Partition coefficients for metals in surface water, soil, and waste

The interactions between contaminations of U(VI) and silicon oxide nanoparticles (SONPs), both of which have been widely used in modern industry and induced serious environmental challenge due to their high mobility, bioavailability, and toxicity, were studied under different environmental conditions such as pH, temperature, and natural organic matters (NOMs) by using both batch and spectroscopic approaches. The results showed that the accumulation process, i.e., sorption, of U(VI) on SONPs was strongly dependent on pH and ionic strength, demonstrating that possible outer- and/or inner-sphere complexes were controlling the sorption process of U(VI) on SONPs in the observed pH range. Humic acid (HA), one dominated component of NOMs, bounded SONPs can enhance U(VI) sorption below pH~4.5, whereas restrain at high pH range. The reversible sorption of U(VI) on SONPs possibly indicated that the outer-sphere complexes were prevalent at pH 5. However, an irreversible interaction of U(VI) was observed in the presence of HA (Fig 1). It was mainly due to the ternary SONPs-HA-U(VI) complexes (Type A Complexes). After SONPs adsorbed U(VI), the particle size in suspension was apparently increased from ~240 nm to ~350 nm. These results showed that toxicity of both SONPs and U(VI) will decrease to some extent after the interaction in the environment. These findings are key for providing useful information on the possible mutual interactions among different contaminants in the environment.

/pdf/interactions-between-silicon-oxide-nanoparticles-sonps-and-u-2w0tq5s900.pdf

Interactions between Silicon Oxide Nanoparticles (SONPs) and U(VI) Contaminations: Effects of pH, Temperature and Natural Organic Matters

Testing Models of Chemical Speciation in Freshwaters

Marine sediment cores sampled in three different areas, during the 1997/98 Italian Antarctic Expedition, were studied. The cores (40 cm) were immediately subdivided into 13 or 14 layers (2–4 cm) in order to obtain a high-depth resolution in the metal content and humic substance analyses. The results obtained for the amount of metals strongly bound to humic acids showed the following order: Cu ≫ Zn ≫ Co > As ≥ Mn. The fraction of Cu, Zn and As bound to humic acid (μg g−1 of HA) increases in the first 10–12 cm of cores, then a decrease is observed. This observation could be related both to the presence of a mobile fraction of metals in sediments successively bound to humic acids and to different structural features showed by humic acids along the cores, due to transformation processes. For the other metals a variable pattern along the cores was found.

Copper and other trace elements strongly bound to humic acids along sediment cores in the Ross Sea, Antarctica.

Die Ackerhumusformen: Kryptomull, Wurmmull und Ackermoder wurden aus den Definitionen fur „Ochric”, „Mollic” und „Umbric” der Soil Taxonomy und der FAO-Klassifikation abgeleitet, um die Standortokologie naher zu charakterisieren. 45 Oberboden unter landwirtschaftlicher Nutzung wurden diesen Humusformen zugeordnet und Aufbau und Zusammensetzung ihrer organischen Substanz mittels naschemischer Verfahren und CPMAS 13C-NMR- Spektroskopie untersucht. Wurmmull bedeutet einen hoheren Carbonyl-bzw. Carboxylanteil aus Proteinen, Polysacchariden und Huminstoffen gegen-uber Ackermoder. Die Wurmmull-Horizonte besitzen daruber hinaus 10% mehr Streustoffe als die Ackermoder-Horizonte. In diesen dominieren die Huminsauren, die bei der Humusform Wurmmull als Humine vorliegen. Im Wurmmull stehen mehr leicht abbaubare Substanzen zur Verfugung als abgebaut werden. Der humusarme Kryptomull zeigt einen erhohten Anteil an leichtloslichen Verbindungen und einen erhohten Aromaten- und Carboxylgehalt der Huminstoffe. Die Ergebnisse zeigen, das sich Quantitat und Qualitat der organischen Bodensubstanz bei den untersuchten Ackerhumusformen deutlich voneinander unterscheiden. Die vorgeschlagene Differenzierung im Rahmen der Bodenaufnahme ackerbaulich genutzter Boden (Blume & Beyer, 1996) sollte als Diskussionsgrundlage fur die Entwicklung und spatere Ausweisung von Ackerhumusformen behandelt werden, um spezifische Aussagen zur Standortokologie bzw. -qualitat machen zu konnen.



The definition of humusforms from soils under cultivation. II. Quantity and quality of soil organic matter



In the new edition of the German textbook “Practical Studies in Soil Science” the authors presented a proposal of mapping humusforms in arable soils in order to characterize soil and site ecology (Schlichting et al., 1995). This proposal was developed from the definitions “Ochric”, “Mollic” and “Umbric” of the Soil Taxonomy and the FAO classification.



The characterization of humusforms in 45 arable surface soils was carried out according to this proposal while soil organic matter (SOM) composition was investigated by means of wet chemistry and CPMAS 13C-NMR spectroscopy. “Mollic” in contrast to “Umbric” humusforms could be characterized by a higher carbonyl/carboxyl carbon content probably deriving from proteins, polysaccharides and humic substances. In addition the mollic epipedon contains 10% more litter compounds, whereas in the umbric epipedon humic acids are of major importance. The humin fraction in the mollic epipedon is thought to be raised by the formation of Ca-humates. Our data suggest, that with regard to microbial decomposition a surplus of available organic matter is present in the mollic horizons. The ochric-like epipedon has a much lower humus content compared to “Mollic” and “Umbric” horizons and exhibits the highest amounts of soluble organic matter as well as aromatic and carboxylic C-compounds in the humic fraction. Our data suggest, that SOM quantity and quality of the mollic, umbric and ochric epipedons differ substantially. These findings suggest that the proposal of Schlichting et al. (1995), which was extended by Blume & Beyer (1996), should be regarded as a useful basis to discuss the development of humusforms in soils under cultivation and facilitate soil survey in order to improve site characterization.

Zur Definition von Humusformen ackerbaulich genutzter Böden. II. Quantität und Qualität der organischen Bodensubstanz

Modelling of cation binding by natural organic matter in soils and waters

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Modelling of cation binding by natural organic matter in soils and waters