Abiotic behaviour of organic micropollutants in soils and the aquatic environment. A review: I. Partitioning

Citation
Sj. Stangroom et al., Abiotic behaviour of organic micropollutants in soils and the aquatic environment. A review: I. Partitioning, ENV TECHNOL, 21(8), 2000, pp. 845-863
Citations number
140
Categorie Soggetti
Environment/Ecology
Journal title
ENVIRONMENTAL TECHNOLOGY
ISSN journal
09593330 → ACNP
Volume
21
Issue
8
Year of publication
2000
Pages
845 - 863
Database
ISI
SICI code
0959-3330(200008)21:8<845:ABOOMI>2.0.ZU;2-0
Abstract
Recent research has confirmed the significance of organic carbon (OC) as th e key sorbent for hydrophobic organic chemicals (HOC), as well as for many polar compounds. However, the triazine herbicides exhibit a variable affini ty for soil organic matter (SOM) which is attributed to the extent of humif ication of the organic fraction. Charge transfer mechanisms are important f or triazine sorption to OC and either proton or electron transfer may accou nt for the reaction mechanism with humic acids. For many uron herbicides (e .g, chlorotoluron, metabromuron chloroxuron, defenoxuron), sorption correla tes with SOM. However, specific interactions between uron herbicides and a limited quantity of active constituents within SOM have also been proposed to explain deviations from sorption linearity at low herbicide relative con centration. Other studies indicate that isoproturon sorbs to organic colloi ds in solution and that a sorption threshold to SOM may be operative. Below the threshold, isoproturon appears to sorb predominantly to clays, indicat ing the presence of a limited number of 'active' sorptive sites within clay minerals. Research suggests that pesticide interactions with clay minerals may be influenced by near-surface day geometry; the accessibility of the s orbing region of the sorbate to the active site of the clay; the identity o f exchangeable cations on the clay and solution electrolytes. These recent studies indicate that interactions between micropollutants and soils and se diments often need to be evaluated on a compound-specific basis. This is es pecially the case for polar compounds which may partition to these environm ental phases by diverse mechanisms.