Distribution,Sources Identification,and Ecological Risk of PAHs and PCBs in Coastal Surface Sediments from the Northern Persian Gulf

Hormozgan Province plays a vital role in fishery, petroleum, and industrial activities in southern Iran. However, no comprehensive studies on organic pollution have been performed. PCBs and PAHs were analyzed in surface sediments from areas receiving industrial (nine sites), river (one site), and urban (two sites) effluents. The sediment samples were collected in March and September 2010 (in dry and wet seasons) at the highest tidal time. The overall pollution level of PCBs ranged from 2.5 ± 0.8 to 462.0 ± 206.7 ng/g dry weight. CB153 congener dominated in most of the sediment samples. Congener profiles of PCBs showed close similarity with formulations of commercial products such as Aroclor 1260 and 1254 g. A wide range of 55.3 to 1231.6 ng/g dry weight was detected for ∑PAHs. Results of PCA and PCA-MLR tests confirmed both petrogenic and pyrogenic origins for PAH pollution. The higher means of ∑PAHs and ∑PCBs in industrial and urban wastewaters were found near the shore, evidencing the role of these wastewaters in the PAH and PCB contamination in Hormozgan sediment. The concentrations of PAHs and PCBs in detected hotspots exceed the U.S. NOAA sediment quality guidelines.     

Ecotoxicological Risk Assessment of Polychlorinated Biphenyls (PCBs) in Bank Sediments from along the Yamuna River in Delhi,India

The River Yamuna originates from the Yamunotri glacier of the Himalayas and travels 22 km in the Delhi region. The river is used for various purposes in Delhi including drinking water supply. Twenty-eight polychlorinated biphenyls (PCBs) congeners were measured in bank sediments along the river, and their ecotoxicological risk was evaluated. Concentrations of ∑28PCBs varied from 0.20–21.16 ng g^?1 (dry wt.) with mean and median values of 6.63 ng g^?1 and 5.84 ng g^?1 (±0.69 ng g^?1), respectively. The concentration of 12 dl-PCBs concentrations varied from 0.04–2.86 ng g^?1 with a mean of 1.04 ± 0.11 ng g^?1, and their toxic equivalency ranged between <0.01–28.67 pg WHO-TEQ g^?1 with a mean of 10.77 ± 1.06 pg WHO-TEQ g^?1. CB-37, CB-44, CB-114, and CB-118 congeners were dominant among all PCBs congeners. The tri-PCBs (49%) were the main contributors to the PCB homolog followed by tetra-PCBs (35%), and penta-PCB (14%). Because there are no environmental guidelines in India for PCBs in river and marine sediments, concentrations of PCBs and their toxic equivalents were compared in a screening-level assessment with established freshwater sediment quality guidelines and found lower than those guideline values, which suggests no adverse ecotoxicological effect.     

美国威斯康星州的Lower Fox River和Lower Green Bay水域的污染沉积物对鱼类影响的研究

LowerFoxRiver和LowerGreenBy水域的沉积物造成了该地区的轻度污染。经测定和分析,沉积物中含有较高的PCBs和较低含量的PCDFs及PCDDs,在鱼样品中呈现有PCBs和农药。组织病理学检查,鱼体内寄生虫感染发生率较高,部分肝组织坏死,出现肉芽瘤状物,胰腺纤维化,但没有发现鱼体上有肿瘤。     

The role of hydrodynamic sorting on the accumulation and distribution of organic carbon in an impoundment: Englebright Lake,California, USA

