Modelling vegetation greenness responses to climate variability in a Mediterranean terrestrial ecosystem

Accurate knowledge of the quality and environmental impact of the highway runoff in Pear River Delta, South China is required to assess this important non-point pollution source. This paper presents the quality characterization and environmental impact assessment of rainfall runoff from highways in urban and rural area of Guangzhou, the largest city of Pear River Delta over 1 year’s investigation. Multiple regression and Pearson correlation analysis were used to determine influence of the rainfall characteristics on water quality and correlations among the constituents in highway runoff. The results and analysis indicates that the runoff water is nearly neutral with low biodegradability. Oil and grease (O&G), suspended solids (SS) and heavy metals are the dominant pollutants in contrast to the low level of nutrient constituents in runoff. Quality of highway runoff at rural site is better than that of at urban site for most constituents. Depth and antecedent dry period are the main rainfall factors influencing quality of highway runoff. The correlation patterns among constituents in highway runoff at urban site are consistent with their dominant phases in water. Strong correlations (r ≥ 0.80) are found among chemical oxygen demand (COD), total phosphorus, Cu and Zn as well as conductivity, nitrate nitrogen and total nitrogen. O&G, COD, SS and Pb in highway runoff at urban site substantially exceed their concentrations in receiving water of Pear River. The soil directly discharged by highway runoff at rural site has contaminated seriously by heavy metals in surface layer accompanying with pH conversion from original acidic to alkaline at present.     

百年一遇大旱后城区降雨径流中重金属与悬浮物相关性分析

为了探讨2009年入秋至2010年春,西南百年一遇大旱后城市降雨径流中重金属污染特性,对昆明市交通干道路面及路旁一处混凝土屋面的3次降雨径流进行了监测,研究了城区降雨径流中Cu、Zn、Cd、Pb、Fe、Mn、Cr的变化过程,分析了不同重金属之间、重金属与悬浮物(SS)之间的相关性。3次降雨径流中重金属质量浓度随降雨呈不同程度下降。大旱后的首次降雨径流重金属污染最严重,次日的降雨径流重金属污染最轻。降雨径流中各重金属均与SS在含量上明显相关,径流中的重金属主要以吸附在SS上的不溶态存在。屋面与路面径流中的大多数重金属具有良好的同源性。     

Characteristics of Stormwater Quality from Two Urban Watersheds in Singapore

This paper presents the results of a study on the quality of stormwater runoff from two adjacent urban watersheds in Singapore. The study involved continuous recording of rainfall and streamflow within the basins, and systematic sampling of storm runoff during rainfall events. The water samples collected were analysed for its physical and chemical constituents. The ranges and mean concentrations of common quality parameters have been established, and the flushing effects of selected parameters were studied. Correlations of event mean concentrations and pollution loads of total suspended solids and chemical oxygen demand to both antecedent dry weather period and rainfall characteristics were also carried out.     

Multivariate analysis of mixed contaminants (PAHs and heavy metals) at manufactured gas plant site soils

Principal component analysis (PCA) was used to provide an overview of the distribution pattern of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in former manufactured gas plant (MGP) site soils. PCA is the powerful multivariate method to identify the patterns in data and expressing their similarities and differences. Ten PAHs (naphthalene, acenapthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[a]pyrene) and four toxic heavy metals — lead (Pb), cadmium (Cd), chromium (Cr) and zinc (Zn) — were detected in the site soils. PAH contamination was contributed equally by both low and high molecular weight PAHs. PCA was performed using the varimax rotation method in SPSS, 17.0. Two principal components accounting for 91.7% of the total variance was retained using scree test. Principle component 1 (PC1) substantially explained the dominance of PAH contamination in the MGP site soils. All PAHs, except anthracene, were positively correlated in PC1. There was a common thread in high molecular weight PAHs loadings, where the loadings were inversely proportional to the hydrophobicity and molecular weight of individual PAHs. Anthracene, which was less correlated with other individual PAHs, deviated well from the origin which can be ascribed to its lower toxicity and different origin than its isomer phenanthrene. Among the four major heavy metals studied in MGP sites, Pb, Cd and Cr were negatively correlated in PC1 but showed strong positive correlation in principle component 2 (PC2). Although metals may not have originated directly from gaswork processes, the correlation between PAHs and metals suggests that the materials used in these sites may have contributed to high concentrations of Pb, Cd, Cr and Zn. Thus, multivariate analysis helped to identify the sources of PAHs, heavy metals and their association in MGP site, and thereby better characterise the site risk, which would not be possible if one uses chemical analysis alone.     

