Concentrations In Surface Sediments Research Articles

Bisphenol A in the Canadian environment: A multimedia analysis

Bisphenol A (BPA) is an industrial chemical that has been identified by some jurisdictions as an environmental concern. In 2010, Canada concluded that this substance posed a risk to the environment and human health, and implemented actions to reduce its concentrations in the environment. To support these activities, a multimedia analysis of BPA in the Canadian environment was conducted to evaluate spatial and temporal trends, and to infer mechanisms influencing the patterns. BPA was consistently detected in wastewater and biosolids across Canadian wastewater treatment plants (WWTPs) and in landfill leachate. In addition, BPA concentrations were significantly higher in surface water downstream compared to upstream of WWTPs in three of five urban areas evaluated. However, application of biosolids to Canadian agricultural fields did not contribute to elevated BPA concentrations in soil, earthworms, and European Starling (Sturnus vulgaris) plasma one and two years post-treatment. Spatial trends of BPA concentrations in surface water and sediment are influenced by human activity, with higher concentrations typically found downstream of industrial sources and WWTPs in urban areas. BPA was detected in bird plasma at locations impacted by WWTPs and landfills. However, spatial trends in birds were less clear and may have been confounded by metabolic biotransformation. In terms of temporal trends, BPA concentrations in surface water decreased significantly at 10 of 16 monitoring sites evaluated between 2008 and 2018. In contrast, recent temporal trends of BPA in six sediment cores were variable, which may be a result of biotransformation of the flame retardant tetrabromobisphenol A to BPA. Overall, our study provides evidence that Government of Canada actions have been generally successful in reducing BPA concentrations in the Canadian environment. Our results indicate that long-term monitoring programs using surface water are more effective than other media for tracking and understanding future environmental trends of BPA.

Quantifying the contributions of soil surface microtopography and sediment concentration to rill erosion

Soil surface microtopography plays a significant role in rill erosion. In addition, upslope inflow has a large effect on downslope soil erosion processes. Experiments including four different upslope filling areas (0 m2, 0.15 m2, 0.30 m2, and 0.45 m2) with a upslope inflow rate (6 L min−1) were conducted in two 1 m × 2 m boxes on a 15° slope to examine the effects of microtopography and sediment concentration on rill erosion processes. The upslope filling areas were used to simulate different areas of earthen dike terraces. The results showed that the minimum values of soil surface elevation increased from −120 mm to −110 mm as the upslope filling area increased. The values of the simple fractal dimension (f(α)max), the singular index span (Δα) and the difference of multifractal spectrum (Δf(α)) reached minimum values in the 0.45 m2 upslope filling area. With the development of rill erosion, the soil surface microtopography tended to sharpen, and the relative elevation changed greatly. The runoff and soil loss associated with rill erosion gradually decreased as the upslope filling area increased. We identified the temporal evolution of rill erosion using Morlet wavelet analysis. The main period of temporal fluctuation of rill erosion was 28 min under different upslope filling areas. Multi-scale periods of temporal fluctuation of rill erosion emerged with the increase in upslope filling area. The Δα significantly affected the runoff and soil loss. The proportional contributions of Δα to the runoff and sediment yield were 80.95% and 77.34%, respectively. While the contributions of sediment concentration to runoff and sediment yield were 17.05% and 20.66%, respectively. The findings are important significance for better understanding rill erosion mechanisms of purple soil.

Bioavailability assessment in activated carbon treated coastal sediment with in situ and ex situ porewater measurements

