Little is known about the transport of microorganisms through freeze-fractured clay soils. Normally consolidated clay (NCC) and compacted clay (CC) columns (representing a natural clay barrier and a compacted barrier, respectively) were exposed to six consecutive freeze-thaw cycles and permeated for 21 days with an Escherichia coli cell suspension (approximately 1 × 10⁷ colony forming units (CFU)/mL) containing a 2.1-mM bromide tracer. An unfractured sand column was also examined for comparison with the clay columns. While no E. coli was detected in the effluent of both untreated NCC and CC control clay columns, a relatively low density of E. coli (between 228 and 270 CFU/mL compared to 1 × 10⁷ CFU/mL in the influent) was first detected in the effluent of the freeze-fractured NCC and CC columns at 0.29 and 0.31 pore volumes (or at 5.4 and 4.1 h), respectively. It took 11 min for a full breakthrough of E. coli through the sand column, but only about 0.1% of the influent E. coli density was detected in the effluents of the freeze-fractured NCC and CC columns at day 21. These observations show that despite the high bacterial retention capacity of the freeze-fractured clay columns, the fractures were large enough for the E. coli to flow through. Based on batch sorption tests and the permeation data, it is estimated that 18%, 7%, and 84% of the freeze-fractured NCC, CC, and sand columns would be exposed to the influent, respectively, under a full E. coli breakthrough condition. Our data show that the high bacterial retention capacity of clay barriers can be compromised by freeze-thaw conditions.

Extensive use of synthetic pyrethroids has resulted in concerns regarding their potential effects on human health and ecosystems. In the present study, we evaluated the influence of coexisting Cu²⁺, Zn²⁺, soil water contents (15%, 25%, 40% by weight and waterlogged) and temperature levels (15°C, 25°C, 35°C, and 45°C) on the dissipation of cypermethrin, fenvalerate and deltamethrin in red soil. To further clarify the influence of Cu²⁺ and Zn²⁺ on biological and chemical dissipation processes, serial concentrations of the synthetic pyrethroids containing Cu²⁺ (21.3, 50, 100, and 400 mg kg⁻¹) and Zn²⁺ (35.8, 100, 250, and 500 mg kg⁻¹) were used to spike the soil and then incubated at 25°C in the dark at 25% moisture. The results revealed a very severe inhibitory effect on the dissipation rates with increasing Cu²⁺ and Zn²⁺ levels. Conversely, there were no significant decreases in dissipation rates in response to exposure to 50 mg kg⁻¹ Cu²⁺ or 100 mg kg⁻¹ Zn²⁺, and the dissipation rates decreased significantly (p < 0.05) when the Cu²⁺ and Zn²⁺ concentration increased to 100 and 250 mg kg⁻¹, respectively, which were the respective maximum field recommended rates. When compared with unsterilized batch treatments, the t ₁/₂ in sterilized (chemical dissipation) batch treatments increased by 1.0-4.8-fold. Additionally, there was a highly significant difference in the dissipation of pyrethroids in the 15% water content treatments and waterlogged treatments (p < 0.05). Finally, the difference in the dissipation rates at 15°C and 25°C was significant (p < 0.05).

Most alpine ecosystem climate change studies identify changes in biota, several report abiotic factors and conditions, few report temperature changes, and few to none discuss growing degree days (GDD) changes. This study provides results of data analysis on changes in number of GDD in the alpine desert of the San Luis Valley (SLV) whose community is dominated by an irrigated agricultural region. Analysis indicates significant increases (p < 0.05) in annual and growing season GDD₁₀, GDD₄.₄ (potato), and GDD₅.₅ (alfalfa) during 1994-2007 compared to 1958-1993. With one exception, all stations experienced significant increases in mean annual daily GDD between 0.12 and 0.50 day⁻² and growing season GDD day⁻² 0.21 and 0.81. Higher temperatures increase numbers of GDD, quickening growth of crops and maturity at the cost of reduced yield and quality. Increases in GDD indicate the Valley's agricultural region and economy may experience negative impacts as yields decrease and water use increases.

