Assessing the total maximum allocated load of jurisdiction petroleum pollutants in the Bohai Sea

A method for calculation of total maximum allocated load (TMAL) of petroleum in Bohai Sea was established based on jurisdictions by linking land and sea. The TMALs of petroleum pollutants for 51 sea-sink source regions, 356 jurisdictions, and 6 petroleum drilling platforms (PDPs) around the Bohai Sea were calculated. Results showed that the TMALs of petroleum pollutants in 51 sea-sink source regions and 6 PDPs amount to 1.9 × 104 tons/year. The largest TMAL is from the rivers, followed by that of PDPs and wastewater treatment plants (WWTPs), at about 0.22 × 103, 0.13 × 103, and 0.11 × 103 tons/year on average, respectively. The maximum values are 3.05 × 103, 0.47 × 103, and 0.65 × 103 tons/year respectively, while the minimum values are 0.18, 0.10, and 0.31 tons/year respectively. The TMAL of petroleum pollutants on source producing and TMAL on source emission are 11.9 × 104 tons/year and 1.9 × 104 tons/year in 356 jurisdictions, respectively. The TMAL is high in upstream of each basin and the areas of marine water exchange rapidly. Taking Laizhou Bay as an example, 19 jurisdictions are overloaded with petroleum pollutants, and its overload rate is 670% on average.