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
Algae are one of the major groups of soil microflora in agricultural lands. Among algae, the bluegreens are considered to be very valuable in agriculture. The role of them in soil fertility enhancement has been extens...Algae are one of the major groups of soil microflora in agricultural lands. Among algae, the bluegreens are considered to be very valuable in agriculture. The role of them in soil fertility enhancement has been extensively studied worldwide. Sustainable utilization of an organism for any human purpose depends on how successfully the ecology of the same is thoroughly understood. Kuttanadu is a unique tropical paddy-wetland. Ecology of blue-green-algae and the exact diversity of the same in the zone remained unexplored. This is the first report of the blue-green-algal community of Kuttanadu in relation to different soil-regions, seasons, and crop-growth-stages. A rich blue-green-algal diversity of 64 species, with Oscillatoriales as the dominants (38%), is observed in these paddy-fields. The highest values for all the ecological parameters analyzed were found in the Lower Kuttanadu soil region, during Virippu season, at panicle stage of the crop whereas the lowest values for most of the parameters were observed in Upper Kuttanadu soils during puncha season at the seedling and panicle stages. The species richness and diversity index showed positive correlation to crop seasons. Apart from the specific soil and climatic factors, the total number of blue green algal isolates showed positive correlation to total nitrogen and phosphorus in the soils.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.
文摘Algae are one of the major groups of soil microflora in agricultural lands. Among algae, the bluegreens are considered to be very valuable in agriculture. The role of them in soil fertility enhancement has been extensively studied worldwide. Sustainable utilization of an organism for any human purpose depends on how successfully the ecology of the same is thoroughly understood. Kuttanadu is a unique tropical paddy-wetland. Ecology of blue-green-algae and the exact diversity of the same in the zone remained unexplored. This is the first report of the blue-green-algal community of Kuttanadu in relation to different soil-regions, seasons, and crop-growth-stages. A rich blue-green-algal diversity of 64 species, with Oscillatoriales as the dominants (38%), is observed in these paddy-fields. The highest values for all the ecological parameters analyzed were found in the Lower Kuttanadu soil region, during Virippu season, at panicle stage of the crop whereas the lowest values for most of the parameters were observed in Upper Kuttanadu soils during puncha season at the seedling and panicle stages. The species richness and diversity index showed positive correlation to crop seasons. Apart from the specific soil and climatic factors, the total number of blue green algal isolates showed positive correlation to total nitrogen and phosphorus in the soils.