The global proliferation of dams is one of the most significant anthropogenic impacts on the environment, resulting in the trapping of massive loads of sediment and nutrients in impoundments. Few studies, however, have examined these impounded sediments to understand patterns of organic carbon (OC) accumulation and the effects of watershed processes on carbon delivery. This study measured total organic carbon (TOC) and stable isotopes of carbon and nitrogen (δ¹³C and δ¹⁵N) in Englebright Lake, CA to relate changes in OC sources and TOC accumulation to natural and anthropogenic events in the watershed and to depositional processes in the lake. Englebright Lake is a representative system for impoundments in small, mountainous rivers, and anthropogenic disturbances in the watershed caused high sediment accumulation rates in the lake. Throughout its 60-year history, 0.35 Tg OC has been trapped behind Englebright Dam and δ¹³C signatures indicate that more than 50% of the OC in Englebright Lake was derived from terrigenous sources. TOC content ranged from 0.03 to 30.24% of dry weight, and differed across depositional regimes; TOC content in topset deposits (0.35 ± 0.58%) was less than in foreset (2.64 ± 5.95%) and bottomset (1.51 ± 1.41%) deposits (p < 0.001) and TOC accumulation associated with flood events was higher (up to 231 kg_OC m^?2 year^?1) than during non-event periods (0.2 to 39 kg_OC m^?2 year^?1). TOC accumulation rates in Englebright Lake were up to an order of magnitude higher than previous estimates of OC burial in California impoundments. As the number and size of dams continues to expand worldwide, the storage of TOC in impoundments will likely add to the growing number of anthropogenic modifications to the global carbon cycle.     

Assessing measurable adverse changes to benthic invertebrate communities based on site-specific sediment toxicity testing and community data at the Anniston,Alabama PCB site

Laboratory toxicity tests were conducted for polychlorinated biphenyl (PCB)-containing sediment from Choccolocco Creek at the Anniston PCB Site. The objective of this investigation was to develop a site-specific PCB concentration–response relationship for invertebrate test organisms. Test results from reference locations were used to develop background-adjusted 10% (EC10*) and 20% (EC20*) effect concentrations for a range of survival, growth, and reproduction endpoints. The EC20* values ranged from 4.43 to 114 milligrams of PCBs per kilogram (mg/kg) of sediment on a dry weight basis for reproductive endpoints, 28 to 67.7 mg/kg sediment for growth, and 123 to 165 mg/kg sediment for survival. The aggregate EC20* response range for endpoints that demonstrated good test performance with reasonable ranges in control variability (<20%) and reference sample responses was 14.3 to 165 mg/kg. The PCB concentrations in sediments for a majority of the Site rarely exceed even the lowest of these thresholds. Given the protective process used to develop these thresholds, there is a high level of confidence that benthic communities are not impacted. This finding is supported by direct measurements of the benthic communities that have been living and reproducing on the Site.     

太湖沉积物微生物生物量及其与碳、氮、磷的相关性

对太湖沉积物中微生物生物量碳(MBc)、氮(MBN)、磷(MBp),以及沉积物总有机碳(TOC)、总氮(TN)、总磷(TP)进行测定并进行相关性分析,揭示太湖沉积物微生物对太湖沉积物营养盐的响应及反馈特征.结果表明:沉积物微生物生物量(MB)在湖体沿岸地区大于湖心区,平均值为184.66 mg·kg-1,MBc在西部沿岸区以及竺山湾和梅梁湾区域较高,平均值为127.57 mg·kg-1;MBN在梅梁湾、贡湖部分区域以及靠近梅梁湾和贡湖的湖心区域和东部沿岸区较高,平均值为19.25 mg·kg-1;MBp在东部沿岸区及其附近的湖心区最高,平均值为19.09 mg·kg-1;沉积物TOC高值区(≥2.30 g· kg-1)主要集中在竺山湾、西部沿岸区、梅梁湾、贡湖地区,平均值为1.59 g·kg-1;沉积物TN高值区(≥0.30g· kg-1)主要集中在贡湖、梅梁湾、竺山湾部分地区以及西部沿岸区,平均值为0.21 g·kg-1;沉积物TP高值区(≥1.20g·kg-1)主要集中在东部沿岸区以及湖心部分区域,平均值为0.55 g·kg-1;太湖沉积物TOC/TN在7～19,平均值为8.97,表明太湖沉积物中的有机质具有明显的双重来源,其中陆源有机质主要集中在西部沿岸区;太湖沉积物MB与沉积物TOC和TN呈显著正相关,与沉积物TP相关性不显著;沉积物MBc/MBN与沉积物TOC/TN显著相关.太湖沉积物微生物主要受沉积物TOC、TN影响,且沉积物TOC/TN的变化显著影响微生物群落结构.     