Water quality assessment of Ogun river, South West Nigeria

The quality of Ogun river in South-West, Nigeria was studied by a field survey for a period of 1 year (covering dry season and rainy season). Water samples were collected from thirteen sites and analysed for physico-chemical and bacteriological parameters as well as heavy metals using standard methods. Generally, the values obtained for turbidity, phosphate, oil and grease, iron and faecal coliform from all the sites in both seasons were above the maximum acceptable limit set by the World Health Organization (WHO) for drinking water. Also, the manganese content from all the sites in the dry season, lead concentrations from three sites in the dry season and cadmium concentrations from some sites in both seasons were above the WHO limit. The values obtained for total dissolved solids, dissolved oxygen and chloride at site M in the dry season and nitrate at site J in the rainy season were also above the WHO limit. Pollution of Ogun river water along its course is evidenced by the high concentrations of pollution indicators, nutrients and trace metals above the acceptable limit. This poses a health risk to several rural communities who rely on the river primarily as their source of domestic water. The study showed a need for continuous pollution monitoring programme of surface waters in Nigeria.     

An analysis of total gaseous mercury (TGM) concentrations across the UK from a rural sampling network

Total gaseous mercury was collected at ten sites, which comprise part of the UK rural heavy metals monitoring network, between 2005 and 2008. Using the gold amalgam technique to capture total gaseous mercury, samples were analysed using a Tekran 2537A mercury vapour analyser. The data showed no upward or downward trend in atmospheric mercury concentrations over the period, with 4 year average concentrations between 1.3 and 1.9 ng m(-3), which are in line with other studies' observed northern hemispheric background concentrations of between 1.5 and 1.7 ng m(-3). Using data from nine of the sites, we were able to show seasonality within the data and through kriging we were able to interpolate the TGM concentrations over the UK, revealing a south-east to north-west declining concentration gradient. Using continuous speciated mercury measurements from one of the network sites, we show through wind sector analysis and air-mass back trajectories that this spatial trend is likely to be due to air masses moving over the UK from continental Europe on easterly winds. The levels of TGM recorded in the south-east of the UK also more closely match observed background TGM levels on the continent, which could indicate that the TGM concentrations from the north of the UK are a better reflection of the true North Atlantic atmospheric mercury background level.     

Analysis of acidic components, heavy metals and PAHS of particulate in the Changwon–Masan area of Korea

This study is an analysis of the concentrations and components of heavy metals in PM_2.5 and the total suspended particulate (TSP) collected at a mechanical industrial complex (IC) site in Changwon and at a residential site in Masan, Korea. Particulate was collected during two sampling periods, from the late summer to the early fall and from the middle to late fall, at the IC site and one sampling period, from the middle fall to the early winter, at the residential site. PM_2.5 and TSP samples were taken by an annular denuder system and a hi-volume air sampler, respectively. The authors also identified the concentrations and components of heavy metals extracted from the PM_2.5 and TSP filters, the acidic components extracted from the PM_2.5 filters, and the polycyclic aromatic hydrocarbons (PAHs) extracted from polyurethane foam (PUF) plug. The average concentrations of the PM_2.5 collected at the IC and residential sites were very similar. Major sources of PM_2.5 at the study sites, however, were air emissions from vehicles and industry as well as emissions from residential heating and soil origins, respectively. The higher concentrations of the TSP at the IC site, as compared to those at the residential site, were due to either increased suspended dust from vehicle emissions or re-suspended road dust because of increased vehicle speeds near the IC site. Heavy metal concentrations in the TSPs were higher than those in the PM_2.5. The heavy metal concentrations in the PM_2.5 and TSP at the IC site with heavy traffic were substantially greater than those at the residential site. The concentrations of TSP and heavy metals and PAHs in PM during the period of the middle to late fall was much higher than those during the period of the late summer to early fall at the IC site. This is because of the difference in meteorological characteristics and energy uses between two periods. The residential site also showed higher concentrations of acidic anions while the IC site showed higher concentrations of acidic cation. Secondary aerosols or particulates, such as ammonium nitrate or ammonium nitrite, might have been important constituents of the PM_2.5 at the residential site. The PAHs in the TSP collected at the IC site was greatly affected by traffic and industry emissions consisting mostly of high molecular weight PAHs with two to four rings. PAHs in the TSP at the site, however, were affected by residential heating and air emissions from small chemical plants having higher concentrations of low molecular weight PAHs with five to six rings.     

