Assessment of the chemical components of Famenin groundwater,western Iran

The Faminin area in the semi-arid Hamadan state, western Iran is facing a serious deficiency in groundwater resources due to an increasing demand associated with rapid population growth and agricultural development. The chemical composition of 78 well samples throughout the Faminin area was determined with the aim of evaluating the concentration of the background ions and identifying the major hydrogeochemical processes that control the groundwater chemistry. The similarity between rock and groundwater chemistries in the recharge area indicates a significant rock-water interaction. The hydrochemical types Na–HCO₃ and Na–SO₄ are the predominate forms in the groundwater, followed by water types Ca–HCO₃ and Na–Cl. The high values of electrical conductivity and high concentrations of Na⁺, Cl⁻, SO₄²⁻ and NO₃⁻ in the groundwater appeared to be caused by the dissolution of mineral phases and would appeared to be caused by anthropogenic activities, such as intense agricultural practices (application of fertilizers, irrigation practice), urban and industrial waste discharge, among others.     

Endosulfan is toxic to the reproductive health of male freshwater fish, <Emphasis Type="Italic">Cyprinion watsoni</Emphasis>

Endosulfan is an organochlorine pesticide that is toxic to aquatic life. Endosulfan might hamper the reproductive health of indigenous fish in agricultural areas of Pakistan where this pesticide is sprayed widely. The aim of the current study is to investigate the toxic effects of endosulfan on selected reproductive parameters of male freshwater fish, Cyprinion watsoni. Two concentrations of endosulfan (0.5 and 1 ppb for 30 days exposure) were tested for their effects on body weight, body length, and testicular weight, length, and width. Testicular testosterone was assayed from tissue extracts using enzyme immunoassay (EIA). A significant increase in the mortality rate was observed in both treated groups during both spawning and quiescent seasons. The overall behavior of fish in the aquarium was normal in all control and treated groups. However, the treated fish exhibited anxiety after treatment with endosulfan. The body weight and length, and testicular weight, length and width were not significantly different to the control group. The testicular testosterone concentrations were significantly lower in both endosulfan-treated groups compared to the control. The decrease was dose-dependent, with a significant difference between the two treated groups. The histomorphological results demonstrated various testicular alterations in the treated groups. These alterations included an increase in interlobular areas and clumping patterns in spermatocytes/spermatids. Because spermatids eventually differentiate into sperms, their low count will directly result in lower sperm count. Taken together, these results suggest that endosulfan is a toxicant that at least disturbs testosterone levels (possibly others) and negatively impacts the reproductive health of male freshwater fish.     

Competitive sorption of Cd, Cu, Mn, Ni, Pb and Zn in polluted and unpolluted calcareous soils

The objectives of this study were to investigate competitive sorption behaviour of heavy metals (Cd, Cu, Mn, Ni, Pb and Zn) under different management practices and identify soil characteristics that can be correlated with the retention and mobility of heavy metals using 65 calcareous soil samples. The lowest sorption was found for Mn and Ni in competition with the other metals, indicating the high mobility of these two cations. The Freundlich equation adequately described heavy metals adsorption. On the basis of Freundlich distribution coefficient, the selectivity sequence of the metal adsorption was Cu?>?Pb?>?Cd?>?Zn?>?Ni?>?Mn. The mean value of the joint distribution coefficient (K _dΣsp) was 182.1, 364.1, 414.7, 250.1, 277.7, 459.9 and 344.8 l kg^?1 for garden, garlic, pasture, potato, vegetables, wheat and polluted soils, respectively. The lowest observed K _dΣsp in garden soil samples was due to the lower cation exchange capacity and lower carbonate content. The results of the geochemical modelling under low and high metal addition indicated that Cd, Ni, Mn and Zn were mainly retained via adsorption, while Pb and Cu were retained via adsorption and precipitation. Stepwise forward regression analysis showed that clay, organic matter and CaCO₃ were the most important soil properties influencing competitive adsorption of Cd, Mn, Ni and Zn. The results in this study point to a relatively easy way to estimate distribution coefficient values.     

Effect of low-molecular-weight organic acids on kinetics release and fractionation of phosphorus in some calcareous soils of western Iran

Organic acid has been related to nutrient mobilization, mainly in phosphorus (P) insoluble utilization, and therefore enhances P bioavailability. In this study, we examined the effect of low-molecular-weight organic acids (malic, citric, and oxalic acids) on P release of some calcareous soils from western Iran. Fractionation and speciation of P in the soil solution were studied at the initial and final P release. Significantly different quantities of P were extracted by the organic acids. On average the maximum (1,554.9 mg kg^-1) and the minimum (1,260.5 mg kg^-1) P were extracted by 10 mM oxalic and malic acid, respectively. Power equation described well P release. In the initial stage of P release, the solution samples in soils were supersaturated with respect to hydroxyapatite and β-TCP. At the end of P release, all solutions were undersaturated with phosphate minerals. The percentage of Fe-Al oxide fraction generally increased after P release, while carbonate and residual P fractions were decreased in all organic acids. Compared with the native soils, adding malic and citric acids had no effect on Fe-Al oxide fraction, but oxalic acid significantly reduced this fraction.     

Health risk assessment of inhalation exposure to dry fogging of hydrogen peroxide in a dental clinic during the COVID-19 pandemic

Environmental Science and Pollution Research - After the outbreak of COVID-19, many dental clinics use dry fogging of hydrogen peroxide (H2O2) to disinfect the air and surfaces. Inhalation of...