Health Risk of PCBs and DDTs in Seafood from Southern Iran

Levels of polychlorinated biphenyls (PCBs) congeners and dichlorodiphenyltrichloroethane and its metabolites (DDTs) were measured in 18 species of fish, crab, shrimp, and bivalve samples collected from the northern region of the Persian Gulf in Iran. The levels of ∑PCBs varied from 259.92 ± 31.04 ng/g to 1648.88 ± 176.96 ng/g in lipid weight. CB118 showed the highest concentration. ∑DDT variations ranged from ND to 570.45 ± 806.74 ng/g in lipid weight. Health risk was assessed by estimating both dietary intakes and screening values (SVs). Daily intake levels were much lower than the Food and Agriculture Organization (FAO)/World Health Organization (WHO) standards for PCBs and DDTs. Based on an average bodyweight of 73 kg and consumption rates of 0.055 kg/person. day, the SVs for the carcinogen and non-carcinogen effects of PCB and DDT were calculated. Average concentrations of PCBs and DDTs showed that the levels of PCBs exceeded the established SV for carcinogens. This finding suggests the need to enhance risk management regarding seafood consumption through public advisory.     

Surficial sediment phosphorus fractions along a biogeochemical gradient in Nyanza (Winam) Gulf, northeastern Lake Victoria and their possible role in phosphorus recycling and internal loading

Different phosphorus fractions and metal element composition of surficial sediments were measured on three occasions in 2005 and 2006 along a transect between Nyanza Gulf and offshore Lake Victoria, in order to assess the potential for sediments to contribute to the water column P concentrations in Lake Victoria. Total phosphorus (TP), apatite phosphorus (AP), inorganic phosphorus (IP) and organic phosphorus (OP) increased in sediments along the gulf towards the main lake while the non-apatite inorganic phosphorus (NAIP) increases were less defined. The longitudinal gradient of sediment TP and its fractions in Nyanza Gulf is a result of high rates of terrigenous input and resuspension and transport of the light, phosphorus rich inorganic and organic matter towards the main lake. TP in the sediment ranged from 812.7 to 1,738 mg/kg dry weight (DW) and was highest in the Rusinga Channel, the exchange zone between the gulf and the main lake. AP was the most important TP fraction, contributing between 35 and 57.3% of TP. Ca content in the sediment was strongly associated with TP and AP in the sediment (r² = 0.92 and 0.98, respectively) in the gulf and the channel, indicating the importance of apatite in controlling P availability in these zones. In the gulf and the Rusinga Channel, the less bioavailable apatite phosphorus dominated, whereas in the deeper main lake OP was the major fraction illustrating the importance of anaerobic release of P from sediments and acceleration of internal P loading in the main lake.     

Distribution characteristics,sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in sediments from Haizhou Bay,China

Sixteen USEPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed by gas chromatography–mass spectrometry. Twenty samples were collected from the surface sediments of Haizhou Bay in this survey. This research aimed to identify the PAHs' contamination level, composition pattern, pollution sources, and assess the ecological risk of PAHs. The results showed that the sum of PAH concentrations ranged from 116.6 ng g^?1 to 2414.9 ng g^?1 (mean: 662.42 ng g^?1), which is higher than the reported values for different wetlands worldwide. Three- and four-ring PAHs (accounts for more than 70% of the total PAH content) were predominant in the wetland sediment. The PAHs source distribution in the surface sediments were determined using diagnostic ratio and PCA/MLR. Consequently, multiple PAHs sources were found. Of the total PAH, 79.25% was derived from vehicular emission, 20.75% from coal combustion. The effect range low/effect range median (ERL/ERM) values indicated a low toxicity risk level. However, the fluoranthene concentrations exceeded the ERL level, and even the ERM level, in some stations. The mean effects range–median quotient (M-ERM-Q) suggests a low ecological risk for the PAHs in the sediments.     

