Origin Of Suspended Particulate Matter Research Articles

The origin of suspended particulate matter in the Great Barrier Reef

River run-off has long been regarded as the largest source of organic-rich suspended particulate matter (SPM) in the Great Barrier Reef (GBR), contributing to high turbidity, pollutant exposure and increasing vulnerability of coral reef to climate change. However, the terrestrial versus marine origin of the SPM in the GBR is uncertain. Here we provide multiple lines of evidence (13C NMR, isotopic and genetic fingerprints) to unravel that a considerable proportion of the terrestrially-derived SPM is degraded in the riverine and estuarine mixing zones before it is transported further offshore. The fingerprints of SPM in the marine environment were completely different from those of terrestrial origin but more consistent with that formed by marine phytoplankton. This result indicates that the SPM in the GBR may not have terrestrial origin but produced locally in the marine environment, which has significant implications on developing better-targeted management practices for improving water quality in the GBR.

Monitoring Suspended Particle Matter Using GOCI Satellite Data After the Tohoku (Japan) Tsunami in 2011

The Fukushima Daiichi nuclear disaster that occurred on March 11, 2011, was caused by the Tōhoku tsunami, which was itself triggered by the devastating 9.0 Mw moment magnitude earthquake. This study investigates spatial and temporal changes of the suspended particulate matter (SPM) content in the North-Eastern part of Japan (Pacific Ocean) using a geostationary ocean color sensor. The Geostationary Ocean Color Imager (GOCI), which is centered on the Korean peninsula but could also observe the Japanese area, is able to acquire eight images per day, thus allowing the analysis of rapid daily changes in water mass. The analysis of GOCI data shows that SPM concentration notably increased both along the coast and within the Bay of Sendai shortly after the tsunami. Motionless patterns of SPM were observed at 2, 14, 25, and 37 km from the coast. It is shown that SPM concentration rapidly decreased one month later. The SPM concentration did not remain high the following year, contrary to what was observed for the Sumatra Tsunami in 2004. The origin of SPM is also investigated in this study. Our analysis suggests that some of the SPM originates from the resuspension of bottom sediments due to the reflection of the tsunami on the coastline that leads to the migration of marine particles toward the sea surface. The fate of the SPM concentration is then discussed based on the analysis of meteorological conditions, river discharge, and tsunami wave properties.

Sediment mobility in response to tidal and wind-driven flows along the Belgian inner shelf, southern North Sea

The effect of hydro-meteorological forcings (tidal and wind-induced flows) on the transport of suspended particulate matter (SPM), on the formation of high-concentrated mud suspensions and on the occurrence of sand–mud suspensions has been studied using long-term multi-parametric observations. Data have been collected in a coastal turbidity maximum area (southern North Sea) where a mixture of sandy and muddy sediments prevails. Data have been classified according to variations in subtidal alongshore currents, with the direction of subtidal flow depending on wind direction. This influences the position of the turbidity maximum; as such also the origin of SPM. Winds blowing from the NE will increase SPM concentration, whilst SW winds will induce a decrease. The latter is related to advection of less turbid English Channel water, inducing a shift of the turbidity maximum towards the NE and the Westerschelde estuary. Under these conditions, marine mud will be imported and buffered in the estuary. Under persistent NE winds, high-concentrated mud suspensions are formed and remain present during several tidal cycles. Data show that SPM consists of a mixture of flocs and locally eroded sand grains during high currents. This has implications towards used instrumentation: SPM concentration estimates from optical backscatter sensors will only be reliable when SPM consists of cohesive sediments only; with mixtures of cohesive and non-cohesive sediments, a combination of both optical and acoustic sensors are needed to get an accurate estimate of the total SPM concentration.

Geochemistry of Suspended Particulate Matter (SPM) in the Murray-Darling River System: A Conceptual Isotopic/Geochemical Model for the Fractionation of Major, Trace and Rare Earth Elements

A conceptual isotopic/geochemical model is presented to explain the variation of major, trace and rare earth element (REE) geochemistry and Sr isotope systematics in suspended particulate matter (SPM) as a function of particle/colloid size. This conceptual model is an extension of a previous investigation of the origin of SPM in the Murray-Darling River system (MDRS) that utilised Sr isotope systematics to examine aspects of SPM (particle/colloid) origin, structure and mineralogy. The geochemical processes that give rise to the often coherent trends in major, trace and REE geochemistry and Sr isotopic signature as a function of particulate ( 1 μm) size in the MDRS have been identified using an enhanced SPM size fractionation technique as a basis to not only obtain a broad range of particle/colloid size ranges, but also to provide sufficient material for subsequent geochemical and isotopic analysis. The conceptual isotopic/geochemical model proposed here contains three major components: (i) the differential weathering of micas and alkali (K-) feldspars to form the majority of the particulate ( 1 μm) fractions (low 87Sr/86Sr ratio), with a range of geochemical signatures related to the relative proportions of inorganic and organic constituents, and (iii) the presence of natural organic matter as coatings on the particulate ( 1 μm) matter and possibly as organo-colloids which exert an increasing influence in particular on bulk colloid geochemistry with decreasing colloid size. This conceptual isotopic/geochemical model also accounts for the distinct variation in major, trace and REE geochemistry and Sr isotopic systematics between the particulate ( 1 μm) fractions, the variation being primarily a function of the distinctly different precursor mineralogies of the SPM fractions and geochemical fractionation during the weathering and transport. Additionally, this model explains a systematic fractionation of REE apparent within colloidal (>1 μm) fractions. Statisitcal (hierachical cluster) analysis of two particulate and three colloidal fractions from 23 samples from the MDRS is used as a basis to investigate geochemical and mineralogical associations within the particulate and colloidal size fractions and to provide additional supporting evidence for the conceptual isotopic/geochemical model.