Measurement of organic contaminants and biological effects in Scottish waters between 1999 and 2005

Concentrations of organic contaminants were determined in sediment and fish collected annually at six sites around Scotland between 1999 and 2005, as part of the UK National Marine Monitoring Programme. Polycyclic aromatic hydrocarbons (PAHs) and chlorobiphenyls (CBs) were measured in sediment, while CBs and ethoxyresorufin-O-deethylase (EROD) activities were measured in the fish. Highest PAH concentrations in sediment were found at sites where higher coastal influences would be expected (e.g., Clyde and Solway) and four of the six sites gave PAH concentrations above OSPAR background assessment concentrations (BACs). A significant downward trend in the median total PAH concentrations, normalised to total organic carbon (TOC), was found at one of the six sites (Minches). The PAH profiles at all sites were consistent over the 6 year period, indicating that the sites are relatively stable and PAH sources are not changing. There was an indication of a greater petrogenic input on the west coast, with sediment from the Clyde, Solway and Minches having a greater proportion of 2- and 3-ring PAHs and a lower proportion of 5-ring PAHs. CB concentrations at all sites were low compared with UK estuarine sites and similar to sediment from more remote areas: however, BACs were exceeded. No significant trends were detected in either the sediment CB concentrations or patterns at any of the six sites. CB concentrations were significantly higher in fish liver collected from the Clyde. Concentrations at the other five sites were low, with the majority of samples having concentrations for the ICES7 CBs of <500 microg kg(-1) lipid weight. However, individual CB concentrations were still above the BACs. Hepatic EROD activities were measured in male plaice from 2002-2005 and were generally low (<10 pmol min(-1) mg protein(-1)). No temporal trends were detected in either CB concentrations or the EROD activity.     

Chemical (polycyclic aromatic hydrocarbon and heavy metal) levels in contaminated stormwater and sediments from a motorway dry detention pond drainage system

Chemical (polycyclic aromatic hydrocarbon - PAH and heavy metal) levels in stormwater and sediment samples collected from the London Orbital (M25) motorway drainage dry detention pond at Oxted, Surrey, UK were determined. Such chemicals are derived from vehicular combustion products and the wear and tear materials deposited onto the motorway surface. Gas chromatography-mass spectrometry (GC-MS) was used for the qualitative and quantitative determination of 16 USEPA priority PAHs in motorway drainage sediments. The GC-MS method, incorporating a solid phase extraction step, provides detection limits ranging from 0.17 to 0.41 mg kg(-1)(dry weight). Almost all of the 16 USEPA listed PAHs were detected. Phenanthrene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(a)pyrene and benzo(g,h,i)perylene (PAH numbers 5, 7, 8, 9, 10, 11, 13 and 16) were among the PAHs found at "higher" levels (ranging from 0.3-10.2 mg kg(-1), dry weight) in the sediment samples. PAH levels show little change along the motorway drainage silt trap (facility for reducing the levels of suspended particulate matter in the stormwater). PAH concentrations are considerably higher in the dry detention pond outflow interceptor. Statistical analysis showed that significant correlation coefficients (based on a t-test at the 95% confidence interval) were obtained between those PAHs found at high concentrations over all of the sampling sites. Several PAHs were dispersed beyond the treatment facility and accumulation in the sediment of the deer park resulted in levels ranging from 0.3-1.6 mg kg(-1), dry weight. These PAHs found beyond the treatment facility (in the local farm deer park) may contribute a serious health threat to farm animals or even fish in the aquatic environment. Heavy metal levels (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, Sb and Pb) of the drainage stormwater and sediments were determined by inductively coupled plasma mass spectrometry (ICP-MS), with quality control evaluation using two certified reference materials. Typical detection limits were found to be below 0.1 [micro sign]g l(-1) for stormwater and 0.005 mg kg(-1) for acid digested sediments. Raised heavy metal levels were found throughout the dry detention pond facility and only decrease when the stormwater is diluted following discharge into the river Eden. Statistical analysis also confirms that some significant correlations exist between various heavy metals and PAHs. However, no overall conclusive trend is found indicating that a particular PAH is deposited in sediment relative to a specific heavy metal/s. These results raise some serious concerns about the dispersion and accumulation of chemicals in the sediments of motorway stormwater drainage systems and the need for maintenance and clean-up of contaminated material from such systems.     

