【作者】 林志灵；

【导师】 曾希柏； 张杨珠；

【作者基本信息】 湖南农业大学 ， 土壤学， 2013， 博士

【摘要】 本研究选取人工合成水铁矿、针铁矿和水铝矿以及镁铝双金属氧化物(Mg/Al-LDO)四种化学钝化剂为材料,通过开展室内模拟培养试验和盆栽试验的方法,明确化学钝化措施对降低土壤中砷的生物有效性的效果；同时,结合低吸收作物调控和育苗期氮、磷、钾、钙、镁、铁和锰七种营养元素调控的盆栽试验,为高风险农田的安全利用提供新的方法和途径。本研究的主要结果如下：1.土壤中添加水铁矿和针铁矿对酸性土壤中砷的钝化效应较好,两种矿物作用效果相当,较水铝矿和Mg/Al-LDO效果好。添加铁铝矿物均降低了土壤有效砷的含量,下降幅度为1.89%-64.15%,而添加Mg/Al-LDO则使土壤有效砷含量增加；添加水铁矿和针铁矿各处理对提高土壤残留态砷含量的作用较明显。2.四种钝化剂的应用均在一定程度上降低了作物对砷的吸收,其中水铁矿的添加效果最佳,水铝矿次之,针铁矿最差。与对照相比,添加水铁矿、水铝矿和Mg/Al-LDO不仅能够明显的降低小白菜地上部和地下部砷含量、富集系数,还明显降低了小白菜植株砷的富集量,其中以水铁矿添加效果最佳；添加四种钝化剂均有效抑制砷由小白菜地下部向地上部的转运,其中水铁矿调控效果最佳,降低幅度达34.03%-69.44%；水铁矿、针铁矿和Mg/Al-LDO都在1.0%添加比例下对降低小白菜植株砷的富集量、各部分砷含量、富集系数以及转移系数表现出最优效果,而水铝矿的最佳投加比例则出现在0.25%或者0.5%添加处理下。3.小白菜对砷的敏感性大于玉米,高砷含量土壤中更适宜种植玉米。生长在总砷含量为194mg·kg-1土壤的小白菜可食部位砷含量高达0.80mg·kg-1,大大超过了食品安全国家标准规定的限量值,而生长在此浓度土壤中生长的玉米籽粒则可放心食用；随着土壤含砷量的增加,小白菜和玉米各器官中的砷含量及植株累积砷的总量随之增长,但增长规律不尽相同；小白菜地上部砷含量远低于根系,成熟期玉米体内砷的分布规律为：根系>叶片>茎秆>籽粒。4.育苗期添加氮、磷、钾、钙、镁、铁和锰七种营养元素能够有效抑制砷由玉米地下部向地上部的转移；除锰养分外,其余六种养分的添加均能够达到降低玉米籽粒中的砷含量、降低玉米植株富集量砷的总量以及抑制砷从玉米根系向地上部特别是玉米可食部位(籽粒)中的转运的效果；氮素添加1536mg·kg-1、磷素添加355mg·kg-1、钾素添加1071mg·kg-1、钙素添加549mg·kg-1、镁素添加220mg·kg-1、铁素添加25.60mg·kg-1等处理对降低玉米吸收砷的效果较好；氮、磷、钾、钙、铁与砷在作物中存在着双重效应,这与营养元素的添加量息息相关。更多还原

【Abstract】 In this paper, in order to find new methods and ways in safe utilization of fields with high arsenic content, laboratory incubation experiments and pot culture experiments were conducted to investigate the regulating effects of several amendments (ferrihydrite, goethite, gibbsite and Mg/Al layered double oxides) and nutrient elements (N, P, K, Ca, Mg, Fe, Mn) addition during the seedling stage on the bioavailability of arsenic in contaminated soils. The main results were as follows:1. Goethite and ferrihydrite showed a better immobilization effect of arsenic (As) than Mg/Al-LDO and gibbisite, and could be applied as amendments to immobilize As in soils. The contents of available As in soils were decreased by1.89%-64.15%by adding goethite, ferrihydrite and gibbsite, while they were increased by adding Mg/Al layered double oxides. The contents of residual As in soils by adding goethite and ferrihydrite were obviously elevated.2. The application of four amendments reduced the contents of arsenic in crops, ferrihydrite showed the best effect, gibbisite was better, and goethite showed the worst results. Compared to the control pots, not only the enrichment of arsenic in pakchio cabbage, but also the arsenic concerntration and enrichment capacity of overground and underground part of pakchio cabbage were dropped dramatically when adding ferrihydrite, gibbsite and Mg/Al layered double oxides; In addition, the application of four amendments inhibited the transport of arsenic form underground part to the overground part in pakchio cabbage at the same time, it dropped greatest when adding ferrihydrite, and the range was34.03%-69.44%; Compared with four different adding proportion, the availability of the arsenic to crops showed the largest decline under the addition level of1.0%by adding ferrihydrite, goethite and Mg/Al layered double oxides, while0.25%or0.5%was proved to be the best addition level for gibbsite.3. The pakchoi cabbage showed a greater enrichment capacity of arsenic than maize, so pakchoi cabbage is more suitable than maize for planting in the soils with high arsenic concentration. The arsenic concentrations in the overground part (edible part) of the pakchoi cabbage were reached up to0.80mg·kg-1when grown in soils with190mg·kg-1of total arsenic concentration, which substantially exceeded the limited value of national food safety standards (0.5mg·kg-1), however, the grains of maize harvested from the same soils were safely edible; With the increasing concentration of total arsenic in soils, the arsenic concentrations in different organs and the enrichment of arsenic in plants both showed a corresponding growth, but they were presented different correlation. Arsenic concentrations in the overground part of pakchoi cabbage were significantly lower than that in the root, and the distribution trends of arsenic in mature maize was:root> leaf> straw> grain.4. The addition of different levels of N、P、K、Ca、Mg、Fe and Mn inhibited the transportation of arsenic upto the overground part from the underground part; Futher more, the addition of N、P、K、Ca、Mg and Fe was able to reduce the arsenic content in the grain of maize, the enrichment amount of arsenic in mazie, and inhibited the transportation of arsenic upto the grain from the root;The addition level of N1536mg·kg-1、P355mg·kg-1、K1071mg·kg-1、Ca549mg·kg-1, Mg220mg·kg-1and Fe25.60mg·kg-1showed a better results in reducing the absorption capacity; Arsenic with N、P、K、Ca and Fe existed a dual effect, it was closely related with the addition amount of the nutrients.更多还原