Potentially toxic metals of vegetable gardens of urban schools in Lages, Santa Catarina, Brazil

ABSTRACT: Urban environments are contaminated in many ways with persistent organic and inorganic pollutants as a result of anthropogenic activities, endangering human health and natural resources. The objective of the present study was to evaluate the soil contamination by cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) in 10 vegetable gardens of urban schools located near or on Botucatu sandstone outcrops of Guarani Aquifer in the urban areas of Lages, Santa Catarina, Brazil. In each garden, three soil samples at each position (in the soil immediately outside and the soil in the garden) were collected at a depth of 0-20 cm. The ISO 11466 method was used to extract the metals. Inductively coupled plasma optical emission spectrometry was used to quantify the elements and certified materials to evaluate the quantities (SRM 2709a - San Joaquin Soil - NIST). To evaluate the data, principal component analyses and cluster analyses were performed. The cluster analysis for the evaluated metals showed that the highest contents of elements were reported in three gardens. Values above the prevention value defined by resolution no. 420/2005 of the National Council for the Environment -Conselho Nacional do Meio Ambiente (CONAMA) - were reported for cobalt in one garden and copper in three gardens; thus, these areas were categorized as Class III areas. Principal component analysis explained 74.7% of the data and showed the enrichment of some elements within gardens.

摘要：城市环境因人类活动受到多种持久性有机与无机污染物的污染，严重威胁人类健康与自然资源安全。本研究以巴西圣卡塔琳娜州拉热斯市城区内10所城市学校的菜园为研究对象，评估其土壤中钴（Co）、铬（Cr）、铜（Cu）、锰（Mn）、镍（Ni）、铅（Pb）与锌（Zn）的污染状况，这些菜园位于瓜拉尼含水层（Guarani Aquifer）博图卡图砂岩露头附近或直接覆于该露头之上。每个菜园均采集两个位置的土壤样品各3份，采样深度为0~20 cm，采样位置分别为菜园外侧紧邻的土壤与菜园内部土壤。采用ISO 11466标准方法进行金属元素提取，通过电感耦合等离子体发射光谱法（Inductively coupled plasma optical emission spectrometry）对元素含量进行定量，并使用美国国家标准与技术研究院（National Institute of Standards and Technology, NIST）的圣华金土壤标准参考物质SRM 2709a对定量结果进行质量控制。采用主成分分析与聚类分析对实验数据进行评估。针对目标金属的聚类分析结果显示，3个菜园的元素整体含量最高。钴元素在1个菜园、铜元素在3个菜园中的含量超出了巴西国家环境委员会（Conselho Nacional do Meio Ambiente, CONAMA）第420/2005号决议规定的土壤污染预防限值，因此这些区域被归类为三类区域。主成分分析可解释74.7%的数据集方差，并显示部分元素在菜园内部存在富集现象。