Recent progress on in-situ chemical oxidation for the remediation of petroleum contaminated soil and groundwater.

Accidental oil leaks and spills can often result in severe soil and groundwater pollution. In situ chemical oxidation (ISCO) is a powerful and efficient remediation technology. In this review, the applications and recent advances of three commonly applied in-situ oxidants (hydrogen peroxide, persulfate, and permanganate), and the gap in remediation efficiency between lab-scale and field-scale applications is critically assessed. Feasible improvements for these measures, especially solutions for the 'rebound effect', are discussed. The removal efficiencies reported in 108 research articles related to petroleum-contaminated soil and groundwater were analyzed. The average remediation efficiency of groundwater (82.7%) by the three oxidants was higher than that of soil (65.8%). A number of factors, including non-aqueous phase liquids, adsorption effect, the aging process of contaminants, low-permeability zones, and vapor migration resulted in a decrease in the remediation efficiency and caused the residual contaminants to rebound from 19.1% of the original content to 57.7%. However, the average remediation efficiency of ISCO can be increased from 40.9% to 75.5% when combined with other techniques. In the future, improving the utilization efficiency of reactive species and enhancing the contact efficiency between oxidants and petroleum contaminants will be worthy of attention. Multi-technical combinations, such as the ISCO coupled with phase-transfer, viscosity control, controlled release or natural attenuation, can be effective methods to solve the rebound problem.

Global transcriptional profiling in porcine mammary glands from late pregnancy to peak lactation.

Sow milk yield and quality is crucial for the survival and growth of piglets. To understand the molecular mechanisms of lactogenesis and lactation, mammary tissue samples were taken from six sows at -17(±2), 1 and 17(±2) days relative to parturition. Mammary tissues from two sows in the same stage were used to extract RNA, which were subsequently pooled in equal amounts. Nine pooled samples were hybridized to porcine Affymetrix GeneChips. Totally 1,524 genes were detected as significantly differentially expressed over the time course tested (p<0.01, q<0.01, fold change≥2 or ≤-2), including 709 upregulated and 575 downregulated genes identified at peak lactation compared to late pregnancy. Gene ontology analysis revealed that most of the upregulated genes were involved in transport, biosynthetic processes, and homeostasis, whereas most of the downregulated genes were involved in intracellular signaling cascades, cell cycle, and DNA replication. Furthermore, we identified 64 differentially expressed genes of the solute carrier families. Taken together, our microarray analysis provides insights into previously uncharacterized changes in transcriptome between late pregnancy and peak lactation in the porcine mammary gland. The solute carrier genes and other differentially expressed genes identified in this study will guide further characterization of their function to enhance milk yield and piglet growth.

[Sorption of 1-naphthol to plant cuticular waxes with different states].

Wax components are ubiquitous in natural environments (such as plant and soil) and play a significant role in sorption of organic contaminants. To elucidate their sorption characteristics, cuticular waxes were isolated from the fruits of apple by organic solvent extraction method, and then the isolated-wax was reconstructed on montmorillonite with different loadings. Sorption behaviors of one polar organic pollutant, 1-naphthol, to isolated-wax, reconstructed-wax, and cuticle-associated-wax samples were compared by batch sorption method. Sorption properties of wax-montmorillonite complexes dependent on different wax-loadings were also investigated. Isotherms of 1-naphthol to wax samples were nonlinear, and fitted well with Freundlich equation. Although sorption of wax in the plant cuticle was weakened by other components of cuticle, its contribution to whole sorption of the cuticle increased with solute aqueous equilibrium concentration. Sorption coefficients at three equilibrium concentrations (1, 10, 100 microg/mL) were calculated, depending on solute concentrations and wax-loadings. Sorption coefficients normalized organic carbon contents (Koc) decreased with the increase of solute aqueous concentration. At low solute aqueous concentration, Koc values increased with the wax-loading increasing, reached maximum, and then decreased. At high solute aqueous concentration, Koc values were almost independent on wax-loadings. These observations indicated that partition was the dominant mechanism at high solute concentration, while specific interactions were involved as additional mechanisms at low solute concentration. Koc values of wax components in different states were in the order of reconstructed-wax (321.2) > isolated-wax (190.4) > cuticular-attached-wax (128.4), suggested that the sorption capability of wax was promoted once they were input into soil environment and then coated on mineral surface.

Sorption of 1-naphthol by plant cuticular fractions.

