The reclamation of tidal fiats has been one of the important approaches to replenish the arable lands in the coastal areas; pollution status of reclaimed soils has received wide attention recently, especially for the ...The reclamation of tidal fiats has been one of the important approaches to replenish the arable lands in the coastal areas; pollution status of reclaimed soils has received wide attention recently, especially for the study of heavy metals due to the relative high pollutant concentrations in wetlands. To understand the impact of land use change on heavy metal and arsenic （As） geochemistry by the reclamation of wetlands for agriculture, surface soils and soil profiles were collected from the agricultural land reclaimed in the 1990s and the intertidal flat wetland at Dongtan on Chongming Island in the Yangtze River Estuary, China. The soil samples were analyzed for total concentrations and chemical speciation of chromium （Cr）, zinc （Zn）, copper （Cu）, lead （Pb）, nickel （Ni）, cadmium （Cd） and As using inductively coupled plasma mass spectrometry （ICP-MS）. Results showed that soil properties （salinity, total organic carbon and grain-size distribution） and the concentrations of heavy metals and As in the soils differed under the different land use types. The conversion of wetland to forest had caused obvious losses of all the measured heavy metals. In paddy field and dryland with frequent cultivation, the concentrations of Cr, Zn, Cu, Ni and As were higher when compared to forest land which was disturbed rarely by human activities. Speciation analysis showed that Cr, Zn, Cu, Ni and As were predominated by the immobile residual fraction, while Pb and Cd showed relatively higher mobility. In general, metal （except Ni） and As mobility decreased in the following order： wetland 〉 dryland 〉 paddy field 〉 forest land, which suggested that the reclaimed soils had lower metal and As mobility than the intertidal fiat wetland. The results of this study contribute to a better understanding of the effects of land use on heavy metals and As in the reclaimed soils of the study area and other similar coastal areas.展开更多
Estuarine and intertidal wetlands are important sites for nitrogen transformation and elimination.However,the factors controlling nitrogen removal processes remain largely uncertain in the highly dynamic environments....Estuarine and intertidal wetlands are important sites for nitrogen transformation and elimination.However,the factors controlling nitrogen removal processes remain largely uncertain in the highly dynamic environments.In this study,continuous-flow experiment combined with 15 N isotope pairing technique was used to investigate in situ rates of denitrification and anaerobic ammonium oxidation(anammox)and their coupling with nitrification in intertidal wetlands of the Yangtze Estuary.The measured rates varied from below the detection limit to 152.39μmol N/(m^2·hr)for denitrification and from below the detection limit to 43.06μmol N/(m^2·hr)for anammox.The coupling links of nitrogen removal processes with nitrification were mainly dependent on nitrate,organic carbon,sulfide,dissolved oxygen and ferric iron in the estuarine and intertidal wetlands.Additionally,it was estimated that the actual nitrogen removal processes annually removed approximately 5%of the terrigenous inorganic nitrogen discharged into the Yangtze Estuary.This study gives new insights into nitrogen transformation and fate in the estuarine and intertidal wetlands.展开更多
利用2003年8月2日L andsat5-TM多光谱遥感影像,运用遥感处理软件ERDA S Im ag ine 8.6,经几何校正分幅裁剪等图像预处理后,采用监督分类和目视解译相结合对上海市滩涂植被进行解译分析。结合全球定位系统(GPS)样点定位,对分类结果进行...利用2003年8月2日L andsat5-TM多光谱遥感影像,运用遥感处理软件ERDA S Im ag ine 8.6,经几何校正分幅裁剪等图像预处理后,采用监督分类和目视解译相结合对上海市滩涂植被进行解译分析。结合全球定位系统(GPS)样点定位,对分类结果进行全面的野外核实和修正,同时利用地理信息系统(G IS)对解译结果进行数据合成,统计出滩涂各类植被的分布区域及面积等数据。实际调查及其分析统计显示,上海滩涂植物群落总面积为21302.1hm2,主要植被组成为芦苇、海三棱草及互花米草三大群落,滩涂植物群落具有明显的高程梯度分布规律。大尺度的上海市滩涂植被的空间分布现状及其数量调查为上海市滩涂资源的合理规划、生物多样性保护和可持续开发利用提供科学依据。展开更多
