地下水非洗井采样的样品代表性研究

Study on the Representativeness of Samples for Non-well Flushing Sampling of Groundwater

分别测定非洗井和洗井2种情况采集的样品的物理指标、无机氮和金属元素,并比较了结果数据,探讨了非洗井采样的可能性。结果表明:由于溶入CO_(2)和O_(2),非洗井较洗井采集的样品测得的pH值更小、溶解氧更大、氧化性更强,但水体的酸碱性和氧化还原氛围无实质性差别。无机氮的浓度受水体氧化还原氛围的影响呈规律性差异。蒸发作用会引起井内滞水化学组分浓度增大,易水解金属铁、锰等水解后形成胶体或被胶体吸附,团聚后密度增大向下迁移,其浓度在筛管下方高、水面下1.0 m处低,而洗井后样品的测定浓度在两者之间。

The possibility of non-flushing sampling was explored by comparing the physical indicators,inorganic nitrogen,and metal element results measured in both non flushing and flushing situations.The results showed that due to the dissolution of carbon dioxide and oxygen,the pH value measured by non-well washed samples was lower;dissolved oxygen was greater,and oxidation was stronger than that of well washed samples.However,there was no substantial difference in the acidity,alkalinity,and redox atmosphere of the water body.The concentration of inorganic nitrogen varies regularly depending on the redox atmosphere.Evaporation may cause an increase in the concentration of chemical components in stagnant water in the well.Metals such as iron and manganese may form colloids or are adsorbed by colloid safter hydrolysis.After colloid aggregation,the density increases and migrates downwards,resulting in an increase in metal concentration at the lower part of the sieve tube and a decrease at 1.0 m below the water surface.The metal concentration of the sample after well flushing is between the concentration at the lower part of the non-well flushing sieve tube and 1.0 m below the water surface.