Evaluating Water Quality and Distribution of Phosphates and Nitrates in Soils, Water and Sediments from Agrochemicals Usage in Santa, Cameroon

Abstract

Worldwide pollution of soils, rivers, streams and lakes from anthropogenic activities has been one of the most crucial environmental problems since the beginning of the 20th century. In Santa, the increasing use of agrochemicals is disturbing, as most farmers have little or no idea about application techniques or the effects of these chemicals on the environment. The objective of this work was to determine the knowledge on pesticides and fertilizer use by tracing their availability in surface and subsurface soils, in water and sediments using nitrates and phosphates, and by evaluating the quality of some water sources in Santa. Questionnaires were used to survey the knowledge of fertilizers and pesticide utilization by farmers, while water, soil and sediment samples were collected from selected field sites to determine the distribution of phosphates and nitrates. The pollution of water from some water sources in Santa was evaluated using the National Sanitation Foundation Water Quality Index (NSFWQI). The results show that most farmers cultivate vegetables (86%), with high applications of pesticides for pest control, and 100% cultivate without fallowing using much fertilizer. 90% of the farmers used nitrogen, phosphorus and potassium (NPK) fertilizers along with urea fertilizers. Phosphates were present in soils and sediments but absent in water, while, nitrates were present in soils, water and sediments. While phosphates were significantly higher than nitrates in soils and sediments, the reverse was observed in water, where nitrate concentrations were significantly higher than those of phosphates. Phosphates showed more mobility in the soil than nitrates, as phosphate concentration values were higher in subsurface soils than surface soils. NSFWQI values for three water bodies studied indicated moderate pollution, making them not suitable for drinking. The absence of fallowing and lack of proper knowledge on soil nutrient content have led to excessive use of agrochemicals by farmers in Santa, which has resulted in soil, water, and sediment contamination.