Passive sampling and bioaccumulation assessments were used to evaluate the performance of activated carbon (AC) remediation of polychlorinated biphenyl (PCB) contaminated sediment offshore in Parcel F of the former Hunters Point Naval Shipyard (HPNS) (San Francisco, California). Two different composite AC materials, AquaGate+PAC™ (86 tons) and SediMite™ (24 tons) were placed on the sediment surface covering an area of 3200 m2. PCB tissue concentrations in the clam Macoma nasuta were reduced 75 to 80% in pilot amendment areas after 8 months and 84–87% in non-lipid normalized tissues after 14 months during in situ monitoring, confirming the effectiveness of the AC at reducing bioavailability of the PCBs. Polydimethylsiloxane (PDMS) passive samplers were applied to evaluate and monitor freely dissolved concentrations (Cfree) of PCBs in sediment porewater before AC placement (i.e., during baseline) and at 8 months, 14 months and 26 months following placement. Although AC composite materials were placed only at the surface, 80% reductions were observed to a depth of 16 cm after 8 months and up to 26 cm after 26 months in AquaGate+PAC treatment area. Total PCB porewater concentrations in surface sediments (1–6 cm) were reduced 89 and 91% in the AquaGate+PAC and SediMite areas during final sampling. Ex situ passive sampling showed porewater concentrations 2–5 times larger than in situ measurements due to the absence of hyporheic exchange in laboratory measurements and near equilibration between sediment and porewater. Estimated post placement ex situ porewater concentrations were more consistent with a model of bioaccumulation using the octanol-water partition coefficient (KOW) as a bioaccumulation factor leading to a hypothesis that the bioaccumulation factor in the deposit feeding clam is better estimated by equilibrium ex situ porewater measurements.

Potential Ecological Risk Assessment of Heavy Metals Contamination in Surface Sediments of Ikpoba River, Southern Nigeria

The potential ecological risk assessment of heavy metals contamination in surface sediments of Ikpoba River, Edo State was estimated in this study after assessment of heavy metal concentrations in surface sediments from seven stations of the study area. Heavy metals were analyzed in the sediments using Atomic Absorption Spectrophotometer. The index of geo-accumulation for the metals (Lead (Pb); Iron (Fe); Nickel (Ni) and Copper (Cu)) studied were less than zero showing that the stations sampled were unpolluted with heavy metals. Contamination factor followed same pattern. Generally, there was a low potential ecological risk for heavy metal contamination to sediment dwelling organisms. However, station 4 (Capitol) was moderately contaminated and extremely enriched with Cu. Heavy metal values in this study were below the EPA limits for sediments except station 4 which was heavily polluted with Cu following the EPA guidelines. Regular monitoring and assessment of pollution load of Ikpoba River is recommended.

Origin of tungsten and geochemical controls on its occurrence and mobilization in shallow sediments from Fallon, Nevada, USA

Tungsten (W) occurrence and speciation was investigated in sediments collected from Fallon, Nevada where previous studies have linked elevated W levels in human body fluids to an unusual cluster of childhood leukemia cases. The speciation of sedimentary W was determined by μ-XRF mapping and μ-XANES. The W content of the analyzed surface sediments ranged between 81 and 25,908 mg/kg, which is significantly higher than the W content in deeper sediments which ranged from 37 to 373 mg/kg at 30 cm depth. The μ-XANES findings reveal that approximately 20–50% of the total W in the shallow sediment occurs in the metallic form (W0); the rest occurs in the oxide form (WVIO3). Because W0 does not occur naturally, its elevated concentrations in surface sediments point toward a possible local anthropogenic origin. The oxidation of metallic W0 with meteoric waters likely leads to the formation of WVIO3. The chief water-soluble W species was identified as WO42− by chromatographic separation and speciation modeling. These results led us to postulate that W0 particles from a currently unknown but local source(s) is (are) deposited onto the soils and/or surface sediments. The W0 in interaction with meteoric water is oxidized to WVIO3, and as these sediment-water interactions progress, WO42− is formed in the water at pH ∼7. Under pH < 7, and sufficient W concentrations, tungstate tends to polymerize, and polymerized species are less likely to adsorb onto sediments. Polymerized species have lower affinity than monomers, which leads to enhanced mobility of W.

Distribution of Some Selected Surface Active Agents (SAAs) in the Aquatic and Global Environment with Their Toxic Impact: A Comprehensive Review

Surface active agents (SAAs) are a class of compounds, which find various applications in different fields of human activities. Surfactants are generally amphiphilic molecules, which are strongly adsorbed at interfaces between the phases. Surfactants windily used as detergency, emulsion, stabilizing and dispersing agents have led to the discharge of highly contaminated wastewaters in aquatic environment. Once reached in the various compartments of the environment such as rivers, lakes, soils, and sediments, surfactants can undergo aerobic or anaerobic degradation. Concentrations of surfactants in wastewaters, river waters, and sewage waters can range milligrams in maximum cases, while it reaches several grams in sludge, soil and sediments in environments. The environmental facts of SAAs and concentration in surface waters, soils or sediments are reviewed in details. This review provides information on levels of surface-active agents in various environmental samples including soil, sediments, sewage wastewater, river wastewater and aerosols.

