Study On Settling Particulate Matter Flux And Impact Factors In Harny Bay

Suspended substance in the sea is the main form of heavy metals, nutrients andother substances. The process of its migration and transformation in the nearshoreenvironment is the key to understand the interaction between land and sea. Researcheson the distribution and spreading mechanism of suspended substance in the horizontalspace are widely carried out, and in comparison the suspended substance vertical fluxnearshore is more complex and seldom studied. The analysis on settling particulatematter (SPM) vertical flux nearshore and its influencing factors are limited by theinstruments and other observation conditions. SPM is of great importance to thedynamics sedimentary process in the shallow sea, nutrient cycle and the developmentprocess of submarine morphology and seafloor relief. Therefore, to carryout observation and research on SPM is necessaryNowadays the widely distributed raft cultivation of sea kelp in costal water areamay have changed the pattern of suspended substance concentration, suspended sandsource, suspend sand transportation and SPM characteristics. Widely distributed raftsand sea kelp hinder the waves from the outer sea from broadcast to the seashore, forma new up boundary layer at the sea surface, and decrease the current speed in thecultivation area. With this change of hydrodynamic condition, the dynamicsedimentary process, especially SPM vertical flux process is in great need of research.Research on this topic is mostly done in the ocean of its natural state, and the study onnearshore dynamic sedimentary process with human disturbance is just in its infancy.In this paper, raft based sea kelp cultivation area is selected as the study object,difference between the dynamic sedimentary environment in and out of the cultivationarea is studied, the modification process of the bay influenced by culture of sea kelp isresearched. The related interaction mechanism and other research results will provide useful references to the study on nearshore matter flux procedure research with theinterferance of human activities.Gale and surge will affect near shore sedimentation dramatically, and they arevery important outer factors to change the seaboard and seafloor relief. Yellow sea isless affected by typhoon weather, but the typhoon process is an important externalcondition to the change and development process of the bank and seabed topography.With the interruption of typhoon, changes of nearshore dynamic sedimentary process,especially SPM vertical flux process, are of great importance to scientific research andocean engineering. Seldom research is carried out on dynamic sedimentary process intime of typhoon because of terrible observation condition and the suddenness of theevent. In this study, one typhoon process and its impacts on dynamic sedimentarycondition are recorded. With this observed data, the change of SPM in typhoonprocess is studied, and related analysis is carried out based on the hydrodynamicenvironment. The research result will provide reference to the study of dynamicsedimentary process in extreme weather conditionIn this study, data from two observation station in and out of raft culture area ofsea kelp from April to July in2007are compared. Other data observed synchronouson different ships, which covered in and out of the raft cultivation area of sea kelp insummer and winter, is used. With these data, the wave decrease function and otherfunctions on the distribution of ocean currents and suspended sand transportation fromculture of sea kelp are studied. In addition, three groups of self-made sediment trapscollected samples in spring and autumn separately, and got SPM samples in differentlocations and depths in the raft cultivation area. The flux, loss of ignition (LOI), grainsize parameters are analyzed to see the changes among seasons and locations. And thereasons of the distribution layout are explained from the viewpoint of hydrodynamicenvironment and suspend sand matter source. Then，the mechanism is revealed onhow raft cultivation affected hydrodynamics environment and matter source, and thenaffected sedimentary environment. Time series sediment trap is used to collect SPMduring the process of typhoon Muifa. Wind, wave data collected near the study area isused to analyze the process of hydrodynamic condition being affected by the passing typhoon. At the end, we explained the reason why and how SPM changed whentyphoon Muifa passed by.With these studies, the nature and characteristics of SPM in Harny Bay arerevealed, including flux, spatial distribution, seasonal changes, matter source, grainsize distribution, impacts from sea kelp cultivation, and impacts from gale and surge.This study revealed the mechanism of near shore dynamic sedimentation and itsinfluencing factors. It enriches the theories on sea-land interaction and moderndynamic sedimentation, and is of great scientific significance to ocean developmentand ocean engineering.