Residues of organochlorine pesticides in water and suspended particulate matter from the Yangtze River catchment of Wuhan, China

The residues of 13 organochlorine pesticides (OCPs) in surface water and HCHs and DDTs in suspended particulate matter (SPM) from rivers and lakes in Yangtze River catchment of Wuhan, China, were investigated. The concentration of total OCPs in surface water varied from 1.01 to 46.49 ng l⁻¹ (mean 10.55 ng l⁻¹). The levels of total HCHs (ΣHCH) and total DDTs (ΣDDT) in surface water were in the range of 0.55–28.07 ng l⁻¹ and lower than detection limit to 16.71 ng l⁻¹, respectively, which was lower than Chinese standards on the whole. For OCPs residues in SPM, the mean levels varying from 0.20 to 34.72 ng l⁻¹ and 0.46 to 2.72 ng l⁻¹ for ΣHCH and ΣDDT, respectively, which ranked the relatively higher levels among Chinese studied rivers. Results from this investigation showed that previous excessive usage of technical OCPs was the main reason for the residues of HCHs and DDTs both in surface water and SPM, although some new sources were likely to occurred in the region. Apart from the OCPs in SPM originated from upstream in flood season, one of the important sources of OCP residues both in water and SPM in Yangtze River was supposed to be the inputs of its tributaries. Additionally, in situ water-SPM phase distributions of OCPs indicated that HCHs tended totransport with water as well as DDTs was prone to combine with SPM in Yangtze River catchment of Wuhan.     

Residual levels, tissue distribution and risk assessment of organochlorine pesticides (OCPs) in edible fishes from Taihu Lake, China

Tissue distribution and bioaccumulation of organochlorine pesticides (OCPs) in edible fishes collected from Taihu Lake, Cyprinus carpio (C. carpio) and Ctenopharyngodon idellus (C. idellus), were studied. OCPs were detected in all samples with hexachlorocyclohexanes (HCHs), aldrins (including aldrin, dieldrin, endrin, endrin aldehyde, and endrin ketone), heptachlors (heptachlor and heptachlor epoxide) and dichlorodiphenyltrichloroethanes (DDTs) being the predominant compounds for both fish species. Gill and gonad were found to be the dominant tissues for OCP bioaccumulation followed by liver, while muscle showed the least affinity of OCPs for both fishes. Tissue distribution indicated the exchange of contaminants between water and gill, as well as the food intake from environment were the dominant pathways for OCP bioaccumulation in gill-breathing fish, and the following tissue distribution was affected by both the physiological properties of target tissues and physicochemical characteristics of pesticides. OCP residues in fish were species-specific (45.63–1575.26 ng/g dry weight (dw) for C. idellus; 8.40–60.23 ng/g dw for C. carpio) mainly due to the growth rate of individuals as well as the metabolic capacity difference among species. HCHs and DDTs observed in fishes from Taihu Lake were comparable and moderate with other reported places in China. Human exposure risk assessment performed with the estimated daily intake values demonstrated the consumption of target fish species in Taihu Lake at present was safe.     

Persistent Organochlorine Pesticide Residues in Soil and Surface Water of Northern Indo-Gangetic Alluvial Plains

This study reports the concentration levels and distribution pattern of the organochlorine pesticide (OCPs) residues in the soil and surface water samples collected from the northern Indo-Gangetic alluvial plains. A total of 31 soil and 23 surface water samples were collected from the study region in Unnao district covering an area of 2150 km² and analyzed for aldrin, dieldrin, endrin, HCB, HCH isomers, DDT isomers/metabolites, endosulfan isomers (α and β), endosulfan sulfate, heptachlor and its metabolites, α-chlordane, γ-chlordane and methoxychlor. In both the soil and surface water samples β- and δ-isomers of HCH were detected most frequently, whereas, methoxychlor was the least detected pesticide. The results showed contamination of soil and surface water of the region with several persistent organic pesticides. The total OCPs level ranged from 0.36–104.50 ng g^–1 and 2.63–3.72 μg L^–1 in soil and surface water samples, respectively.     

