Seasonal and Spatial Detection of Pesticide Residues Under Various Weather Conditions of Agricultural Areas of the Kilombero Valley Ramsar Site, Tanzania

Abstract

This study was conducted in the Kilombero Valley Ramsar Site (KVRS), the largest low-altitude freshwater wetland in East Africa to: 1) determine pesticide contamination of soil, water, and sediment at different seasonal weather conditions 2) critically analyze the seasonal and spatial ecological impacts of pesticide contaminations under tropical weather conditions 3) estimate the potential environmental risks from pesticide exposure based on analytical data. Surface sediments, soil and water samples were collected from sugarcane, teak and rice plantations of the KVRS during the dry (January 2012) and the rainy (March–April 2013) seasons. Samples were screened for 97 different types of pesticide residues using and LC–MS and HPLC–MS. Physical-chemical properties of the sediment and soil samples and meteorological data were analyzed. 92% of soil and sediment samples had relatively low OM content (<5%) while 60% of samples had high clay content, indicating high cation exchange capacity that can bind pesticides to the soils. Field soil and air temperature ranging 28–35°C, total sunshine hours-208 h/month, photo radiation −764 MJ/m2, average precipitation 300 mm/month, wind speed >60 km/h, humidity >80% were recorded. Frequency of detection and concentration of pesticides residues depended on seasons. For the dry season sampling, glyphosate/AMPA (0.01–0.55 µg/g), and diuron (0.026–1.7 µg/g) were mostly detected in the sediment and soils. Monuron (1.28–3.9 µg/L) and propoxur (0.05–0.6 µg/L) were mostly detected in the rainy seasons (water and sediments). Glyphosate was above limit of detection in the dry season water samples indicating that its emission into the water system may have been directly through application. Maximum diuron concentrations in water were >30 times higher than the estimated predicted no-effect concentration (PNEC) value (0.054 µg/L) indicating a risk to aquatic community. Calculated pore water concentrations (0.992–0.081 µg/L), exceeded the estimated PNEC values during the dry season, indicating a risk to benthic organisms. Detection of pesticide is influenced by application, environmental factors and the timing of sampling. Further research is recommended to increase our knowledge on soil-water-sediment interactions in the tropics with regard to pesticides.

Pesticides monitoring in surface water of a subsistence agricultural catchment in Uganda using passive samplers

“…In Ethiopia, more than half of the water samples showed contamination from malathion, dimethoate, metalaxyl, diazinon, chlorpyrifos, fenitrothion, and endosulfan (Merga et al 2021). Similarly, Materu et al (2021) demonstrated the widespread occurrence of polar pesticides in Tanzania.…”

“…3 Pesticide concentrations quantified (above the limit of quantification) from the three sampling methods: SDB disks, WLP, and PDMS et al 2016). A recent study from Tanzania (Materu et al 2021) screened for almost 100 pesticides and detected 11 compounds including six herbicides, two insecticides, and three herbicide transformation products.…”

The strategic applications of natural polymer nanocomposites in food packaging and agriculture: Chances, challenges, and consumers’ perception

“…For this reason, it is essential to have new nanotechnology-based fertilizers on the market. Moreover, pesticides are also largely lost from the field to other non-target sites due to weather factors (Materu et al, 2021) (Figure 3). Nanomaterials (NM) are promising for use in agriculture because they have advantages, among the main ones is the low amount of product applied, remain for the desired time in the environment thus the active ingredients can be dosed and therefore control the pest or pathogen .…”

Continuous high-frequency pesticide monitoring in a small tile-drained agricultural stream to reveal diel concentration fluctuations in dry periods

“…Due to confidentiality, we could not study the relationship between PPPs applications and their detections in the stream. It is known that PPPs applications, environmental drivers and timing of sampling are important factors for explaining PPPs detections in water (Materu et al, 2021;Schönenberger et al, 2022). Yet, mitigation measures may be effective at reducing water pollution by attenuating the mobilization and transport of PPPs (Chow et al, 2020).…”