Organochlorines and heavy metals in 17-year cicadas pose no apparent dietary threat to birds

Organochlorine and heavy metal concentrations in 17-year cicadas from Prince Georges and Anne Arundel Counties, Maryland, were well below levels known to be harmful to birds. Cicadas contained concentrations of metals similar to or less than other local invertebrates except they contained more copper than did earthworms. Copper and lead concentrations in cicadas from one site may have been elevated by sewage plant effluent deposited during river floodings. Cicadas from the median of a major highway did not contain more lead than cicadas from non-traffic sites.     

Soil heavy metal contamination in an industrial area: analysis of the data collected during a decade

Soil contamination by heavy metals has become a serious problem mainly because, above certain concentrations, all metals have adverse effects on human health. In particular, the accumulation of heavy metals in agricultural soils leads to elevated uptake by crops and affects food quality and safety. In this paper, we present the results of a study carried out over a decade for evaluating the impact of a new industrial settlement in an area geared to agriculture and livestock and far from urban sites. We focus our study on the bioavailable fraction of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in soil samples. Heavy metal concentrations in soil are analysed with both univariate and multivariate statistical procedures. The main goal of this paper is the development of a statistical procedure, based on a mix of multivariate analysis, able to compare field surveys carried out during different years and to characterize spatial and temporal changes in soil heavy metals concentrations.     

城市河流重金属元素对降雨径流的动态响应

以海口市美舍河市区河段为研究对象,于2020年雨季分别采集降雨径流以及降雨径流汇入后的河流瞬时水样,测定并分析主要重金属元素的浓度及其变化规律,探讨其对降雨径流的动态响应。研究结果表明：降雨径流对河流可溶态污染元素质量浓度的贡献不突出,对可溶态锌（Zn）、砷（As）、镉（Cd）、硒（Se）具有一定稀释作用,排水口下游 3 m处是可溶态铬(Cr）、锰（Mn）、钴（Co）对降雨径流响应最显著区域;降雨径流对各悬浮态元素质量浓度贡献较大,排水口下游7 m处是绝大多数悬浮态元素对降〖JP〗雨径流响应最显著区域;Mn、Zn、Cr、镍（Ni）、As、Co、Cd 7种元素的总质量浓度对降雨径流的动态响应表现为先上升后下降。其中,排水口下游3 m处是Cr、As总质量浓度对降雨径流响应最显著区段,排水口下游7 m处是Mn、Co、Ni、Zn及Cd总质量浓度对降雨径流响应最显著区段。降雨径流对河流主要污染元素年输入总量估算结果表明,海口市建成区降雨径流向美舍河等受纳水体直接年输入量最大的是Mn和Zn,其次是Cr、As、Ni,Se与Cd的年输入量最小。     

Determination of selected heavy metals in air samples from the northern part of Jordan

In this work, the atmospheric concentrations of selected heavy metals including lead (Pb), iron (Fe), cadmium (Cd), copper (Cu), nickel (Ni), manganese (Mn), and zinc (Zn) were measured for two different sampling sites (urban and rural) in the northern part of Jordan (Irbid city). Samples were collected according to a certain schedule for 1 year. High volume air samplers and glass fiber filters were used to collect the samples. Collected samples were digested using a mixture of analytical grade nitric acid and analytical grade hydrochloric acid, and analyzed to evaluate the levels of heavy metals by atomic absorption spectrophotometry. Six heavy metals (Pb, Fe, Cu, Ni, Mn, and Zn) were measured in all samples; the concentrations of Cd and Co were not detected in Irbid atmosphere by atomic absorption spectroscopy. The results were used to determine the levels of heavy metal pollutants in air, possible sources, and to compare the levels of selected heavy metals in the two studied sites. Aerosols from the rural site have lower concentrations for all the metals compared to those from the urban site. The daily and monthly variations of the elements were investigated. All heavy metals in urban and rural sites reached maximum concentrations in June, July, and August. This is consistent with the increased activities leading to particulate matter emission during the summer period. The enrichment factors with respect to earth crust and correlation coefficients of heavy metals were investigated to predict the possible sources of heavy metals in air.     

