扬州雨水质量分析及其利用

本文针对地处南水北调东线源头的扬州地区雨水进行了分析,除了测定雨水中含有的重金属和常见元素Pb、Zn、Cu、K、Na、Ca、Mg、NH4 -N外,对雨水样品酸度、温度、固体悬浮物(SS)、化学需氧量(COD)等参数进行了测定分析,结果发现,扬州雨水质量尚好.从沥青屋面雨后积水COD的变化曲线看,降雨开始50min后,COD值基本稳定在Ⅲ-Ⅳ类水质标准之间,110min后符合Ⅰ类水质量标准.     

Spatial distribution and accumulation of heavy metals in tidal flat sediments of Shanghai coastal zone

Surface and core sediments from the high, middle and low tidal flats of Shanghai coastal zone were analyzed for heavy metal (e.g. Cu, Pb, Zn, Cr, Cd, Fe, Mn) concentrations. Besides Cd, the concentrations of Cu, Zn, Cr and Pb are 2-5 times higher than their background values and show serious pollution trend due to the direct discharge of industrial and municipal sewage along the Shanghai tidal flat, as well as the wet and dry depositions of industrial dusts. It seems that heavy metals prefer to accumulate and be enriched in the sediments near large sewage outlets, high flats, and the subsurface layer at the depth of 10-30 cm. Several main factors, which include the direct sewage discharge along the tidal flat, tidal hydrodynamic action, large engineering activity, early diagenesis and windstorm tide, are considered to be responsible for influencing spatial distribution patterns of heavy metals in the Shanghai tidal flat.     

Magnetic normalization of particle size effects in a heavy metal pollution study of intertidal sediments from the Yangzte Estuary

Magnetic, granulometric and geochemical analyses were conducted on an intertidal sediment core from the Yangtze Estuary to evaluate the possibility of normalizing samples for particle size effects in a heavy metal pollution study by means of magnetic proxies. It has been found that the magnetic parameter XARM, indicating fine grained ferrimagnetic minerals, correlates well with the clay content and organic matter concentration of the sediments. XARM also shows significant relationship with heavy metals. Therefore XARM is proposed as a proxy for clay content in the sediments, and can be used to compensate for the particle size effect in sedimentary heavy metal records, where magnetic minerals are not subject to significant post-depositional alteration.