Monitoring and Assessment of Persistent Organochlorine Residues in Sediments from the Daliaohe River Watershed, Northeast of China

Surface sediment samples from 12 sites of the three selected rivers in Daliaohe River watershed (Hunhe River, Taizihe River and Daliaohe River) were analyzed with the objective of establishing sources and hazard of the organochlorinae pesticides (OCPs) and polychlorinated biphenyl (PCBs) in surface sediments. The total concentrations of OCPs varied from 3.06 to 23.24 ng g⁻¹. ∑HCH (α-HCH, β-HCH, δ-HCH, γ-HCH), ∑DDT (p, p′-DDE, p, p′-DDD, o, p′-DDT, p, p′-DDT) and ∑Cyclodiene (Heptachlor, Aldrin, Heptachlor epoxide, Dieldrin, Endrin) ranged from 1.86 to 21.48, 0.5 to 2.81 and 0.56 to 1.53 ng g⁻¹, respectively. Results of OCPs also illustrate that the most dominant pollutants among the OCPs was ∑HCH, and γ-HCH was the most dominant isomer in HCH, which was evidence of recent input of lindane. It possibly came from the runoff of polluted soils and long-scale transportation. Total PCB concentrations ranged between 1.88 and 16.88 ng g⁻¹. The peak concentrations of PCBs were found in sediments from station T5 and D3, which are in the vicinity of industrial areas and ferry, respectively. These data show a moderate level of OCPs and PCBs contaminations compared to that in other countries.     

Organochlorines and Mercury in Waterfowl Harvested in Canada

Samples of breast muscle from 32 species of waterfowl collected from 123 sites across Canada were analyzed for chlorobenzenes (CBz), chlordane-related compounds (CHL), hexachlorocyclohexanes (HCH), DDT, mirex, dieldrin, PCBs and mercury. ΣDDT, ΣCBz and ΣPCB were the compounds most frequently found above trace levels. ΣHCH and ΣMirex were detected the least often. Mercury was detected in all of the mergansers, over 50% of dabbling, bay and sea ducks, and in less than 2% of the geese analysed. The highest levels of contaminants were generally found in birds feeding at higher trophic levels such as sea ducks and mergansers. With the exception of a few samples of mergansers and long-tailed ducks from eastern Canada, which contained ΣPCB concentrations of 1.0–2.4 mg kg⁻¹, ΣPCB levels were less than 1 mg kg⁻¹ wet weight. Only one merganser from eastern Canada had a ΣDDT concentration (2.6 mg kg⁻¹ ww) which was greater than 1 mg kg⁻¹ ww. The highest ΣCHL (0.10 mg kg⁻¹ ww) was also found in mergansers from eastern Canada. Levels of total mercury in breast muscle were either low (< 1 mg kg⁻¹ ww) or below detection limits with the exception of a few samples of mergansers from eastern Canada which contained mercury concentrations of 1.0–1.5 mg kg⁻¹ ww. Health Canada determined that the organochlorine and mercury levels found in samples of breast muscle of ducks and geese analysed in this study did not pose a health hazard to human consumers and therefore these waterfowl were safe to eat.     

Distribution and bioaccumulation of organochlorine pesticides (OCPs) in food web of Nansi Lake,China

The concentration of 12 organochlorine pesticides (OCPs) were measured in water, sediment, aquatic plant, and animal (shrimp and fish) of Nansi Lake by gas chromatography equipped with an electron capture detector. The total OCPs concentrations were 65.31–100.31 ng L^?1 in water, 2.9–6.91 ng g^?1 dry weight (dw) in sediments, 1.29–6.42 ng g^?1 dw in aquatic plants and 7.57–17.22 ng g^?1 dw in animals. The OCPs composition profiles showed that heptachlor compounds was also the predominant OCPs contaminants in addition to hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in Nansi Lake. According to the source of HCHs and DDTs in sediment samples, there was no new input and the HCHs pollution mainly came from the use of Lindane in Nansi Lake. Bioaccumulation of OCPs in aquatic biota indicated that DDTs and heptachlor compounds had a strong accumulation, followed by HCHs and drins. The accumulation abilities of fish for OCPs were higher than those of plants and shrimps. The OCPs biota-sediment accumulation factor values of Channa argus was the highest in fish samples, followed by Carassius auratus, and Cyprinus caspio. Risk assessment of sediment showed that heptachlor epoxide had a higher occurrence possibility of adverse ecological effects to benthic species. Based on the calculation of acceptable daily intake and hazard ratio, HCHs in fish and shrimps from Nansi Lake had a lifetime cancer risk of greater than one per million. The risk assessment of water, sediment, and fish indicated the water environment of Nansi Lake is at a safe level at present.     

