Five typical land use soils, collected from the acid red soil zone of South China, were analyzed to explore Pb and Cu adsorption-desorption characteristics of the soils.The research results show that:①In terms of Pb or Cu adsorption capacity with initial maximum concentrations of Pb or Cu added(100 mg·L-1 solutions), a decreasing order was observed as paddy soil(2 254.35,1 254.63 mg·kg-1)>Chinese fir forest soil(2 237.33,732.81 mg·kg-1)>Pinus massoniana forest soil(2 010.66,581.94 mg·kg-1)>bamboo forest soil(1 730.47,470.56 mg·kg-1)>tea plantation soil(1 574.01,322.69 mg·kg-1).The order was same as the soil organic matter and CEC content.②Isothermal curves of Pb and Cu adsorption these five soils fit well to Langmuir and Freundlich equations(P<0.05).The adsorption intensity of Pb (1) ranked as follows: paddy soil(0.711 7)>Chinese fir forest soil(0.695 3)>Pinus massoniana forest soil(0.647 9)>bamboo forest soil(0.533 4)>tea plantation soil(0.462 5.The adsorption intensity of Cu (1) ranked as follows: paddy soil(1.061 7)>Pinus massoniana forest soil(0.839 6)>Chinese fir forest soil(0.537)>bamboo forest soil(0.517 7)>tea plantation soil(0.421 7).③The desorptive rates of Pb2+ was 4.85%(Pinus massoniana forest soil),2.72%(Pinus massoniana forest soil),6.07%(bamboo forest soil),5.47%(tea plantation soil),1.45%(paddy soil).The desorptive rates of Cu2+ was 27.31%(Pinus massoniana forest soil),25.95%(Pinus massoniana forest soil),35.09%(bamboo forest soil),52.82%(tea plantation soil),14.89%(s paddy soil).The desorptive rates of Cu2+was much higher than that of Pb2+.④The selective sequence of five soils to Pb and Cu adsorption was Pb>Cu in competitive adsorption.The competitive adsorption of Pb and Cu was observed as paddy soil>Chinese fir forest soil>Pinus massoniana forest soil>bamboo forest soil>tea plantation soil.The desorptive rates of Cu2+ in tea plantation soil was relative bigger, so the exogenous Cu was easily absorbed by tea tree to effect rock tea quality.The risk of Cu2+ to the regional water body was higher.%研究了南方酸性红壤5 种典型土地(马尾松、杉木、竹林、茶园、稻田)利用的土壤对Cu、Pb的吸附-解吸特性.结果表明,①在Pb2+、Cu2+最大初始浓度(100 mg·L-1)条件下,Pb、Cu的吸附量表现为稻田(2 254.35、1 254.63 mg·kg-1)﹥杉木林(2 237.33、732.81 mg·kg-1)﹥马尾松林(2 010.66、581.94 mg·kg-1)﹥竹林(1 730.47、470.56 mg·kg-1)﹥茶园(1 574.01、322.69 mg·kg-1),这与土壤中有机质和阳离子交换量(Cation exchange copaeifg,CEC)大小顺序一致.②Cu 和 Pb的吸附等温线用 Langmuir和Freundlich 方程拟合的相关性达到显著水平(P<0.05).土壤对 Pb 的吸附强度(1)表现为稻田(0.711 7)>杉木林(0.695 3)>马尾松林(0.647 9)>竹林(0.533 4)>茶园(0.462 5),对Cu的吸附强度(1)表现为稻田(1.061 7)>马尾松林(0.839 6)>杉木林(0.537)>竹林(0.517 7)>茶园(0.421 7).③在实验最大吸附量条件下,马尾松、杉木、竹林、茶园、稻田土壤Pb的解吸率分别为4.85%、2.72%、6.07%、5.47%、1.45%,Cu的解吸率分别为27.31%、25.95%、35.09%、52.82%、14.89%,Cu的解吸率远大于Pb的.④ 当Pb2+、Cu2共存时,Pb的竞争能力大于Cu的,不同土壤Pb和Cu的竞争作用表现为稻田﹥杉木林﹥马尾松林﹥竹林﹥茶园.茶园土壤Cu的解吸率较大,外源Cu易被茶树吸收,影响岩茶品质;且研究区内降雨量大且集中,Cu2+随径流向区域内水体流失的风险较大.
展开▼
