Dissipation and sorption of six commonly used pesticides in two contrasting soils of New Zealand

Abstract

We investigated dissipation and sorption of atrazine, terbuthylazine, bromacil, diazinon, hexazinone and procymidone in two contrasting New Zealand soils (0-10 cm and 40-50 cm) under controlled laboratory conditions. The six pesticides showed marked differences in their degradation rates in both top-and subsoils, and the estimated DT 50 values for the compounds were: 19-120 (atrazine), 10-36 (terbuthylazine), 12-46 (bromacil), 7-25 (diazinon), 8-92 (hexazinone) and 13-60 days for procymidone. Diazinon had the lowest range for DT 50 values, while bromacil and hexazinone gave the highest DT 50 values under any given condition on any soil type. Batch derived effective distribution coefficient (K eff d ) values for the pesticides varied markedly with bromacil and hexazinone exhibiting low sorption affinity for the soils at either depth, while diazinon gave high sorption values. Comparison of pesticide degradation in sterile and non-sterile soils suggests that microbial degradation was the major dissipation pathway for all six compounds, although little influence of abiotic degradation was noticeable for diazinon and procymidone.

Relative persistence of commonly used forestry herbicides for preventing the establishment of broom (Cytisus scoparius) seedlings in New Zealand plantations

“…20 days apart. Sarmah et al (2009) determined that the half-life for hexazinone was either 8 or 45 days at 20°C for two New Zealand silt loam soils, which is consistent with our result given the temperatures over December and January. They also found the half-life in these two soils increased to 36 or 96 days respectively at 7.5°C.…”

“…Estimates of half-life for hexazinone determined here are broadly consistent with previous published research (Sarmah et al 2009). The differences in persistence between the two rates of herbicide (7.5 kg ai ha −1 and 3.75 kg ai ha −1 ) used in the current trial provide an approximate indication of the half-life of herbicides with one half-life being the time taken for 7.5 kg to reduce to 3.75 kg within the soil.…”

“…For example, hexazinone was found to be more persistent under cold and dry conditions than under warm and wet conditions and was more mobile in a sandy loam soil than in a silt loam soil (Rahman 1981). These results are in agreement with other studies in North America (Rhodes 1980;Feng 1987;Roy et al 1989) and New Zealand (Close et al 2008;Sarmah et al 2009). Coackley and Moore (1977) assessed the persistence of hexazinone in various radiata pine plantations under different climatic conditions throughout New Zealand and suggested that the optimum time of application was September (early spring) compared with other times assessed due to less rainfall after this time and thus less loss from leaching.…”

Antibiotics and Antibiotic Resistance Genes in Bulk and Rhizosphere Soils Subject to Manure Amendment and Vegetable Cultivation

“…Alteration of these specific factors has been observed to affect the rate of biodegradation of other organic compounds in soil (Thiele‐Bruhn, 2003). Microbial biodegradation is usually accepted as the primary mechanism of organic compound dissipation (Prado et al, 2009; Sarmah et al, 2009; Oliveira et al, 2016), whereas bacteria capable of using antibiotics as a sole C source have been identified (Dantas et al, 2008). Biodegradation of antibiotics in the soil environment mainly occurs in the aqueous phase (Thiele‐Bruhn, 2003), and the relative migration potential of antibiotics can be estimated from their partition coefficients between solid and liquid phase ( K d ).…”

Evaluation of two pesticide leaching models in an irrigated field cropped with corn

“…Sarmah et al (2009) reported that half-lives of atrazine at the topsoil and the subsoil of a silt loam soil were 18 days and 47 days, respectively. using the PEARL model, tried to simulate the movement of water, and the transport of bentazone and imidacloprid in a cracked clay soil.…”