Organochlorine pesticide contamination in marine organisms of Yantai coast,northern Yellow Sea of China

To evaluate the contamination of organochlorine pesticides (OCPs) in marine organisms and their potential health risk on consumers in the northern Yellow Sea of China, mollusks, wild shrimps, and crabs were collected from the Yantai coast, and the OCP contents in the samples were analyzed and compared. The results indicate that all the samples have been contaminated by OCPs, and OCP concentrations varied in individual species and in sampling sites. Among the studied OCPs, ∑HCH and ∑DDT concentrations ranged from 0.91 to 13.92 ng g^?1 and from 10.16 to 411.19 ng g^?1, respectively. Meretrix was highly enriched with HCHs, while the highest DDT concentration was found in Crassostrea. For the OCP isomers, β-HCH was the predominant isomer of HCHs, and p,p′-DDE concentration was much higher than other isomers of DDTs. The concentrations of other OCPs (HCB, t-CHL, endrin, and mirex) were relatively low. For the shrimp and crab samples, Alpheus distinguendus samples accumulated a higher level of HCHs but lower DDTs than Oratosquilla aratoria and Carcinoplax vestitus in all sampling areas. HCHs in the samples of contrast area were not significantly lower than that of the sewage outfall area and port area, whereas DDTs in the samples of contrast area were relatively lower than that of the other two areas. Generally, all the OCP contents in the samples are in the range of the edible hygienic criteria except the total concentration of DDTs in Crassostrea.     

Levels and source of organochlorine pesticides in surface waters of Qiantang River, China

Qiantang River is a typical river used for drinking water source, flowing through agricultural area in east China. Surface water samples at 45 sampling sites from the river were collected and analyzed for 13 organochlorine pesticides (OCPs) during six surveys in 2 years of 2005–2006. Sediments, soils, farmland runoff water and dry/wet deposition of this region were also measured for their OCPs residue in order to know possible source of OCPs contamination. The total OCPs concentrations in surface water were 7.68–615.2 ng/l. β-HCH, δ-HCH, Aldrin, Heptachlor, Heptachlor epoxide are the major OCPs in water. The maximum levels of OCPs in water were found in July, while significantly lower OCP concentrations were measured in January. Significant linear correlation was found between the concentration of HCH and that of total 13 OCPs in water. The measured OCP concentrations in sediments, soils, farmland runoff water and dry/wet deposition are discussed in relation to concentrations and patterns found in the surface water. Comparison of OCP levels in sediments and soils led to conclusion that erosion of soil contribute significantly to the contamination of water. The OCPs dry and wet deposition to water body was estimated to 0.49 and 0.86 ton/year, respectively. The ratio of α/γ-HCH and (DDE+DDD)/∑DDT in environmental matrix indicated there probably existed new OCPs input of lindane and dicofol into the river.     

