南京地区多目标地球化学调查基本成果及其相关问题初探

Basic results of multi-target geochemical survey in the Nanjing area and its relevant problems

南京地区是长江三角洲第四系厚层覆盖区的一个典型代表,本文报道了该区开展多目标地球化学调查工作以来所取得的一些基本成果。认为本区采用-20目的土壤样品筛分粒级、表层土壤取样深度定为0～-20m、深层土壤取样深度定为-150cm以下及有关的采样密度试验结果都是切实可行的。发现南京地区局部表层土壤中存在两个重金属元素富集带,局部土壤中重金属元素的明显富集对有关农作物的安全性有直接影响。讨论了诸如怎样确定土壤中元素的背景值、如何检查评价环境地球化学异常、如何看待土壤中元素总含量及其有效态含量等具体问题,并提出了相关建议。

The Nanjing area is a typical representative of the very thick Quaternary cover areas in the Yangtze River delta.This paper reports some basic results obtained since multi-target geochemical survey has been carried out in the area.Through experiments,some key technical criteria and requirements have been worked out and generalized.The authors think that it is feasible to take samples from topsoil at a depth of0to20cm and deep soil at a depth of≤150cm respectively,use the–20mesh fraction of soil and adopt sampling densities of one sample per square kilometer for topsoil and one sample per4square kilometers for deep soil.Two belts polluted by some heavy metallic elements exist in topsoil in the Nanjing areas,and marked enrichment of heavy metallic elements in topsoil has direct influence on the safety of crops and vegetables in the study area.At last,the authors discuss a number of questions as to how to determine the geochemical background values in studied soils,how to examine and appraise environmental geochemical anomalies and how to treat the relationship between the total content of some elements and their effective concentrations in topsoil and so on,and propose relevant suggestions.