The Comparative Study For The Composition,Source And Distribution Of Particles In The Pearl River Estuary Of The Northern South China Sea

The seawater particles have many sources,and the spatial and temporal distribution of its content is affected by many factors.However,due to its small particle size,and the small quantity,the water particles are extremely hard to study.Accordingly,there are limited observations.The seawater particle is one of the key links of many ocean circulation process,their structure and sources can provide many important scientific basis for the marine biogeochemistry process.To understand the seawater particles sources?composition and spatial and temporal distribution in the Pearl River Estuary section in the northern South China Sea,this paper analyzed six samples for surface station in spring of 2016 in South China Sea voyage.We obtained 1054 electron microscopy images and 6050 test results of particles using single particle analysis.Based on the structure characteristics and X-ray spectra,we divide all the particles into following classes:strontium sulfate containing particles,siliceous biogenic particles,calcareous biogenic particles,bio-organic detritus particles,nitrogen and phosphorus containing particles,silicon and aluminum containing particles,heavy metal containing particles,sulfur containing particles,Salts,thin-film particles.Compared with previous results,we concluded conclusions:(1)We found four different strontium sulfate containing particles in biological particles.According to the literature we suspected,it may belong to the protozoa,but not acanharia which has most data in previous studies,so whether it is new species or not is still an open question.(2)We found some particles contain high level of N and P.Some of them are bacteria,may be related to the nitrogen fixation process in the ocean.(3)This study clearly captures the shape of the thin film particles and finds the main components are Cl,Na,S,Si,Mg and Al.(4)Compared with the results in 2014,we find particle composition?quantities?distribution and types have big differences although the samples are collected in the similar season and position in the northern South China Sea.The number of particles in the South China Sea in the spring of 2014 is significantly higher than that in 2016,with one order of magnitude 106 and 105.In addition to the trend of the total particles in the Pearl River Estuary,the trend of different type particles nearly have no similarity.For two investigations in spring,types and quantities of siliceous biogenic particles and calcareous biogenic particles also have big difference.In 2016,calcareous biogenic particles are few in number and siliceous biogenic particles are the major component of biological particles,meanwhile the advantage species of siliceous biogenic particles are different with thespring of 2014.At the same time,when the number of calcium particles was lower,the number of copper-containing particles declined.When the proportion of siliceous biogenic particles in biological particles rises,the zinc-containing particles become the main components of the heavy metal particles.