Sediment provenance of a carbonate bioclastic pocket beach—Le Dune(Ionian Sea,South Italy)

This study focuses on the analysis of a carbonate bioclastic pocket beach located along a coastal sector of the Apulia Ionian Sea,Le Dune beach,South Italy.The beach develops for about 800 m and it is exposed to the south-westerly and southerly seas.Coastal sediments range from very coarse to medium-fine sands and they are mainly composed of bioclasts(more than 90%)which include molluscs,foraminifers,echinoderms,algae branched,bryozoans,spicules of sponges and arthropods.The study area is one part of a marine protected reserve characterised by 15 different habitats of the typical Mediterranean submerged populations and the presence of Posidonia oceanica meadows.The aim of our research is to highlight the correlation between physical and biological processes influencing Le Dune beach dynamics and its sediment provenance by analysing the textural and compositional characteristics of beach sands,which is fundamental for pocket beach conservation.The beach sand analysis,deriving from textural,compositional and bioclast investigations,underlines that one of the main indicators of the beach dynamics is the bioclast component,which provides relevant information about sand provenance and sediment transport.The beach constitutes a semi-close system only nourished by the shells of organisms and by the erosion of headlands and dunes without important sediment interchange with adjacent littoral sectors.

Carbon sequestration processes and mechanisms in coastal mariculture environments in China

China is the global leader in mariculture production. Increasing sequestered marine carbon(also known as blue carbon) via mariculture activities is a promising approach for mitigating climate change and promoting the development of a low-carbon economy. Mariculture blue carbon is also considered an important component of China's "sea granary". In addition to shellfish and macroalgae yields, which represent carbon removed from mariculture environment, blue carbon also includes other important components, which have been largely neglected in the past, such as the carbon transformed by microbes,dissolved organic carbon(mainly referred to as recalcitrant dissolved organic carbon), and sedimentary particulate carbon. Hence,from different aspects, a comprehensive study on the formation processes and mechanisms of carbon sequestration is of great significance for comprehensively unveiling the carbon sequestration capability in coastal mariculture environment, which will contribute to the sustainable development of the fishery economy and construction of an ecological civilization. Moreover, it may add significant economic benefits to the future carbon-trading market.

The relationship between the black carbon and bisphenol A in sea and river sediments(Southern Baltic)

This study was derived from field investigations to assess bisphenol A（BPA）concentrations in the sea and river sediments of the Gulf of Gdansk.Black carbon（BC）and total organic carbon（TOC）were identified as influencing factors on the accumulation.As a result of the transportation of BC with organic matter via rivers into the Gulf of Gdansk,the highest mean concentrations（11.26 ng BPA/（g dry weight（dw）））,were determined in the sediments of river estuaries.Sediments in coastal stations were characterized by the lowest mean concentrations（5.73 ng BPA/（g dw））.TOC content below 0.1% determined the sorption of BPA on BC particles in sediments,and statistically significant correlation between the concentration of BPA and the BC/TOC ratio was found in these cases.In addition,dependency between the concentration of BPA and the content of BC was discovered in sediments where the BC/TOC ratio was 〉 0.33.

Effects of seagrass leaf litter decomposition on sediment organic carbon composition and the key transformation processes

Seagrass leaf litters are an important source of sediment organic carbon(SOC). However, the mechanisms of seagrass leaf litter decomposition influencing SOC composition and the key transformation processes remain unknown. We performed a laboratory chamber experiment to compare the labile organic carbon(OC) composition and the enzyme activities governing SOC transformation between the seagrass group(seagrass leaf litter addition) and the control group. The results showed that the seagrass leaf litter decomposition significantly elevated the salt-extractable carbon(SEC) content and the SEC/SOC. Additionally,the levels of invertase, polyphenol oxidase, and cellulase in the seagrass leaf litters addition group were generally higher than in the control group, which could elevate recalcitrant OC decomposition. Following 24 days incubation, addition of seagrass leaf litter increased the amount of CO_2 released, but decreased the SOC content. Therefore, seagrass leaf litter decomposition leached abundant dissolved OC, which enhanced the activity and transformation of SOC.

Stabilization of heavy metals in sediments:A bioavailability-based assessment of carbon adsorbent efficacy using diffusive gradients in thin films

This study investigated the effectiveness of carbon adsorbents as remediation material for sediments contaminated with heavy metals and the feasibility of utilizing diffusive gradients in thin films(DGT)as a biomimetic tool to estimate the accumulation of heavy metals in Venerupis philippinaram(Manila clam).The results showed that carbon materials had significant inhibitory effects(14.0-53.0%)on the enrichment of heavy metals in organisms and the order of increasing overall inhibitory effect was:charcoal,peat,activated carbon,and biochar.There were significant correlations(P<0.0001)between the four heavy metals accumulated in Venerupis philippinaram and those accumulated in DGT devices after 28 days in the laboratory.Observed concentrations of heavy metals enriched in DGT(5.4-42.0%)were less than accumulations in Venerupis philippinaram.The results of in situ DGT applications showed significant correlations between the amount accumulated in DGT and the acid-soluble portion in sediments for both Cu and Pb,with positive linear correlations and R-squares of 0.97 and 0.92,respectively.These results supported the notion that a DGT device can be used as a biomimetic tool that predicts and monitors the accumulation of heavy metals in aquaculture ponds.Future studies should focus on improving the stabilization of heavy metals in sediments using different types of carbon sorbents,as well as minimizing simulation deviations using DGT.