材料期刊网

海洋区域环境背景值具有很强的地域性特点,在评价人为污染强度时,使用全球页岩或其他大范围的地球化学背景值,会使得判断结果出现较大偏差.本文针对鸭绿江口前期重金属研究中因背景值选择差异化造成的评价结果失真的问题,从已发表的鸭绿江的重金属数据中选取210pb测年数据较为可靠、沉积环境相对稳定的4个柱状样用于区域重金属背景值的确定.通过筛选未受人类污染影响和自然强烈干扰的段落,计算获得鸭绿江口与邻近海岸沉积物重金属元素的背景值为:Cu 10.9 mg·kg-1、Pb 23.2 mg·kg-1、Zn72.9 mg·kg-1、Cd 0.203 mg· kg-1、Cr 49.8 mg·kg-1、Ni 21.6 mg·kg-1.这一背景值与工业化前全球沉积物重金属最高值相比普遍偏低,与中朝地台页岩重金属背景值相比相对偏高,与其他大范围的重金属背景值的差距也较大;但与中国海域的重金属背景值接近,说明可信度较高.影响鸭绿江口与邻近海岸沉积物重金属背景值的主要因素是粒度、物源和总有机碳(TOC),这一背景值更具有自然性和地域性.

Background values of heavy metals in marine areas differ extremely among regions.Thus,the results of pollution assessment will be quite different if different background values are used.It is more credible to choose background values within a study area as references.In early studies on the pollution evaluation of the Yalu River estuary and adjacent coasts,incorrect background values of heavy metals were used,therefore,in this study,values that are more appropriate were defined for the first time for the given area.These basic data were collected from the published research results on the contents of heavy metals in four cores with reliable 210Pb dating and a stable sedimentary environment.Background values were determined from sediments that suffered no anthropogenic or natural disturbance.The results showed that background values of the heavy metals in the sediments of the Yalu River estuary and adjacent coasts were:Cu 10.9 mg· kg-1,Pb 23.2 mg· kg-1,Zn 72.9 mg·kg-1,Cd 0.203 mg· kg-1,Cr 49.8 rag· kg-1,and Ni 21.6 mg· kg-1.Compared with preindustrial global maximum values,the background values in the study area were generally low.Compared with background values in the Sino-Korean platform shale,they were relatively high.Compared with background values in other larger regions,they were also very different.However,they were close to background values in the waters in China,which indicated that these data were more credible.The main factors affecting background values of heavy metals in sediments of the Yalu River estuary and adjacent coasts were grain size,provenance,and total organic carbon (TOC).Therefore,the identified background values had more characteristics of naturality and territoriality.