Impact of Land Use and Urban Runoff on the Contamination of the Sarno River Basin in Southwestern Italy.

A study was conducted to determine the contaminant level of the Sarno River basin, a small creek located in southwestern Italy. Six sampling site locations were selected to coincide with two previous studies conducted in 1975 and 1985 to provide a basis for comparison. For each location, twelve samples were collected over the period October 1997–September 1998. Results indicated a degradation in river water quality, especially near the mouth. This was reflected by a dissolved oxygen concentration of about 0.8 mg L^-1 near the urban areas of Scafati, Pompei and Castellamare of Stabia. At the same locations, BOD₅ and COD values were two to five times higher than the allowable regulatory maximum levels, respectively. About 4 km from the headwaters, the average oxygen concentration was 4.7 mg L^-1, BOD₅ values were close to the standard limit (37 vs 40 mg L^-1), and COD values were above the standard limits (252 vs 160 mg L^-1). Highest concentrations were detected during peak tomato production. During this time, settleable solids were also elevated, two to six times the regulatory standard. Coliform bacteria densities were found in excess of the standard limits at all sites. Near the head of the river, mean fecal coliform (22,571 MPN mL^-1) and streptococci densities (14,214 MPN mL^-1) surpassed the regulatory level of 120 and 20 MPN mL^-1, respectively, reflecting the input from the urban settings of Sarno and agricultural fields. The heavy metal dissolved concentrations were low at all sampling sites. Most of the analyzed contaminants increased when comparend with 1985 data. BOD₅ increased 5 to 10 times at sites near the urban settings of Scafati, Pompei and Castellamare di Stabia, whereas COD increases were twofold at all sites. A decline of chromium levels was observed due to the recent effective treatment of waste water from the tanning plants. [ABSTRACT FROM AUTHOR]