Influence of agricultural activities and seasonality on levels of selected physico-chemical parameters and heavy metals along River Yala in Lake Victoria Basin

The aim of the work was to establish the effect of anthropogenic activities and seasonality on physico-chemical parameters and heavy metal levels of River Yala (RY) within RY Basin of Lake Victoria (LV), as well as the associated ecological risks. Analyses were done on the collected samples in order to establish the levels of EC, pH, DO, temperature, conductivity, turbidity, acidity, alkalinity, BOD, COD, DOC, TOC and heavy metals (Cu, Fe, Pb, Mn, Zn, Cr and Cd) in RY water and sediments adjacent to Agricultural Farms during dry and wet seasons. The levels in terms of μg/mL, μS/cm (EC), NTU (turbidity) of analyzed parameters in the Agricultural Farms in water ranged from 0.01±0.00 to 121.75±15.23 (Upstream pristine sources of RY - S), 0.02±0.01 to 184.83±23.43 (Nandi Tea Estate and Kaimosi Agricultural Farms - N), 0.02±0.01 to 149.67±22.77 (Subsistence Farms - Sub), 0.02±0.01 to 209.33±18.09 (Lake Agro Limited Agricutural Farms and Yala Swamp - D) and 0.01±0.00 to 164.25±30.33 (Terminal of RY - T). The levels in μg/g of analyzed parameters in sediments ranged from 7.2±1.46 to 3342.8±538.7 (S), 9.12±0.2 to 4063.2±90.4 (N), 3.15±1.14 to 5998.5±588.4 (Sub), 2.03±0.76 to 4519.8±194.9 (D) and 2.13±0.75 to 5514.4±201.4 (T). The significant differences in the levels of analyzed parameters in water between dry and wet seasons were computed as; EC (+20.54 μS/cm), alkalinity (-2.85 μg/mL), DOC (+0.24 μg/mL), Fe (+0.58 μg/mL), Pb (+0.11 μg/mL), Zn (+0.07 μg/mL) and Cd (+0.01 μg/mL) while that for Mn in sediment samples was +163.8937 μg/g. The significantly (p ≤ 0.05) positive values indicated that wet season had more impact on the levels than dry season. There was positive correlation of zinc in water and sediments during dry and wet season. Chromium correlated positively in water and sediments during wet season. Copper and cadmium correlated negatively during dry and wet season while Mn only wet season. Results of geostatistical indices (CF, Cd, mCd, PLI, Er and RI) indicated that sediments located at regions N, D and T were highly contaminated with the heavy metals. However, a wetland at the mouth of Lake Victoria cleaned the water before it drained into the lake. Therefore, despite contamination of RY through anthropogenic activities, wetland mitigation protects LV from pollution by the river, indicating the important ecological and restorative functions played by wetlands.

Tracking Fecal Bacterial Dispersion from Municipal Wastewater to Peri-Urban Farms during Monsoon Rains in Hue City, Vietnam

Disease outbreaks attributed to monsoon flood-induced pathogen exposure are frequently reported, especially in developing cities with poor sanitation. Contamination levels have been monitored in past studies, yet the sources, routes, and extents of contamination are not always clear. We evaluated pollution from municipal wastewater (MWW) discharge and investigated fecal contamination by Escherichia coli (E. coli) in three agricultural fields on the outskirts of Hue City, Vietnam. After E. coli concentration was determined in irrigation water (IRW), MWW, soil, vegetables (VEG), and manure, its dispersion from MWW was tracked using multilocus sequence typing (MLST) and phylogenetic analyses during the wet and dry seasons. IRW was severely contaminated; 94% of the samples were positive with E. coli exceeding the stipulated standards, while VEG contamination was very low in both seasons. The confirmed total number of isolates was comparable between the seasons; however, results from MLST and phylogenetic clustering revealed more links between the sites and samples to MWW during the wet season. The wet season had four mixed clusters of E. coli isolates from multiple locations and samples linked to MWW, while only one mixed cluster also linking MWW to IRW was observed during the dry season. The most prevalent sequence type (ST) complex 10 and two others (40 and 155) have been associated with disease outbreaks, while other STs have links to major pathotypes. Irrigation canals are significant routes for E. coli dispersion through direct links to the urban drainage-infested river. This study clarified the genotype of E. coli in Hue city, and the numerous links between the samples and sites revealed MWW discharge as the source of E. coli contamination that was enhanced by flooding.

Pesticide practices in coastal agricultural farms of Lebanon

The agricultural sector in Lebanon relies heavily on agrochemicals for crop protection; thus exposing humans and the environment to the harmful effects of pesticides. This study investigated Lebanese farmers' pesticide use practices and explored the underlying factors associated with farmers' choices. Of the 104 surveyed farmers, around 87% were willing to use pesticides that are less toxic to humans and the environment than those currently using, if available. The majority of these farmers (92%) planted their crops in greenhouses. Willingness to use less toxic pesticides was significantly associated with farmers using greenhouses as opposed to open fields, after adjusting for demographic and behavioural characteristics (OR = 7.50; p = 0.010). There was no association between willingness to use less toxic pesticides and perceptions of pesticides' health effects. Policies banning the import and sale of internationally banned pesticides must be enforced. Farmers must be supported to make informed choices about pesticides and their use.