天津近岸表层沉积物重金属和放射性核素分布特征

对渤海湾天津海域14个表层沉积物样品进行粒度、重金属和核素放射性活度测量,结果显示,沉积物组成以粉砂为主,其粒径在研究区横纵向上分别呈由南至北、由东至西逐渐变粗的分布特征.重金属元素含量为Cu:25.6~35.1mg/kg、Pb:44.1~67.7mg/kg、Zn:60~73.5mg/kg;210Pb活度为13.2~35.3Bq/kg,137Cs活度为0.05~1.28Bq/kg,重金属含量和放射性活度随粒径减小而增大,总体上呈由北至南逐渐增大的分布特征,在中部和南部分别呈由西北至东南和由西至东逐渐增大的分布特征.这主要是因为细颗粒组分对Cu、Pb、Zn、210Pb和137Cs的吸附作用大于粗颗粒组分,因此,其分布受渤海湾水流及其所导致的粒径变化所影响.

Characteristics of heavy metals and radionuclides in surface sediments from the inner Bohai Bay (Tianjin coastal sea)

Fourteen surface sediment samples were collected from the inner Bohai Bay (Tianjin coastal sea) to measure particle size, heavy metal and radioactivity. The sediments were majorly silt-size and the particle size decreases southwards and eastwards in study area. The ranges of heavy metal concentrations were 25.6~35.1mg/kg, 44.1~67.7mg/kg and 60~73.5mg/kg for Cu, Pb, Zn, respectively. The radioactivities for 210Pb and 137Cs were 13.2~35.3Bq/kg and 0.05~1.28Bq/kg, respectively. Heavy metals concentration and radioactivity decreases with the increase of particle size, and generally increases both from north to south spatially. In particular, the level of heavy metals and radioactivity in the central and southern area increases southeastwardly and eastwardly, respectively. That might be due to the fact that the fine particles are more effective in adsorbing metals than coarse particles, and the surface sediment particle size distribution can be affected by flow in Bohai bay.