磷肥对土壤中镉的植物有效性影响及其机理

为寻求保障镉污染农田稻米质量安全的有效措施，采用盆栽方法研究了低镉磷肥(Cd＜0.2 mg·kg^-1)及不同施磷量(0.10、0.20 g P₂O₅·kg^-1)对污染稻田土壤中(潮泥田)镉的植物有效性影响，并探讨了相关机理.结果表明： 在0.10 g·kg^-1磷剂量水平下，与对照(无磷肥)相比，钙镁磷和磷酸二氢钾处理显著提高了土壤pH和降低了土壤镉活性，钙镁磷和过磷酸钙处理显著降低了水稻对镉的吸收累积；当施磷量增至0.20 g·kg^-1时，磷酸氢钙处理显著提高了土壤pH和降低了土壤镉活性，钙镁磷、磷酸二氢钾和磷酸氢钙处理下DTPA提取态镉含量降低11.8%、9.8%和11.8%，NH₄OAc提取态镉含量降低9.5%、7.1%和7.1%；5种磷肥处理均显著降低了水稻茎叶中镉含量(降幅24.9%～50.8%)，除磷酸氢钙处理外，糙米镉含量的降幅均达到显著水平，钙镁磷和过磷酸钙处理下糙米镉含量接近国家粮食卫生标准(GB 2715-2005).5种供试磷肥中，能提高土壤pH的磷肥(钙镁磷、磷酸二氢钾和磷酸氢钙)降低土壤镉有效性的效果显著，含钙磷肥(钙镁磷和过磷酸钙)降低水稻镉积累的效果较好.磷肥化学性质的差异可能是影响其效果的主要原因，选择碱性含钙磷肥对控制污染农田中作物吸收累积镉更有效.

Research advances in eco-environment assessment using dragonfly as a bioindicator

Dragonfly,due to its wide distribution,in-depth research and easy to sample,is an ideal bioindicator for eco-environment assessment.In recent decades,more and more related researches are using dragonfly to assess eco-environment.In this review,the related researches were generalized into five types,i.e.,general environmental assessment,environment pollution degree assessment,environmental improvement assessment,climate change assessment,and large-scale environmental assessment,and a brief introduction for each type of the researches was given.The current status and deficiency of the researches in China were discussed,and the broad prospects of using dragonfly as a bioindicator for eco-environment assessment were analyzed through the comparison of the superiority of this bioindicator than the others.It was point out that to build up a thoroughly sourced database of dragonfly diversity in China and to develop specific assessment methods could be the most important things to make progress.Using dragonfly as a bioindicator to assess ecological environment would be low-cost,high-efficient,and environmentally friendly,not only important but also necessary to the needs of China today’s economic development.