Understanding Sorption Behavior and Properties of Radionuclides in the Environment

Prediction of fate and behavior of radionuclides in the environment is largely governed by sorption processes. Radionuclides physico-chemical species interacting with prevailing abiotic properties of the environment vary widely among varying constituting environmental components. Herein, this work discussed the most significant aspects of sorption processes and properties at the solid-water interface. Main sorption mechanisms were investigated using kinetic, thermodynamic analyses, and various mathematical models in current use for description of sorption–desorption processes in the environment. Knowledge of environmental transport, environmental pathways, and exposure pathways to radionuclides is also an important aspect of any strategy to protect the public and the natural ecosystems. In the final analysis, the choice of a functional sorption equation model will be dictated by the risk-based under consideration, the level of information available, and the intrinsic accuracy of the predictive model

Ex Situ Surfactant-Enhanced Bioremediation of NAPL-Impacted Vadose Zone

This work presents a review of surfactant-enhanced bioremediation of hydrophobic organic contaminants in the soil with a focus on ex situ method. Conventional strategies of disposal methods in secure landfill and incineration have become cost prohibitive and environmentally risky and do not restore the contaminated soil, whereas chemical and physical methods have shown very limited success and can also be expensive.Traditional bioremediation pertaining to remedial technology of hydrophobic organic contaminants in soil has empirically demonstrated limited success due to their low aqueous solubility. Addition of single synthetic surfactant or biosurfactant, or in combination, has the potential to increase their mass transfer phase, hence their bioavailability. Surfactant-enhanced biodegradation represents a promising cost-effective alternative to complete mineralization of hydrophobic organic contaminants in soil. In this work, the potential of surfactants on the remediation of contaminated soil in an ex situ approach is reviewed with considerations given to the practical aspects of field components. Surfactant-enhanced biodegradation represents a promising cost-effective alternative to complete mineralization of hydrophobic organic contaminants in soil. In this work, the potential of surfactants on the remediation of contaminated soil in an ex situ approach is reviewed with considerations given to the practical aspects of field components

Surfactants and Their Applications for Remediation of Hydrophobic Organic Contaminants in Soils

Soil contaminated with ubiquitous hydrophobic organic contaminants (HOCs) is a worldwide recurring concern arising from their indiscriminate disposal, improper management, and accidental spills. A wide range of traditional remedial strategies have been the common practice. However, these treatment methods have become cost prohibitive, not environmental friendly, and less accepted by society. Surfactant-enhanced remediation technology represents a cost-effective and green technology alternative to remediate such contaminated sites. Surfactant remediation technologies are conducted in-situ or ex-situ as two broad categories, or in combination. Among these technologies are soil flushing, washing, phytoremediation, and bioremediation. More applied research continues to quantify the efficiency of surfactant-enhanced mass transfer phase using a single surfactant solution while their binary blends to remove mixed HOCs in soils are also a focus of interest for research. There is a great potential to develop novel synthetic and biosurfactants that will exhibit higher biodegradability, less toxicity, higher removal efficiency, more economical and more recyclable. This work thus provides a review of the applications and importance of surfactant-enhanced remediation of soil contaminated with HOCs. Relevant environmental factors, soil properties, surfactant chemistry, mechanisms, mass transfer phase, and field designs are summarized and discussed with purposes of providing greater context and understanding of surfactant-enhanced remediation systems

Evaluation of laboratory procedures for prediction of available soil nitrogen in Nebraska

Soil organic matter decomposition and the resulting mineralization of N is a source of plant-available N seldom considered in the US when making fertilizer recommendation, and may contribute to a significant portion of the soil NO\sb3-pool. Large mineral N pools created by excessive fertilization and soil organic N mineralization may lead to less efficient use of N and potential for N pollution of the nation\u27s surface and ground water. Although several soil N availability indexes have been set forth, none of those tests have gained cohesive acceptance in terms of commercial application. Electro-ultrafiltration (EUF) is one such procedure that has been recently proposed to effectively quantify soil potentially mineralizable N. The technique is based on vacuum extraction of a soil-water suspension at different voltages and temperatures across anode and cathode. This procedure provides for extraction of NO\sb3\sp- and NH\sb4\sp+ and of readly soluble N compounds from soils using the principles of ultrafiltration and electrodialysis. The investigation encompassed both laboratory and field study. Nitrogen availability indexes differed in the amount of N extracted for a group of Nebraska surface soils. The data showed a correlation coefficient of 0.71 between the results obtained with the waterlogged method and those achieved using the EUF technique. However, the autoclave, KCl, pH 11.2 phosphate-borate buffer, and NaHCO\sb3-UV methods were more highly correlated (r $\geq$ 0.87) with the EUF technique than was the waterlogged method. The results obtained with the alkaline KMnO\sb4 method yielded the lowest correlation coefficient (r = 0.25) with the EUF technique. The slopes of the regression equations between EUF and the chemical indexes tested indicated that the EUF procedure was a relatively stronger extractant than the KCl method. Soil organic N mineralized determined by plant N uptake varied between geographical locations and ranged from 16 to 174 kg ha\sp{-1}. $\Sigma$EUF-N\sb{\rm organic} correlated poorly (r = 0.03) with total N uptake for four different locations. Multiple regression including $\Sigma$EUF-N\sb{\rm NO3}, $\Sigma$EUF-N\sb{\rm organic} and growing degree days as independent variables resulted in a high correlation (r = 0.95) with total N uptake. Within each field location, $\Sigma$EUF-N\sb{\rm extractable} correlated well with total N uptake (r $\geq$ 0.75). Autoclave Labile-N + residual NH\sb4- + NO\sb3-N exponentially correlated (r = 0.90) with total N uptake for all sites. Potentially mineralizable N differed widely in the amounts of N extracted from soils under various land treatments. Total NO\sb3-N loading to a depth of 9.50 m in the soil profiles associated with various kinds of land use was feedlot $\u3e$ irrigated corn fields $\u3e$ lawn $\u3e$ grassland. The data showed that the amount of NO\sb3-N moving through the vadose zone was very small under native grassland and urban lawns. In contrast, the potential for ground water pollution appeared relatively high under the feedlot and irrigated corn fields receiving manure and fertilizer N