不同Cd污染特征稻田施用钝化剂对水稻吸收积累Cd的影响

Effect of passivator on Cd uptaking of rice in different Cd pollution characteristics paddy soils

选择长株潭地区典型化工点源污染、污水灌溉面源污染和大气沉降面源污染的镉(Cd)污染稻田,研究钝化剂施用对稻田土壤Cd形态、水稻Cd含量的影响。结果表明,不同Cd污染特征稻田施用石灰对水稻产量无显著影响,但能显著提高土壤pH,降低土壤有效态Cd含量和水稻稻米及茎叶Cd含量;而施用钝化剂不仅可显著提高土壤pH,降低土壤有效态Cd含量、水稻稻米与茎叶Cd含量,还可增加水稻产量。通过钝化剂用量与产量的二次拟合曲线计算可知,北山、梅林桥、大同桥三实验点最高理论产量分别为7 879、9 274和9 064 kg·hm^(-2),对应的钝化剂施用量分别为1 557、1 248和2 752kg·hm^(-2);而钝化剂用量与稻米Cd含量的二次拟合曲线计算可知,三实验点最低理论稻米Cd含量分别为0.143 8、0.063 7和0.232 4 mg·kg-1,对应的钝化剂施用量分别为2 079、1 823和1 689 kg·hm^(-2)。研究结果还表明,Cd污染源对钝化剂降低土壤Cd有效性无显著影响,但会影响水稻对Cd的吸收积累。大同桥点施用石灰和钝化剂皆可显著降低土壤有效态Cd含量,但受污水灌溉的影响,稻米Cd含量较高;化工点源污染的北山点土壤有效Cd含量虽高,因污染源已断,施用石灰和钝化剂皆能显著降低土壤Cd的有效性和稻米Cd含量;而受大气沉降污染的梅林桥点,土壤Cd含量虽高,但土壤Cd有效性较低,施用石灰和钝化剂皆可有效钝化土壤中的Cd,并显著降低稻米Cd含量。

A field experiment on the influence of a passivator on cadmium（ Cd） present in soil and rice was carried out on chemical point source pollution,sewage irrigation non-point source pollution,and atmospheric deposition non-point source pollution in typical Cd polluted paddy fields in the Chang-Zhu-Tan area of the Hunan province. The results showed that liming of Cd polluted paddy fields had no obvious effects on rice yields as compared with the controls,while the rice yields increased by applying a passivator. However,both liming and use of a passivator could increase the soil pH significantly and could decrease the available Cd content of the soil and the Cd content of rice grains and stems. The maximum theoretical yields at the Beishan,Meilinqiao,and Datongqiao sites were calculated to be 7 879,9 274,and 9 064 kg·hm^（-2）,respectively from the quadratic curve between rice yields and the amounts of passivator applied,while the corresponding passivator applications were1 557,1 248,and 2 752 kg·hm^（-2）,respectively. The minimum theoretical Cd content of rice was calculated tobe 0. 143 8,0. 063 7,and 0. 232 4 mg·kg^-1from the quadratic curve between the Cd content of rice and the amounts of passivator applied,which were 2 079,1 823,and 1 689 kg·hm^（-2）at the Beishan,Meilinqiao,and Datongqiao sites,respectively. The existing Cd pollution sources had no obvious effect on reducing the soil＇s Cd effectiveness by the passivator but would affect the absorption of Cd by rice. The available Cd content decreased significantly after liming and applying a passivator at the Dotongqiao site; however,the Cd content of rice was still high because of sewage irrigation. At the Beishan site,the available Cd in the soil and the rice Cd content all decreased significantly through liming and application of a passivator because of the removal of the Cd pollution sources even though the soil available Cd content was high. At the Meilinqiao site,polluted by atmospheric precipitation,the total Cd content was high and the Cd effectiveness was low,which could lower the available Cd content of the soil by liming and applying passivator and decreased the rice Cd contents significantly.