The goal is to focus on the quantitative evaluation and analysis of the relationship between sorption and broader soil properties, the coupling effect of sorption on degradation, and potential molecular structure-activity relationships that differentiate environmental fate behavior. The completed review and analysis may offer a set of quantitative tools through calibration and customization of available data (e.g. from Europe and North America) for data deficient regions lacking pesticide fate studies (e.g. tropical soils and scientifically emerging regions). Results will also directly benefit refinement of pesticide assessment models in general.
Pesticide sorption and degradation (either through chemical or biological pathways) in soil are two critical and extensively studied processes for assessing its environmental mobility and persistence. Several publically available databases (e.g., FOOTPRINT) have accumulated a significant amount of sorption and degradation data from published literature. Majority of the data in these databases, however, originated from studies in Europe and North America, thus may not represent many scientifically emerging regions in Africa, Asia and South America. In these regions, little local data on pesticide sorption and degradation are available and environmental fate assessments have to often rely on databases which are drawn largely from very different soil and environmental conditions. Obviously such data extrapolation requires careful quantitative analysis of sorption and degradation in relationship with environmental factors (soil and climate conditions).
Increasing evidence has shown that the environmental fate processes are coupled and may simultaneously depend on environmental conditions. Sorption in soil is a microscopically heterogeneous and time-dependent process1,2 which may not only depend on the content but also the chemistry of soil organic matter and mineralogy3,4,5. The heterogeneity in both soil composition and micro-surface reactivity may further affect degradation, especially bio-degradation which relies on microbial population that are highly localized in the unsaturated soil pore space with limited mobility6,7,8. It is expected that these effects varies among different classes of pesticide chemistry, soil types and climatic zones.
The goal of this proposal is to focus on the quantitative review and analysis of the coupling relationships among sorption, degradation, molecular structure-activity, and environmental factors. The completed review and analysis may offer a set of quantitative tools for estimating sorption and degradation based on local environmental conditions and pesticide structural activity. Results from these analyses are expected to help address data deficiency problems in regions of limited pesticide studies. It will also directly benefit refinement of pesticide assessment models in general.
The project will take the advantage of the IUPAC worldwide expertise to assemble and assimilate diverse data from published literature around the globe. The project team may be organized in three subgroups, each responsible for a core objective:
- Sorption calibration with broader soil properties (led by Dr. Kookana).
- Coupling relationship between sorption and degradation and the effect of soil and climate factors (led by Dr. Chen).
- Quantitative structure-activity relationship (QSAR) (led by Dr. Nakagawa).
The project working procedures are outlined below.
- Data collection. A consistent Excel format will be designed and used with specified fields for reference sources and review remarks. A set of standards for data qualification will be proposed.
- Data evaluation. Each data set will be examined for completeness of reporting parameters, and categorized into groups. Computational methods to remove confounding effects may be proposed and used.
- Relationship quantification. Various statistical modeling approaches will be explored.
- Report and manuscript preparation.
Successful completion of this project may set direction for future projects focusing on model sensitivity analysis and relational database development.
(1) W. Chen, R.J. Wagenet. Environ. Sci. Technol., 29 (1995): 2725-2734.
(2) W. Chen, R.J. Wagenet. Soil Sci. Soc. Am. J. 61 (1997): 360-371.
(3) R.D. Wauchope et al. Pest Manag. Sci. 58 (2002): 419-445.
(4) R.S. Kookana, L.J. Janik, and S.T. Forrester. J. Agric. Food Chem. 56 (2008): 3208-3213
(5) M. Forouzangohar, R.S. Kookana, S. T. Forrester, R Smernik and D Chittleborough. Environ. Sci. Technol., 42 (2008): 2725-2734.
(6) K. Scow. SSSA Special Publication # 32 (1993): 73-114.
(7) A. Katayama et al. Rev. Environ. Contam. Toxicol. 203 (2010): 1-86.
(8) D. Or. AGU Hydrology Secetion News Letter (2010): 14-17.
March 2011 – project announcement published in Chem. Int. Mar-Apr, p. 23
May 2014 update – Six chapters have been drafted and are in current peer-review stage for publication in an ACS-sponsored Book Series tentatively titled “Non-First Order Degradation and Time-Dependent Sorption of Organic Chemicals in Soil”. Written chapters covered contents of coupled sorption and degradation kinetics, chemometrics approach for estimating sorption, QSARs of sorption and biodegradation, relation of field degradation with soil, climatic, and geographic factors, and sorption spatial variability. A poster presentation is being prepared for the 2014 IUPAC San Francisco conference <www.iupac2014.org>.
April 2016 update – The project has generated an ACS Symposium Series Book in 2014, “Non-First Order Degradation and Time-Dependent Sorption of Organic Chemicals in Soil” (https://pubs.acs.org/isbn/9780841229785).
Page last updated 15 Jan 2018