Effect of soda ash industry effluent on bioaccumulation of metals by seaweeds of coastal region of Gujarat, India

Abstract

The bioaccumulation ability of five species of seaweeds to 15 metals was studied in the seawater polluted by the effluent of soda ash industry. The bioaccumulation of Al, Mn and Fe in these seaweeds increased continuously as distance increased from outfall. However, Padina tetrastromatica showed reverse trend. Quite a number of metals like Au, Co, Hg, Ni, Pb, Pt and Sn were not recorded from any species of seaweeds from all sampling stations. Cr was recorded in Gracillaria acerosa from control site only. Accumulation of Cu in Gracilaria corticata was maximum near effluent discharge point and least at control, whereas its accumulation in P. tetrastromatica was more at station with lower pollution (station-3) than higher polluted station (station-2). Seaweeds had different pattern of bioaccumulation to Cu and Ag under the influence of the effluent. The bioaccumulation of Cd in quite a number of species was in non-detectable range, however in case of red seaweed it was more under polluted condition and non-detectable in control. The biosequestering capacity of different seaweed to different metals and their suitability for bioremediation under the influence of effluent is discussed. Bioconcentration factor for different seaweed species from different distances from outfall has been computed and discussed. The undiluted soda ash industry effluent is characterized by very high pH, density, settleable solids, total dissolved solids, ammonia and nitrate. The specific gravity, density, total suspended solids and total dissolved solids decreased continuously from undiluted effluent to seawater affected up to 1 km.