The chemical interactions of hydrophobic organic contaminants (HOCs) with soils and sediments (geosorbents) may result in strong binding and slow subsequent release rates that significantly affect remediation rates and endpoints The underlying physical and chemical phenomena potentially responsible for this apparent sequestration of HOCs by geosorbents are not well understood This challenges our concepts for assessing exposure and toxicity and for setting environmental quality criteria Currently there are no direct observational data revealing the molecular-scale locations in which nonpolar organic compounds accumulate when associated with natural soils or sediments Hence macroscopic observations are used to make inferences about sorption mechanisms and the chemical factors affecting the sequestration of HOCs by geosorbents Recent observations suggest that HOC interactions with geosorbents comprise different inorganic and organic surfaces and matrices, and distinctions may be drawn along these lines,

Sequestration of hydrophobic organic contaminants by geosorbents

The effect of organic and inorganic fertiliser amendments is often studied shortly after addition of a single dose to the soil but less is known about the long-term effects of amendments. We conducted a study to determine the effects of long-term addition of organic and inorganic fertiliser amendments at low rates on soil chemical and biological properties. Surface soil samples were taken from an experimental field site near Cologne, Germany in summer 2000. At this site, five different treatments were established in 1969: mineral fertiliser (NPK), crop residues removed (mineral only); mineral fertiliser with crop residues; manure 5.2 t ha −1  yr −1 ; sewage sludge 7.6 t ha −1  yr −1 or straw 4.0 t ha −1  yr −1 with 10 kg N as CaCN 2  t straw −1 . The organic amendments increased the C org content of the soil but had no significant effect on the dissolved organic C (DOC) content. The C/N ratio was highest in the straw treatment and lowest in the mineral only treatment. Of the enzymes studied, only protease activity was affected by the different amendments. It was highest after sewage amendment and lowest in the mineral only treatment. The ratios of Gram+ to Gram− bacteria and of bacteria to fungi, as determined by signature phospholipid fatty acids, were higher in the organic treatments than in the inorganic treatments. The community structure of bacteria and eukaryotic microorganisms was assessed by denaturing gradient gel electrophoresis (DGGE) and redundancy discriminate analyses of the DGGE banding patterns. While the bacterial community structure was affected by the treatments this was not the case for the eukaryotes. Bacterial and eukaryotic community structures were significantly affected by C org content and C/N ratio.

Structure and function of the soil microbial community in a long-term fertilizer experiment

The partition behavior was determined for three polycyclic aromatic hydrocarbons (PAHs), i.e., naphthalene, phenanthrene, and pyrene, from water to a range of soil and sediment samples. The measure...

Partition characteristics of polycyclic aromatic hydrocarbons on soils and sediments

The binding of pyrene to a number of humic substances isolated from various aquatic sources and a commercial humic acid was measured using the solubility enhancement method. The humic materials used in this study were characterized by various spectroscopic and liquid chroma tography methods. A strong correlation was observed between the pyrene binding coefficient, Kdoc, and the molecular weights, molar absorptivities at 280 nm, and aromaticity of the aquatic humic substances. Binding of pyrene to the commercial humic acid, however, was significantly stronger and did not obey the relationships observed between Kdoc and the chemical properties of the aquatic humic substrates. These results suggest that the molecular weight and the aromatic content of the humic substrates exert influences on the binding of nonpolar and planar aromatic molecules and that the physicochemical properties of both humic materials and organic solutes are important in controlling the speciation of nonpolar organic contaminants in na...

Binding of pyrene to aquatic and commercial humic substances: The role of molecular weight and aromaticity

Sorption of pyrene on various types of natural organic matter (NOM) varying in chemical composition (e.g. high aliphaticity or aromaticity) was examined in batch sorption studies. The NOM samples (cuticle, humin, humic acid, degraded lignin, peat and lignite) were characterized by elemental analyses and solid-state 13C NMR spectra. Previous studies on polycyclic aromatic hydrocarbons (PAHs) sorption on soils and sediments led to the conclusion that aromatic component of the NOM determines the binding of nonionic compounds and that the polarity of the NOM reduces the binding coefficient of the aromatic NOM moieties. In this study we tested the hypothesis that aliphatic moieties of NOM derived from soils or sediments can contribute significantly to the binding of PAHs in aqueous media. Cuticle and a humin sample from an algal deposit exhibited the highest distribution coefficients (Koc). Both samples were rich in aliphatic structures and had very low aromaticity (4.6 and 8.8% for cuticle and humin samples, ...

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Pyrene Sorption by Natural Organic Matter

Solubility enhancement and fluorescence quenching of pyrene by humic substances : the effect of dissolved oxygen on quenching processes

Response to Comment on ``Solubility Enhancement and Fluorescence Quenching of Pyrene by Humic Substance: The Effects of Dissolved Oxygen on Quenching Processes''

Water and wastewater utilities that track emerging contaminants in response to upcoming regulations can learn from a Michigan community's forward-thinking approach. 

Karlin M. Danielsen

Papers

Binding of pyrene to aquatic and commercial humic substances: The role of molecular weight and aromaticity

Solubility enhancement and fluorescence quenching of pyrene by humic substances : the effect of dissolved oxygen on quenching processes

Response to Comment on ``Solubility Enhancement and Fluorescence Quenching of Pyrene by Humic Substance: The Effects of Dissolved Oxygen on Quenching Processes''

Use Proactive PFAS Source Tracking to Prepare for Future Regs