Water and sediment samples have been collected from five different stations, located along Djendjen River between February and June, 2016 so that the concentrations of Cd, Ni, Zn, and Cu could be determined. The extent of the sediment pollution has been assessed, using the multiple pollution indices, namely Contamination Factor (CF), Pollution Load Index (PLI), and the geoaccumulation index (Igeo).The distribution of trace elements in water and sediment follows Ni>Zn>Cd>Cu and Zn>Ni>Cu>Cd, respectively. The water sample analysis from Djendjen River shows that the total concentrations of Cu, Ni, Cd, and Zn have been lower according to the references. In comparison, sediment mean metal concentrations with several environmental contamination parameters, like probable effect level (PEC) and background levels, indicates that the concentrations of all investigated elements are lesser than PEC, except for Ni, but higher than the background levels. The Igeo values reveal that Cd has been the most accumulated compared to the other metals.  Contamination Factor (CF) confirms that the sediment samples have been moderate in terms of all studied metals contamination. The Pollution Load Index (PLI) values have been above one (>1), indicating an advanced decline of the sediment quality.

The current paper determines heavy metals in sediments of six freshwater wetlands of greater Dhaka district from November 1999 to September 2000. The sampling took place in summer, rainy season, and winter, wherein for each season five soil samples were collected from the wetland at a depth of 0 – 15 cm. To assess the status of heavy metal pollution in the sediments, geo-accumulation factor (Igeo), contamination factor (CF), degree of contamination (Cd), and enrichment factor (EF) have been evaluated, with the concentrations of Cd, Mn, Ni, Zn, Cu, Fe, and Pb in the sediments ranging within 0.005 – 0.055 mg/kg, 35.0 – 275.04 mg/kg, 0.35 – 2.19 mg/kg, 0.77 – 12.54 mg/kg, 4.11 – 19.17 mg/kg, 115.60 – 955.94 mg/kg, and 1.82 – 3.93 mg/kg, respectively, standing in the following order: Fe > Mn > Cu > Zn > Pb > Ni > Cd. The maximum concentrations of Mn, Ni, and Pb belonged  to summer. Significant temporal variation was observed only in case of Cd, whereas concentrations of Cd, Fe, and Mn varied spatially. The Igeo for Mn indicates a strongly to extremely polluted condition in wetlands, whereas that of Ni and Pb show moderately polluted condition, and for Zn and Cu, it suggests moderately to strongly polluted conditions. The CF values for heavy metals in sediment have been below 1, indicating low contamination. In addition, Cd < 6 indicates low degree of heavy metal contamination. The EF for heavy metals in wetland sediments are in the following order: Cu>Mn>Pb>Cd>Zn>Ni, suggesting that the sediments very highly rich in Cu, while Mn, Pb, and Cd exhibit significant enrichment. In the studied wetlands the EF for Zn and Ni shows moderate and deficiency to minimal enrichment, respectively. Implications of these findings can be used as baseline information to monitor and assess the degree of sediment pollution in lentic wetlands.

International audience | The level and the ecological risk assessment of heavy metals (Zn, Cu, Mn, Fe, Ni, Cr, V, As, Pb, Cd and Co) were evaluated in surface sediments from fifty-one stations along the Algerian coast. The main objective was to evaluate the risk that such metals may cause to the ecosystem, and thus the stations were choose in relation with the fishing trawlable areas of Algeria. The usual chemical indexes Geoaccumulation index (Igeo), Enrichment factor (EF) and Pollution Load Index (PLI) as well as potential ecological risk index reveal that the metal pollution along this coast is low, and is only related to As contents. Nevertheless, the concentrations of Ni, Cr and As exceed their respective ERL values (Effect range low) usually applied for Sediment Quality Guideline. However, Cr and Ni are mainly natural and cannot be related to anthropogenic inputs and their ecotoxicological levels as to be questioned.

While (N-ethyl perfluorooctanesulfonamido ethanol)-based phosphates (SAmPAPs) have been proposed as a group of perfluorooctanesulfonate (PFOS) precursors, investigation of their occurrence and fate has been limited to SAmPAP diester. In this study, SAmPAP diester and triester were simultaneously determined in freshwater sediment from Taihu Lake using a newly developed UPLC-MS/MS method, and their biotransformation to PFOS in lake sediment was investigated. SAmPAP diester and triester were detected in sediments with a detection frequency of 56% and 88%, and their mean concentrations were 0.24 ± 0.11 ng/g dry weight (dw) and 0.12 ± 0.03 ng/g dw, respectively. The SAmPAP diester/triester ratio in sediment was 1.1 ± 4.2, much lower than that (6.7) observed in the technical product, and the positive correlation was found between the concentrations of SAmPAP diester and PFOS in sediments (r² = 0.45, p = 0.01), suggesting that SAmPAP diester would be biotransformed to PFOS in the lake sediment. The microbial degradation test in the lake sediments further clarified that SAmPAP diester was biodegraded to PFOS, but SAmPAP triester was highly recalcitrant to microbial degradation. This study suggests that the occurrence of SAmPAP diester in freshwater lake sediments may be an important precursor of PFOS.