VARIAÇÃO ESPAÇO-TEMPORAL DAS CONCENTRAÇÕES DE METAIS EM ZONAS ESTUARINAS DA BAÍA DE TODOS OS SANTOS, BAHIA, BRASIL

The knowledge of metal behavior in the aquatic environment is important for understanding its effects in estuarine zones and mangrove areas. These important and precious ecosystems are affected by many different factors that may vary temporally and spatially. The present study investigated the spatial and temporal variation of physicochemical parameters (pH, dissolved oxygen, temperature, salinity, etc.) and metal concentrations (Zn, Fe, Ni, Cu) at three different locations along the Todos os Santos Bay, North East Brazil, by analyzing surface water, sediment and mangrove oysters (Cassostrea rhizophorae (Guildin, 1828)). Metal concentrations in surface waters and sediments differed between the three sampling times (March and August 2014; January 2015) and locations and were affected by fluctuating physicochemical parameters, which in this way also affected the metal bioconcentration in the oysters. The pH of the surface waters, for example, increased from the 1st to the 3rd sampling time while the concentrations of Zn and Fe decreased during the same period. The sediment concentrations of Zn and Fe were strongly correlated with organic matter content. These results suggests that seasonality as well as the different water and sediment properties along the bay directly affect metal concentration and bioavailability in the environment.

Perfluoroalkyl substances in sediments from the Bering Sea to the western Arctic: Source and pathway analysis

Although perfluoroalkyl substances (PFASs) are ubiquitous in the Arctic, their dominant pathways to the Arctic remain unclear. Most modeling studies support major oceanic transport for PFASs in the Arctic seawater, but this conclusion contradicts the rapid response of PFASs to global emissions in some biota species. Sediments, which act as important PFAS sinks for seawater and potential PFAS source to the benthic food web, are important for interpreting the fate of PFASs in the Arctic. Here we investigate the occurrence of 9 PFASs in one core (1945–2014) and 29 surface sediments from the Bering Sea to the western Arctic. Total PFAS concentrations (0.06–1.73 ng/g dw) in surface sediments were dominated by perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA) and perfluorobutyl sulfonate (PFBS), with higher levels in the Bering Sea slope and the northeast Chukchi Sea. Historical trends in PFASs varied among individuals, with PFOS declining in the early 2000s while PFNA showing an increasing up-core trend. Analysis of positive matrix factorization model identified that the major PFAS sources in the sediment core were dominated by the atmospheric oxidation of consumer use of PFOS precursor-based products (45.0%), while the oceanic transport of fluoropolymer manufacture of polyvinylidene fluoride (mainly PFNA) exhibited an increasing trend over time, becoming dominant in surface sediments (42.8%). Besides, local input of possible aqueous fire-fighting foams (mainly PFOS and PFBS) also acted as an important source currently (30.1%) and historically (34.9%). Our study revealed that the pathways of PFASs in Arctic sediments varied greatly for individuals and the conclusion of PFOS originating from mainly atmospheric oxidation was different from seawater modeling results. This, together with the high possibility of sediments as direct source to Arctic food web (supported by similar PFAS compositions and temporal variations), help provide additional evidence regarding PFAS pathways to the Arctic.