Assessment of persistent organochlorine compounds contamination on the Lake Victoria water and sediments: a case study in Tanzania

The current study was conducted to establish the levels of organochlorine pesticides (OCPs), its degradation products, and indicatory polychlorinated biphenyls (PCBs) in water and sediments from Lake Victoria in Tanzania. Seven indicator PCBs were identified in sediments, and five were identified in water. The PCBs loading ranged from lower than the limit of detection (LOD) to 10.28 µg kg^?1 DW and 0.95 to 2.24 µg l^?1 in sediments and water, respectively. PCBs, CB 138 and CB 153 dominated the load, because of their chemical stability and high degree of chlorination. In addition, ten OCPs were identified in sediments, and seven OCPs were identified in water. The levels of organochlorine compounds in sediments were higher than in water samples, implying that sediments may serve as a sink for these compounds. The presence of these compounds is probably as a result of either historical use, long-range environmental transport or environmental persistence. The levels of organochlorine compounds in the lake water and sediments are below the maximum residue limit set by EU and FAO, except for aldrin and dieldrin. Based on the Threshold Effect Concentration (TEC) for freshwater ecosystems, aldrin and dieldrin are the only OCPs that seem to be a threat to the lake environment.     

Distribution and ecological risks of polychlorinated biphenyls (PCBs) in surface sediment of the Forcados River,Niger Delta,Nigeria

Concentrations of Σ15 PCBs in sediments of the Forcados River, Nigeria, were determined in 2012 to provide information on the profile, sources and ecotoxicological risks of PCBs in the sediment. The screening concentrations of PCBs were quantified using a gas chromatograph equipped with a Ni-63 electron capture detector. The concentrations of the Σ15 PCBs ranged from 2.7 to 202.3 µg kg???1 with a mean concentration of 46.5 µg kg???1. The composition of PCB congeners was clearly dominated by octa-PCBs, hepta-PCBs and hexa-PCBs, constituting 68.1% to 93.7%, respectively, of the total amounts of PCBs. All sites had Σ15 PCB levels below the prescribed probable effect concentrations, and therefore no adverse effects are expected for the majority of sediment-dwelling organisms of the Forcados River system.     

Influence of anthropogenic activities on polycyclic aromatic hydrocarbons in sediments from mangrove wetland at Dongzhai Harbor,China: distribution,sources, probability risk,and temporal trend

Sixteen polycyclic aromatic hydrocarbons (PAHs) in 37 surface sediments and a sediment core from the Dongzhai National Nature Reserve in Hainan island of China were analysed. The total concentration of the 16 PAHs ranged from 15.7 to 464.0 ng g^?1 (mean value of 76.7 ng g^?1) in the surface sediments, and 8.6–115.9 ng g^?1 (average 39.3 ng g^?1) in the sediment core. Combustions of petroleum, biomass, coal, and grass were the major pyrogenic sources in surface sediments, and some areas had petrogenic sources (mainly petroleum spills). Results of the ecological risk assessment show little negative effect of most of the PAHs in the study area. The depositional flux of PAHs generally increased from the deeper layers toward the upper layers of the sediments. The flux rate rapidly increased after the 1980s, in contrast to that of some developed countries.     

Bacterial Diversity and Community Structure in High Arsenic Aquifers in Hetao Plain of Inner Mongolia,China

