Seasonality in Particulates Distribution from Dumpsites in the Niger Delta Region of Nigeria: A Health Risk Assessment Approach

Abstract

Seasonality in the Niger Delta is a function of two main seasons, dry and wet periods, with rainfalls beginning from April to October with intermittent break often referred to as: August break and dry season from November terminating in March of the following year. In August, there is a decline in amount of rainfall often referred to as little dry season i.e end of July to beginning of August (Adejuwon and Odekunle, 2006). In recent times, it appears that rainfall pattern is beginning to shift from the conventional known time. For instance, Adejuwon (2011) studied seasonal patterns in the Niger Delta between 1931 and 1997 and reported that raining season begins from February/March to November and dry season from December to January/February. This variation could be associated to difference in rainfall determinant factors linked to inter-tropical discontinuity (Adejuwon, 2011). The patterns, distribution and total amount of rainfall are important aspects of the Niger Delta climate. According to Omogbai (2010), the factors that enhance or inhibit rainfall precipitation in West Africa and Nigeria in particular is the progression or regression of the zone of influence of the tropical maritime air mass and related discontinuity zone. Several human activities often cause air pollution. But in developing country like Nigeria most of the activities are seldom monitored apart from oil and gas sector and few other manufacturing/ production facilities. Many of these manufacturing sectors generate wastes some of which are treated before discharge into the environment. However, the Abstract: This study evaluated seasonality in particulates distribution from waste dump sites in some selected Niger Delta states. The particulates (PM1, PM 2.5, PM 4, PM 7, PM 10, and TSP) were determined at 3 distances (3.05 meter, 7.62 meter and 15.24 meter) for 6 months covering the predominant seasons (wet and dry) Delta, Bayelsa, Rivers and Abia states. The particulates were measured with mini-volume air sampler and the health risk was carried out following standard protocol. The health risk assessment was carried under two background scenarios (median and geometric mean). Results for PM1, PM2.5, PM4, PM7, PM10, TSP ranged from 16.43 – 24.71μg/m3, 26.44 – 40.10 μg/m3, 41.64 – 61.53 μg/m3, 62.37 – 98.54 μg/m3, 81.63 – 141.51μg/m3, 110.20 – 270.91μg/m3, respectively. Analysis of variance showed that there were significant variations at p<0.05 across the distances, locations and months of study and their interactions. In addition, the particulates showed significant relationship with each other at p<0.01. The particulates were higher during the dry season compared to wet season, suggesting the influence of climate/weather condition. Health risk assessment showed that particulates were within slight pollution (50<HRA≤100) to Hazardous (200<HRA≤250). The health risk assessment under both background scenarios showed slight variations. The health assessment suggests that sensitive group could be at risk of diseases associated with particulates in the study area over a prolong period of time. As such, there is need to use most suitable approach in waste management in the study area.