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This study was performed to determine the distribution and chemical fractions of five heavy metals (Cd, Cr, Cu, Pb, and Zn) in sediment from three sampling areas in Swan Lagoon, and their relation to the physiochemical properties of sediment were explored. The results revealed that Cd in sediment from the sand part (SP), muddy sand part (MSP) and sand muddy part (SMP) were potentially highly susceptible and bioavailable since the exchangeable fractions were 21.0%, 27.4%, and 32.1%, respectively, of the total concentrations. A portion of Pb and Zn were observed as reducible fractions owing to their affinity to Fe-Mn; they were able to complex with Fe-Mn oxides and oxyhydroxides in the sediment. A large amount of Cu in the oxidizable fraction may be due to the fact that Cu can easily form stable complexes with organic matter. Cr was overwhelmingly found in the residual fraction, suggesting that Cr was strongly bound in mineral lattices. Enrichment factors (EF) indicated that Cd in three sampling areas suffered severe enrichment, whereas other metals were present in only minor amounts. In addition, Cd may pose a medium to high risk in the MSP and SMP based on risk assessment codes. According to the mean probable effects level quotient, the samples from the MSP and SMP had a 21% probability of toxicity. The multivariate statistical analysis suggested that sediment texture (d0.5, sand and silt), Fe-Mn, and the total organic carbon (TOC) influenced the distribution of the studied metals and their chemical fractions. [ABSTRACT FROM AUTHOR]

Surface sediments from five stations within Gonghu Bay in Taihu Lake, China, were sampled for seasonal and spatial metal contamination analysis variations and ecological risks assessment from April 2009 to January 2010. The Contamination Factor (CF) and geo-accumulation index (Igeo) indicated that the sediments in Gonghu Bay ranged from unpolluted to moderately polluted, except for Cd. The one-way ANOVA analysis results showed that the Pb, Zn, Cr, and Cu concentrations were higher at station 3 (lake inlet) and the Cr, Pb, and Zn concentrations were significantly higher in the spring. Additionally, using BCR' s sequential extraction, the results showed that the fractionated metals Zn and Cd were observed as bioavailable fractions in the sediments, which could have potential moderate mobility in the water system. There was a significant increase in the bioavailable form during winter. The ratio of secondary and primary phrase (RSP) decreased according to the order Zn > Cu > Ni > Pb > Cd > Cr. Finally, these results indicated that the sediments of Gonghu Bay were polluted by Cd, Zn, and Cu, which provides a scientific basis for effectively protecting sediments in watershed areas from long-term heavy metal accumulation. [ABSTRACT FROM AUTHOR]

Congener specific distributions of polybrominated diphenyl ethers (PBDEs) were investigated in sediment and mussel (Mytilus edulis) collected from the coast of Bo Sea, China. The median values of BDE-209 and ΣPBDEs (including BDE-17, -28, -47, -66, -71, -85, -99, -100, -138, -153, -154, -183 and -190) were 2.29 and 0.16ngg−1 dry weight in sediment, and 2.43 and 0.68ngg−1 dry weight in mussel, respectively. BDE-209 was the predominant congener (61–99% in mussel and 75–99% in sediment except for one sample with 17%). Different congener patterns (excluding BDE-209) were observed between sediment and mussel, which were attributed to individual congener’s bioaccumulation potential and/or the ability to metabolize. The four most abundant congeners were BDE-47 (40.3%), -99 (22.5%), -71 (8.9%) and -28 (5.8%) in sediment, and -47 (36.4%), -28 (14.5%), -154 (8.6%) and -71 (8.6%) in mussel, respectively. The ratios of BDE-47/BDE-99 and BDE-100/BDE-99 in sediment were lower than those in mussel, indicating higher transformation and uptake rate of BDE-99 in mussel. The biota-sediment accumulation factor (BSAF) of individual PBDE congeners declined with the increase of their logarithm of octanol–water partition coefficients (log K OW) except for BDE-154, indicating congeners with higher log K OW were more likely to retain in sediment. These can be explained with a high affinity of these compounds for carbonaceous geosorbents, and molecular steric hindrance that limits large, very hydrophobic organic compounds from penetrating the cellular membranes. [Copyright &y& Elsevier]

Mai Po Nature Reserve (Hong Kong) is an internationally important wetland for waterbirds. Roundup®, a formulation based on glyphosate, has been used to control the widespread weeds within the reserve for many years but the fate and non-target impact of the herbicide is unknown. To fill this knowledge gap, we applied Roundup® by hand-held sprayer to an estuarine and a freshwater pond in the dry season of year 2002. The surface water and sediment were sampled routinely for glyphosate concentrations following one month of application. In situ bioassays using local edible fish species were performed along with the herbicide application. Up to 52% of glyphosate in the surface water was transported to the unapplied regions by wind-driven current in the estuarine pond at 1 DPT (day post treatment). For both ponds, glyphosate concentrations in the water decreased rapidly after 1–3 DPT, but then decreased gradually over time. Both physical adsorption to the bottom sediments and microbial degradation are thought to contribute to these decreases. Interestingly, the persistence of glyphosate in the freshwater pond was longer than in the estuarine system, which is likely due to the considerably higher concentrations of chelating metals (i.e. Cu and Fe) present in the sediment (4.5 and 11-fold higher, respectively) which potentially reduced the bioavailability of glyphosate to the microbial decomposers. Lastly, fishes used in the in situ bioassays (both in applied and unapplied areas) showed similar survival rates, indicating that the use of Roundup® at the provided application rate posed no serious hazard. [Copyright &y& Elsevier]

The pollution status of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in the sediments of Haihe River, which is the most polluted among the seven largest basins in China, Dagu Drainage River flowing through a chemical industry zone, and two other rivers flowing into Bohai Sea in Tianjin City, China were investigated. The concentrations of PCDD/Fs and PCBs in the sediments from the mainstream of Haihe River were 1.3–26pgI-TEQg−1 dry weight (dw) and 0.07–0.54pgTEQg−1 dw, respectively. Heavy PCDD/Fs and PCBs pollution, with 1264pgI-TEQg−1 dw and 21pgTEQg−1 dw, was found in sediment from Dagu Drainage River. The congener profiles of PCDD/Fs indicated that the principal contamination source was the production of pentachlorophenol (PCP) or PCP-Na in this area. The correlation between PCDD/Fs or PCBs and total organic matter (TOM) showed that PCDD/Fs or PCBs were independent on TOM. [Copyright &y& Elsevier]