The bacterial diversity and community structure of high arsenic (As) aquifers was investigated using an integrated approach adopting both geochemistry and molecular biology (polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone library analyses). Nine borehole sediments and one groundwater sample from the living place of a villager (affected by arseniasis) and 12 sediments from a control borehole in Hetao Plain were investigated. The As concentrations ranged from 33.6 to 77.6 mg/kg in high As borehole sediments and 1.5 to 5.8 mg/kg in those samples from the control. The As concentration in the groundwater was 744.8 μg/L. Ratios between As(III) and total As in high As sediments increased gradually with depth and ranged from 0.02 to 0.34. Similarly, the Fe(II)/total Fe presented the same increasing trend with depth. The correlation between TOC contents and total As was positive. High concentrations of total As, S, Fe and TOC were found in clay and low in sand samples. Phylogenetic analysis showed significantly different bacterial communities among high As sediments, control sediments and the high As groundwater. Both DGGE and 16S rRNA gene clone library results showed that the high As sediments were dominated by Thiobacillus, Pseudomonas, Brevundimonas, and Hydrogenophaga, with Thiobacillus being distinctly dominant (63.5%). Whereas the low As sediments were dominated by some other genera including Psychrobacter, Massilia and Desulfotalea. The bacterial populations in the high As groundwater mainly included Pseudomonas, Acinetobacter and Aquabacterium. These results improve our understanding of the bacterial diversity in high As aquifers in Hetao Plain and suggest how specific bacterial populations help mediate the mobilization of As into high As groundwaters.     

Erosion and sediment yield in the Atna river basin

Variability in suspended sediment transport and its relation to erosion processes in two different catchments within the Atna river basin are discussed on the basis of 14 years of data collection. The upper Atna catchment is a headwater system covering 157 km². Extensive glacifluvial deposits are the main sediment source of the river. Sediment transport in the upper Atna during 1988–2001 ranged from 79.4 t to 13,200 t. The extreme upper value was due to an extreme rainflood in 1996. Suspended sediment concentrations varied from less than 1.0 mg l^?1 to a maximum of 2023.8 mg l^?1. There was no correlation between water discharge and suspended sediment concentration. Despite a fairly constant volume of total runoff, sediment concentrations remained at a high level during the first years after extreme floods, and then decreased over several more years. The complicated pattern of short term and long term variations in suspended sediment concentration and load was explained in terms of channel changes and variations in exposure of the sedimentary deposits to fluvial erosion. The catchment of the lower Atna drains an area of 672 km². Concentrations of inorganic suspended sediments were found to vary between <1.0 and 897 mg l^?1, with only a weak correlation to water discharge. The suspended sediment transport per year ranged from a minimum value of 574 t in 1991 to 60,651 t per year in 1995, the extreme flood year. The mean annual transport for all the years was 6271 t. The sediment transported in the lower Atna is derived from the same types of sources as in the upper catchment, but the sediments are supplied from a larger area. Grain size distribution analyses indicate that the transported sediments in upper Atna have a sand content of 10 to 65% compared to 2–20% in lower Atna. The transport of particulate organic matter in the upper and lower Atna catchments amounted to 9.8% and 12.6% of the total load, respectively.     

SPI-ing on the seafloor: characterising benthic systems with traditional and in situ observations

This work aimed to show that the sea bed of two environmentally-different regions of the North Sea varies both spatially and temporally with respect to their biological communities and bioturbation characteristics. The two contrasting sites studied were north of the Dogger Bank (ND) (85 m) and the Oyster Grounds (OG) (45 m). The physical environment varied between and within sites, mainly influenced by sediment chlorophyll a content and water temperature. Our data revealed that the depth of the apparent Redox Potential Discontinuity (aRPD) layer at OG varied between 2.2 cm in February and 6.5 cm in October; evidence of bioturbation activity (e.g., feeding voids) was observed within the sediment profile. In contrast, at the ND site the aRPD values ranged from 1.7 cm in February to 2.5 cm in May and feeding voids and infaunal burrows were restricted to sediment depths far shallower than those observed at OG. Communities at ND were dominated by a number of surficial-sediment dwelling polychaete species (e.g., Notomastus latericeus, capitellids) while those of OG were dominated by the brittlestar Amphiura filiformis, together with significant numbers of deeper-dwelling taxa such as the ghost shrimp Callianassa subterranea and the bivalve mollusc Corbula gibba. Our data imply that regions of the North Sea which experience dissimilar environmental conditions not only possess different infaunal communities but also contrasting seasonal fluctuations and bioturbation capacities. The ecological implications of these findings, including inferences for carbon and nutrient cycling, are discussed in relation to the wider North Sea ecosystem.     

