Characteristics of metal enrichment in Deep Bay,Hong Kong

Sediment cores, suspended particles and overlying water were collected in Deep Bay, Hong Kong. Enrichment of Zn in surface sediments in the landward direction and the decreasing of exchangeable Cd, Ni and Zn in sediment from the inner bay to the outer bay indicated the influence of anthropogenic pollutants discharged from the riparian runoffs.

Study on the Purification Effect of Phosphorus in Sewage from Sediments in Coastal Wetland of Yellow River Delta

[Objectives] This study was conducted to explore whether the coastal wetlands in the Yellow River Delta have become secondary pollution sources. [Methods] With a coastal reed wetland in the Yellow River Delta as a research object, the SMT method and DGT technology were combined to study the vertical distribution of different forms of phosphorus in the sediment and the distribution characteristics of phosphorus at the sediment-interstitial/overlying water interface of the wetland to clarify the receiving and purification capabilities of wetlands in this region. [Results] The total phosphorus content in the wetland’s water intake area, dense reed area and water outlet area increased with the depth increasing;and the wetland phosphorus accumulated in the deep layer, and the total phosphorus content in the wetland sediments was as high as 936.30 mg/kg. The research on the phosphorus forms in the wetland sediments found that the content of Ca phosphorus was the highest in the wetland sediments, followed by the content of Fe/Al-bonded phosphorus, and the exchangeable phosphorus content was the lowest. The DGT sampling technology was used to investigate the distribution characteristics of phosphorus at wetland sediment-interstitial/overlying water micro-interface. It was found that the concentrations of phosphorus in the overlying water of the water intake area, dense reed area and water outlet area were significantly higher than that in the interstitial water. The wetland pollution level in this research area was high and had an obvious cumulative effect. [Conclusions] The results show that the wetland sediments in this region have a strong ability to retain phosphorus, and can control the migration and transformation of endogenous phosphorus, and the wetland has not become a secondary pollution source.

Spatial variations of bacterial community composition in sediments of the Jiaozhou Bay,China

Spatial variations of sediment microbes pose a great challenge for the estimation of anthropogenic influence on biogeochemical processes,yet remain very unclear in coastal ecosystems.Surface sediments in 9 stations from the eutrophic Jiaozhou Bay,China,were sampled,DNA was extracted within the sediments,and the 16 S rDNA was sequenced with the Illumina Hiseq sequencing.Results reveal considerable heterogeneity of sediment bacteria in the Jiaozhou Bay,of which Proteobacteria and Bacteroidetes accounted for over 75%.Bacterial alpha-diversity indices decreased generally from the outside to the inner part of the bay and from the offshore to the nearshore area.Bacterial community structures of S3,S4,S7,and S8 clustered,those of S5,S13,and S14 grouped together,while those of S6 and S10 were distinct from each other and from those of the other stations.Major class Gammaproteobacteria were more abundant at the stations with mesoeutrophic to eutrophic levels(S4,S5,S8,and S10)and less abundant at oligotrophic stations(S6,S13,and S14),while Deltaproteobacteria had an opposite distribution pattern.Overall,bacterial community composition transitioned from being Xanthomonadales-dominant at S4 and S8 to being unidentifedGammaproteobacteria-dominant at S5,S6,S13,and S14,while in other stations there were comparable orders.The biogeochemical processes correspondingly changed from being nitrogen cycling-dominant at S4 and S8 to being sulfur cycling-dominant at S5,S6,S13,and S14.The bacterial distribution patterns were especially affected by the factors(dissolved organic phosphorus,DOP)in the overlying seawater due to the habitat status of P-insu fficiency in the bay.Both orders Xanthomonadales and Alteromonadales could serve as bioindicators of anthropogenic pollution to different pollution types.At last,divergent distribution patterns of individual bacterial populations in the bay were revealed,the influential environmental gradients were clarified,and the uncertainty of microbes was reduced,helping to predict environmental functions in coastal areas.