小浪底水库水体中重金属含量的测定和健康风险评价

Identification of the heavy metal contents in the water of Xiaolangdi Reservoir and its health risk assessment

在小浪底水库坝上约10 km处主航道上设置采样垂线,采集水体不同深度的样品,采用冷原子荧光光谱法和电感耦合等离子体质谱法测定了样品中汞、砷、铅、镉、铬、铜、锌、锰、镍等元素的质量浓度。结果表明,在所有样品中,铬、镉、锌、铅均未检出,汞、铜和砷的质量浓度分别为（0.95±0.44）ng/L、（0.35±0.07）μg/L和（1.12±0.20）μg/L,锰和镍的质量浓度分别为（0.14±0.06）μg/L和（0.59±0.09）μg/L。汞质量浓度随水深增加逐渐升高,至水深7.5 m处达到最大值,然后逐渐降低,在接近底层时重新升高,达到次峰值。其他重金属质量浓度呈现随水深增加而升高的趋势。健康风险评价结果表明,致癌物质砷引起的健康危害较高,风险值为10-6-10^-5a^-1,底层水中砷的风险值接近国际辐射防护委员会（ICRP）推荐的最大可接受风险水平;非致癌物质汞、铜、镍和锰引起的健康风险分别为1.43×10^-12a^-1、0.31×10^-10a^-1、0.13×10^-10a^-1和0.45×10^-12a^-1,均远低于ICRP推荐的最大可接受水平。

The present article is aimed to provide a case study sample on the identification of the heavy metal contaminants in the water of Xiaolangdi Reservoir and its health risk assessment.In order to assess the water quality of the reservoir,we have collected water samples at different depths of the main course,about10 km upstream of the dam. When the samples were gathered,we have analyzed the total mercury content of the samples via the US environmental protection agency（ US EPA） method 1631,which consists of oxidation,reduction,purge and trap pre-concentration,and the determination by an atomic fluorescence spectrometer. All the other heavy metal contaminants can be determined by using a inductively coupled plasma mass spectrometry with the following US EPA method 200. 8. And,the next,our assessment has been done in association of the health risk with the heavy metal contaminants in the water. However,in all the water samples collected,the concentrations of Cr,Cd,Zn and Pb have all been proved below the corresponding detection limits. The detailed concentration data of the heavy metal contaminants,such as those of mercury,copper and arsenic were found to be（ 0. 95 ±0. 44） ng / L,（ 0. 35 ± 0. 07） μg / L and（ 1. 12 ± 0. 20） μg / L,respectively,which can meet the standard of Class I of the national environmental quality for the surface water（ GB 3838—2002）.The concentrations of manganese and nickel stand for（ 0. 14 ±0. 06） μg / L and（ 0. 59 ± 0. 09） μg / L,respectively,which are considered to meet the specific criteria set for the surface drinking water sources stipulated in the above mentioned national standard（ GB 3838—2002）. As to the mercury concentration,the increasing rate proves gradually going up with the increase of the depth of water,with its maximum data at a depth of 7. 5 m,and then began to drop down gradually. However,it rose up again at the bottom of the water body. Other heavy metal contents prove to be going up with the increase of the water depth. Moreover,the health risk likely to be induced by the arsenic content has been assessed to be 10- 6a- 1to 10- 5a- 1,with their risk liabilities of the bottom water being close to the maximum acceptable level of risk recommended by the International Commission on Radiological Protection（ ICRP）. Health risk likely to be induced by copper and mercury contents tend to be 1. 43 × 10- 12a- 1,0. 31 ×10- 10a- 1,0. 13 × 10- 10a- 1and 0. 45 × 10- 12a- 1,respectively.All the above mentioned data turn out to be much lower than the maximum acceptable levels of the risk recommended by ICRP.