Lu Jianhang, Wu Laosheng
Department of Environmental Sciences, Univ. of California, Riverside, CA 92521, USA.
J Environ Qual. 2003 Mar-Apr;32(2):674-80. doi: 10.2134/jeq2003.6740.
Knowledge of how polyacrylamide (PAM) penetrates and distributes in a soil profile after application in irrigation water is important for understanding PAM conditioning depth and evaluating its environmental effects. Little is known, however, about PAM distribution in soil because of the difficulty in quantifying PAM content in natural soils. By using a recently modified substrate-borne PAM quantification method, PAM distribution in columns of organic matter-removed soils was determined. Results showed that penetration of PAM into the soil was affected by salt level of irrigation water, soil texture, initial soil water content, water application method, and other factors. Polyacrylamide penetration depth was about one-eighth to one-half of the water penetration depth, with a particularly high PAM retention in the top few centimeters of the soil. Under different experimental conditions, the PAM retained in the top 0 to 2 cm of soil ranged from 16 to 95% of the total applied amount. More favorable solution-soil contact conditions, longer solution-soil contact time, and lower initial soil moisture caused much more PAM retention in the top few centimeters of the soil. High sorptive affinity of PAM on soil is the main reason for its low penetration into the soil. Although these results were not obtained from natural soils, they are still helpful in improving our understanding of PAM transport behavior in soils.
了解聚丙烯酰胺（PAM）在灌溉水中施用后如何在土壤剖面中渗透和分布，对于理解PAM的改良深度和评估其环境影响至关重要。然而，由于难以量化天然土壤中的PAM含量，人们对PAM在土壤中的分布知之甚少。通过使用最近改进的基于底物的PAM定量方法，确定了去除有机质的土壤柱中PAM的分布。结果表明，PAM在土壤中的渗透受灌溉水盐度、土壤质地、初始土壤含水量、灌水方式和其他因素的影响。聚丙烯酰胺的渗透深度约为水分渗透深度的八分之一至二分之一，在土壤顶部几厘米处PAM的截留率特别高。在不同的实验条件下，保留在土壤顶部0至2厘米处的PAM占总施用量的16%至95%。更有利的溶液与土壤接触条件、更长的溶液与土壤接触时间以及更低的初始土壤湿度，会使更多的PAM保留在土壤顶部几厘米处。PAM对土壤的高吸附亲和力是其在土壤中低渗透的主要原因。虽然这些结果并非来自天然土壤，但它们仍有助于增进我们对PAM在土壤中迁移行为的理解。
