Effect of mariculture on sediment grain size and its potential environmental significance in Sishili Bay, Yellow Sea, China

The grain-size distribution of sediment is associated with series of environment problems in mariculture area; however, there is still disparity in the effect of marine culture on grain size partly because it is hard to exclude the contribution of other factors such as sources, hydrodynamic. Sediment grain size of two cores (C3 in culture area and A5 in control area) was compared. The results show that the particle sizes of the two cores have the same compositions and variation laws at the bottom sections (during non-culture period), while sand grain-size contents increases from several to 25 % in C3 core than that in A5 core at the surface section (during the culture period), with an average of 15 %. It suggests the grain sizes are coarsened due to marine culture. Moreover, the deviation values of sand grain-size contents, calculated by subtracting grain-size contents of A5 core from those of C3 core at the surface section, were used to quantificationally estimate the variation of grain-size components. It is found that the deviation values of grain size increase with the intensifying of marine culture outputs. Marine culture outputs result in the coarsening of grain sizes; thus, the variation of grain size should be considered when the environmental problems in culture areas are explained, such as heavy metal pollutants, nutrient elements and benthic community structure and so on.