Evaluation of trace elements concentration in surface sediments of Parishan International Wetland (Fars Province, SW Iran) by using geochemical and sedimentological analysis

This study investigated the concentration of trace metals in surface sediments of Parishan Lake. Parishan Lake is one of the biggest freshwater lakes in the Middle East, situated in Kazerun area (Fars Province, Iran). This preliminary study concerns the mineralogy, enrichment level, and trace elements source identification in surface sediment of this lake. The geochemical Enrichment Factor (EF) and Geo-accumulation index (Igeo) and sedimentological approaches were applied to characterize the contamination by heavy metals, comparing with Average Shale. Multivariate statistical analysis was also used to identify probable studied elements sources in collected samples. The XRD and microscopic analysis show that main mineral of surface sediments is aragonite with small amounts quartz and nepheline. Chemical analysis of sediments showed that the mean concentrations of As, Cd, Cr, Cu, Ni, Pb, Zn, and Sr were 1.88, 27.2, 32.4, 18.6, 8.1, 38.4, and 3934.9 mg/kg, respectively, and average concentrations of Cd, Cu, and Sr exceeded the corresponding values of upper continental crust (UCC) values. The outcomes of this study indicate that geochemical indices (EF and Igeo) revealed an extremely high enrichment for Sr, whereas other elements had minimal enrichment. The levels of potential ecological risk index (RI) for studied trace elements in all sampling locations were 41.13 and 23.76, lower than baseline value (150), signifying that ecological risks displayed by those elements in sediments were moderate. The multivariate statistical analysis indicated that Sr had a geogenic source (natural source), while As and Cd came probably from Industrial source (chemical fertilizers), Ni and Cr were likely derived from vehicle emissions, particularly agricultural machinery, and Pb originated from exhaust and non-exhaust traffic emissions.

Heavy metal concentrations in surface water, sediments and fish and their potential toxicity in highly degraded multipurpose peri-urban Eleyele Lake, Ibadan City, Oyo State, south-western Nigeria

Metal concentrations in water, sediments and gills and edible stomach muscle tissues of two fish species, African Sharptooth mud catfish (Clarias gariepinus) and the Nile Tilapia (Oreochromis nilot...

İkizcetepeler Baraj Gölü (Balıkesir) Çökellerindeki Organik Karbon Miktarının Zamansal ve Mekansal Dağılışı

Bu çalışma İkizcetepeler Barajı tabanından alınan yüzey çökeli ve karot örneklerinde organik karbon konsantrasyonlarının zamansal ve mekansal değişimlerini saptamak amacıyla gerçekleştirilmiştir. Organik karbon sulak alanlarda belirli bir miktarın üzerinde bulunduğunda kirliliğe yol açmakta ve ortamdaki çözünmüş oksijeni azaltarak diğer canlıların yaşamını risk altına sokmaktadır. Bu nedenle sulak alanlardaki organik karbon miktarının zamansal ve mekansal dağılışının tespit edilmesi son derece önemlidir. Çalışma kapsamında toplanan yüzey ve karot örneklerinde titrasyon yöntemiyle elde edilen veriler Arc – Map 10.5 yazılımı kullanılarak mekansal dağılış haritası ve zamansal dağılış grafiklerine dönüştürülmüştür. Elde edilen tüm bulgular değerlendirildiğinde organik karbon miktarının Kille Çayı, Koca Çay ve Çınarlı Dere ağzı ile eski yerleşim yerlerinin bulunduğu örneklem noktalarında en yüksek değerlere ulaştığı tespit edilmiştir. Zamansal dağılışa göre en yüksek değerler 5 – 10 cm dilimleri arasında tespit edilmiştir. Bu durum organik karbonun Bağırsak Dere dışındaki akarsular tarafından havza içerisinden taşınarak baraja deşarj edildiğini ve deşarjın son yıllarda maksimum düzeye çıkarak günümüzde azalma eğilimine geçtiğini göstermektedir. İkizcetepeler Baraj Gölü çevresinde gerçekleştirilen arazi çalışmaları, mevcut literatür verileri ve analitik prosedürlerden elde edilen verilere göre barajda organik karbon kökenli kirliliğe rastlanmamıştır.

Assessment of nutrient and heavy metal contamination in surface sediments of the Xiashan stream, eastern Guangdong Province, China.