The arsenic contamination of Bangladesh groundwater involves heavy arsenic inputs to irrigated rice fields. Beside adsorption on soil colloids, iron-arsenic co-precipitation phenomena can affect arsenic retention in soils. In paddy fields of Satkhira District, Bangladesh, the study of the arsenic and iron forms in the irrigation waters and in soils at different times and distances from the irrigation well evidenced that a higher Fe/As ratio in the well water was related to a faster oxidation of Fe(II) and As(III) in water and to a close Fe-As association in soils, together with a greater accumulation of arsenic and poorly ordered iron oxides. The concentration of arsenic and of labile iron forms decreased with the distance from the well and with the depth, as well as the reversibility of arsenic binding. The fate of the arsenic added to the soils by irrigation hence resulted strongly influenced by iron-arsenic co-precipitation, depending on the Fe/As ratio in water. Irrigation systems favouring the sedimentation of the Fe-As flocks could help in protecting the rice from the adverse effects of dissolved arsenic.

More than 50 tanneries are operated in Kula, Turkey which is located on highly permeable geological units. The untreated effluents from the tanneries discharged onto the ground surface may cause pollution in surface waters, in groundwater, and in soil. Since the water resources of the region are used for drinking, agricultural, and industrial purposes, the quality assessment of groundwaters and surface waters is completed in the content of this study. Additionally, the surface soil samples are analyzed for their heavy metal content to describe the size of the pollution. The results obtained from the analysis of the water samples show that the concentrations are mostly within drinking water limits. But, concentrations are expected to increase in the next years as no effective effluent collection and treatment is present in the tanneries. Although the concentrations of K, SO₄, Mg, Na, and Cl exceed the permissible limits for drinking water in some cases, they may not directly be caused by tannery activities. Nevertheless, they should be assessed as an indicator of the beginning of groundwater pollution. Also, soil samples collected near the tannery district are extremely polluted. This paper discusses the assessment of the geochemical dispersals of Cr and other pollutants derived from the tannery activities within soil and water in Kula.

The research and interest towards the use of constructed floating wetlands for (waste)water treatment is emerging as more treatment opportunities are marked out, and the technique is applied more often. To evaluate the effect of a floating macrophyte mat and the influence of temperature and season on physico-chemical changes and removal, two constructed floating wetlands (CFWs), including a floating macrophyte mat, and a control, without emergent vegetation, were built. Raw domestic wastewater from a wastewater treatment plant was added on day 0. Removal of total nitrogen, NH₄-N, NO₃-N, P, chemical oxygen demand (COD), total organic carbon and heavy metals (Cu, Fe, Mn, Ni, Pb and Zn) was studied during 17 batch-fed testing periods with a retention time of 11 days (February-March 2007 and August 2007-September 2008). In general, the CFWs performed better than the control. Average removal efficiencies for NH₄-N, total nitrogen, P and COD were respectively 35%, 42%, 22% and 53% for the CFWs, and 3%, 15%, 6% and 33% for the control. The pH was significantly lower in the CFWs (7.08 ± 0.21) than in the control (7.48 ± 0.26) after 11 days. The removal efficiencies of NH₄-N, total nitrogen and COD were significantly higher in the CFWs as the presence of the floating macrophyte mat influenced positively their removal. Total nitrogen, NH₄-N and P removal was significantly influenced by temperature with the highest removal between 5°C and 15°C. At lower and higher temperatures, removal relapsed. In general, temperature seemed to be the steering factor rather than season. The presence of the floating macrophyte mat restrained the increase of the water temperature when air temperature was >15°C. Although the mat hampered oxygen diffusion from the air towards the water column, the redox potential measured in the rootmat was higher than the value obtained in the control at the same depth, indicating that the release of oxygen from the roots could stimulate oxygen consuming reactions within the root mat, and root oxygen release was higher than oxygen diffusion from the air.

