Application of GETFLOWS Coupled with Chemical Reactions to Arsenic Removal through Ferrihydrite Coprecipitation in an Artificial Wetland of a Japanese Closed Mine

Passive systems that utilize a natural power such as a pond, plant, or microorganisms, is expected to be a cost-effective method for acid mine drainage (AMD) treatment. The Ningyo-toge mine, a non-operational uranium mine located in Okayama Prefecture, Japan, generates AMD containing arsenic and iron. To quantitatively study arsenic and iron ion removal in an artificial wetland and pond, chemical reactions were modeled and incorporated into the GETFLOWS (general-purpose terrestrial fluid-flow simulator) software. The chemical reaction models consisted of arsenite and ferrous oxidation equations and arsenic adsorption on ferrihydrite. The X-ray diffraction analysis of sediment samples showed ferrihydrite patterns. These results were consistent with the model for arsenite/ferrous oxidation and arsenic adsorption on ferrihydrite. Geofluid simulation was conducted to simulate mass transfer with the utilized topographic model, inlet flow rate, precipitation, and evaporation. The measured arsenic and iron ions concentrations in solution samples from the wetland and pond, fitted well with the model. This indicated that the main removal mechanism was the oxidation of arsenite/ferrous ions and that arsenic was removed by adsorption rather than dilution.

Lipid Peroxidation in Hepatopancreas, Gill, and Hemolymph of Male and Female Crabs Platyxanthus Orbignyi after Air Exposure

Levels of lipid peroxidation in hepatopancreas (HP), gill (G), and hemolymph (HYM) of stone violaceous crab Platyxanthus orbignyi (Milne Edwards and Lucas (1843)) were performed to examine the effect of short exposure to air. After four hours animals were collected, 14 from exposure to air and 10 from seawater were dissected and their lipid peroxidation (LPO) levels were evaluated using the ferrous oxidation-xylenol orange (FOX) method, in gill, hepatopancreas, and hemolymph. The total mortality of those crabs was evaluated after seven hours at 22 ± 1 °C on exposure to air conditions. Levels of LPO in hepatopancreas (female/male = 4.68 ± 1.60/5.12 ± 1.59 Eq-H2O2/g wet tissue) and hemolymph (female/male = 1.48 ± 1.42/1.28 ± 1.06 Eq-H2O2/g wet tissue) displayed no significant differences, in contrast, gills displayed significant differences (male/female = 5.63 ± 0.83/4.63 ± 0.44 Eq-H2O2/g wet tissue, p < 0.05). The results showed that air exposure in the short term in this study induces a different response in oxidative stress levels and damage could be accompanied by accumulation of peroxide lipids (LOOH). These results suggest that different organs can show different responses to oxidative stress between male and female crabs to this species.

DETECTION OF HYDROPEROXIDES IN SOLUTIONS OF PHOTOOXIDIZED PSORALEN

Photooxidized psoralen solutions possess a variety of biological effects, which implementation mechanism may presumably involve hydroperoxides. Here, the hydroperoxide content in photooxidized psoralen solutions was assessed using photometric FOX assay (from Ferrous Oxidation + Xylenol Orange). FOX reagent with 10× content of Xylenol Orange, modified for quantitative analysis of up to 50 μM of hydroperoxides in aqueous phase was used in experiments. During photooxidation of 0.1 mM psoralen in phosphate buffer solution, hydroperoxide production increases with dose of UVA irradiation (~2.5 μM eq. of H2O2 for dose of 252 kJ/m2 and ~11 μM eq. of H2O2 for dose of 1512 kJ/m2) and reaches ~16.5 μM eq. of H2O2 at the highest dose investigated (3024 kJ/m2). A comparison of kinetics of psoralen photolysis and hydroperoxide generation allows us to suggest that generation of hydroperoxide results from the secondary photochemical processes involving psoralen photoproducts, presumably from photoinduced autooxidation of aldehydic photoproducts of psoralen.