Water quality evaluation and classification of pollutant sources of Tianjin coastal zone in the Bohai Bay
渤海湾天津段水体质量评价及污染源分类

The Bohai Sea is one of the most seriously contaminated sea areas of China. A number of contamination indices of water samples collected from the Bohai Sea Gulf have been measured and studied here. The study area has weak alkalic water with major pollutants of inorganic nitrogen, zinc, lead and mercury. The tested indices are lower than the second-grade water quality criteria except the inorganic nitrogen, which is only lower than the third-grade water quality criterion. Fluvial input is the predominant factor affecting the water quality in the study area, while sea-farming, oil exploitation, industrial and civil waste water discharge also affect much. In the article, we have provided further information for the Bohai Sea environment recovering and suggested that it is necessary to target controlling and treating the existing and potential risky factors.