In this study, nutrient and heavy metal contamination in surface sediments of the Xiashan stream were investigated. Determining pollution degree of nutrient and heavy metal were the main objectives of this investigation. For this reason, the concentrations of total nitrogen (TN), total phosphorus (TP), seven heavy metals (Cu, Zn, Pb, Cd, Cr, Ni, Hg), and metalloid (As) were analyzed at 55 sampling sites. The mean TN concentration in surface sediments was 5.007 g/kg, while the mean TP concentration was 0.385 g/kg. Based on the sediment quality guideline (SQGs) and background values of Chinese soil and sediment, the majority of the mean TN concentrations in surface sediments were higher than their background values, while the TP concentrations were different from those observed for TN. For heavy metal concentrations in surface sediments, most of sampling stations were higher than their background values. The mean geo-accumulation (Igeo) indices for heavy metals were ranked as follows: Cd > Hg > Cu > Zn > Pb > Ni > Cr > As. The potential ecological risk index (RI) indicated heavy metal contamination level in Xiashan stream was very high ecological risk. According to Igeo and RI values, heavy metals especially Cd and Hg are influenced significantly by anthropogenic activities. Cd and Hg are not only as pollutant but also considerable contributor to ecological risk. Multivariate statistical investigations showed that there is a significant and positive correlation between Pb, As, and Cd. Cu, Ni, and Cr have similar characteristic and therefore probably originated from the same sources. Suggested by the results, it is necessary to control nitrogen and heavy metal contamination caused by human activities in the study area.

The accumulation of metals and methylmercury in Nerita lineata and the relation to intertidal surface sediment concentrations.

This study was conducted to assess the reliability of Nerita lineata as a bioindicator for metals in sediment and the factors influencing the accumulation of metals and methylmercury in its soft tissue. The two matrices were analyzed for Co, Cr, Cu, THg, MeHg, Mn, Ni, Pb, and Zn. The metal concentrations in N.lineata were comparable to previously reported results with the exception of Ni which was higher. Cu, Mn, and Pb in N.lineata were significantly (p<0.05) positively correlated with the respective elements in the sediment, while the biota-sediment accumulation factor showed that Cu, THg, MeHg, and Ni were bioconcentrated in N.lineata. This suggests that N.lineata has the potential to be a bioindicator for Cu, THg, MeHg, Mn, Ni, and Pb. The results also suggest an indirect relationship between THg in the sediment and the MeHg concentration in N.lineata in which periphyton might play a role. The affinity of Cr, Cu, Pb, and Zn with Mn (oxides) in sediment was also found to be a factor influencing their accumulation in N.lineata.

Numerical assessment of the environmental impacts of deep sea cage culture in the Yellow Sea, China

In light of environmental deterioration in coastal areas, deep sea cage aquaculture is becoming an increasingly attractive mode of mariculture. A key factor in determining the potential of deep sea cage aquaculture is to evaluate the environmental impacts of these practices. Here, a numerical model consisting of coupled hydrodynamic-, tracer-tracking- and 3-D Lagrangian particle-tracking models was set up and applied to evaluate the environmental impacts of deep sea cage cultivation of sea bass (Lateolabrax japonicus) in the Yellow Sea, China. The model was verified using water level data on August 1–31, 2018 and nutrient concentration in water and surface sediments in May, August, and November 2018, and January 2019. Results show that the model successfully captures the characteristics of local tidal currents and the total particulate nitrogen and phosphorus concentrations of the underlying sediments. Water quality simulations indicate that deep sea cages account for 26% of the total dissolved inorganic nitrogen and 19% of the active phosphorus content. Residual feed particles are predicted to fall in an ellipse centered on the cage location, with a long axis of 200 m and a short axis of 50 m. Feces are predicted to fall in an ellipse with a long axis of 1400 m and a short axis of 600 m. The Superposition particles are predicted to settle in an ellipse with a long axis of 320 m and a short axis of 150 m. The model results indicate that installation of all deep sea cages will lead to acceptable levels of water quality, but that sediments may become polluted. The coupled model can be used to predict the environmental impacts of deep sea cage farming and provide a useful tool for designing the layout of integrated multi-trophic aquaculture of organic extractive or inorganic extractive species.

