松花江冰封期江水和沉积物中汞形态研究

2005年12月中、下旬对松花江哈达湾至佳木斯江段冰封期江水和沉积物进行了采样与分析。结果表明,江水总汞质量浓度为29.74~136.88 ng/L,均值为50.21 ng/L,以悬浮颗粒态为主(53.38%~85.99%)。沉积物总汞的质量分数介于0.013~1.543 mg/kg之间,与铁、锰和有机碳含量呈显著正相关;运用连续化学浸提法,对哨口至松原江段沉积物汞的形态进行了分析,沉积物汞主要以碱溶态、强有机质结合态和残渣态存在,可交换态和盐酸溶态汞的比例较小,仅占总汞的0.91%~33.7%。研究发现,沉积物再悬浮作用是影响松花江冰封期江水悬浮颗粒态汞及总汞空间分布的主要因子,沉积物汞释放是一个缓慢长期的过程。

Speciation of Mercury in Water and Sediments from the Songhua River during the Icebound Season

Samples were collected from the reach between the Hadawan and the Jamusi along the Songhua River to characterize the distribution and speciation of mercury in water and sediments during icebound season in December,2005,and total mercury and its speciation in sediments and water were determined.Results showed that total mercury concentrations in water averaged 50.21 ng/L,ranged from 29.74 ng/L to 136.88 ng/L.Suspended particulate mercury was the dominate phase(53.38% to 85.99%),while soluble mercury accounted for 14.01% to 46.62%.Overall,total mercury and suspended particulate mercury concentrations in water were comparatively higher in the reach from the Baiqi to the Haerbin;however,soluble mercury concentrations were higher in the Haerbin,the Sifangtai,the Songyuan,and the Hadawan reaches.Total mercury concentrations in sediments ranged from 0.013 mg/kg to 1.543 mg/kg,reduced from upstream to downstream.Especially,between the Hadawan and the Songyuan reach in the Secend Songhua River total mercury concentrations in sediments averaged 0.61 mg/kg,which was significantly higher than background of that area,while in mainstream they were parallel to the background.The strong positive correlation was observed between total Hg and Fe,Mn,TOC respectively.Moreover,a sequential selective extraction procedure was used to study the bioavailabililty of mercury in sediments from the Shaokou to the Songyuan reach.The mercury in sediments existed mainly as alkaline,H2O2 leached mercury and residue mercury.The percentage of exchangeable and HCl soluble mercury in sediments were only 0.91% to 33.7%.In conclusion,sediments resuspension of mercury from sediments exert a significant influence on the distribution of total mercury and suspended particulate mercury in water;because of high concentrations of total mercury and strong association with sediments,mercury in sediments of the Second Songhua River would release slowly for a long time.