Material fluxes （e.g., nutrients） from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by cha...Material fluxes （e.g., nutrients） from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by changing nutrient structures. In this study, naturally occurring isotopes, ^226Ra and ^228Ra, were measured with the alpha spectrometry in the Wenjiao-Wenchang and Wanquan estuaries and adjacent sea areas along the east coast of Hainan Island. The excess ^226Ra and ^228Ra activities were observed by comparison with the values derived from the conservative mixing of freshwater and seawater end-members in both estuaries. Using a one-dimensional diffusion model, the horizontal eddy diffusion coefficient of 3.1 6 × 10^5 cm^2/s, for nutrients diffusing from their sources, was derived from 228Ra activities. Consequently, the corresponding nutrient fluxes flowing into the coastal waters were assessed. The results can provide useful information for the study of the mixing and exchange processes of coastal waters as well as dissoluble pollutant transport in this sea area.展开更多
As the mesoscale eddies in oceans and semi-enclosed seas are significant in horizontal dispersion of pollutants,we investigate the seasonal variations of these eddies in the Persian Gulf(PG)that are usually generated ...As the mesoscale eddies in oceans and semi-enclosed seas are significant in horizontal dispersion of pollutants,we investigate the seasonal variations of these eddies in the Persian Gulf(PG)that are usually generated due to seasonal winds and baroclinic instability.The sea surface height(SSH)data from 2010 to 2014 of AVISO are used to identify and track eddies,using the SSH-based method.Then seasonal horizontal dispersion coefficients are estimated for the PG,using the properties of eddies.The results show an annual mean of 78 eddies with a minimum lifetime of one week.Most of the eddies are predominantly cyclonic(59.1%)and have longer lifetimes and higher diffusion coefficients than the anti-cyclonic eddies.The eddy activity is higher in warm seasons,compared to that of cold seasons.As locations with high eddy diffusion coefficients are high-risk areas by using maps of horizontal eddy diffusion coefficients,perilous times and locations of the release of pollutants are specified to be within the longitude from 51.38°E to 55.28°E.The mentioned areas are located from the Strait of Hormuz towards the northeast of the PG,closer to Iranian coast.Moreover,July can be considered as the most dangerous time of pollution release.展开更多
基金supported by the Natural Science Foundation of China (Grant No.41021064)the Sino-German Cooperation Project of Ministry of Science and Technology of China (Grant No.2007DFB20380)the Ph. D. Program Scholarship Fund of East China Normal University (Grant No.2010047)
文摘Material fluxes （e.g., nutrients） from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by changing nutrient structures. In this study, naturally occurring isotopes, ^226Ra and ^228Ra, were measured with the alpha spectrometry in the Wenjiao-Wenchang and Wanquan estuaries and adjacent sea areas along the east coast of Hainan Island. The excess ^226Ra and ^228Ra activities were observed by comparison with the values derived from the conservative mixing of freshwater and seawater end-members in both estuaries. Using a one-dimensional diffusion model, the horizontal eddy diffusion coefficient of 3.1 6 × 10^5 cm^2/s, for nutrients diffusing from their sources, was derived from 228Ra activities. Consequently, the corresponding nutrient fluxes flowing into the coastal waters were assessed. The results can provide useful information for the study of the mixing and exchange processes of coastal waters as well as dissoluble pollutant transport in this sea area.
文摘As the mesoscale eddies in oceans and semi-enclosed seas are significant in horizontal dispersion of pollutants,we investigate the seasonal variations of these eddies in the Persian Gulf(PG)that are usually generated due to seasonal winds and baroclinic instability.The sea surface height(SSH)data from 2010 to 2014 of AVISO are used to identify and track eddies,using the SSH-based method.Then seasonal horizontal dispersion coefficients are estimated for the PG,using the properties of eddies.The results show an annual mean of 78 eddies with a minimum lifetime of one week.Most of the eddies are predominantly cyclonic(59.1%)and have longer lifetimes and higher diffusion coefficients than the anti-cyclonic eddies.The eddy activity is higher in warm seasons,compared to that of cold seasons.As locations with high eddy diffusion coefficients are high-risk areas by using maps of horizontal eddy diffusion coefficients,perilous times and locations of the release of pollutants are specified to be within the longitude from 51.38°E to 55.28°E.The mentioned areas are located from the Strait of Hormuz towards the northeast of the PG,closer to Iranian coast.Moreover,July can be considered as the most dangerous time of pollution release.
