新型POPs污染物TBBPA和DP与重金属镉在土壤-植物系统中的归趋及生态毒理效应

Organic pollutants flame retardant and heavy metal Cd are the most serious polluters in the soil of the electronic waste dismantling field, two kinds of typical flame retardant such as Tetrabromobisphenol A (TBBPA) and Dechlorane Plus (DP) were the representative species of brominated flame retardants and chlorinated flame retardants which were the maximum amount of the worldwide used respectively, and they belong to a new type of POPs pollutants, its residue existed in the electronic waste dismantling the venue and its soil nearby, the pollution and destruction of the soil-plant system are becoming more and more serious，It has very important significance that the research of fate and toxicological effect for organic pollutants flame retardants and cadmium in the soil-plant system. The two typical flame retardants and heavy metal Cd were chose as the research object, using the toxicity test of higher plants and soil exposure method, to study the effect of acute toxicity on the higher plant by the single and combined pollution of flame retardant and cadmium. Different varieties of rice and hyperaccumulator ryegrass were selected as model organisms by pot experiment method, through the study of soil-plant system, the regular patterns of the migration, transformation and accumulation of flame retardants and heavy metal Cd in the different types of plants are discussed, and the mechanisms of toxic effect on the organisms under the conditions of single and combined pollution are explored, and the varity of low-accumulating plant rice and were selected. The response and accumulation ability of ryegrass to pollution stress and the effect of phytoremediationon on soil structure were investigated. Through the study, the toxicological effects of two typical flame retardants and heavy metal Cd on different types of plants are revealed, and it is very significant that the risk of potential exposure to the food chain is assessed, and it provides scientific basis for the ecological toxicity assessment and the remediation of contaminated soil by ryegrass.

阻燃剂和重金属Cd在电子垃圾拆解场地和附近土壤中污染严重，四溴双酚A和得克隆为目前世界范围内使用量最大的溴化阻燃剂和氯化阻燃剂代表种类，属于新型POPs污染物，对“土壤-植物”系统中有机污染物阻燃剂和重金属Cd复合污染物的归趋和毒理效应的研究具有重要的意义。本课题拟选择这两种典型阻燃剂和重金属Cd为研究对象，利用高等植物毒性试验和土壤染毒方法，研究阻燃剂和镉单一及复合污染对植物的急性毒性效应。拟选择不同品种的水稻和超积累植物黑麦草为模式生物，利用盆栽试验方法，研究两种阻燃剂和重金属Cd在不同品种水稻内的迁移、转化和积累规律及其对水稻的毒性效应机制，筛选出低积累水稻品种；探讨黑麦草对阻燃剂四溴双酚A和得克隆单一和复合污染胁迫的响应和富集能力及其植物修复对土壤结构和土壤生物的影响。本研究为评估对食物链的潜在暴露风险具有重要的意义，为受污染土壤生态毒性评价和黑麦草修复受污染土壤提供科学依据。

卤代阻燃剂四溴双酚A与得克隆属于新型POPs污染物，与镉在电子垃圾拆解场地和附近土壤中污染严重，以水稻和小麦为模式生物，采用土壤染毒方法和种子发芽试验，研究对植物幼苗生长发育的毒性，对水稻的毒性均大于小麦，小麦比水稻耐受镉的污染，小麦根对四溴双酚A敏感性大于芽。建立了多种样品中痕量得克隆和四溴双酚A的残留测定方法。采用田间盆栽试验研究了黑麦草对卤代阻燃剂与镉污染胁迫的响应和富集能力，得克隆的两种顺反异构体在种植黑麦草土壤中T1/2缩短为42.01~59.24 d和39.38~55.45 d，黑麦草根和茎对DP两种异构体吸收均具有显著的差异；TBBPA在种植黑麦草土壤中的T1/2缩短为74.53~91.20d，不同处理下，黑麦草根和茎中TBBPA残留量分别为289.35~216.48 ng/g和58.01~43.86 ng/g。黑麦草对镉具有富集作用（根为27.82~28.02 mg/kg），60天为最佳修复时间，黑麦草使土壤有效态镉浓度呈现先降低再增加再降低的趋势。黑麦草的根系作用对土壤的晶粒结构影响较小，但提高了土壤脱氢酶和多酚氧化酶活性，对土壤微生物种类和细菌菌种丰富度具有显著的影响。采用室外盆栽试验，研究土壤中污染物向两种水稻的迁移转化，镉在水稻根系中残留浓度最大，茎叶和稻谷中均低于土壤；四溴双酚A逐步降解为不同的溴代产物和双酚A，两种稻谷中四溴双酚A和双酚A残留水平具有显著差异，水稻品种决定污染物的吸收量，为选择低积累水稻品种提供参考依据；得克隆在两种水稻组织中的残留量无显著性差异（根＞茎叶＞稻谷），不同处理对两种稻谷品质的影响具有显著的差异。选用水稻和旱稻研究对其种子萌发和幼苗生长的影响，幼苗通过调节细胞中脯氨酸和可溶性糖等提高对污染胁迫的耐受性，两种水稻抗氧化酶活性和丙二醛均有较大的变化，水稻幼苗对阻燃剂和镉具有较强的生物积累作用(根部>茎)；四溴双酚A和双酚A更容易在国色天香1号水稻幼苗中积累，两种水稻幼苗对DP的积累能力无显著性差异。本研究为评估对食物链的潜在暴露风险具有重要的意义，为受污染土壤生态毒性评价和黑麦草修复受污染土壤提供科学依据。