Mitigation of two insecticides by wetland plants: feasibility study for the treatment of agricultural runoff in Suriname (South America)

In agricultural areas, pesticides can enter receiving waterbodies by means of agricultural runoff and pollute these systems. Constructed wetlands are capable of removing several pollutants including pesticides. Unfortunately, few studies are from South America, and therefore, information is urgently needed on pesticide mitigation in agricultural runoff by native plants. To this aim, an experimental setup of polypropylene tubs was used, which were planted with two types of native plants (Nymphaea amazonum and Eleocharis mutata). Mesocosms were exposed to low (10 mu g/l) and high (30 mu g/l) target concentrations of lambda-cyhalothrin, while for imidacloprid, a low (60 mu g/l), high (180 mu g/l), and an extra high (1,000 mu g/l) dose, were applied using batch experiments of 2 weeks each. Removal efficiencies for lambda-cyhalothrin from the water phase showed 100 % removal at 72 h for both low and high target concentrations for N. amazonum mesocosms, while for E. mutata mesocosms, a 100 % removal was observed at 48 h for mesocosms exposed to low target concentrations and for high target concentrations at 72 h. For imidacloprid, a 100 % removal was observed for E. mutata and 86 % for N. amazonum mesocosms exposed to low target concentrations (60 mu g/l) at 216 h. For the highest dose (1,000 mu g/l), the removal efficiency was on average 72 % at 216 h for both types of mesocosms. Statistical two-way ANOVA analysis (alpha=0.05) showed that the removal of lambda-cyhalothrin was independent of the dose applied and the plant type, while for imidacloprid, removal was dependent on the dose applied and independent of the plant type. After the experimental period, analyses of the plants and sediment showed that 48.5 % of the applied amount of lambda-cyhalothrin was detected in the sediment and 0.4 % in plant material (shoots and leaves), while the amount in roots was below the limit of detection for N. amazonum mesocosms. For E. mutata mesocosms, 44.6% of lambda-cyhalothrin was detected in sediment and 0.5 % in roots. For N. amazonum mesocosms, 78.9 % of the applied amount of imidacloprid was retained in plants (plant material and roots) and 17.31 % in sediment, while for E. mutata mesocosms only 0.5 % of imidacloprid was detected in plant material and roots. In this experiment, the DT50 of lambda-cyhalothrin in the water phase of both types of mesocosmswas on average 1 day, while for imidacloprid, this was calculated to be around 1-10 days. The results obtained provide necessary information for the construction of a field scale wetland capable of efficient removal of pesticides in agricultural runoff

Risk assessment of pesticide usage by farmers in Commewijne, Suriname, South America: a pilot study for the Alkmaar and Tamanredjo regions

Limited scientific work is available on pesticide use and exposure in Suriname. Therefore, research was conducted to assess the application, safety practices (use of personal protective equipments (PPEs)), and potential risk of pesticide use by means of a face-to-face questionnaire and determination of the international estimated short-term intake (IESTI)). The amount of pesticide used was compared with the label and the in the European Union (EU) authorized dose. The majority of the farmers was male between 41 and 60 years and followed a primary education only. Less than 5 % of farmers used non-authorized pesticides. Results showed that most farmers (58 up to 100 %) apply a dose, which is within 0-100 % of the regulated dose (label and EU). Good results were obtained for the use of most PPEs. Statistical analysis did not reveal a significant difference between the different age classes, the different levels of education, and the use of PPEs. Pesticide residue analysis of four major crops showed that 22 % of the samples contained pesticides (13 % imidacloprid and 9 % chlorothalonil). The results for imidacloprid were higher than their respective maximum residue levels (MRLs) and were used for calculation of the IESTI. The highest observed IESTI value was 74.5 % of the EU acute reference dose (ARfD), giving rise to concern about pesticide usage. In Suriname, educational programs, good agricultural practices (GAP) training, sustainable agricultural practices, food monitoring studies, and legislative control mechanisms are urgently needed to protect farmer's health and the environment and to ensure food safety