The influence of environmental factors on microbiological indicators of coastal water pollution

The relationships between bacteriological and viral indicators of sewage po llution (TC, FC, E coil, FS, Salmonella, somatic coliphages and F-RNA phage s) and environmental variables in coastal water and weather were studied at three beaches in San Sebastian, the Basque Country. The microbiological in dicators in bathing water presented high counts associated with the followi ng conditions: early morning, overcast skies, low and high tides, groundswe ll, intense turbidity and the presence of flotsam (P = <0.05). Coliphage de nsity was significantly related (P = <0.05) to cloud cover, groundswell and flotsam. Correlations between microbiological indicators proved high (0.62 less than or equal to r less than or equal to 0.90, P = <0.001). The perce ntage of Salmonella presented significant (<0.05), albeit low (r < 0.4), co rrelations with all microbiological parameters. Somatic coliphages also rev ealed highly significant (0.32 less than or equal to r less than or equal t o 0.66) correlations (P = <0.001). Those obtained for F-RNA phages, in cont rast, were low (r less than or equal to 0.33). The equations obtained using a multiple regression analysis with a view to predicting microbiological, viral, and Salmonella indicator density demonstrated that environmental var iables facilitate the construction of highly significant equations, but tha t these have low predictive capability (R-2 = <0.50). (C) 1998 Published by Elsevier Science Ltd on behalf of the IAWQ. All rights reserved.