Estuarine trace metal distributions in Galveston Bay: importance of colloidal forms in the speciation of the dissolved phase

Wen, Liang; Santschi, Peter H.; Gill, Gary A.; Paternostro, Christopher

doi:10.1016/s0304-4203(98)00062-0

Cited by 250 publications

(247 citation statements)

References 71 publications

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“…Figure 6 shows that the concentrations of Cu and Cd in the soil fractions are highly correlated with their respective OC content. This finding suggests that Cu is complexed with organic matter (Wen et al 1999). The high affinity of Cd for organic ligands, however, is inconsistent with the results from other studies (Zhou and Wangersky 1989).…”

Section: Cff Performancementioning

confidence: 57%

Size fractionation and characterization of nanocolloidal particles in soils

Zhi-yun

Luo

et al. 2008

Environ Geochem Health

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A protocol was developed to fractionate soil particles down to the nanocolloid scale by combining sieving, sedimentation, centrifugation, and cross-flow filtration (CFF). The validity of the method and the performance of the CFF system were tested by characterizing fractions using laser granulometry, electron microscopy, and chemical analysis. The 0.1-lm-pore-size membrane CFF system effectively retained nanocolloids (\0.1 lm) as shown by laser granulometry and observed directly by transmission electron microscopy. However, environmental scanning electron microscopy images of freeze-dried colloids were very different from their TEM counterparts, suggesting that sample preparation influenced microscopy imaging. Chemical analysis of Cu, Cd, and organic carbon in each fraction showed that the concentrations of these components increased as particle size decreased, indicating colloids and nanocolloids play an important role in retaining trace metals. Particle-size fractionation combined with chemical analysis and electron microscopy can provide insight into the nature and properties of nanocolloids in soil.

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Section: Cff Performancementioning

confidence: 57%

Size fractionation and characterization of nanocolloidal particles in soils

Zhi-yun

Luo

et al. 2008

Environ Geochem Health

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“…One of the processes is the adsorption-desorption of trace metals in estuarine mixing zones. Salinity and pH have been found to strongly affect mobility and flux rates of trace metals [13] when they are carried by rivers to various estuarine/coastal systems around the world; for instance, in the Galveston Bay estuary in Texas [14], the San Francisco Bay Estuary in California [15], the Changjiang Estuary in China [16,17], the Bang Pakong Estuary in Thailand [18], the Scheldt Estuary in the Netherlands [19], and the Conwy Estuary in North Wales [20]. The ongoing saltwater intrusion in the world's estuaries may shift metal mobilization and precipitation landwards, the occurrence and effects of which are not well investigated.…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal Distributions of Sr and Ba along an Estuarine River with a Large Salinity Gradient to the Gulf of Mexico

2016

Water

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Strontium and barium to calcium ratios are often used as proxies for tracking animal movement across salinity gradients. Many estuarine rivers face saltwater intrusion due to sea level rise, potentially causing changes in mobility and distribution of these metals upstream. From May 2013 to August 2015, monthly water samples were collected and in-situ measurements were performed at six sites along an estuary strongly affected by saltwater intrusion, the Calcasieu River, with salinity ranging from 0.02 to 29.50 Parts Per Thousand (ppt). Results showed that the total Sr concentration and the Sr/Ca ratio both increased significantly with increasing salinity. The average Sr concentration at the site closest to the Gulf of Mexico (Site 6) was 46.21 µmol/L, about 130 times higher than that of the site furthest upstream (Site 1, 0.35). The average Sr/Ca ratio at Site 6 (8.41 mmol/mol) was about three times the average Sr/Ca ratio at Site 1 (2.89). However, the spatial variation in total Ba concentration was marginal, varying from 0.36 to 0.47 µmol/L. The average Ba/Ca ratio at Site 1 (4.82 mmol/mol) was about 54 times the ratio at Site 6 (0.09), showing a negative relation between the Ba/Ca ratio and salinity. All elemental concentrations and ratios had considerable seasonal variations, with significant differences among sampling months for the Sr and Ba concentrations and the Ba/Ca ratio (p < 0.01). The results suggest that for low-gradient estuarine rivers such as the Calcasieu River, water chemistry upstream would experience substantial Sr and Ca enrichment, potentially affecting aquatic environments and biological communities.

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“…As proporções destas formas variam para os diferentes metais e para os diferentes sistemas como resultado de condições ambientais locais como a litologia, biota, pH e o potencial redox. 57,58 No entanto, como resultado dos processos de adsorção/desorção as partículas finas e a matéria orgânica, floculação e coagulação de espécies coloidais, a fração particulada é enriquecida e tende a ocorrer a acumulação nos sedimentos, onde a concentração é muito maior do que na água. Mais do que 50%, e até 99.9%, do total de metais presentes nas águas naturais está usualmente adsorvido a partículas em suspensão, o que é particularmente relevante quando da avaliação da descarga de metais em rios.…”

Section: Figura 10 Razão De Silício E Nitrogênio Inorgânicos Dissolvunclassified