A Study On The Bohai Sea In Environmental Capacity Of Petroleum Hydrocarbon

When the land resource runs out and the ecological environment runs down day by day, the immense ocean, covering 71% of the global surface, attracts more and more people's attention for her vast resource, energy and environmental function. No doubtly, the study of ocean Environmental Capacity (EC) quantitatively will provide the scientific basis for drawing out environmental policy. Considering this point, the dissertation makes an exploration on EC of Bohai Sea.First, the thesis introduces main viewpoint and practical definition of Environmental Capacity (EC), then summarizes and analyzes the mainly 3 methods for calculating marine EC, i.e., Box Model, Sharing Coefficient and Optimization method. Box model serves the turn of smaller sea and will over estimate its EC; Sharing coefficient method is convenient for management and is equal to assign EC with current ratio; Maximum economy method accords to the thinking of sustainable development but is complex in operation. After comparison and analysis, the thesis decides to adopt Maximum Volume method to compute EC of Bohai Sea.. Then, HAMSOM model is adoptted to simulate Bohai Sea's current field, temperature field and salinity field with the driving force of five tidal components, M2, S2, N2, Kl, 01, at open boundary and the wind field, heat flux at sea surface. The results accord to former study, therefore the model is reliable. Next, the particle tracing model is applied to simulate Bohai Sea's concentration field to obtain the responding field of 4 rivers, which is the foundation of EC calculation. Compared with other numerical methods, this one has the advantage of good numerical stability and being prone to append new biochemical procedures.Next, Maximum Discharge Volume Method is applied to coputer EC of COD in Bohai Sea on the basis of s current field, temperature field and salinity by selecting seawater control points correctly. The results are as follows, according to national seawater quality standard class 1 to class 4, Bohai's EC of COD are 36.59 ×414t/a, 54.88 × 104t/a, 73.13 ×104t/a and 91.45 ×104t/a respectively. Then the thesis employs an existed EC of PHs model, which contains microbiology module, atmosphere module and hydrodynamic module, to calculate EC of PHs in Bohai Sea, the results are, according to national seawater quality standard class 1 to class 4, Bohai's EC of PHs are 2.82× 104t/a, 16.86×104t/a and 28.17× 104t/a respectively. Then input the result to Bohai Sea to obtain opimized concentration field. The opimized concentration field accords to correspond standard, therefore the results are reliable.Finally, the dissertation points out some flaw in it and bring out some question for further study, as are the mechanisms of all kinds of self-purification, the determination of specific parameter and especially the more scientific and more rational methods for EC calculation.