Complexity of anthropogenic influences on coastal ecosystems necessitates use of an integrated assessment strategy for effective interpretation and subsequent management. In this study a multiple lines of evidence (LOE) approach for sediment assessment, that combined use of chemistry, toxicity, and benthic community structure in the sediment quality triad was used to assess spatiotemporal changes and potential risks of persistent toxic substances (PTSs) in sediments of Masan Bay highlighting “long-term changes” between 1998 and 2014. Specific target objectives encompassed sedimentary PTSs (PAHs, alkylphenols (APs), and styrene oligomers), potential aryl hydrocarbon receptor (AhR; H4IIE-luc assay)- and estrogen receptor (ER; MVLN assay)-mediated activities, and finally several ecological quality (EcoQ) indices of benthic community structure. Concentrations of target PTSs in Masan Bay sediments were generally less by half in 2014 compared to those measured in 1998. Second, AhR-mediated potencies in sediments also decreased during this time interval, whereas ER-mediated potencies increased (+3790%), indicating that there has been substantial ongoing, input of ER agonists over the past 16 years. Potency balance analysis revealed that only 3% and 22% of the AhR- and ER-mediated potencies could be explained by identified known chemicals, such as PAHs and APs, respectively. This result indicated that non-targeted AhR and ER agonists had a considerable presence in the sediments over time. Third, EcoQ indices tended to reflect PTSs contamination in the region. Finally, ratio-to-mean values obtained from the aforementioned three LOEs indicated that quality of sediments from the outer region of the bay had recovery more during the period of 16-years than did the inner region. Overall, the results showed that even with the progress supported by recent efforts from the Korean governmental pollution control, PTSs remain a threat to local ecosystem, especially in the inner region of Masan Bay.

Numerous studies on microplastics (MPs; Ø < 5 mm) in the aquatic environment have been published, but knowledge about the occurrence and ecological risks of MPs is limited. This is in part because current data on the distribution of MPs are comparable only to a limited extent, due to the many different methods of investigation. In addition, sample preparation is often difficult such that standard procedures are lacking. The aim of this work was to simplify the preparation of different kinds of MP samples. Our method makes use of the electrostatic behavior of plastic particles to facilitate their separation from sample matter, with up to 99% of the original sample mass removed without any loss of MPs. To determine the efficacy of this approach, four different materials (quartz sand, freshwater suspended particulate matter, freshwater sediment, and beach sand) were spiked with MPs (size: 0.063–5 mm from the seven most common types of plastics, one bioplastic type, polyethylene fibers, and tire wear. A modified electrostatic metal/plastic separator was used to reduce the sample mass and concentrate the plastics based on their physical separation. The recovery achieved with this method was as high as nearly 100% for each type of material. The method was then tested on plastic particles of different shapes and types isolated from the Rhine River. These were successfully electroseparated from the four materials, which demonstrated the utility of this method. Its advantages include the simplified handling and preparation of different field samples as well as a much shorter processing time, because after the last separation step there is hardly any biological material remaining in the sample fraction.

The temporal and spatial trends in sediment of 22 poly- and perfluorinated (PFAS) compounds were investigated in the southern Great Lakes Erie and Ontario as well as Lake St. Clair. Surface concentrations measured by Ponar grab samples indicated a trend for greater concentrations near to urban sites. Mean concentrations ∑22PFAS were 15.6, 18.2 and 19 ng g−1 dm for Lakes St. Clair, Erie and Ontario, respectively. Perfluoro-n-butanoic acid (PFBA) and Perfluoro-n-hexanoic acid (PFHxA) were frequently determined in surface sediment and upper core samples indicating a shift in use patterns. Where PFBA was identified it was at relatively great concentrations typically >10 ng g−1 dm. However as PFBA and PFHxA are less likely to bind to sediment they may be indicative of pore water concentrations Sedimentation rates between Lake Erie and Lake Ontario differ greatly with greater rates observed in Lake Erie. In Lake Ontario, in general concentrations of PFAS observed in core samples closely follow the increase in use along with an observable change due to regulation implementation in the 1970s for water protection. However some of the more water soluble PFAS were observed in deeper core layers than the time of production could account for, indicating potential diffusion within the sediment. Given the greater sedimentation rates in Lake Erie, it was hoped to observe in greater resolution changes since the mid-1990s. However, though some decrease was observed at some locations the results are not clear. Many cores in Lake Erie had clearly observable gas voids, indicative of gas ebullition activity due to biogenic production, there were also observable mussel beds that could indicate mixing by bioturbation of core layers.