Physical and bacterial processes affecting suspended particulate matter in a tidal river

In order to clarify the origin and behavior of suspended particulate matter (SPM) in a tidal river, variation of SPM in a tidal river was investigated with regard to its size and constituents. SPM was separated into three groups according to size. Change of contents of titanium and organic substances of each group of SPM was examined. SPM which was discharged by run-off was transported with decomposition and sedimentation in a tidal river. Concentration of SPM with a particle size greater than 0.45 μm increased due to resuspension in a tidal river. Origin of SPM with a size of less than 0.45 μm at upstream areas was from natural soil and most of such SPM which had been transported settled near a river mouth. It was determined from examination of the CN ratio and the ratio of the number of attached bacteria to free bacteria that SPM with a size greater than 1.0 μm at upstream areas was decomposing intensively. At the downstream areas, SPM with a size of less than 0.45 μm came from the sea. SPM with particle size greater than 1.0 μm consisted of plankton and substances which were decomposed sufficiently while flowing.

Physical and bacterial processes affecting suspended particulate matter in a tidal river

In order to clarify the origin and behavior of suspended particulate matter (SPM) in a tidal river, variation of SPM in a tidal river was investigated with regard to its size and constituents. SPM was separated into three groups according to size. Change of contents of titanium and organic substances of each group Of SPM was examined. SPM which was discharged by run-off was transported with decomposition and sedimentation to a tidal river. Concentration of SPM with a particle size greater than 0.45 εm increased due to resuspension in a tidal river. Origin of SPM with a size of less than 0.45 εm at upstream areas was from natural soil and most of such SPM which had been transported settled nears river mouth. It was determined from examination of the CN ratio and the ratio of the number of attached bacteria to free bacteria that SPM with a size greater than 1.0 εm at upstream areas was decomposing intensively. At the downstream areas, SPM with a size of less than 0.45 εm came from the sea. SPM with particle size greater than 1.0 εm consisted of plankton and substances which were decomposed sufficiently while flowing.

A strontium isotopic investigation of the origin of suspended particulate matter (SPM) in the Murray-Darling River system, Australia

The strontium isotopic composition of suspended particulate matter (SPM) from the Murray-Darling River system (M-DRS) in eastern Australia varies significantly as a function of particle size. Colloidal matter ( < 1 μm) defines a linear trace (colloidal mixing line) on both 87Sr86Sr vs. 1/Sr mixing and 87Sr86Sr vs. 87Rb86Sr isochron diagrams indicating simple two component mixing; isotopic ratios decrease as a function of particle size (e.g., Murray River-Merbein, 87Sr86Sr = 0.7221−0.7160). This is the first time this type of mixing has been recognised in fluvial systems and highlights the influence of particle size on isotopic composition. The two components involved are detrital silicate grains (aggregates) and varying amounts of natural organic matter present as surface coatings. The proportion of natural organic matter increases from approximately 10–80% with decreasing particle size. The natural organic matter contains high concentrations of unradiogenic Sr which has been complexed from solution (e.g., Murray River-Merbein, 87Sr86Sr = 0.7164). Particulate fractions (>1 μm) are dominated by the silicate component and are isotopically heterogeneous and displaced from the colloidal mixing lines, with distinctly more radiogenic Sr (e.g., Murray River-Merbein, 87Sr86Sr = 0.7316−0.7354). The variation in the strontium isotopic composition is due to the differential weathering of minerals in the sediment source. Weathering of plagioclase produces unradiogenic Sr which dominates the colloidal and dissolved (<0.003 μm) fractions; the particulate fractions are mainly produced by the weathering of relatively radiogenic K-feldspar and mica. The Murray and Darling River systems have dramatically different ranges of 87Sr/86Sr; 0.7160–0.7316 and 0.7076–0.7114 respectively, due to differences in the composition and ages of rocks in their catchments. The total SPM (>0.003 μm) and dissolved (<0.003 μm) fractions contain much less radiogenic Sr and higher [Sr] and lower [Rb] concentrations than mean estimates of the catchment rocks. Relative to “World Average” estimates, the M-DRS has similar 87Sr86Sr and [Sr] concentration, but markedly lower [Rb] concentration and Rb/Sr.