A geochemical record of environmental changes in sediments from Sishili Bay, northern Yellow Sea, China: Anthropogenic influence on organic matter sources and composition over the last 100 years

Total organic carbon (TOC), total nitrogen (TN), delta C-13 and delta N-15 were measured in sediment cores at three sites in Sishili Bay, China, to track the impacts of anthropogenic activities on the coastal environment over the last 100 years. The increased TOC and TN in the upper section of sediment cores indicated a eutrophic process since 1975. In comparison, the TOC and TN in the sediment core near to a scallop aquaculture area displayed a much slower increase, indicating the contribution of scallop aquaculture in mitigating eutrophication. Combined information from delta C-13, delta N-15 and TOC:TN indicated an increased terrestrial signal, although organic matter sources in Sishili Bay featured a mixture of terrestrial and marine sources, with phytoplankton being dominant. Increased fertilizer use since 1970s contributed to the eutrophic process in Sishili Bay since 1975, and increased sewage discharge from 1990s has added to this process. (C) 2013 Elsevier Ltd. All rights reserved.Total organic carbon (TOC), total nitrogen (TN), delta C-13 and delta N-15 were measured in sediment cores at three sites in Sishili Bay, China, to track the impacts of anthropogenic activities on the coastal environment over the last 100 years. The increased TOC and TN in the upper section of sediment cores indicated a eutrophic process since 1975. In comparison, the TOC and TN in the sediment core near to a scallop aquaculture area displayed a much slower increase, indicating the contribution of scallop aquaculture in mitigating eutrophication. Combined information from delta C-13, delta N-15 and TOC:TN indicated an increased terrestrial signal, although organic matter sources in Sishili Bay featured a mixture of terrestrial and marine sources, with phytoplankton being dominant. Increased fertilizer use since 1970s contributed to the eutrophic process in Sishili Bay since 1975, and increased sewage discharge from 1990s has added to this process. (C) 2013 Elsevier Ltd. All rights reserved

The distribution characteristics and the speciation of heavy metals pollutants in soil along roadway in JiaoKe，Jiaozuo city, China

The heavy metals pollution in farm soil around the transportation skeleton line in Jiaoke was investigated.14 soil samples were collected and treated with HNO3-HF-HCLO4,then the contents of Cd、Cr、Cu、Ni、Pb 、Zn and As were determined by ICP-MS and assessed systematically, forms of the heavy metals were analyzed by Tessier method. The results indicted that the soil belonged to polymetalic compound pollution in which As、Cd and Pb were the most serious pollutants. The pollution was the heaviest in farm soil that 15m apart from the transportation line, with Nemerow index 6.1465. We found that the Nemerow index reduced with the increase of the distance. Forms of the heavy metals showed: the valid state percentage of heavy metal in soil followed the order of Pb＞ Ni＞Cr＞Cu＞Cd＞Zn＞As. The forms of Ni,Cd,Zn and Pb in farm soil showed: residual fraction ＞Fe-Mn oxidizable fraction＞organic fraction＞exchangeable fraction＞acid extractable fraction, The forms of Cu and As in farm soil showed: residual fraction＞organic fraction＞Fe-Mn oxidizable fraction＞exchangeable fraction＞acid extractable fraction ; The forms of Cr in farm soil showed: residual fraction ＞ Fe-Mn oxidizable fraction ＞ organic fraction ＞ acid extractable fraction ＞ exchangeable fraction. The higher valid state and lower residual fraction percentage of Pb in soil implied that it should be paid attention to potential effects of heavy metals on regional ecosystem.特集 : 「資源、新エネルギー、環境、防災研究国際セミナー

Diatom and silicoflagellate assemblages in modern surface sediments associated with human activity: A case study in Sishili Bay, China

The spatial distribution of diatom and silicoflagellate fossils deposited in modern surface sediments was studied in inshore and offshore zones of Sishili Bay, China, to explore the impact of human activity on the coastal ecosystem. The sediments from 28 sites representing a gradient in intensity of human activity from inshore to offshore were sampled. Although the nutrient parameters inshore showed far higher concentrations than the offshore area, due to sewage discharge and waste dumping in the bay, the average fossil abundance did not differ significantly between the two areas. The diatom fossil Paralia sulcata, supposed to be a eutrophic indicator dominated most sediment samples and displayed a significant and positive correlation with dissolved inorganic nitrogen and phosphorus in the upper water column, but did not show a significant difference in abundance between inshore area and offshore area. Factors such as sediment disturbance (e.g., shipping), grazing pressure (e.g., shellfish aquaculture farm) and sediment characteristics (e.g., grain size) can affect the preservation of fossil debris in the sediment and lower the precision with which human activities can be associated with the fossil abundance.The spatial distribution of diatom and silicoflagellate fossils deposited in modern surface sediments was studied in inshore and offshore zones of Sishili Bay, China, to explore the impact of human activity on the coastal ecosystem. The sediments from 28 sites representing a gradient in intensity of human activity from inshore to offshore were sampled. Although the nutrient parameters inshore showed far higher concentrations than the offshore area, due to sewage discharge and waste dumping in the bay, the average fossil abundance did not differ significantly between the two areas. The diatom fossil Paralia sulcata, supposed to be a eutrophic indicator dominated most sediment samples and displayed a significant and positive correlation with dissolved inorganic nitrogen and phosphorus in the upper water column, but did not show a significant difference in abundance between inshore area and offshore area. Factors such as sediment disturbance (e.g., shipping), grazing pressure (e.g., shellfish aquaculture farm) and sediment characteristics (e.g., grain size) can affect the preservation of fossil debris in the sediment and lower the precision with which human activities can be associated with the fossil abundance. (C) 2012 Elsevier Ltd. All rights reserved

Free transverse vibrations of orthotropic thin rectangular plates with arbitrary elastic edge supports

A so-called Spectro-Geometric Method (SGM) is presented for the free transverse vibration analysis of orthotropic thin rectangular plates with arbitrary elastic supports along each of its edges, a class of problems which are rarely attempted in the literature. Regardless of boundary conditions, the displacement function is invariably and simply expressed, in spectral form, as a trigonometric series expansion with an accelerated polynomial rate of convergence as compared with the conventional Fourier series. All the unknown expansion coefficients are treated as the generalized coordinates, and determined using the Rayleigh-Ritz technique. This work allows a capability of modeling a wide spectrum of orthotropic thin rectangular plate under a variety of boundary conditions, and changing the boundary conditions as easily as modifying the material properties or dimensions of the plates. The accuracy and reliability of the SGM prediction are demonstrated though numerical examples. The SGM prediction can be readily and directly extended to other more complicated boundary conditions involving non-uniform restraints, point supports, partial supports and their combinations