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61.
呋喃丹和阿特拉津在土柱中的淋溶及其影响因素 总被引:5,自引:0,他引:5
通过室内柱淋溶试验研究呋喃丹与阿特拉津在河南潮土及2种太湖水稻土中的淋溶作用及其影响因素。结果表明:2种农药在河南潮土中的淋溶作用比在太湖水稻土中弱。在表土中添加2 mg农药、模拟1次降水200mm条件下,呋喃丹最大淋溶量峰值可达25—30 cm深处,阿特拉津最大淋溶量峰值可达15—20 cm。表明呋喃丹、阿特拉津2种农药在供试土柱中均表现出较强淋溶特性。土壤和农药性质对淋溶作用均有很大影响。土壤有机质和粘粒含量越高,对农药的吸附性越强,土壤中农药越不容易随水下移;土壤大孔隙越多,农药在土壤中淋溶作用也越强,且相邻大孔隙对农药淋溶存在协同作用。土柱中插入4根直形多孔玻璃管后,土壤淋出液中农药量比插入2根的高2.7倍,比不插玻璃管对照高10倍。土柱中插入扭曲(60°)形玻璃管与插入直形玻璃管相比,农药在土壤中持留性增强,淋溶作用减弱。同一土柱中农药水溶性越大,淋溶作用也越强。 相似文献
62.
X.J. Xie W. Ran Q.R. Shen C.Y. Yang J.J. Yang Z.H. Cao 《Environmental geochemistry and health》2004,26(2):237-243
Field experiments were done in two sites, Yixing and Changshu, Jiangsu province, China, to study P movement and leaching in flooded paddy soils. P movement in soil was investigated by using the KH2
32PO4 tracker method, and the amount of P leached from the soil layer in different depths was estimated by measuring P concentrations in the soil solution and saturated hydraulic conductivities in field. Determination was done about one month after P application. There was 46% and 42% of total 32P retained in the 0–5cm layer of soil in the Yixing site and in the Changshu site respectively. The 32P retained in the 25–30 cm layer was only about 1–2% of the total 32P added. Furthermore, 8.01% of 32P in the soil of Yixing site and 16.8% of 32P in the soil of Changshu site was lost from the layer 0–30cm soil. The seasonal amounts of P leached from the top soil layer and from bottom layer are about 4.5–5.8% and 1.6–2.1% of the total P application, respectively. Changes of total P concentrations in soil solutions during rice growth showed that the fertilizer P applied before flooding of the paddy fields suffered a flash leaching loss and a slow leaching loss. We concluded that the fertilizer P could quickly move in the flooded paddy rice field and parts of it can enter into surface water and ground water. Unless the P application is well managed the risk of P loss and consequently environmental pollution exist. 相似文献
63.
64.
模拟酸雨对土柱中稀土元素迁移的影响 总被引:4,自引:0,他引:4
模拟研究酸雨对土柱中稀土元素迁移的影响.结果表明,在雨水、酸雨淋溶下,对照组红壤土柱中所含稀土元素有向下迁移的趋势,并且随淋溶液pH值的降低,稀土元素向下迁移的能力增加.外源稀土迁移量的大小顺序为;Ce>La>Nd>Pr,其顺序与各稀土元素在稀土微肥中含量大小的顺序相同.表明外源稀土的迁移性与外源稀土的总量密切相关.外源稀土在土柱中的含量随着红壤深度的增加而减少,稀土元素主要在土柱中第一、二层持留;随着淋溶液酸度的下降,稀土元素向下迁移的能力增加. 相似文献
65.
This study delineated the mathematical forms for the reactions involved in the mass balance of As in cropland soils. Even
mathematically simplified, many model parameters are required to define the reactive processes involved. Example simulations
were conducted based on the range of parameter values and initial conditions derived from published literature. The outcomes
showed that the As inputs due to fertilizers and irrigation water caused total As content of the root zone to gradually increase
over time. The plant uptake and leaching were equally important as pathways for removal of the added As. In turn, the dissolution
kinetics of the mineral phase and the distribution coefficient of the adsorbed phase affected the availability of the As for
plant uptake and leaching. Parameters based on laboratory-derived data on the dissolution of As mineral phase, mineralization
and oxidation of As(III), and the As plant uptake however appeared to overestimate the As transformations in soils. While
the development of mathematical model was a straightforward process, its application to realistic situations was hindered
by difficulties of defining model parameter values with confidence. Current knowledge on the processes and reactions of As
transformation in the soil–plant system is inadequate to calibrate or validate the model. Studies are needed to understand
the kinetics of soil As mineral dissolution and precipitation and the dynamics of root growth and As uptake by plant in soils. 相似文献
66.
应用HYDRUS-1D模型模拟农田土壤水渗漏及硝态氮淋失特征 总被引:1,自引:0,他引:1
在定位试验基础上,应用HYDRUS-1D模型对黄淮海平原典型土壤(黄潮土)中土壤水渗漏及硝态氮淋失动态进行了模拟分析。结果表明:在传统水氮管理模式下,黄潮土2m土体深处的土壤水渗漏和硝态氮淋失非常严重,2个轮作期内,土壤水渗漏总量占地表总入水量的23.7%,硝态氮淋失总量占总输入N量的15.9%,冬小麦生长季的硝态氮淋失量大于夏玉米生长季;改良灌溉和改良施肥模式下产生的硝态氮淋失量比传统灌溉和传统施肥模式减少74.7%,节约灌溉水211.5mm、节省施N423.5kg·hm-2。 相似文献
67.
主要原材料为高炉矿渣的碱矿渣胶凝材料(HAS)、掺3%沸石的HAS、掺5%沸石的HAS、水泥等4种固化材料被用来固化人工合成含铅、镉、铬等重金属的污泥。污泥固化体中污泥与固化材的掺和比例为4:1。实验结果表明,HAS固化剂对重金属污泥的固化效果要好于水泥,其污泥固化体的无侧限抗压强度高于水泥固化体,同时其固化体的重金属浸出量明显低于水泥。沸石的掺入使HAS固化体的重金属浸出量减小,且随着沸石掺加量的增大,HAS固化体的重金属浸出量相应的减少。 相似文献
68.
69.
利用模拟淋溶实验测定了中国几种土壤(砖红壤,赤红壤,红壤,黄棕壤和紫色土)的风化速率,并研究了土壤pH值和降水量对土壤风化速度的影响,结果表明,土壤的风化速度在pH≥4时随pH值的下降而显著增加,但是当pH值低于4时,风化速率却急剧下降,造成这种现象的原因可能是在低pH值时盐基阳离子和铝离子大量溶出,过高的产物浓度限制了风化反应的进行。土壤的风化速度与淋溶速率之间近似成线性关系。用淋溶液pH值和淋溶液量两个因素对实验结果进行了校正。 相似文献
70.