and mineral (C_min and lithogenic trace elements) parameters therefore enables reconstructing the environmental history of the lake and anthropogenic pollutant input (trace metals, DDT and PCBs) at high resolution. A major change in the physical properties of the lowermost sediments occurred following the artificial rise of the dam in 1922. After ca. 1940, there was a long-term up-core increase in organic matter deposition attributed to enhance primary production and anoxic bottom water conditions due to excessive nutrient input from a watershed predominantly used for agriculture that also received domestic effluents of two wastewater-treatment plants. This pattern contrasts with the terrigenous element input (Eu, Sc, Mg, Ti, Al, and Fe) which doubled after the rising of the dam but continuously decreased during the last 60 years. By comparison, the trace metals (Cu, Pb and Hg) presented a slight enrichment factor (EF) only during the second part of the 20th century. Although maximum EF Pb (>2) occurred synchronously with the use of leaded gasoline in Switzerland (between ca. 1947 and 1985) the Hg and Cu profiles exhibited a relatively similar trend than Pb during the 20th century, therefore excluding the alkyl-lead added to petrol as the dominant (atmospheric) source of lead input to Lake Brêt. Conversely, the Cu profile that did not follow the decrease registered in Pb and Hg during the last 10 years, suggests an additional source of Cu probably linked to the impact of agricultural activities in the area. In absence of heavy industries in the catchment, the atmospheric deposition of DDT and PCBs via surface runoff followed the historical emissions of POPs in Switzerland. Such result highlights the regional contamination of freshwater resources by the large-scale emission of toxic industrial chemicals in the 1960s and 1970s as well as the efficiency of the regulatory measures subsequently taken.     

Source characterization for atmospheric trace metals over Kiel Bight

Atmospheric concentrations of Na, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Rb, Sr, Ba and Pb are reported for 59 weekly air filter samples collected over the Kiel Bight. The contributions of sea salt, mineral dust and anthropogenic emissions to each of these elements were assumed to be represented by the concentrations of indicator elements, which were Na, Al and Zn, respectively. Based on this assumption a multiple regression analysis was applied to the concentration data. The results showed that atmospheric sea salt contributed significantly only to Sr and, of course, Na. Considerable portions of Al, K, Ca, Ti, Cr, Mn, Fe, Rb, Sr and Ba were derived from mineral dust. Anthropogenic sources were responsible for total V, Ni, Cu, Zn, As and Pb, and there was an anthropogenic component for most of the other elements.Moreover, the anthropogenic contribution was characterized by a nearly constant composition with respect to Ca, Ti, Cr, Mn, Fe, Cu, Zn, As, Rb, Sr, Ba and Pb, indicating that trace metals over the Kiel Bight are mainly derived from one source area. This conclusion was confirmed by correlating anthropogenic trace metal concentrations with the wind direction. A 40° wind sector directed to the south of the sampling site was identified as the major pathway for the transport of anthropogenic trace metals to the Kiel Bight.