水库疏浚底泥农用对芥菜生长和品质的影响

疏浚底泥重金属污染是限制底泥农用的主要因素。采用土培盆栽试验,研究了底泥与土壤按不同质量比混合,对芥菜生物量、重金属、硝酸盐、维生素C（Vc）、以及可溶性糖含量的影响;并研究了m（底泥）：m（土壤）=2：1时,施加20mg·kg-1的碳酸钙对土壤有效态重金属含量影响,以及对芥菜生物量和品质的影响。结果表明：加入水库底泥可以显著促进芥菜的生长,随着底泥加入比例的增加,芥菜地上部生物量表现出先上升后降低的趋势,以m（底泥）：m（土壤）=2：1芥菜地上部生物量最高,是对照的1.71倍。底泥处理均能显著地增加芥菜地上部重金属含量,其中以全底泥处理芥菜地上部鲜质量Zn、Cd质量分数最高,分别是53.3、0.595mg·kg-1,是食品卫生标准的2.67、2.98倍。施用底泥可以提高芥菜地上部Vc、降低其硝酸盐含量。在m（底泥）：m（土壤）=2：1的土壤上,施入20mg·kg-1的碳酸钙处理可以显著降低土壤有效态重金属质量分数,有效态Cu、Zn、Pb、Cd质量分数分别下降到对照的58.7%、75.4%、59.8%、44.0%,从而有效地降低了芥菜对重金属的吸收积累,施加碳酸钙处理后,芥菜地上部Cu、Zn、Pb、Cd分别下降66.1%、83.2%、70.5%、53.1%。施加碳酸钙处理不仅可以促进芥菜生长还可以提高芥菜品质,与对照相比施加20mg·kg-1的碳酸钙处理后,芥菜生物量、可溶性糖质量分数、Vc质量分数分别增加了3.2%、6.0%、27.5%,而地上部硝酸盐质量分数降低了24.4%。

The effects of dredged sediment land application on growth and quality of mustard

The heavy metal contamination in dredged sediment is the major limitation for its land use. Soil pot culture experiments were conducted to study the effects of different dosage sediment application on biomass, heavy metal, nitrate, vitamin C and water-soluble sugar contents in mustard. The experiments were also conduced to study the effects of 20 mg·kg-1 calcium carbonate application on bio-available heavy metal concentration in soil, biomass and quality of mustard grown on soil applied with sediment at the dosage of 2∶1 (sediment: soil). Results showed that sediment application promoted the growth of mustard, significantly. With the increasing of sediment dosage application, the fresh weight of mustard shoots increased firstly, then decreased when the sediment dosage was 2∶1 (sediment: soil). The treatments of sediment application at the dosage of 2∶1 was found with the highest fresh weight of mustard shoots that was as high as 1.71 times as that of the control. The sediment land use increased the heavy metal concentration in mustard shoots, significantly. When the dosage of sediment application was 1∶0 (sediment: soil), the Zn and Cd concentration in mustard shoots was 53.3 and 0.595 mg·kg-1 on the base of fresh weight respectively, that was about 1.67 and 1.98 times higher than that of the limit concentration in foods permitted by the Ministry of Public Health of China. With sediment application, the vitamin C in mustard shoots increased, while the nitrate contents decreased significantly. When 20 mg·kg-1 calcium carbonate added in the sediment applied soil (the proportion of the sediment to soil at the rate of 2∶1), the bio-available concentration of Cu, Zn, Pb and Cd in soil decreased to 58.7%, 75.4%, 59.8% and 44.0% of control and the content of Cu, Zn, Pb and Cd in mustard shoots dropped to 66.1%, 83.2%, 70.5% and 53.1% of control, respectively. The calcium carbonate application also improved the quality of mustard grown on sediment applied soil. Comparing with the control, the fresh weight, soluble sugar and vitamin C content in mustard shoots was increased by 3.2%, 6.0% and 27.5% respectively, while the nitrate content in mustard was decreased by 24.4% with 20 mg·kg-1calcium carbonate application.