The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because of their preservation and accumulation in the soil environment, but sorption mechanism is still not fully understood. In this study, sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction. Toward this end, cuticular materials were isolated from the fruits of tomato by chemical method. The tomato cuticle sheet consisted of waxes (6.5 wt%), cuticular monomer (69.5 wt%), and polysaccharide (24.0 wt%). Isotherms of 1-naphthol to the cuticular fractions were nonlinear (N value (0.82 - 0.90)) at the whole tested concentration ranges. The K(oc)/K(ow) ratios for bulk cuticle (TC1), dewaxed cuticle (TC2), cutin (TC4), and desugared cuticle (TC5) were larger than unity, suggested that tomato bulk cuticle and cutin are much powerful sorption medium. Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3). The 1-naphthol interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions. Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of the cuticular material. There was a linear negative trend between K(oc) values and the amount of polysaccharides or fraction's polarities ((N+O)/C); while a linear positive relationship between K(oc) values and the content of cutin monomer (linear R2 = 0.993) was observed for present in the cuticular fractions. Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction was the cutin monomer, contributing to 91.7% of the total sorption of tomato bulk cuticle.

Thermodynamics of phenanthrene partition into solid organic matter from water.

The thermodynamic behavior of organic contaminants in soils is essential to develop remediation technologies and assess risk from alternative technologies. Thermodynamics of phenanthrene partition into four solids(three soils and a bentonite) from water were investigated. The thermodynamics parameters (deltaH, deltaG degrees, deltaS degrees) were calculated according to experimental data. The total sorption heats of phenanthrene to solids from water ranged from -7.93 to -17.1 kJ/mol, which were less exothermic than the condensation heat of phenanthrene-solid (i.e., -18.6 kJ/mol). The partition heats of phenanthrene dissolved into solid organic matter ranged from 23.1 to 32.2 kJ/mol, which were less endothermic than the aqueous dissolved heat of phenanthrene (i.e., 40.2 kJ/mol), and were more endothermic than the fusion heat of phenanthrene-solid (i.e., 18.6 kJ/mol). The standard free energy changes, deltaG degrees, are all negative which suggested that phenanthrene sorption into solid was a spontaneous process. The positive values of standard entropy changes, deltaS degrees, show a gain in entropy for the transfer of phenanthrene at the stated standard state. Due to solubility-enhancement of phenanthrene, the partition coefficients normalized by organic carbon contents decrease with increasing system temperature (i.e., ln Koc = -0.284 ln S + 9.82 (n = 4, r2 = 0.992)). The solubility of phenanthrene in solid organic matter increased with increasing temperatures. Transports of phenanthrene in different latitude locations and seasons would be predicted according to its sorption thermodynamics behavior.

[Survey sources of polycyclic aromatic hydrocarbons in surface water of Hangzhou by K(OC)* values].

Ten polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in 9 surface water samples of Qiantang River and Hangzhou Canal in Hangzhou, China, in December of 2002. It was observed that the sum of PAHs concentrations ranged from 1.104 to 9.663 microg x L(-1) in surface water, from 132.7 to 7343 microg x kg(-1) dry sediments, and from 59.71 to 219.5 microg x kg(-1) dry soils. The accumulative coefficients of PAHs in sediments and soils (K) and apparent partition coefficients normalized by solid organic carbon contents (K(OC)*) were calculated. In Hangzhou Canal, K and K(OC)* values in sediments increased with downstream, and ratio of K(OC)* on sediment to K(OC)* on soil were much larger than 1. Those indicated that Hangzhou Canal was heavily polluted by PAHs released from factory wastewater and PAHs in sediment were mainly sources of PAHs in surface water. In Qiantang River, K and K(OC)* values in sediments decreased with the downstream, and the ratio of K(OC)* on sediment to K(OC)* on soil near 1, and ratio fOC of sediment to fOC of soil approximate to 1, which showed that PAHs in Qiantang River were attributed to soil runoff.

Chemical behavior of organic compounds in the interface of water/dual-cation organobentonite.

The sorption behavior of polar or ionizable organic compounds, such as p-nitrophenol, phenol and aniline, in the water/organobentonite systems is investigated. Both adsorption and partition occur to the sorption of organic compounds to dual-cation organobentonites. The separate contributions of adsorption and partition to the total sorption of organic compounds to dual-cation organobentonites are analyzed mathematically in the first time. The factors to the contributions are also discussed. The results indicated that the contribution of adsorption and partition is related to the composition and ratio of dual-cation surfactants exchanging onto the bentonite. The sorption of organic compounds to dual-cation organobentonite is dominated by adsorption at low concentrations and by partition at high concentrations, making the organobentonites powerful sorbents for organic contaminants over wide range of concentrations.