Distribution and Significance of Fecal Indicator Organisms in the Upper Chesapeake Bay

Total viable aerobic, heterotrophic bacteria, total coliforms, fecal coliforms, and fecal streptococci were enumerated in samples collected at five stations located in the Upper Chesapeake Bay, December 1973 through December 1974. Significant levels of pollution indicator organisms were detected at all of the stations sampled. Highest counts were observed in samples collected at the confluence of the Susquehanna River and the Chesapeake Bay. The indicator organisms examined were observed to be quantitatively distributed independently of temperature and salinity. Counts were not found to be correlated with concentration of suspended sediment. However, significant proportions of both the total viable bacteria (53%) and fecal indicator organisms (>80%) were directly associated with suspended sediments. Correlation coefficients (r) for the indicator organisms examined in this study ranged from r = 0.80 to r = 0.99 for bottom water and suspended sediment, respectively. Prolonged survival of fecal streptococci in most of the sediment samples was observed, with concomitant reduction of the correlation coefficient from r = 0.99, fecal streptococci to total coliforms in water, to r = 0.01, fecal streptococci to fecal coliforms in sediments. The results of this study compared favorably with fecal coliforms: fecal streptococci ratios for the various sample types. Characterization of organisms beyond the confirmed most-probable-number procedure provided good correlation between bacterial indicator groups.     

Macronutrients along the sediment profile in a subtropical monsoonal wetland in India

We analyzed 144 composite sediment samples to appraise the seasonal variation in select major nutrients in the bed sediments of Keoladeo National Park (KNP), Bharatpur, a subtropical monsoonal wetland system in India, from September 2003 to July 2005. Total organic carbon (TOC, %) and total nitrogen (TN, %) in the sediments were in the range of 0.61–14.01 and 0.26–0.68, respectively. The total available phosphorus (TAP, %) and total available sulphur (TAS, %) ranged from 0.001 to 0.034 and from 0.001 to 0.012, respectively. While C:N ratio was within a narrow range (1.38–13.56), C:P ratios varied widely (18.81–5995.83). Similar wide variations were seen in C:S ratio (352.2–3929.5) as well as N:P ratio (9.34–56.6). All the parameters except TAS showed depth-wise declines along the sediment profile. In contrast, the pH gradually increased along the depth. Most of the parameters significantly varied across months and sediment layers. A positive correlation (Two-tailed, P < 0.05) existed between TOC and all the nutrients and their ratios except TAP and N:P. TAP was positively correlated with electrical conductivity (EC) and water soluble substances (WSS), suggesting the contribution of phosphate to the dissolved salts. During certain months elements such as P were comparatively low in concentration, in spite of input through agricultural runoff and large scale bird droppings, probably due to its higher uptake by macrophytes growing luxuriantly in the wetland. Organic materials appear to decay at a faster rate during the drier periods as indicated by the fall in TOC and the rise in TN. Principal Component Analysis (PCA) shows that three components contributed to 68.9% of the total variance. The first component that accounted for 26.4% of the total variance reflects the importance of total organic carbon in wetland sediments and the ratio of carbon to other nutrients. The second one accounting for 23.7% of the variance correlated with water soluble substances (EC, WSS and TAS). The third component accounting for 18.7% of the variance reflects the influence of two major nutrients, nitrogen and phosphorus, in sediments those affect the biogeochemical processes in wetlands. Thus, the three PCA components can be characterized as ‘sediment organic carbon and its ratios with other elements’, ‘WSS, TAS’ and ‘the limiting nutrients such as N and P’, respectively.     

