Worldwide regulatory frameworks for the assessment and remediation of contaminated soils have moved towards a risk-based approach, taking contaminant bioavailability into consideration. However, there is much debate on the precise definition of bioavailability and on the standardization of methods for the measurement of bioavailability so that it can be reliably applied as a tool for risk assessment. Therefore, in this paper, we reviewed the existing definitions of heavy metal bioavailability in relation to plant uptake (phytoavailability), in order to better understand both the conceptual and operational aspects of bioavailability. The related concepts of specific and non-specific adsorption, as well as complex formation and organic ligand affinity were also intensively discussed to explain the variations of heavy metal solubility and mobility in soils. Further, the most frequently used methods to measure bioavailable metal soil fractions based on both chemical extractions and mechanistic geochemical models were reviewed. For relatively highly mobile metals (Cd, Ni, and Zn), a neutral salt solution such as 0.01 M CaCl2 or 1 M NH4NO3 was recommended, whereas a strong acid or chelating solution such as 0.43 M HNO3 or 0.05 M DTPA was recommended for strongly soil-adsorbed and less mobile metals (Cu, Cr, and Pb). While methods which assessed the free metal ion activity in the pore water such as DGT and DMT or WHAM/Model VI, NICA-Donnan model, and TBLM are advantageous for providing a more direct measure of bioavailability, few of these models have to date been properly validated.

Understanding of the aquifer hydraulic properties and hydrochemical characteristics of water is crucial for management plan and study skims in the target area, and flow motions and chemical species of groundwater are regarded as precious information on the geological history of the aquifers and the suitability of various usages. Cations and anions of groundwater are used to estimate the characteristics and origin of groundwater. In this study, we try to evaluate the quality of groundwater based on the comparison of the physiochemical characteristics and distribution of cations and anions in groundwater from rural areas. Therefore we focused on the evaluation of groundwater as some specific purposes such as agricultural and industrial use, general types of groundwater, lithological origin of chemical component in groundwater. In this point of view, major objectives of this study were grouped as following three categories: 1) quality assessment of groundwater as a special usage (agricultural, industrial); 2) determination of groundwater types; 3) tracing of ion sources of groundwater. The quality of agricultural water was evaluated using SAR, sodium (%), RSC, PI, SSP, MH, PS, and Kelly's ratio, and was classified as SAR (Excellent (100%)), Sodium ((Excellent (34%), Good (55%), Permissible (9%), Doubtful (1.6%), Unsuitable (0.4%)), RSC (Good (95.7%), Medium (3.5%), Bad (0.8%)), PI((Excellent (40.6%), Good (59%), Unsuitable (0.4%)), SSP ((Excellent (26.3%), Good (59.8%), Fair (13.1%), Poor (0.8%)), MH ((Acceptable (94.4%), Non-Acceptable (5.6%)), Kelly's Ratio ((Permissible (93%), NonPermissible (7%)), PS ((Excellent to Good (98%), Good to Injurious (1.2%), and Injurious to Unsatisfactory (0.2%)). Evaluation based on the Wilcox diagram was classified as "excellent to good" or "good to permissible", and the water quality evaluated using the U.S. salinity Laboratory's Diagram was classified as C1S1 (Excellent/Excellent) and C2S1 (Good/Excellent). And, in the applications of two factors of Langelier Saturation Index (LSI) and Corrosive ratio (CR), we could get similar results for defining the suitabilities of groundwater for the industrial purpose. And the groundwater samples were also clas- Ca -HCO + − type. And, estimation of dominance type (evaporation, rock, precipitation) based on the Gibbs diagram showed that the origin of anion and cation in groundwater are from the rock-do-minance, and the estimation of origin of anions using the Chadha diagram showed that the most of the ionic species was originated from the interactions between alkaline earths and alkali metals contained in the soil. And through the source-rock deduction followed by the comparison of Gibbs and Chadah diagram, it was shown that the chemical components in the groundwater were mostly induced from the water-rock deduction and major types of groundwater samples following the Chadah diagram were categorized such as following group types: dolomite type, gypsum type, alkaline and alkaline earth type.

