Suppressive effect of soil application of carbonaceous adsorbents on dieldrin uptake by cucumber fruits

Abstract

The use of aldrin and dieldrin as pesticides was prohibited in 1975 in Japan. However, some of the soils still remain contaminated with dieldrin, because aldrin is easily oxidized to dieldrin and dieldrin is extremely stable in soil. In recent years, dieldrin at concentrations exceeding the limit set by the Food Sanitation Law of Japan (dieldrin < 0.02 mg kg -1 fresh weight) has been detected in cucumber fruits produced in some areas of Japan. We examined the effect of the soil application of selected adsorbents on reducing dieldrin concentrations in cucumber fruits in three steps of pot experiments. Among the three types of biochar made from wood chip, rice husk, and bamboo, wood chip charcoal was found to be the most effective (pot experiment 1). The effect of wood chip charcoal was enhanced by high-temperature burning and crushing (pot experiment 2). However, the effect of activated carbon was superior to that of optimized (hightemperature-treated and crushed) wood chip charcoal (pot experiment 3). Therefore, activated carbon was selected as the most effective adsorbent. The effect of activated carbon to reduce dieldrin concentrations in cucumber fruits was confirmed in a field experiment, and the effect continued to a certain extent for at least four years after the application. We calculated the cost of activated carbon necessary to maintain a sufficient suppressive effect in the field, and this cost would appear to be acceptable to cucumber farmers. Consequently, application of activated carbon to dieldrin-contaminated soils can be considered a promising practical technique for reducing dieldrin concentrations in cucumber fruits.

Assessment of an NDL-PCBs Sequestration Strategy in Soil Using Contrasted Carbonaceous Materials through In Vitro and Cucurbita pepo Assays

“…For AC materials, AC2 and AC3 were the most effective in reducing PCB concentrations given their larger specific surface area and mesoporous surface, while AC1 was less effective due to its granular shape. This result confirms that surface properties and textural characteristics impact the sorption properties of carbonaceous materials in contaminated soils [11,12,14,26,27]. Regarding the type of pollutants, no difference could be shown in terms of sequestration efficiency by the different carbonaceous materials probably because the physicochemical properties related to adsorption in soil such as lipophilicity are of the same order (about log Kow of 7).…”

A review of measured bioaccumulation data on terrestrial plants for organic chemicals: Metrics, variability, and the need for standardized measurement protocols

“…For example, partitioning into the roots is a function of root lipid content in addition to the hydrophobicity of the chemical [31]. Another example of species differences is the enhanced ability of "gold rush" zucchini (Cucurbita pepo, subspecies pepo) to transfer hydrophobic organics from roots to aboveground tissues, relative to other plants [32][33][34][35]. This enhanced root to shoot transfer is thought to be partly attributable to interactions with various proteins that increase the solubility of these compounds in the xylem sap [36,37].…”

Relationship between plant uptake of pesticides and water-extractable residue in Japanese soils

“…Recent studies of crops contaminated by persistent organic pollutants (POPs), including dieldrin and heptachlor exo-epoxide, showed that application of carbonaceous adsorbents, such as activated carbon, to soils [4][5][6] and a grafting technique using a low-uptake rootstock 4,7) effectively decreased concentrations of POPs in cucurbit crops. However, the pesticides on the market are more degradable than POPs in soils.…”