Pollution by organochlorine pesticides in Navachiste-Macapule,Sinaloa, Mexico

The lagoon system of Navachiste-Macapule is located in northern Mexico, in the state of Sinaloa, with an area of 24,000 ha. The main economic activity in the area is agriculture, and the lagoon lies next to the irrigation district ID-063 which covers 116,615 ha. The purpose of this study is to evaluate the levels of pollution generated by organochlorine pesticides (OC) in the surface sediments of the lagoon and in the agricultural drains of the ID-063 that are supposedly transported into the system as a result of agricultural activities and runoff from adjacent land. For this, between 2006 and 2007, 45 surface sediment samples were collected (warm dry, rainy and cold dry) from 15 sampling sites, during the three climatic seasons. Of these, eight were located inside the lagoon in marine conditions (salinity >31 PSU) and seven in the agricultural drains of the ID-063 in freshwater conditions (salinity <5 PSU). The average concentration of the OC in the sediments was 44.75 ng g^− 1, among which the group of the alicyclic compounds presented the greatest concentrations. The average value of the total organic carbon (TOC) in the sediments of the system was 0.90%. The sediments collected inside the lagoon had an average OC concentration of 18.97 ng g^− 1, and the predominant type of sediment was fine to very fine sand. The average OC concentration in the sediments collected in the agricultural drains was 75.69 ng g^− 1, where fine sediments (silt) were predominant. The presence of methoxychlor, endrin and heptachlor suggested that these compounds were continuously used in the system, even though their use is forbidden in Mexico.     

珠江三角洲城市群及高海拔地区表层土中有机氯农药的空间分布特征

利用GC-ECD方法测定了珠江三角洲城市群及高海拔地区表层土壤中的有机氯农药。有机氯农药变幅为2.4~78.7 ng/g,平均15.9 ng/g。最高值出现在江门。总HCHs变幅为ND~19.2 ng/g,平均2.91 ng/g, 最高值出现在佛山。总DDTs变幅为ND~74.6 ng/g,平均值为9.91 ng/g。最高值出现在东莞。六氯苯在佛山较高。灭蚁灵在深圳的污染较其它地区严重。总体来说,HCHs污染程度较低,但部分地区有林丹的使用;有些采样点DDTs的污染程度超过了国家土壤环境质量标准的一级自然背景值,且有些区域可能有非三氯杀螨醇的DDTs外源输入。     

Atmospheric depositional fluxes and sources apportionment of organochlorine pesticides in the Pearl River Delta region, South China

Organochlorine pesticides (OCPs) have variously been phased out in agricultural activities, but they are still widely detected in air, water, and soil systems due to their recalcitrant nature in the environment. The purposes of this study were to assess potential OCP pollution via dry and wet deposition over the fast developing Pearl River Delta area with 41,700 km², where the main effort has been focused on emerging pollutants such as petroleum hydrocarbons and PM2.5. We quantified both the dry and wet deposition fluxes of 19 OCPs including dichlorodiphenyltrichloroethanes (DDTs), endosulfans (Endos), and hexachlorocyclohexanes (HCHs). The results showed that each year about 67.4, 42.0, 15.0, and 8.07 kg of total OCPs, DDTs, Endos, and HCHs were returned to the ground, among which 11.7, 10.4, 0.84, and 0.16 kg were in the dry deposition forms. The large spatial variations in OCP deposition fluxes indicated that OCP pollution in the air is mainly influenced on local scales because evaporation from local soil is likely the major source of the phased out OCPs. Source analysis indicated that DDTs may be still in use as antifouling agent and/or dicofol, but Endos and HCHs were mainly derived from the residual of historical usage. The study suggests that the historical OCP pollutants are persistent at high levels in this area and should not be overlooked, while we tackle emerging pollutants.     

Heavy metals and PCDD/Fs in solid waste incinerator fly ash in Zhejiang province,China: chemical and bio-analytical characterization

Fly ash samples were taken from solid waste incinerators with different feeding waste, furnace type, and air pollution control device in six cities of Zhejiang province. The solid waste incinerators there constitute one fifth of incinerators in China. Heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in the fly ash. Moreover, the fly ash samples were extracted by toxicity characteristic leaching procedure (TCLP). The biotoxicity of the leachate was evaluated by Chlorella pyrenoidosa. High variation and contents were found for both the heavy metals and PCDD/Fs. The contents of Zn, Cu, As, Pb, Cd, Cr, Ni, and Hg in the fly ash samples varied from 300 to 32,100, 62.1–1175, 1.1–57, 61.6–620, 0.4–223, 16.6–4380, 1.2–94.7, and 0.03–1.4 μg g⁻¹ dw, respectively. The total contents of 17 PCDD/Fs varied from 0.1128 to 127.7939 μg g⁻¹ dw, and the 2,3,7,8-TeCDD toxic equivalents (TEQ) of PCDD/Fs ranged from 0.009 to 6.177 μg g⁻¹ dw. PCDF congeners were the main contributor to the TEQ. The leachate of the fly ash showed biotoxicity to C. pyrenoidosa. A significant correlation was found between the Cd and EC₅₀ values. Further research is required to investigate the environmental impact of the various pollutants in the fly ash.     