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Methyl tert-butyl ether (MTBE) is added to gasoline to enhance the octane number of gasoline, tert-butyl alcohol (TBA) is major degradation intermediate of MTBE in environment, and benzene, toluene, ethyl benzene and xylene (BTEX) are also major constituents of gasoline. In this study, a simplified headspace analysis method was adapted for simultaneous determination of MTBE, TBA and BTEX in ground water samples. The sample 5.0 mL and 2 g NaCl were placed in a 10 mL vial and the solution was spiked with fluorobenzene as an internal standard and sealed with a cap.

Review: 183 refs.

The variation patterns of groundwater mobility and chemical distribution are regarded as a very important factor for determining the geochemical features and therefore, the classifications of groundwater based on the chemical properties are highly valued for the expansion of study areas for setting up the regulations and management plans of governmental level for the preservation of local groundwater. Based on these prerequisites, in this study we focused on the evaluations, the comparison of the physiochemical characteristics and distribution of cations and anions in groundwater samples sampled in rural areas of Korea. The major goals of this study were classified as four categories such as followings; 1. On-site monitoring of groundwater qualities by instrumental and laboratory experiment, 2. Classifications of groundwater by using of Piper, Gibbs and Chadah diagram methods, 3. Tracking of the origins of anions and cations by using of rock-dominance types and relative ionic distributions. As a result of this study, the classifications of groundwater based on the Piper diagram showed that the groundwater type is grouped as the Ca In the applications of CAI 1 and CA 2, the negative values were more dominance than positive values so there might be reverse ion reaction between groundwater and rock-soils. Finally, by the carbonate weathering, silicate weathering and evaporation diagrams there were more complex mechanisms in chemical evolutions induced by the lithological influences such as weathering processes, ion exchange and other anthropogenic sources.

In order to develop liquid fertilizer using rendering by-product, rates and velocities of degradation from rendering by-product using pig cadaver investigated under different amount of injection and time with degradation agents (KOH, NaOH, HNO 3 and H 2 SO 4 ). The amount of residue by degradation agent of HNO 3 treatment method was higher than that in KOH, NaOH and H 2 SO 4 treatment methods. The degradation velocities (K; hr -1 ) of rendering by-product in KOH treatment method were higher in the order of 25% (0.0309 hr -1 ) > 30% (0.0268 hr -1 ) > 20% (0.0142 hr -1 ) > 15% (0.0111 hr -1 ) > 10% (0.0102 hr -1 ) of weight of rendering by-product. In all conditions, the degradation velocity of rendering by-product using H 2 SO 4 30% of weight of rendering by-product was rapid than that for KOH, NaOH and HNO 3 treatment methods. Degradation rates of rendering by-product using NaOH were similar to that of KOH and H 2 SO 4 except for HNO 3 under injecting 25% and 30% of rendering by-product weight.

The previously proved method of Ames test was followed to measure the mutagenic activity. We used Salmonella typhimurium which has special gene mutation site with a single compound characteristic and histidine operon, and measured at the four (Gumi, Gangjung, Gachang, Hyunpung) branch points of Nakdong river for one year. We used Standard Methods for general water analysis with the items as water temperature, pH, DO, BOD, COD, KMnO 4 , T-N, T-P, NH 3 -N, TOC, and AOX. Hyunpung branch, where the Nakdong and the Gumho river seems to be mixed enough, showed higher mutagenic activity than the other 3 branches. Every point of Nakdong river showed the TA98 mutagenic activity higher than 2, while TA100 was lower than 2. Most of the mutagenic activity was detected from methanol extracts. These results indicate that Nakdong river water quality is getting deteriorated, and that Nakdong river is influencing the mutagenic activity by Frame-shift type mutation and its polar substances. Correlations (R) between mutagenic activity and concentrations of water analysis items as TOC, AOX, BOD, COD, T-N, and T-P, resulted as 0.768, 0.787, 0.743, 0.688, 0.757, 0.628, respectively, and mutagenic activities of TA98 and TA100, after the treatment of ozone and activated carbon, decreased by chlorine pre-treatment. Finally, if the injected concentration of ozone was higher than 1.0 mL, TA98 and TA100 showed lower mutagenic activities than 2.