DOM 絮凝聚合：一种分离游离态和 DOM 束缚态除草剂的合适方法？

DOM-Flocculation: A suitable approach for separating free and DOM-bound herbicides?

机构信息

Institute of Soil Science (310), Department of Soil Chemistry, University of Hohenheim, D-70593, Stuttgart, Germany.

出版信息

Environ Sci Pollut Res Int. 1999;6(2):77-82. doi: 10.1007/BF02987552.

PMID:19009407

Abstract

Dissolved organic matter (DOM) in soil solution is considered to interact with herbicides enhancing their mobility and promoting subsequent leaching.Batch experiments were conducted to test if free and DOM-bound herbicides can be separated by a DOM-flocculation technique with Cu as a coagulant.DOM was extracted from the H and A horizons of two soils (Terric Histosol, Cumuli-Calcaric Cambisol) and from the O horizon of a forest soil (Humic Cambisol). DOM-solutions (100 mL) were fortified with the herbicides terbuthylazine and pendimethalin (100 microg active ingredient each) and equilibrated for 14 hours. After DOM-flocculation with Cu (addition of 0.5 mM CuCl(2)) herbicide recovery was determined in the supernatant solutions and in the precipitate of Humic Cambisol-DOM, respectively.Recovery of the herbicides from pure water was 85-99% and was not influenced by the addition of Cu. At low pH (4.8-5.3) DOM-flocculation of different DOM-extracts was insufficient and varied in a range of 18 - 90%. Herbicide recovery from DOM-solutions decreased moderately for terbuthylazine (60-90%) and strongly for pendimethalin (5 - 30%). In general, the addition of Cu caused no further reduction of herbicide recovery from supernatant solutions, except for Humic Cambisol-DOM. The effects of Cu-addition were most evident for pendimethalin (strongly reduced concentration in the supernatant solutions) and were considered to be caused by a flocculation of DOM-bound moieties. Flocculation of Humic Cambisol-DOM increased from 18 - 24% at pH 5 to > 95% at pH 8. However, at this pH the formation of Cu(OH)(2) as a sorbing subcomponent of the flocculated matter lead to an overestimation of DOM-bound pendimethalin. Calculating this side effect 6% of pendimethalin added was DOM-bound. Only traces of terbuthylazine (< 1%) were found in the solid matter of flocculated Humic Cambisol-DOM.To sum up, the new approach to separate freely dissolved herbicides from DOM-bound moieties not fully corresponded to our expectations. DOM-flocculation was found to depend strongly on pH-environment influencing not only DOM-herbicide interactions but also the clear separation of DOM-bound herbicides from herbicides in solutions.

摘要

土壤溶液中的溶解有机物质（DOM）被认为与除草剂相互作用，增强其流动性并促进随后的淋溶。进行了批量实验以测试是否可以使用 Cu 作为凝结剂的 DOM 絮凝技术分离游离和 DOM 结合的除草剂。从两种土壤的 H 和 A 层（Terric Histosol，Cumuli-Calcaric Cambisol）和森林土壤的 O 层（Humic Cambisol）中提取了 DOM。DOM 溶液（100 mL）中添加了莠去津和二甲戊灵（各 100 微克有效成分），并平衡 14 小时。在用 Cu（添加 0.5 mM CuCl(2)）进行 DOM 絮凝后，分别测定上清液和 Humic Cambisol-DOM 沉淀物中的除草剂回收率。从纯水中回收的除草剂为 85-99%，不受 Cu 添加的影响。在低 pH（4.8-5.3）下，不同 DOM 提取物的 DOM 絮凝不足，范围为 18-90%。莠去津（60-90%）和二甲戊灵（5-30%）的 DOM 溶液中除草剂回收率适度降低。一般来说，除了 Humic Cambisol-DOM 之外，添加 Cu 不会进一步降低上清液中除草剂的回收率。Cu 添加的影响对二甲戊灵最为明显（上清液中浓度强烈降低），并被认为是由于 DOM 结合部分的絮凝引起的。Humic Cambisol-DOM 的絮凝从 pH 5 时的 18-24%增加到 pH 8 时的>95%。然而，在此 pH 下，Cu(OH)(2)作为絮凝物质的吸附亚组分的形成导致对絮凝的 DOM 结合的二甲戊灵的过度估计。计算这种副作用，添加的 6%二甲戊灵与 DOM 结合。仅在絮凝的 Humic Cambisol-DOM 的固体物质中发现莠去津的痕量（<1%）。总之，从游离的 DOM 结合部分分离游离除草剂的新方法并没有完全符合我们的预期。发现 DOM 絮凝强烈依赖于 pH 环境，不仅影响 DOM-除草剂相互作用，而且还影响从溶液中分离 DOM 结合的除草剂。