Distribution and sources of organochlorine pesticides in sediments of the Xiangjiang River, south-central China

The Xiangjiang River (XR), the second largest tributary of the Yangtze River, is mainly located in Hunan province in south-central China. Nineteen surface sediment samples (the top 3-cm layer) collected from XR were analyzed to determine the concentrations, distribution, sources, and ecological risk of organochlorine pesticides (OCPs). The concentrations of OCPs were 3.0–29.8 ng/g (dry weight) with a mean of 12.6?±?7.7 ng/g. The widely detected compounds included HCHs, DDTs, HCB, and dieldrin. Overall, the dominant OCPs in the sediments were mainly composed of residual and degradation products, e.g., β-HCH with a mean of 42.2 % in HCHs and p,p′-DDE with a mean of 43.5 % in DDTs, implying that OCPs in the sediments had suffered from long-term aging without fresh inputs in XR. However, there was a high proportion of p,p′-DDT to DDTs in three sites, suggesting that there was use of technical DDT from their surrounding areas at present. The ratios of α-HCH/γ-HCH and p,p′-DDD?+?p,p′-DDE/DDTs increase from the upper reaches to the lower reaches of XR, suggesting sediments enriched with α-HCH and metabolites DDD and DDE during sediment transport process and could be attributed to the transformation of γ-HCH to α-HCH and DDT to DDE or DDD. The assessment of the ecological risk indicates that the OCPs in the sediments of XR have a moderate adverse biological effect on organisms.     

Residues and ecological risks of organochlorine pesticides in Lake Small Baiyangdian, North China

The levels of hexachlorocyclohexane (HCH) and dichloro-diphenyl-trichloroethane (DDT) in the water, suspended particulate matter (SPM), and sediments from Lake Small Baiyangdian were measured by gas chromatograph with a ⁶³Ni microelectron capture detector. The residual levels of the total HCHs in the water, SPM, and sediments were 1.59?±?2.24 ng L^?1, 25.42?±?1.72 ng g^?1 dw (dry weight), and 0.86?±?1.44 ng g^?1 dw, respectively. DDTs were not detected in the water samples. The concentrations of total DDTs were 158.79?±?1.67 ng g^?1 dw in SPM and 0.46?±?1.97 ng g^?1 dw in the sediments. Compared to other areas in China and abroad, the levels of residual HCH and DDT were relatively low in the water and sediments, but they were moderate to high in the SPM. Organic carbon partition coefficient values for HCH in this study were higher than previously published values and may reflect new input in this area. The residual HCHs in this area could be derived from a mixture of technical HCH and lindane because ongoing lindane use may be occurring. DDT in the majority of the study area was primarily attributed to historical discharge, but some regions may be receiving new input. The ecological risks of γ-HCH in the water were very low according to species sensitivity distribution models. The concentrations of HCH and DDT in the sediments from the study area did not exceed the sediment quality guidelines, which indicate little risk for benthic organisms.     

Assessing environmental impacts of treated wastewater through monitoring of fecal indicator bacteria and salinity in irrigated soils

To assess the potential for treated wastewater irrigation to impact levels of fecal indicator bacteria (FIB) and salinity in irrigated soils, levels of Escherichia coli, Enterococcus, and environmental covariates were measured in a treated wastewater holding pond (irrigation source water), water leaving the irrigation system, and in irrigated soils over 2 years in a municipal parkland in Arizona. Higher E. coli levels were measured in the pond in winter (56 CFU 100 mL⁻¹) than in summer (17 CFU 100 mL⁻¹); however, in the irrigation system, levels of FIB decreased from summer (26 CFU 100 mL⁻¹) to winter (4 CFU 100 mL⁻¹), possibly related to low winter water use and corresponding death of residual bacteria within the system. For over 2 years, no increase in FIB was found in irrigated soils, though highest E. coli levels (700 CFU g⁻¹ soil) were measured in deeper (20–25 cm) soils during summer. Measurements of water inputs vs. potential evapotranspiration indicate that irrigation levels may have been sufficient to generate bacterial percolation to deeper soil layers during summer. No overall increase in soil salinity resulting from treated wastewater irrigation was detected, but distinct seasonal peaks as high as 4 ds m⁻¹ occurred during both summers. The peaks significantly declined in winter when surface ET abated and more favorable water balances could be maintained. Monitoring of seasonal shifts in irrigation water quality and/or factors correlated with increases and decreases in FIB will aid in identification of any public health or environmental risks that could arise from the use of treated wastewater for irrigation.     