A pesticide monitoring study including 80 and 60 active ingredients (in surface waters and sediments, respectively) was carried out in a river basin in Costa Rica during 2007–2012. A special emphasis was given on the exceptional ecological conditions of the tropical agro-ecosystem and the pesticide application strategies in order to establish a reliable monitoring network. A total of 135 water samples and 129 sediment samples were collected and analyzed. Long-term aquatic ecotoxicological risk assessment based on risk quotient in three trophic levels was conducted. Short-term risk assessment was used to calculate the toxic unit and prioritization of sampling sites was conducted by the sum of toxic units in both aquatic and sediment compartments. Dimethoate (61.2 μg/L), propanil (30.6 μg/L), diuron (22.8 μg/L) and terbutryn (4.8 μg/L) were detected at the highest concentrations in water samples. Carbendazim and endosulfan were the most frequently detected pesticides in water and sediment samples, respectively. Triazophos (491 μg/kg), cypermethrin (71.5 μg/kg), permethrin (47.8 μg/kg), terbutryn (38.7 μg/kg), chlorpyrifos (18.2 μg/kg) and diuron (11.75 μg/kg) were detected at the highest concentrations in sediment samples. The pesticides carbendazim, diuron, endosulfan, epoxyconazole, propanil, triazophos and terbutryn showed non-acceptable risk even when a conservative scenario was considered. Sum TUsite higher than 1 was found for one and two sampling sites in water and sediment compartments, respectively, suggesting high acute toxicity for the ecosystem.Exceptional ecological conditions of the tropical agro-ecosystem affect the fate of pesticides in water and sediment environment differently than the temperate one.

Mariculture activities including enclosure, raft and cage cultures employ a variety of plastic gear such as fishing nets, buoyant material and net cages. The plastic gear poses a potential source of microplastics to the coastal environment, but relevant data on the impacts of mariculture are still limited. To this end, a semi-enclosed narrow bay (i.e., Xiangshan Bay, China) with a long-term mariculture history was investigated to assess how mariculture activities affect microplastics in seawater and sediment. The results indicated that mariculture-derived microplastics accounted for approximately 55.7% and 36.8% of the microplastics in seawater and sediment, respectively. The average microplastic abundances of seawater and sediment were 8.9 ± 4.7 (mean ± SD, n = 18) items/m³ seawater and 1739 ± 2153 (n = 18) items/kg sediment, respectively. The types of mariculture-derived microplastics included polyethylene (PE) foam, PE nets, PE film, polypropylene (PP) rope, polystyrene (PS) foam and rubber. PE foam had the highest proportion (38.6%) in the seawater samples. High usage rates and the porous structure of PE foam led to the high abundance. The average microplastic sizes of seawater and sediment are 1.54 ± 1.53 mm and 1.33 ± 1.69 mm, respectively. The spatial variations in the abundance and size of microplastics implied that the mariculture-derived microplastics in Xiangshan Bay were transported along the Bay to the open sea. The results of this study indicate that mariculture activity can be a significant source of microplastics. Further research is required to investigate how the high microplastic abundance in mariculture zone affects marine organisms, especially cultured seafood.

Antibiotics resistance genes (ARGs) are considered as an emerging pollutant among various environments. As a sink of ARGs, a comprehensive study on the spatial and temporal distribution of ARGs in the estuarine sediments is needed. In the present study, six ARGs were determined in sediments taken along the Yangtze Estuary temporally and spatially. The sulfonamides, tetracyclines and fluoroquinolones resistance genes including sul1, sul2, tetA, tetW, aac(6’)-Ib, and qnrS, were ubiquitous, and the average abundances of most ARGs showed significant seasonal differences, with relative low abundances in winter and high abundances in summer. Moreover, the relative high abundances of ARGs were found at Shidongkou (SDK) and Wusongkou (WSK), which indicated that the effluents from the wastewater treatment plant upstream and inland river discharge could influence the abundance of ARGs in sediments. The positive correlation between intI1 and sul1 implied intI1 may be related to the occurrence and propagation of sulfonamides resistance genes. Correlation analysis and redundancy discriminant analysis showed that antibiotic concentrations had no significant correlation to their corresponding ARGs, while the total extractable metal, especially the bioavailable metals, as well as other environmental factors including temperature, clay, total organic carbon and total nitrogen, could regulate the occurrence and distribution of ARGs temporally and spatially. Our findings suggested the comprehensive effects of multiple pressures on the distribution of ARGs in the sediments, providing new insight into the distribution and dissemination of ARGs in estuarine sediments, spatially and temporally.