苏南村镇河道疏浚底泥农用对水稻生长、产量及品质的影响

Effects of Agricultural Use of Dredged Sediment from Rural Rivers on Rice Growth, Yield and Quality in Southern Jiangsu Province

随着人们对农村环境污染的重视以及农村河道底泥疏浚工程的不断增加,疏浚底泥的处置也成为一个日益严峻的问题。本研究以江苏省常熟市辛庄镇河道疏浚底泥为研究对象,通过盆栽试验研究了4种底泥农用对水稻生长、产量及品质的影响。结果表明,底泥种植的水稻株高、穗数、生物量和籽粒产量均低于普通土壤,水稻生物量、产量与底泥碱解氮含量呈显著正相关(0.585*、0.556*),与底泥可溶性盐含量呈极显著负相关(–0.914**、–0.897**),与底泥Eh呈极显著正相关(0.887**、0.857**)。通径分析表明,底泥可溶性盐和Eh是影响水稻生长和产量的主要限制因子。稻米重金属平均富集因子顺序为Zn(0.23)>Cu(0.09)=Cd(0.09)>Cr(0.005)>Ni(0.0025)>Pb(0.0017),逐步回归分析表明稻米重金属的积累与土壤有效态重金属、pH和有机质有关。稻米单一重金属目标风险系数值均小于1,其顺序为:Cu>Zn>Cd>Pb>Ni>Cr,而稻米重金属复合目标风险系数值大于1,表明食用该类底泥栽种的稻米可能存在潜在健康风险,并且成人食用稻米的重金属复合目标风险系数值高于儿童。

With widespread attention to rural environmental pollution and the increase of rural river sediment dredging project, the disposal of dredged sediment has become an increasingly serious problem. Pot experiment in greenhouse was carried out and multivariate statistical analysis was used to explore the effects of agricultural useof dredged sediment from rural river on rice growing, yield and quality. The results indicated that the height, spike numbers, biomassand grain yield of rice growing in sediments were lower than those growing in soil. Significant positive correlations were obtained between alkali-hydrolyzable nitrogen and plant biomass （0.585＊）, and alkali-hydrolyzable nitrogen and grain production （0.556＊）. In addition, both biomass and grain yield of rice showed extremely significant negative correlation with soluble salts （-0.914＊＊ and -0.897＊＊ respectively） and extremely significantly positive correlation with Eh （0.887＊＊ and 0.857＊＊ respectively）. Path analysis showed that soluble salts and Eh were the key limiting factors in sediment agricultural use. The bioconcentration factors of heavy metals in rice followed the order of Zn（0.23） 〉 Cu（0.09）=Cd（0.09） 〉 Cr（0.005） 〉 Ni（0.002 5） 〉 Pb（0.001 7）. Stepwise regression analysis showed that the accumulations of heavy metals in rice were related to soil available heavy metals, pH and organic matter. The target hazard quotient （THQ） value of the single heavy metal was lower than 1 and the order was Cu 〉 Zn 〉 Cd 〉 Pb 〉 Ni 〉 Cr. However, the total target hazard quotient （TTHQ） value of heavy metals was higher than 1 and the TTHQ value through consumption of rice for adults was higher than that for children. This indicated that adultsand children may experience adverse health effects and the risk of non-carcinogenic effects foradults is slightly higher than that for children.