Contribution of Anthropogenic pollutants on the fertility of the coastal marine waters at Mtwapa Creek, Coast Province, Kenya
Mr. Tunje Pole
Dr. M. Maarifa
Dr. N. Mohamed
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Marine environment pollution from urban development, tourism industry, animal and crop farming has been on the rise world-wide. This affects the quality of water on marine and aquatic environments creating serious health risk on aquatic life, wild animals and humans, in addition to reduced uses for recreation and aesthetics. Pollutants from these sources include deposition of nutrients, sediments, pesticides, heavy metals and microbial contaminants into marine waters.. The study sampled stations close to tourist establishments, urban developments, and agricultural areas upstream of the creek which represent both the area and point sources of effluents into the creek, with control samples collected from the outer open ocean. Quantitative one way ANOVA was used to determine the variations between treatment means and samples. Linear Correlation analysis between nutrients and carbon and nutrients and rainfall were also computed. The study revealed that the levels of nutrients kept on fluctuating throughout the entire study period along the creek and within the sampling stations. The levels of nitrates analysis were within the oligotrophic range throughout the study period. The creek waters recorded an average of between 0.00069 – 0.00087 mg/L of nitrates between the lowest and highest sampling station. Phosphate levels along creek were generally not different throughout the sampling period. The averages were between 0.00076 – 0.00114 mg/L. Ammonia levels were very high in the outer creek than in the inner creek. At the Shimo-La-Tewa sampling station where sewage waters discharges into the creek, the levels of ammonia fell within the higher mesotrophic range of up to 0.009mg/L. Correlation coefficient between phosphates and carbon assimilation revealed a positive relationship and also a positive correlation existed between phosphates and rainfall in outer creek of Mtwapa. These results show that although other biological and chemical processes affect the productivity, nutrients especially phosphates seemed to have influenced carbon assimilation in most of the sampling stations. An appropriate coastal planning and development is urgently required and be enforced under Intergrated Coastal Zone Management.