Characterization and Dynamics of the Pollutant Load Discharge Carried by the Mazafran River (N Algeria) on the Coastal Environment

The shoreline of the bay of Bou Ismail (Algeria) has been subjected to several anthropic pressures during the last 15 years, including discharges of pollutant loads carried by the Mazafran River. For evaluating this pollution, a sampling campaign on the bed of Mazafran River and in the coastal zone in front of its mouth was conducted during August 2016. The Riverbed was sampled at three different points in order to evaluate their pollution levels, whereas the coastal stations are located along semicircles centred at the river mouth with a radius of 300, 1000, and 1800 m. Principal Component Analysis (PCA) was performed for identifying pollution flux direction and importance. The results from the river show excess of pollution load with different origin sources. The upstream station (MS1) is dominated by biodegradable effluents, which are gradually diluted along the River, until the second sampling station (MS2). However, the water quality is altered, between MS2 and MS3 down-stream stations, by the release of nitrogen-rich industrial wastewater. The coastal zone in front of the river mouth is characterized by seasonal temperatures (21.1–21.8 °C), normal pH (8.14–8.19), and good oxygenation of water despite high levels of suspended solids (up to 111 mg/l), which can be related to phytoplankton production (chlorophyll a of 0.40 and 0.80 μg/l). Nutrients show a horizontal east–west and inshore–offshore gradient resulting from Mazafran Riverine inputs. Overall, this study highlighted the high degree of contamination of Mazafran River leading to nutrient enrichment of the coastal zone.