深水栽培无节水芹铅污染原因探究

Abstract

为探索金坛无节水芹铅污染原因及控制技术，对其主产区土壤、灌溉水、肥料和水芹产品进行了取样检测分析。结果表明，主产区土壤样品铅含量均不超标，肥料中铅含量也符合国家标准要求，而灌溉水中铅浓度却有18.2%超标。当灌溉水中铅浓度达到无公害芹菜生产水环境质量标准中允许铅含量的上限时(0.05 mg/L, NY 5010-2002)，主栽品种扬州白芹茎中铅含量为0.263 mg/kg，超过国家标准允许值(0.1 mg/kg, GB 2762-2012) 163%。相关分析表明，灌溉水中铅浓度与成熟期扬州白芹茎中铅含量呈极显著正相关(r = 0.7980, P < 0.01)。造成金坛无节水芹铅污染的原因，主要是灌溉水铅含量超标，其次是长期的深水灌溉的栽培方式。金坛无节水芹特殊的深水栽培方式决定了其灌溉水执行的标准要高于无公害蔬菜产地环境条件中规定的灌溉水质量指标要求，即不是≤0.05 mg/L，而应≤0.03 mg/L。 In order to investigate Pb pollution causes in Jintan inarticulate water dropwort (Oenanthe stolonifera) and the control technologies, soils, irrigation water, fertilizers and water dropwort products were sampled to test Pb concentrations in the production areas. The results showed that Pb concentrations in all soil and fertilizer samples were below the maximum allowable concentrations (MAC, according to the Chinese Standards) for safe production, but Pb concentrations exceeded the MAC in 18.2% of the irrigation water samples. When Pb concentration in the irrigation water reached the MAC (0.05 mg/L, NY 5010-2002), Pb concentration of water dropwort was 0.263 mg/kg, which was 163% higher than the MAC for water dropwort (0.1 mg/kg, GB 2762-2012). Further analysis indicated that there was positive and highly significant (r = 0.7980, P < 0.01) correlation between irrigation water and Jintan inarticulate water dropwort in Pb concentrations. There- fore, the Pb pollution in irrigation water is the main cause for Pb accumulation in Jintan inarticulate water dropwort. The secondary cause for Pb pollution of Jintan inarticulate water dropwort is deep water cultivation. The results reveal that Pb concentration in the irrigation water, for safe production of Jintan inarticulate water dropwort, must be controlled below 0.03 mg/L.