The Settling Particulate Matter and Their Geochemical Compositions in Jiulongjiang Estuary in Dry Season

Key words: 
• settling particulate matter /
• the chemical composition /
• settlement flux /
• Jiulongjiang estuary

Abstract: The settling particulate matter(SPM) was collected respectively by selfmade sediment trap in Jiulongjiang estuary from March 28 to March 29 in 2009. The collected samples were analyzed using scanning electron microscope (SEM), laser particle size analyzer and ICPMS instrument, and the particulate vertical fluxes were caculated. SEM analysis using the LEO1530 scanning electron microscope made in Philip company in nanometer technology centre of Xiamen University(resolution for the 3 nm, the largest magnification is 30 millions times). Grain size analysis was analyzed by Mastersizer 2000 type laser granulometer, samples were determined after ultrasonic dispersed, particle size interval for 0.25, precision is 2%, the work was done by open laboratory of ocean & coast environmental geology, third institute of oceanography. ICPMS analysis, element analysis are finished by using inductively coupled plasma mass spectrometer (Agilent 7500ce ICPMS, American Agilent) in key laboratory of global change and marineatmospheric chemistry,SOA. We have analyzed 47 elements, including Na, Mg, Al, K, Ca, Fe, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sn, Sb, Hg, Tl,Pb,Th,U, such elements (partly elements because of low content were not detected), the instrument measuring precision standard deviation is less than 5%. Using the scales measurement accuracy for 1/100000 to calculated vertical settlement particulate flux. SEM analysis shows that biological debris and minerals are the main components of settling particulate matter, the flocculation types are different in disparate levels. Every surface and bottom are silty sand, median diameter vary slightly. The change of size parameters were effected by flocculation. The vertical flux of settlement between sea level changes greatly. The surface of settlement flux are higher than the bottom in A and C station, B staion emerge to the contrary. Settlement flux peak in B station bottom, settlement flux for 747.0 g.m2.d1,lowest appeared in A station bottom, settlement flux for 245.7 g m2 d1, investigate its reason should be derived from Jiulongjiang of particulate yakees along the subsidence. There are certain differences in different sources of substance in the chemically, particle chemical composition is the comprehensive embodiment of the source. The content and distribution characteristic of each element in settlement particle is one of the important indexes of material sources, biogeochemical process, material exchange between particles and ecological environment of marine.In order to reveal the relationship between each element, the principal component analysis is carried on the factor analysis, former four factors have given a fully summary to the vast majority figures and explained 94.927% variance of the total. Factor1 reflects the effect of distribution of the particle caused by inputing of landsourced material. Factor 2 is also reflect the terrestrial material input on the distribution of the settlement of particles, and indicates that the trace elements of particle did not exists in the form of carbonate. Factor 3 reflects the effect of the distribution of the settlement particle by human activities in the study area .Factor 4 revals the same conclusion with factor 3.