Levels and distribution of PCDD/Fs, dl-PCBs, and organochlorine pesticides in sediments from the lower reaches of the Haihe River basin, China

The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), and organochlorine pesticides (OCPs) in surface sediments from the lower reaches of the Haihe River basin, northern China, were determined by high-resolution gas chromatograph–high-resolution mass spectrometer. The concentrations of 2,3,7,8-substituted PCDD/Fs, dl-PCBs, and total OCPs [sum of hexachlorobenzene, hexachlorocyclohexanes, and dichlorodiphenyltrichloroethane (DDTs)] in 17 sediment samples were in the ranges of 11.6–1,180,924 pg/g dry weight (dw), 18.7–50,017 pg/g dw, and 1.7–35,280 ng/g dw, respectively. The contamination levels in the samples varied significantly between the different sites. Abnormally high concentrations of PCDD/Fs, dl-PCBs, and some OCPs were found in sediments from the lower reaches of the main channel of the Haihe River and the Dagu Drainage River, which were attributed to the historical production of pentachlorophenol and other pesticides near these locations. High levels of DDTs were detected in the Yongding New River sediment, which were likely to have originated from the discharge of wastewater from a dicofol factory upstream. In samples taken from other sites, the concentrations of these pollutants were at levels comparable to those documented in other areas of China. This preliminary investigation suggests that historical pesticide production in the Haihe River basin has contributed significantly to the contamination of this aquatic ecosystem and that further attention to this issue is warranted.     

Distribution of Metals in the Edible Plants Grown at Jajmau, Kanpur (India) Receiving Treated Tannery Wastewater: Relation with Physico-Chemical Properties of the Soil

The implications of metal contamination of agricultural soils due to long term irrigation with treated industrial wastewater and their subsequent accumulation in the vegetables/crops growing on such soils has been assessed in an area of industrial complex, Jajmau, Kanpur (India). Physico-chemical properties of the soil were also studied. The soil and vegetables/crops were sampled from an area of 2100 acre agricultural land and analyzed for physico-chemical properties and metal accumulation in different parts of the plants. The comparison of the data of physico-chemical properties of control and contaminated soil showed that salinity, electrical conductivity, available phosphorous, sodium and potassium content (both water soluble and exchangeable) were found high in contaminated soil. The analysis of plant available metal content in the soil showed the highest level of Fe, which ranged from 529.02 to 2615 μg g⁻¹ dw and lowest level of Ni (3.12 to 10.51 μg g⁻¹ dw). The analysis of the results revealed that accumulation of toxic metal Cr in leafy vegetables was found more than fruit bearing vegetables/crops. Thus, it is recommended that the leafy vegetables are unsuitable to grow in such contaminated sites. It is important to note that toxic metal, Ni was not detected in all the plants. The edible part of the vegetables (under ground) such as, garlic (19.27 μg g⁻¹ dw), potato (11.81 μg g⁻¹ dw) and turmeric (20.86 μg g⁻¹ dw) has accumulated lowest level of toxic metal, Cr than leafy and fruit bearing vegetables. In some fruit part of vegetables such as, bitter gourd, egg plant, jack tree, maize and okra, the accumulation of Cr was not detected and may be grown in this area.     