An effective method based on wet-heat treatment for the selective isolation of Micromonospora from estuarine sediments

Several methods for the isolation of Micromonospora from soil samples have been developed; however, it is unclear whether these methods are optimal for estuarine samples. In this study, we optimized the conditions of a wet-heat method for the selective isolation of Micromonospora from estuarine sediments. Sediments were collected from the Arakawa River (estuarine sediments) and Tokyo Bay (marine sediments). Sediment samples were wet-heated at 45, 55, or 65 °C for 30 min and then incubated at 27 °C for 3 weeks. After incubation, most of the actinomycete colonies were macroscopically determined to be of the genus Micromonospora or Streptomyces. In contrast to the treatment at 55 °C, treatment at 65 °C drastically reduced the number of Streptomyces colonies but increased the number of Micromonospora colonies from the estuarine sediments. This procedure allowed us to grow cultures that were composed of more than 90 % Micromonospora. In addition, treatment at 65 °C did not affect the diversity of Micromonospora species compared with treatment at 55 °C. These results indicate that the wet-heat method, which involves pre-treating the sediment at 65 °C for 30 min, is a very simple and effective method for the selective enrichment of a large number of diverse Micromonospora from estuarine sediments. Our results may lead to the isolation of new Micromonospora species, which produce novel bioactive compounds, from different estuarine sediments.     

Ecological Risk Assessment of Sediments in Sydney Harbour,Nova Scotia,Canada

Contamination within sediments of Sydney Harbour (once a major industrial port) were evaluated using a multiple lines-of-evidence (LOE) ecological risk assessment (ERA) approach prior to divestiture of the harbor. The multiple LOE approach included: (1) measurement of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals, metalloids, petroleum hydrocarbons(PHCs), and total organic carbon (TOC) concentrations in surface sediments from multiple Sydney Harbour locations; (2) identification and application of sediment quality guidelines (SQGs) from various jurisdictions; (3) comparisons of harbor sediment chemistry against background/reference sediment chemistry; (4) determining number and frequency of exceedances over SQGs; (5) calculating mean probable effect level-quotients (PEL-Qs); (6) PAH forensic source evaluation; (7) review of previous sediment chemistry and biota tissue data; and (8) characterizing benthic habitat at harbor stations. The ERA determined that current sediments exhibited mostly low probability of adverse effects. Furthermore, contaminated sediments exhibiting a high probability of adverse effects were localized to only a few stations within the harbor. Ongoing natural recovery of harbor sediments is likely responsible for attenuating contaminants that historically were higher than those measured in this study and were previously distributed over much wider areas of the harbor. Results suggest that legacy industrial activities and current urban sewage effluents are the major sources of contamination in Sydney Harbour sediments.     

Organochlorine contaminants in freshwater mussels; occurrence,bioaccumulation pattern,spatio-temporal distribution and human health risk assessment from the tributaries of River Ravi,Pakistan

The present study was conducted to investigate the bioavailable levels and human health risk of organochlorine contaminants (OCs), particularly organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in freshwater mussels from northern three tributaries of River Ravi, Pakistan that provides the pioneer data for the occurrence of POPs in the freshwater mussels from Pakistan. The Σ₂₃OCPs and Σ₃₅PCBs concentrations in mussels were ranged from 189.66–2049.40 ng/g and 25.81 to 135.38 ng/g, respectively. The comparison of current bioavailable levels of OCs with maximum residual limits (MRLs) established by Food and Agricultural Organization and European Union revealed that Σendosulfan (100%), ΣDDTs (93%), HCB (87%), β-HCH (77%), endrin (77%), γ-HCH (70%), heptachlor (67%), aldrin (67%), dielrin (67%), Chlordane (70%), α-HCH (40%), and WHO-TEQ (2005) values for PCB-126, PCB-169 and Σ₈DL-PCBs were exceeding the permissible limits. The human health risk assessment revealed the occurrence of substantial lifetime carcinogenic risk for OCPs and PCBs at both 50th and 95th percentile concentrations in freshwater mussels from the tributaries of River Ravi. Therefore, the freshwater mussels are recommended to be used in environmental toxicological studies to assess the bioavailable levels of pollution in hostile environment.