传统的监测和绘图方法是费力的,贵,并且耗时,因为它们需要大量的数据,因此需要大量的采样和实验操作。因此,由于人们越来越担心重金属(HM)污染土壤和农产品的可能性,在设拉子(伊朗)东南部2300公顷的77个农田上进行了田间试验,以调查土壤和蔬菜中金属污染的来源,并对HMs的空间分布进行建模(铁,铁;锰,锰;铜,铜;锌,锌;镉,Cd;镍,Ni,和领导,铅)使用地理信息系统(GIS)和地统计学(普通克里格法,确定)方法并将结果与确定性方法(距离反加权,具有不同加权功率的IDW)。此外,一些生态和健康风险指数,包括污染指数(PI),内梅罗综合污染指数(NIPI),污染负荷指数(PLI),污染程度(Cdeg),改性污染度(mCd),土壤质量的PIaverage和PIvector,多元素污染(MEC),毒性概率(MERMQ),潜在生态指数(RI),基于摄入的总危害指数(THI)和总致癌风险指数(TCR),吸入,计算了成人和儿童的皮肤暴露途径,分别分析了非致癌和致癌风险。计算了上述HM的实验半变异函数和理论模型(即,指数,球形,高斯,和线性模型)进行拟合,以对其空间结构进行建模并研究最具代表性的模型。此外,主成分分析(PCA)和聚类分析(CA)用于识别土壤中HMs的来源。结果表明,IDW方法比OK方法更有效地估算土壤和植物中的性质和HMs含量。Pb和Ni的每日金属摄入量(DIM)值超过了其安全限值。此外,Cd是造成生态风险的主要元素。PIave和PIvector指数表明,研究区土壤质量不合适。根据mCd值,被归类为铜和镉超高污染的土壤,Zn和Pb极高,非常高,高,镍的污染程度非常低,Mn,Fe,分别。36%,60%和4%的采样点都很高,中等,和低风险水平,49%,21%和9%的毒性概率,分别。Ni的最大健康风险指数(HRI)值为20.42,对儿童具有极高的风险,成人和儿童的HI分别为0.22和1.55。与其他研究的HM相比,Pb和Cd的THI值最高,揭示了与接触这些金属相关的儿童可能的非癌症风险。对THI和TCR指数影响最大的暴露途径为摄入>吸入>皮肤。因此,摄取,作为暴露的主要途径,是对健康风险做出最大贡献的途径。PCA分析表明,Fe,Mn,Cu,镍可能来自天然来源,虽然铁似乎是由肥料控制的,铜主要来自农药,而Cd和Pb主要与人为污染有关,大气沉积,在城市土壤中也很棒。同时,锌主要来源于施肥。研究结果对于开发用于控制污染物分布以及监测和绘制土壤资源的质量和健康的修复方法至关重要。
Conventional monitoring and mapping approaches are laborious, expensive, and time-consuming because they need a large number of data and consequently extensive sampling and experimental operations. Therefore, due to the growing concern about the potential of contamination of soils and agricultural products with heavy metals (HMs), a field experiment was conducted on 77 farm lands in an area of 2300 ha in the southeast of Shiraz (Iran) to investigate the source of metal contamination in the soils and vegetables and to model spatial distribution of HMs (iron, Fe; manganese, Mn; copper, Cu; zinc, Zn; cadmium, Cd; nickel, Ni, and lead, Pb) over the region using geographic information system (GIS) and geostatistical (Ordinary Kriging, OK) approaches and compare the results with deterministic approaches (Inverse Distance Weighting, IDW with different weighting power). Furthermore, some ecological and health risks indices including Pollution index (PI), Nemerow integrated pollution index (NIPI), pollution load index (PLI), degree of contamination (Cdeg), modified contamination degree (mCd), PIaverage and PIvector for soil quality, multi-element contamination (MEC), the probability of toxicity (MERMQ), the potential ecological index (RI), total hazard index (THI) and total carcinogenic risk index (TCR) based on ingestion, inhalation, and dermal exposure pathways for adults and children respectively for analyzing the noncarcinogenic and carcinogenic risks were calculated. Experimental semivariogram of the mentioned HMs were calculated and theoretical models (i.e., exponential, spherical, Gaussian, and linear models) were fitted in order to model their spatial structures and to investigate the most representative models. Moreover, principal component analysis (PCA) and cluster analysis (CA) were used to identify sources of HMs in the soils. Results showed that IDW method was more efficient than the OK approach to estimate the properties and HMs contents in the soils and plants. The estimated daily intake of metals (DIM) values of Pb and Ni exceeded their safe limits. In addition, Cd was the main element responsible for ecological risk. The PIave and PIvector indices showed that soil quality in the study area is not suitable. According to mCd values, the soils classified as ultra-high contaminated for Cu and Cd, extremely high for Zn and Pb, very high, high, and very low degree of contamination for Ni, Mn, and Fe, respectively. 36, 60, and 4 % of the sampling sites had high, medium, and low risk levels with 49, 21, and 9 % probability of toxicity, respectively. The maximum health risk index (HRI) value of 20.42 with extremely high risk for children was obtained for Ni and the HI for adults and children were 0.22 and 1.55, respectively. The THI values of Pb and Cd were the highest compared to the other HMs studied, revealing a possible non-cancer risk in children associated with exposure to these metals. The routes of exposure with the greatest influence on the THI and TCR indices were in the order of ingestion > inhalation > dermal. Therefore, ingestion, as the main route of exposure, is the route of greatest contribution to health risks. PCA analysis revealed that Fe, Mn, Cu, and Ni may originate from natural sources, while Fe was appeared to be controlled by fertilizer, and Cu primarily coming from pesticide, while Cd and Pb were mainly associated with the anthropogenic contamination, atmospheric depositions, and terrific in the urban soils. While, Zn mainly originated from fertilization. Findings are vital for developing remediation approaches for controlling the contaminants distribution as well as for monitoring and mapping the quality and health of soil resources.