| Suspended matters(SMs),as the source of marine sediments,play a significant role in marine material cycling,ecological environment evolution and hydrological conditions reseach,and thus has been one of the hot topics in recent oceanological studies.In the East China Sea(ECS),the transportation of suspended matters is most intensive in winter due to the strongest winter hydrodynamics.To systematically understand the distribution,migration and deposition as well as the composition and microstructure of SMs in the ECS,the author filtered the SMs in the winter seawater through the filter membrane with the pore size of 0.22 ?m for determining their concentrations.Combining with the measured data of temperature and salinity,the effects of source and hydrodynamic factors on the winter distribution and migration of SMs were extensively investigated.The comparative analysis between the SMs near and far shore was performed through scanning electron microscope(SEM)and energy dispersive X-ray analysis(EDX).Based on the SEM photographs,the grain sizes and contents of fine-grained(? < 0.45 ?m)SMs were determined via the software AutoCAD.Combining the concentrations of SMs with the current mode(HYCOM),the winter budget of SMs was evaluated in the ECS.The main innovative results of this study are described as below:(1)The fine-grained SMs are important component of SMs in the ECS,with an average of 4.78-8.40%.It is the first time to evaluate the contents of fine-grained SMs in the ECS.The result not only changes our opinion on fine-grained SMs,but also indicates that the obtained contents of SMs would be underestimation results from the inobservance of fine-grained SMs when adopting the filter membrane with the pore size of 0.45 ?m.(2)The SMs in the ECS consists of mineral,biologic,flocs and other organic particles.Mineral particles mainly include feldspar,quartz,clay minerals and carbonate minerals,while the biological particles are dominated by detrital diatoms and coccoliths.The SMs in near shore are governed by mineral particles,while the predomination shifts to biologic particles in far shore.(3)The contents of the winter SMs range from 2.26 to 12.62 mg/L,with an average of 5.69 mg/L.The SMs are mainly derived from the resuspension of surface sediments,as well as the inputs of the Yangtze River and marine autogenetic organisms.The high contents of SMs near the shore of the southern ECS are mainly controlled by the southward-flowing Min-Zhe coastal current,which carries the SMs derived from the Yangze River discharge and resuspension of surface sediments to the coastal area.The low contents of the SMs far the shore of the southern ECS are primarily controlled by the Tainwan warm current,which derives from the low-latitude,bringing clean water from the open sea into the ECS.Meanwhile,the seaward diffusion of the SMs was blocked by the Taiwan Warm Current,resulting in a large number of the SMs stranded and eventually deposited in the coastal areas.Consequently,the well-known muddy sedimentary belt was formed along the Fujian-Zhejiang shore.The SMs in the southwestern Cheju were mainly derived from the resuspension of surface sediments in the submarine delta of the Old Yellow River.(4)The budget of SMs in the ECS is in the status of slightly surplus,as shown that the total income of the SMs in the ECS in winter is 1,504.74 ×10~6 t,slightly higher than the total output of 1,489.82 × 10~6 t.For the total income,resuspension of surface sediments was dominated,and the input from the adjacent seas and biologic particles follewed.For the total outcome,the deposition was dominated,and the cross shelf transport and biologic consumption follewed.The comparative analysis between the endogenous and exogenous SMs income as well as the endogenous and exogenous SMs outcome suggest a "self-sufficient" characteristic of the suspended matter budget in the ECS. |
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