Air quality assessment of benzo(a)pyrene from asphalt plant operation

A study has been carried out to assess the contribution of Polycyclic Aromatic Hydrocarbons (PAHs) from asphalt plant operation, utilising Benzo(a)pyrene (BaP) as a marker for PAHs, to the background air concentration around asphalt plants in the UK. The purpose behind this assessment was to determine whether the use of published BaP emission factors based on the US Environmental Protection Agency (EPA) methodology is appropriate in the context of the UK, especially as the EPA methodology does not give BaP emission factors for all activities. The study also aimed to improve the overall understanding of BaP emissions from asphalt plants in the UK, and determine whether site location and operation is likely to influence the contribution of PAHs to ambient air quality. In order to establish whether the use of US EPA emissions factors is appropriate, the study has compared the BaP emissions measured and calculated emissions rates from two UK sites with those estimated using US EPA emission factors. A dispersion modelling exercise was carried out to show the BaP contribution to ambient air around each site. This study showed that, as the US EPA methodology does not provide factors for all emission sources on asphalt plants, their use may give rise to over- or under-estimations, particularly where sources of BaP are temperature dependent. However, the contribution of both the estimated and measured BaP concentrations to environmental concentration were low, averaging about 0.05 ng m(-3) at the boundary of the sites, which is well below the UK BaP assessment threshold of 0.25 ng m(-3). Therefore, BaP concentrations, and hence PAH concentrations, from similar asphalt plant operations are unlikely to contribute negatively to ambient air quality.     

Distributions, sources and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in topsoil at Ji’nan city, China

Surface soil (0-5 cm) samples from 17 sampling sites including different functional areas at Ji'nan city in Shandong Province of China were collected and analyzed for 16 EPA priority polycyclic aromatic hydrocarbons (PAHs). The total PAH concentrations were in the range from 1.31 mg kg(-1) to 254.08 mg kg(-1) (dry weight), and the average level of total PAHs was 23.25 mg kg(-1). The highest total PAHs concentrations were found in steel and iron plant at industrial areas. The total PAHs concentrations in industrial areas were markedly higher than those in other different functional areas. According to comparing total PAHs concentration in Ji'nan city to that of other urban areas, it was found that total PAHs concentrations were 6 to 137 times higher than other areas because of some specific sampling sites such as steel and iron plant and one main roadside. The results showed that PAHs in topsoil of Ji'nan city were suffered from strong pyrogenic influence, especially in industrial areas. However about 52.9% soil samples were mainly originated from both pyrogenic and petrogenic mixed sources based on Flu/Pyr ratios and Phe/Ant ratios. Furthermore, It was found that all individual PAHs except Fle were significantly correlated (P < 0.01) with LMW, HMW, total PAHs and SOM, and individual PAHs except Fle in soils were significantly correlated (P < 0.01) with each other. The nemerow composite index to assess the environmental quality showed that the soil sample of steel and iron plant in industrial areas and one main roadside were heavy pollution of PAHs, and about 47% soil sampling sites were safety, about 53% soil sampling sites were got different grades of PAHs pollution.     

An assessment of persistent organic pollutants in Scottish coastal and offshore marine environments