Retrospective monitoring of persistent organic pollutants,including PCBs,PBDEs, and polycyclic musks in blue mussels (Mytilus edulis) and sediments from New Bedford Harbor,Massachusetts, USA: 1991–2005

Blue mussels (Mytilus edulis) and sediments collected from 1991 to 2005 from New Bedford Harbor (NBH), MA, were analyzed for two polycyclic musks (HHCB or Galaxolide® and AHTN or Tonalide®), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs). HHCB and AHTN were found in mussel tissues at mean concentrations of 836 and 376 ng/g lipid weight (lw), respectively, which were two- to seven-fold higher than those found at a reference site. Mean concentrations of HHCB and AHTN in NBH sediments were 12 and 6.3 ng/g dry weight (dw), respectively. Four- and five-ringed PAHs, such as phenanthrene, anthracene, fluoranthene, and pyrene, collectively accounted for 61 % of the ∑PAHs concentrations in mussels from NBH. Mean ΣPCB concentrations in mussels from upper and lower NBH were 942 and 182 μg/g lw, respectively, and were dominated by tetra- and penta-chlorobiphenyl congeners, collectively accounting for 61 % of the ΣPCB concentrations. The mean concentration of ∑PBDEs in mussels from NBH was 277 ng/g lw, and no significant difference existed in the concentrations between upper and lower NBH. DDTs were the major OCP found in mussels, found at a mean concentration of 778 ng/g lw. The concentrations of HHCB, AHTN, ΣPBDEs, ΣPAHs, and DDTs in mussels decreased significantly (r ²?≥?0.56, p?≤?0.052) from 1991 to 2005. The concentrations of PCBs and chlordanes did not exhibit a decreasing trend in mussel tissues (r ²?<?0.50; p?>?0.076) from 1991 to 2005. Based on the temporal trends in the concentrations of HHCB, AHTN, ∑PAHs, and ∑PBDEs found in mussels from NBH, it was estimated that between 5.5 and 12 years were required for the concentrations of these compounds to decrease by half (i.e., environmental halving time) of the levels found in 1991.     

Organochlorine residual concentrations in cattle egret from the Punjab Province, Pakistan

In this study, residual concentration of organochlorine pesticides (OCPs) in the sediments, prey, and eggs of Bubulcus ibis were measured from three breeding heronries from the Punjab province of Pakistan. Pattern of contamination in eggs followed the order: DDTs > HCHs > heptachlor > aldrin. Overall, pesticide residual concentrations were greater in eggs of cattle egrets collected from heronry on the River Ravi. Among HCHs, ??-HCH was more prevalent in eggs, whereas DDTs followed the order: DDD > DDE > p,p ^??-DDT > o,p ^??-DDT. Eggshell thinning was detected which showed negative relationship with residual concentration of DDE. In prey samples, residual concentration of POPs followed the order: DDTs > HCHs > dicofol > heptachlor; however, contamination pattern in sediments followed a slightly different order: DDTs > heptachlor > dicofol > HCHs > dieldrin > aldrin. Concentration of ??-HCH was more prevalent in sediments and comparatively greater concentrations of POPs were measured in sediments collected from the River Ravi. Dicofol was found for the very first time in the biological samples from Pakistan, and its concentration was measured as relatively high in eggs from heronry from the River Chenab. Residual concentrations measured in eggs were below the levels that could affect egret populations. Biomagnification of the total OCPs through the food chain was evident in three breeding heronries. The concentration of DDE measured in eggs of the cattle egret suggests the need for monitoring this contaminant in other bird species at different trophic levels.     

Spatial and seasonal variability of pore water phosphorus concentration in shallow Lake Swarzędzkie,Poland

Pore waters play an important role in phosphorus dynamics in aquatic ecosystems. Phosphorus concentrations in pore waters are much higher than above the bottom. This is confirmed by the results of this study concerning the hypereutrophic lake. Pore water was analyzed at 11 sampling stations in the upper layer of bottom sediments. This water was separated by centrifugation and phosphorus level was measured spectrophotometrically with ascorbic acid as a reducer. Total phosphorus concentration in pore waters ranged from 0.5 to 8.1 mgP l^− 1 (mean 3.2 mgP l^− 1). Mean phosphorus concentration in pore water samples of this lake was the highest in summer and the lowest in winter. High concentrations were observed in samples from the pelagial and low from the macrophyte zone.