Occurrence of total phosphorus in surface sediments of Chinese lakes and its driving factors and implications

In contrast to instantaneous concentration of phosphorus in water columns, sediments record valuable information on occurrence and sources of phosphorus for a long period associated with human activities and environmental protection. However, much less attention has been paid to phosphorus in sediments. To date the relative contributions of driving factors for TP concentration in sediments has not been elucidated. We investigated the occurrence and driving factors for TP in 270 surface sediments of 83 lakes in the catchments of two large rivers (Yangtze River and Huaihe River) in China, identified the relative contributions of the driving factors, and discussed the implication. The average TP concentration in the surface sediments of these lakes was 0.82 ± 0.04 mg gdw−1. The average TP concentration in the surface sediments of the urban lakes was larger than that in the rural lakes. Mitigation measures, human activities, and lake characteristics contributed 59.0%, 20.5%, and 20.5% to the variation in sediment TP concentration. The average TP concentration in the surface sediments significantly decreased with the percentage of annual investment in pollution control to GDP of the cities where the lakes are located. For the first time we find mitigation measures have exceeded human activities, and lake characteristics to dominate the variation in TP concentration in surface sediments of Chinese lakes. Given the annual investment in pollution control only accounted for 1.14% ± 0.06% of GDP in China from 1991 to 2018, higher percentage would be beneficial to reduce TP concentration in sediments of Chinese lakes.

The Production and Fate of Volatile Organosulfur Compounds in Sulfidic and Ferruginous Sediment

AbstractVolatile organic sulfur compounds (VOSCs) link the atmospheric, marine, and terrestrial sulfur cycles in marine and marginal marine environments. Despite the important role VOSCs play in global biogeochemical sulfur cycling, less is known about how the local geochemical conditions influence production and consumption of VOSCs. We present a study of dimethyl sulfide (DMS), methanethiol (MeSH), and dimethylsulfoniopropionate (DMSP) in sulfide‐rich (sulfidic) and iron‐rich (ferruginous) salt marsh sediment from north Norfolk, UK. Initial results illustrate the importance of minimizing time between sampling in remote field locations and laboratory analysis, due to rapid degradation of VOSCs. With rapid analysis of sediment from different depths, we observe high concentrations of DMS, MeSH, and DMSP, with concentrations in surface sediment an order of magnitude higher than those in previous studies of surface water. We measure systematic differences in the concentration and depth distribution of MeSH and DMS between sediment environments; DMS concentrations are higher in ferruginous sediment, and MeSH concentrations are higher in sulfidic sediment. With repeated measurements over a short time period, we show that the degradation patterns for DMS and MeSH are different in the ferruginous versus sulfidic sediment. We discuss potential biogeochemical interactions that could be driving the observed differences in VOSC dynamics in ferruginous and sulfidic sediment.

Demonstration and validation of enhanced monitored natural recovery at a pesticide-contaminated sediment site

Monitored natural recovery (MNR) combined with a thin-layer cap (TLC), often referred to as enhanced monitored natural recovery (EMNR), has the potential to accelerate and improve the effectiveness of MNR as a remedial strategy while minimizing widespread disturbance to the existing habitat. This study evaluated the effectiveness of a nominal 15-cm thin-layer sand cap as an EMNR remedial strategy to address sediments that were moderately contaminated with the chlorinated pesticide dichlorodiphenyltrichloroethane and its derivatives, collectively DDX. Physical, chemical, and biological measurements were conducted pre-remedy placement and 2, 14, and 25 months post-placement. Measurements were used to evaluate (1) TLC stability; (2) bottom-up mixing of the TLC; (3) advection through the TLC; (4) characteristics of newly deposited sediment atop the EMNR layer compared to pre-remedy surface sediment conditions; (5) changes in contaminant bioavailability; and (6) physical impacts to the benthic community. Significant reductions were observed from measurements conducted pre- and post-placement in surface sediment (84–97%), porewater (33–75%), and tissue concentrations (Lumbriculus variegatus deployed in situ) (72–82%). A 63 to 72% decrease in DDX depositional mass flux also was observed. Multiple lines of evidence indicated that the TLC material remained stable. Deposition of suspended material with low concentrations of DDX influenced low concentrations in the surface sediments. No adverse effects were observed on the benthic invertebrate community after TLC placement, and ecological metrics indicated increases in benthic community health, even in the short time period (2 months) following TLC placement. This demonstration showed that EMNR can be effective at reducing biological exposure in surface sediments while minimizing short-term disturbances to benthic communities at sites where MNR is a remedy option, but natural deposition rates are inadequate to achieve cleanup goals within a reasonable timeframe.

