广西玉林博白县富硒土壤重金属分布特征与来源分析

Distribution characteristics and sources identification of heavy metals in selenium-enriched soils in Bobai county,Yulin city,Guangxi Zhuang Autonomous Region

为推动地方绿色富Se产业发展和巩固脱贫成果,在广西壮族自治区玉林市博白县中北部连片农耕区采集表层土壤样品172件,农作物样品水稻100件、玉米30件和荔枝42件,利用统计学以及正定矩阵因子(PMF)模型分析了研究区土壤中Se和重金属元素的含量、空间分布特征及来源。结果表明,博白县表层土壤富Se率为42.08%,As、Cd、Cu、Hg、Pb和Zn超标率低,Cr和Ni不超标,土壤质量满足地方发展富Se农业的要求。空间分布特征显示,富Se土壤主要分布在径口镇、博白镇、亚山镇、顿谷镇和旺茂镇,土壤Se、As、Cr、Ni、Pb和Zn高值区与泥盆系东岗岭组和志留系连滩组地层分布一致,Cd、Cu、Ni、Pb和Zn在三滩镇明显富集。PMF分析结果表明,研究区土壤Se和重金属来源包括自然源(Se、Cr和Ni)、矿业源(Cd、Cu、Pb和Zn)、大气沉降来源(Hg)和农业源(As),各组来源的综合贡献率分别为29.52%、34.87%、23.15和12.45%。研究区水稻、玉米和荔枝的富Se率分别为90.0%、76.67%和2.38%,但水稻Cd超标率达24%,矿业活动是区域土壤Cd的主要来源,同时土壤整体呈强酸性~酸性,Cd的生物有效性高,导致水稻Cd含量较高。应加强工矿企业废渣、废水、废气排放的监管,开展土壤酸化治理或喷施富含Se元素的叶面阻隔剂,推动博白县绿色富Se水稻产业发展。

In order to promote the development of local green Se-enriched industry and consolidate the achievements of poverty alleviation,172 topsoil samples and main agricultural products samples(100 samples of rice,30 samples of corn and 42 samples of lychee)were collected from the contiguous farming area in the central and northern Bobai county,Yulin city,Guangxi Zhuang Autonomous Region.The contents,spatial distribution characteristics and sources of Se and heavy metals in soil were analyzed by statistics and positive matrix factor(PMF)model.The results showed that the Se-enriched rate of topsoil in Bobai county was 42.08%.Compared with the screening values of GB 15618-2018,the over-standard rates of As,Cd,Cu,Hg,Pb and Zn were low,and Cr and Ni were not exceeding the standard,and the soil quality could meet the local development of Se-enriched agriculture.The spatial distribution characteristics showed that the Se-enriched soils were mainly distributed in Jingkou town,Bobai town,Yashan town,Dungu Town and Wangmao Town.The high values of Se,As,Cr,Ni,Pb and Zn in the soils were consistent with the strata of the Devonian Donggangling Formation and the Silurian Liantan Formation.Cd,Cu,Ni,Pb and Zn were obviously enriched in Santan Town.The PMF analysis indicated that nature sources(Se,Cr and Ni),mining sources(Cd,Cu,Pb and Zn),atmospheric deposition sources(Hg)and agricultural sources(As)were the four major sources of Se and heavy metals in the study area,with contributions of 29.52%,34.87%,23.15 and 12.45%,respectively.The Se-enriched rates of rice,corn and litchi were 90.0%,76.67%and 2.38%,respectively,while the Cd over-standard rate of rice was 24%.Mining activities were the main source of soil Cd in the study area,and the soil as a whole was strong acidic to acidic,and the bioavailability of Cd increased,leading to high Cd content in rice.It is necessary to strengthen the supervision of waste residue,waste water and waste gas discharge of industrial and mining enterprises,carry out soil acidification treatment or spray Se rich leaf barrier to promote the development of green Se-enriched rice industry in Bobai county.