基金supported by the National Natural Science Foundation of China (Nos. 41271466 and 40871216)
文摘The reclamation of tidal fiats has been one of the important approaches to replenish the arable lands in the coastal areas; pollution status of reclaimed soils has received wide attention recently, especially for the study of heavy metals due to the relative high pollutant concentrations in wetlands. To understand the impact of land use change on heavy metal and arsenic （As） geochemistry by the reclamation of wetlands for agriculture, surface soils and soil profiles were collected from the agricultural land reclaimed in the 1990s and the intertidal flat wetland at Dongtan on Chongming Island in the Yangtze River Estuary, China. The soil samples were analyzed for total concentrations and chemical speciation of chromium （Cr）, zinc （Zn）, copper （Cu）, lead （Pb）, nickel （Ni）, cadmium （Cd） and As using inductively coupled plasma mass spectrometry （ICP-MS）. Results showed that soil properties （salinity, total organic carbon and grain-size distribution） and the concentrations of heavy metals and As in the soils differed under the different land use types. The conversion of wetland to forest had caused obvious losses of all the measured heavy metals. In paddy field and dryland with frequent cultivation, the concentrations of Cr, Zn, Cu, Ni and As were higher when compared to forest land which was disturbed rarely by human activities. Speciation analysis showed that Cr, Zn, Cu, Ni and As were predominated by the immobile residual fraction, while Pb and Cd showed relatively higher mobility. In general, metal （except Ni） and As mobility decreased in the following order： wetland 〉 dryland 〉 paddy field 〉 forest land, which suggested that the reclaimed soils had lower metal and As mobility than the intertidal fiat wetland. The results of this study contribute to a better understanding of the effects of land use on heavy metals and As in the reclaimed soils of the study area and other similar coastal areas.
基金supported by the National Natural Science Foundation of China(Nos.41725002,41671463,41601530,41761144062,and41730646)the Fundamental Research Funds for the Central UniversitiesChinese National Key Programs for Fundamental Research and Development(Nos.2016YFA0600904,2016YFE0133700)。
文摘Estuarine and intertidal wetlands are important sites for nitrogen transformation and elimination.However,the factors controlling nitrogen removal processes remain largely uncertain in the highly dynamic environments.In this study,continuous-flow experiment combined with 15 N isotope pairing technique was used to investigate in situ rates of denitrification and anaerobic ammonium oxidation(anammox)and their coupling with nitrification in intertidal wetlands of the Yangtze Estuary.The measured rates varied from below the detection limit to 152.39μmol N/(m^2·hr)for denitrification and from below the detection limit to 43.06μmol N/(m^2·hr)for anammox.The coupling links of nitrogen removal processes with nitrification were mainly dependent on nitrate,organic carbon,sulfide,dissolved oxygen and ferric iron in the estuarine and intertidal wetlands.Additionally,it was estimated that the actual nitrogen removal processes annually removed approximately 5%of the terrigenous inorganic nitrogen discharged into the Yangtze Estuary.This study gives new insights into nitrogen transformation and fate in the estuarine and intertidal wetlands.
文摘利用2003年8月2日L andsat5-TM多光谱遥感影像,运用遥感处理软件ERDA S Im ag ine 8.6,经几何校正分幅裁剪等图像预处理后,采用监督分类和目视解译相结合对上海市滩涂植被进行解译分析。结合全球定位系统(GPS)样点定位,对分类结果进行全面的野外核实和修正,同时利用地理信息系统(G IS)对解译结果进行数据合成,统计出滩涂各类植被的分布区域及面积等数据。实际调查及其分析统计显示,上海滩涂植物群落总面积为21302.1hm2,主要植被组成为芦苇、海三棱草及互花米草三大群落,滩涂植物群落具有明显的高程梯度分布规律。大尺度的上海市滩涂植被的空间分布现状及其数量调查为上海市滩涂资源的合理规划、生物多样性保护和可持续开发利用提供科学依据。
