广西西江流域土壤铅空间分布与污染评价

为了解广西西江流域土壤Pb含量分布特征,采集有色金属矿区土壤、农田土壤(水田土壤和旱地土壤)和自然土壤共2 594个样品,采用地统计分析与GIS相结合的方法研究流域内土壤Pb含量空间分布特征与污染状况.结果表明,西江流域土壤Pb背景值为51.84 mg·kg~(-1),单样本T检验结果表明,显著高于前人背景值研究结果(22.08 mg·kg~(-1))和广西土壤背景值(20.50 mg·kg~(-1)).矿区土壤、旱地土壤和水田土壤Pb含量分别为655.9、116.7和40.63 mg·kg~(-1),矿区土壤Pb含量显著高于其他类型土壤.以《土壤环境质量标准》(GB 15618-1995)和土壤基线值为参考值,超标率分别为57.69%、16.40%、8.92%和54.95%、8.09%、2.03%,矿区和农田土壤存在明显的Pb积累.流域土壤Pb有明显的空间自相关性,以结构性变异为主.西江流域上游至中、下游土壤Pb呈现总体递减趋势,流域特征明显,高Pb含量样点在刁江上游的聚集远大于刁江下游都安段.西江流域土壤样本Pb总体介于轻度污染-中度污染之间,金城江区及南丹县土壤Pb污染突出,与当地频繁的矿业活动密切相关.

Spatial Distribution Study and Pollution Assessment of Pb in Soils in the Xijiang River Drainage of Guangxi

To obtain data for the accumulation of Pb and its risk in soils in the Xijiang River drainage of Guangxi, 2594 samples were collected from nonferrous metal mining soils, farmland soils (paddy soils and dryland soils), and the background soils in the drainage area. Geostatistical analysis combined with GIS was used to study the soil spatial distribution characteristics and pollution distribution of the soil Pb content. The results showed that the Pb background value of the soil was 51.84 mg ·kg^-1 in the Xijiang River Basin, and the results of the single sample T test showed that the soil background value was significantly higher than that of a previous study (22.08 mg ·kg^-1) and the soil background value (20.50 mg ·kg^-1) in Guangxi province. The geometric mean concentration of Pb in the mining soils, dryland soils, and paddy soils were 655.9, 116.7, and 40.63mg ·kg^-1, respectively, significantly higher than that in other soils. Using GB 15618-1995 and the baseline as the limiting value, the corresponding exceedance rate of the mining soils, dryland soils, and paddy soils were 57.69%, 16.40%, and 8.92% and 54.95%, 8.09%, and 2.03%. The mining soils and farmland soils had an obvious lead accumulation trend. There was an obvious spatial autocorrelation of Pb in the soil, and the structural variation was dominant. The content of Pb in the upper reaches of the Xijiang River reached the middle and lower reaches of the Xijiang River, and the soil Pb was characterized by an obvious decrease. The accumulation of high Pb content in the upper reaches of Diaojiang River is much larger than that in the lower reaches of Diaojiang River. The content of Pb in soil samples in the Xijiang River Basin was mainly rated between mild pollution and moderate pollution, and the pollution was concentrated in the municipal administrative area and the mining activity area. The pollution of the soil in Jinchengjiang and Nandan counties was closely related to the frequent local mining activities.