阴离子淀粉对土壤养分离子的吸附作用

减少养分的损失是控制面源污染最有效和经济的方法。通过淋溶试验评价带负电荷的阴离子淀粉对土壤养分离子的吸附作用,寻找对土壤养分离子吸附效果好的淀粉种类。试验1设置5个处理:去离子水、硝酸钾,以及硝酸钾分别与黄原酸酯淀粉、磷酸酯淀粉和羧甲基淀粉等3种不同淀粉混合;试验2设置去离子水、黄原酸酯淀粉、黄原酸酯淀粉和氯化铵混合、氯化铵等4个处理。阴离子淀粉取代度是决定它们对阳离子吸附强度的主要因子,供试的3种阴离子淀粉对土壤中的阳离子吸附作用高低顺序:羧甲基淀粉＞ 磷酸酯淀粉＞ 黄原酸酯淀粉。以黄原酸酯淀粉为载体,用氯化铵溶液处理结果表明:黄原酸酯淀粉对土壤中的钠、钾、镁和钙等4种阳离子均有显著的吸附作用(P＜0.05);而用硝酸钾溶液处理时,黄原酸酯淀粉对土壤中的钠离子、铵离子和钾离子吸附效果较好,而对钙、镁等2种离子的吸附效果不明显,说明淀粉对阳离子的吸附效果与加入的营养液也有很大的关系。阴离子淀粉对阴离子养分没有吸附作用。试验推测,具有较高取代度的黄原酸酯淀粉可作为理想的吸附剂,没有潜在风险;在降水量较小的地区,较高取代度的磷酸酯淀粉也可以作为理想的吸附剂,因为没有铵离子淋失的风险。

Absorption efficiency of soil nutrients with anion starch

Nutrient loss reduction is the most effective and economical method to control non-point source pollution. To find modified starches with favorable absorption of nutrient ions from the soil，two absorbing experiments for a negative charge，anionic starch were conducted. In the first experiment，potassium nitrate solutions were supplied as the nutrient solution and the adsorption effect of three starches: carboxymethyl，phosphate ester，and xanthate，were evaluated. In the second experiment a solution of ammonium chloride was used as the nutrient solution and because of a high sodium ion content in the carboxymethyl starch，the xanthate anion starch was used as the adsorption material for simulation tests such as fertilization，natural drying，and leaching to determine the starch’s adsorption effect. Results showed that the tested anionic starches adsorbed nutrient ions well with carboxymethyl＞phosphate ester＞xanthate. The first experiment showed that when potassium nitrate was supplied as the nutrient solution，the xanthate anion starch had strong adsorption effects with sodium，potassium，calcium，and magnesium；however，in the second experiment when ammonium chloride was used as the nutrient solution there was favorable adsorption with sodium，potassium，and ammonium ions but not calcium and magnesium ions. Thus，although the kinds of nutrient solutions used to test the starches affected adsorption，a high degree of substitution was possible with xanthate starch being an ideal adsorbent without potential risk，and the phosphate ester starch could be an ideal adsorbent in semiarid regions without risk of ammonium ions leaching.［Ch，4 fig. 4 tab. 20 ref.］