山东省临沂市土壤有机氯农药滴滴涕残留量与空间分布特征

Residues and Spatial Distribution Characteristics of Organochlorine Pesticides DDTs in Soil of Linyi City,Shandong Province

通过对临沂市全区表层土壤每36 km2进行样品收集,测试分析了DDTs、Org C、N等指标,主要研究了区域表层土壤DDTs的残留现状、组成和来源、影响因素、空间分布和环境质量特征.结果表明,调查区表层土壤中DDTs检出率为71.75%,平均含量为0.035μg·g-1;检出样品中p,p'-DDT和p,p'-DDE为主要残留物,平均残留分别为0.033μg·g-1和0.010μg·g-1,分别占检出样的60.99%和34.62%.DDTs降解率指示区域58%表层土壤为新近输入区,新近输入区在调查区中南部分布尤为明显;而p,p'-DDD/p,p'-DDE指示区域DDTs降解以氧化环境为主,o,p'-DDT/p,p'-DDT指示71.37%区域土壤DDTs输入可能与工业级DDTs有关.相关分析表明,影响土壤DDTs分布的外在因素包括土壤Org C、N、C和p H等指标,且DDTs中p,p'-DDT组分占比越高,影响越明显.DDTs的空间分布具明显点源特征,市县周围均出现明显浓集中心,中南部部分区域浓度明显较高.全区DDTs土壤环境质量污染程度较低,主要以一二类土壤为主,分别占78.95%和21.05%.

Surface soil samples were collected every 36 km2 from Linyi City to study the residues,composition and origin,influencing factors,spatial distribution and environment quality characteristics of soil DDTs.Measurements were taken for DDTs,Org C,N,etc.for all samples.The results indicated that the detectable rate of DDTs was 71.75%,and the mean content of DDTs was 0.035μg·g- 1.p,p’-DDT and p,p’-DDE were the predominant contaminant compounds,with mean concentrations of 0.033 μg·g- 1and0.010 μg·g- 1,and accounted for 60.99% and 34.62% of the detectable samples,respectively.The degradation rate of DDTs suggested that 58% surface soils were recently inputted,these newly inputted locations were especially distributed in the middle to south of the study area,meanwhile,p,p’-DDD / p,p’-DDE revealed that the degradation of DDTs was mainly under oxidizing condition,and o,p’-DDT / p,p’-DDT illustrated that 71.37% DDTs in soils of the study area were concerned with technical DDTs sources.Besides,the correlation analysis showed that the external factors affecting the distribution of DDTs included Org C,N,C and p H etc.,and the higher the p,p’-DDT proportion of DDTs,the greater the effect.The distribution of DDTs had an obvious point source characteristic,and significant concentration centers were located nearby the cities and counties,typically,the DDTs concentrations of middle to southern area were much higher.However,DDTs environmental quality assessment suggested that the pollution level was relatively low,and the soil was mainly classified into grade I or Ⅱ,which accounted for 78.95% and 21.05% of the whole study area,respectively.