Wet deposition of air pollution at southwest monsoon outbreak and its impact on groundwater resources of Greater Kochi Region

摘要

The replenishable groundwater resources from natural recharge for Greater Kochi Region (GKR) is of low quantity and it suffer from salinity intrusion, with the level of ground water development at 21.02%. The wet deposition of air pollution was evaluated by analyzing the rainwater at the outbreak of southwest monsoon. The acidic nature of rainwater during the first rain of monsoon season over the refinery and industrial belt is significant. The nitrate concentration in rainwater of the magnitude 57umol/l highlights the impact of oil refinery and the fertilizer complex emissions. The industrial belt had nearly 3 times nitrite concentration than of the residential and coastal areas. The continuous showers of the successive days could not eliminate the industrial impact; the possibility of nutrient enriched rainwater peeping into groundwater seems to be a reality. The PO_4 and NH_4 levels remained high at refinery and fertilizer complex. The enriching effect of PO4 by emissions declines with advancement of monsoon and does not pose a threat to ground water resources. Even with the advancement of monsoon season, the industrial complex and the oil refinery influence on the rainwater contamination continues over the industrial and refinery areas and the indirect impact of air pollution on the ground water quality can not be fully ruled out in the GKA region. As the total replenishable ground water from normal natural recharge for GKA is estimated as 5659 (th.ha.m/yr), its conservation from industrial pollution impacts to be taken up with topmost priority. The duration of the dry spell is identified as an important factor controlling the chemical contents in the first showers and the chances of ground water contamination is more with long dry season.