Spatial and Temporal Distributions of Short-, Medium-, and Long-Chain Chlorinated Paraffins in Sediment Cores from Nine Lakes in China.

The spatial and temporal distributions of short-, medium-, and long-chain chlorinated paraffins (SCCPs, MCCPs, and LCCPs) were studied in sediment cores and surface sediment from nine lakes in China. The highest total CP concentrations in surface sediment were found in the plateau lakes of southwest China, followed by lakes in the northeast, east, and remote northwest. The concentrations of three CP groups in cores showed an increasing trend from the 1970s to 2014, with the most rapid increase occurring from the late 2000s to 2014, consistent with the statistics on historical production of CPs in China. The three CP groups showed site-specific profiles in sediments from the nine lakes, and their percentages changed with sedimentary years. In sediment samples with dated year after 1980, MCCPs were dominant in sediment from Lakes Sihailongwan maar, Taihu, Erhai, and Chenghai, and LCCPs were predominant compounds in the other five lakes. The proportions of LCCPs rapidly increased after 1980, reflecting the increasing production and usage of LCCPs in China. The total burdens of ∑SCCPs, ∑MCCPs, and ∑LCCPs in sediment prior to 2006 were estimated to be 0.26-5100, 0.29-21000, and 0.07-4300 kg, respectively, which were 1.4-440-fold higher than those of ∑PBDEs.

Ecological risk assessment and source apportionment of metals in the surface sediments of river systems in Lake Taihu Basin, China.

In this study, the concentrations of Zn, Cr, Ni, Cu, Pb, As, Cd, and Hg in the surface sediments of 94 sites sampled from six water systems in the Lake Taihu Basin in China were measured, and the pollution risks and sources of the metals were identified. The results showed that the mean concentrations of Zn, Cr, Ni, Cu, Pb, As, Cd, and Hg in the riverine surface sediments were 163.6, 102.5, 45.5, 44.7, 37.0, 13.3, 0.5, and 0.1mg/kg, respectively, higher than the corresponding background values (except for Hg). According to the geoaccumulation index (Igeo), the Pb, Ni, Zn, Cu, and Cd concentrations in the riverine surface sediments were generally at low levels of pollution. Based on a pollution load index (PLI) evaluation, the Pb, Ni, Zn, and Cu concentrations in the riverine surface sediments were generally at moderate levels of pollution. According to the thresholds of potential ecological risk, the Cd and Hg concentrations in the riverine surface sediments exhibited moderate potential ecological risks. Multivariate statistical analysis indicated that the Pb in the riverine surface sediments primarily originated from domestic sewage, agricultural wastewater discharge, and petroleum combustion; the concentrations of Cr, Ni, and Zn were influenced by the electroplating and alloy manufacturing industries; the concentrations of Cu and As mainly originated from pesticide use and industrial wastewater discharge; and those of Cd and Hg primarily stemmed from industrial wastewater discharge. This research provides information regarding metallic contamination and the possible associated ecological risks to benthic organisms in the surface sediments of river systems and is useful for developing sustainable strategies for environmental pollution control and management in the Lake Taihu Basin.

Assessment of a coastal lagoon metal distribution through natural and anthropogenic processes (SE, Brazil)

The present study intends to assess the metal pollution of a eutrophic coastal lagoon, analyzing the long-term and actual metal content in surface sediments, suspended particles, aquatic macrophyte and fish species, and the loads emitted from natural processes and anthropogenic sources, including the relative emission of domestic untreated sewage. Distribution indicated contamination of suspended particles with Cd and the predominance of Pb in the bioavailable form in surface sediments which may explain Cd and Pb contamination in fish. Domestic untreated sewage was an important source of Cu and due to the lagoon's management, this source may be increasing the metal content in the lagoon's surface sediments. Soil loss, atmospheric deposition and solid waste disposal also contributed to metal inputs to the lagoon. Extensive contamination has been prevented by the lagoon's management such as sandbar opening. Metal retention within the watershed soils reduce the effective metal transference and lagoon pollution.