Concentrations of persistent organic pollutants (POPs), including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were determined in sediment and biota (fish liver) from around Scotland. The concentrations were investigated using assessment criteria developed by OSPAR and ICES. Organic contaminant concentrations, PAHs, PCBs and PBDEs in sediment, and PCBs and PBDEs in fish liver, were significantly higher in the Clyde compared to all other sea areas. This is mainly due to historic industrial inputs. Highest PCB and PAH concentrations were found in the strata furthest up the Clyde estuary, with concentrations of POPs in these strata being at levels such that there is an unacceptable risk of chronic effects occurring in marine species. Furthermore, for PAHs in Clyde sediment there was a significant negative gradient going from north to south towards the open sea. PAH and PCB concentrations in sediment and biota in all other Scottish sea areas (except for PCBs in sediment from East Scotland) were unlikely to give rise to pollution effects, being below relevant assessment criteria. Although no assessment criteria are available for PBDEs, the concentrations observed in Scottish sediments were low with all congeners below the limit of detection (LoD; 0.03 μg kg(-1) dry weight) in 140 out of a total of 307 samples analysed. Where PBDEs were detected, the dominant congeners were BDE47 and BDE99. PBDEs were detected in fish livers, although concentrations were less than 150 μg kg(-1) lipid weight in all sea areas except the Clyde where concentrations ranged between 8.9 and 2202 μg kg(-1) lipid weight. Few trends were detected in contaminant concentrations in biota or sediment at any Scottish site with more than five years data. Downward trends were detected in PAHs in sediment from the Clyde, Irish Sea and Minches and Malin Sea and PCBs in fish liver from the Moray Firth. Rules were developed for the aggregation of the contaminant data across a sea area. An overall assessment for each sea area was then assigned, looking at the frequency of sites or strata within each sea area that were above or below the relevant assessment criteria. Overall the status of the various sea areas, with respect to the assessed POPs, can be considered to be acceptable in that they were below concentrations likely to result in chronic effects for all sea areas except the Clyde.     

Determination of trace heavy metals in harvested rainwater used for drinking in Hebron (south West Bank,Palestine) by ICP-MS

Rainwater samples harvested for drinking from the west part of Hebron (south of West Bank in Palestine), the largest city in the West Bank, were analyzed for the content of different trace heavy metals (Cr, Mn, Co, Ni, Cu, Zn, Mo, Ag, Cd, Bi, and Pb) by inductively coupled plasma mass spectrometry (ICP-MS). This study was conducted to determine the water quality of harvested rainwater used for drinking of south West Bank (case study, Hebron area). A total of 44 water samples were collected in November 2012 from 44 house cisterns used to collect rainwater from the roofs of houses. The samples were analyzed for their pH, temperature, electrical conductivity, total dissolved solids, and different heavy metal contents. The pH of all water samples was within the US Environmental Protection Agency limits (6.5–8.5), while some water samples were found to exceed the allowed WHO limit for total dissolved solids (TDSs) in drinking water. Results showed that concentrations of the heavy metals vary significantly between the 44 samples. Results also showed that the concentration of five heavy metals (Cr, Mn, Ni, Ag, and Pb) is higher than the WHO limits for these heavy metals in drinking water. Overall, our findings revealed that harvested rainwater used for drinking of this part of south West Bank is contaminated with heavy metals that might affect human health.     

The temporal changes in road stormwater runoff quality and the implications to first flush control in Chongqing, China

This study investigates the quality of stormwater runoff from a driveway in the southwest mountainous urban area of Chongqing, China, from 2010 to 2011. The results showed that the mean concentrations of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) were 4.1, 2.4, and 2.2 times the grade V levels of the national surface water standard of China. The pollutant concentration peak preceded or synchronized with the rainfall intensity peak and occurred 10 min after the runoff started. The significant high pollutant concentration in the initial stage of the rainfall suggested that first flush control is necessary, especially for the most polluted constitutes, such as total suspended solids, COD, and TN. Three potential pollution sources were identified: the atmospheric dry and wet deposition (TN, NO₃ ^?-N, NH₄ ⁺-N, and DCu), the road sediment and materials (total suspended solids, COD, and TP), and the vehicle emissions (DPb and DZn). Therefore, this study indicates that reductions in road sediments and material pollution and dry and wet deposition should be the priority factors for pollution control of road stormwater runoff in mountainous urban areas.     

Trace elements in the livers of cod (Gadus morhua L.) from the Baltic Sea: levels and temporal trends

This paper presents and discusses the levels and temporal trends of concentrations of Cd, Pb, Hg, Cu, Zn, and As in livers and Hg in the muscle tissues of cod (Gadus morhua L) from the Baltic Sea during the period 1994–2010. Concentrations of Pb, Hg, and Cd exhibited significant downward trends. Cu and Zn concentrations exhibited upward trends in the period 1994 to 2010. No trends were detected for concentrations of As. The temporal trends identified in heavy metal concentrations in cod livers corresponded to the directions of changes in concentrations of these elements introduced into the Baltic Sea via river runoff and atmospheric emission, and those in surface and deep waters of the Baltic. Downward trends in the concentrations of toxic metals in cod livers suggest that advantageous changes are occurring in concentrations of heavy metals in the environment of the southern Baltic Sea.