Behavior of chlorpyrifos and its major metabolite TCP (3,5,6-trichloro-2-pyridinol) in agricultural soils amended with drinking water treatment residuals

Purpose: Chlorpyrifos can be effectively adsorbed by drinking water treatment residuals (WTR), ubiquitous and non-hazardous by-products of potable water production. The major metabolite 3,5,6-trichloro-2-pyridinol (TCP) was found to be much more mobile and toxic than its parent chlorpyrifos. To assess the feasibility of WTR amendment for attenuation of chlorpyrifos and TCP pollution, the sorption/desorption and degradation behavior of chlorpyrifos and TCP in WTR-amended agricultural soils was examined in the present study. Materials and methods: Two representative agricultural soils were sampled from southern and northern China, respectively. The soils were amended with WTR at the rates of 0, 2, 5, and 10 % (w/w). Batch sorption/desorption test were applied to investigate the sorption/desorption characteristics of chlorpyrifos and TCP in WTR-amended soils. The influence of WTR amendment on chlorpyrifos degradation and TCP formation was evaluated using the incubation test, and its effect on the soil bacterial abundance was further studied through DNA extraction and PCR amplification. Results and discussion: Results showed that WTR amendment (0–10 %, w/w) significantly enhanced the retention capacity of chlorpyrifos and TCP in both soils examined (P &lt; 0.05). Fractionation analyses further demonstrated that the bioavailability of chlorpyrifos was considerably reduced by WTR amendment, resulting in a decreased chlorpyrifos degradation rate. The WTR amendment also significantly reduced the mobility of TCP formed in chlorpyrifos-contaminated soils (P &lt; 0.001). The chlorpyrifos toxicity to soil bacteria community was largely mitigated following WTR amendment, resulting in increased total bacterial abundance. Conclusions: Results obtained in the present study indicate a great deal of potential for the beneficial reuse of WTR as soil amendments for chlorpyrifos and TCP pollution control.</p

Swimming speed alteration of larvae of Balanus amphitrite as a behavioural end-point for laboratory toxicological bioassays

n this study, we investigate the feasibility of developing a new behavioural toxicity bioassay (Swimming Speed Alteration test-SSA test) with larvae of Balanus amphitrite (Crustacea Cirripedia). This organism was chosen as a model for different reasons: it is present all over the world, simple to be reared, easily available, and also because barnacles play an important role in the coastal ecosystem. In addition, all the operations related to the rearing and test execution are comparatively cheap. This bioassay was performed with several classes of chemical pollutants (antifouling biocides, neurotoxic pesticides, and heavy metals) and with environmental samples (sediment elutriates). The measurement of swimming speed, by means of video-graphic techniques, proved to be a valid instrument in highlighting the sub-lethal levels of toxicity caused by the different tested samples. In conclusion, the SSA test is able to provide in a biomonitoring program a good behavioural integrated output, which is also repeatable, sensitive, easily interpretable, and truly representative of a broad range of toxic compounds and environmental toxic matrices which are, generally, very complex and difficult to analyse. For all of these reasons, it could be proposed as a non-specific behavioural end-point