Pollutant Transfer And Transformation In Marine Environment And Application In The Study Of Marine Environmental Capacity

Ocean is the largest water body on earth,and through the natural water cycle, pollutants contained in other types of water may all flow into the ocean in the end,so this poses a sever threat to marine pollution.Therefore,the study of pollutant transfer and transformation mechanism in the ocean as well as pollution control and protection of marine environment becomes a critical issue.Currently,researches at home and abroad mainly focused on separate studies of the transfer and transformation process of certain pollutant in the ocean,whereas there is no systematic summary and most of them are qualitative description without quantitative calculation.Besides,models used by existing researches on pollutant transfer and transformation are mainly complicated,hard to calculate and involves a larger number of environmental factors,and thus not applicable to the numerical model calculation of the environmental capacity of bay areas.This thesis aims to solve this problem by providing a set of pollutant degradation model which meets the numerical model calculation of environmental capacity of bay areas,and applied the model to actual cases.Major pollutants in Xiamen Bay include nutrients(nitrogen and phosphorus),COD and petroleum hydrocarbons,so the thesis concentrates on the transfer and transformation of these three main pollutants in sea water.There are only indicators of active phosphate and inorganic nitrogen in current national standards of water quality,and no total phosphorus and total nitrogen indicator are included,so the standards have no significance of the calculation of marine environmental capacity and total amount of pollution control.Under such circumstances,the thesis introduces a method of total nitrogen and total phosphorus control by in-situ determination of the amount of total nitrogen,total phosphorus, inorganic nitrogen and inorganic phosphorus in sea water and polluted water,then calculating the ratio of total nitrogen and inorganic nitrogen,as well as total phosphorus and inorganic phosphorus,and finally solves the problems of lacking numerical model in the calculation of nutrients in biochemical transfer and transformation.The ratio of inorganic nitrogen and the total nitrogen as well as the ratio of active phosphate and the total phosphorus in Xiamen Bay is 0.621 and 0.412 separately;the controlled concentration of total nitrogen and phosphorus in the third level of national standards of water quality in Xiamen Bay is 0.999mg/Land 0.055mg/L separately.As to the transfer and transformation of COD in the bay area, this thesis adopts COD degradable dynamic equations.Firstly,build the relationship between the degradation rate constant k and sea water temperature and calculate that the degradation rate constant of COD in Xiamen Bay is 0.05 /d.Secondly,calculates the COD amount in accordance with the first level degradation kinetics relationship C=C₀e^-Kt,and the COD degradable dynamic equation in Xiamen Bay is C = C₀e^-0.05t.The transfer and transformation of petroleum hydrocarbons in the bay is calculated by natural weathering model of petroleum hydrocarbons in the estuaries and bays,and the degradation rate constant of petroleum hydrocarbon in Xiamen Bay areas is 0.009 /d according to the relationship among the degradation rate constant, sea water temperature and salinity,so the transfer and transformation of petroleum hydrocarbons can be expressed as:C=C₀/(0.0091tC₀^0.1 +1)¹⁰.In this thesis,the findings will be used to the numerical calculation of environmental capacity in Xiamen Bay.