This paper reviews the current state of knowledge regarding sources of anthropogenic mercury emission in Poland for the year 2005 and presents projection of mercury emission in perspective to the year 2020. These projections are treated separately as emissions from by-product sources and from product use since abatement strategies for these two source categories are very different. Emission projections until the year 2020 were prepared for: Status Quo scenario, Extended Emission Control scenario (EXEC) as well as for Maximum Feasible Technical Reduction scenario (MFTR). The general results were that Hg emission in Status Quo scenario, where no further action is taken to reduce mercury emission is predicted to rise between 2005 and 2020 for by-product sources, as a consequence of growing production of industrial goods and the consumption of raw materials, and is expected to be at the same level for the year 2020 for product use sources in comparison to the base year 2005, where no changes in consumption model were assumed. For EXEC and MFTR scenarios, assuming implementation of efficient control devices and changes in consumption model, decrease of mercury emission from by-product sources is expected between 2005 and 2020. Emission from mercury use in products for these scenarios is also predicted to decrease as a result of drop in mercury consumption. This paper presents also the social benefits for Poland result from Hg emission reduction and considered separately for ingestion and inhalation pathway. The costs and the social benefits related to the reduction of the heavy metals and PM2.5 are also presented.

Tamarind fruit shell was used as a low-cost biosorbent for the removal of methylene blue from aqueous solution. The various factors affecting adsorption, such as agitation, pH, initial dye concentration, contact time, and temperature, were investigated. The dye adsorption capacity was strongly dependent on solution pH as well as temperature. The Langmuir isotherm model showed good fit to the equilibrium adsorption data, and the maximum adsorption capacity obtained was 1.72 mg g⁻¹ at 303 K. The kinetics of adsorption followed the pseudo-second-order model and the rate constant increased with increase in temperature, indicating endothermic nature of adsorption. The Arrhenius equation was used to obtain the activation energy (E a) for the adsorption system. The activation energy was estimated to be 19.65 kJ mol⁻¹. Thermodynamic parameters such as Gibbs free energy (ΔG ⁰), enthalpy (ΔH ⁰), and entropy (ΔS ⁰) were also investigated. Results suggested that adsorption of methylene blue onto tamarind fruit shell was a spontaneous and endothermic process. The present investigation suggests that tamarind fruit shell may be utilized as a low-cost adsorbent for methylene blue removal from aqueous solution.

Reductive dechlorination of tetrachloroethylene (PCE) by green rust modified with copper (GR(Cu)) was investigated using a batch reactor system. Four different forms of GRs (GR-Cl, GR-SO₄, GR-CO₃, and GR-F) were synthesized by partial air oxidation of Fe(OH)₂ and used in reductive dechlorination. The addition of Cu(II) into GRs produced 100-nm particles on the surface of GRs, which were considered to be metallic Cu and transformed a portion of GR to magnetite. Concentration of Fe(II) in the liquid phase increased and concentration of Fe(II) in the solid phase decreased during the modification process and the extent of these changes was dependent on the amount of Cu(II) added. The most reactive of the modified GRs was GR-F(Cu), which reacted with PCE at a rate that was 80 times faster than that of GR-Cl(Cu). The rate of PCE degradation by GR-F(Cu) was strongly dependent on pH with higher rates at higher pH over the range of pH 7.5-11. Increasing concentrations of Cu(II) over the range of 0 to 5 mM increased rate constants. The rate of dechlorination of PCE by GR-F(Cu) showed surface saturation behavior with respect to PCE concentration.

Reaction behaviors and kinetics of catalytic oxidation of benzene, toluene, and ethyl acetate with feed concentrations in the range of 700-5,000 ppm over Pd/ZSM-5 catalyst were investigated. Results for single components show that ethyl acetate (T ₅₀ = 190-200°C) is more easily oxidized than benzene (T ₅₀ = 215-225°C) and toluene (T ₅₀ = 225-235°C). The conversion of ethyl acetate was increased with the increase of its feeding concentration, while the opposite behaviors were observed for benzene and toluene as their conversion rates were decreased with the increase of the inlet concentration. Different behaviors were observed in catalytic oxidation of volatile organic compound (VOC) multi-components, the presence of benzene or toluene inhibits the conversion of ethyl acetate, and the aromatic hydrocarbons inhibit each other in all cases. Ethyl acetate possesses obvious inhibitory effect on benzene oxidation, while it is interesting to note that ethyl acetate has a promotion effect on toluene conversion. The kinetic data were fitted by the Power-law and Mars-van Krevelen kinetic models. The fitting result shows that the Power-law model is more suitable for predicting the conversion of benzene than the other VOCs, and the Mars-van Krevelen model can accurately express the reaction rate of all investigated VOCs.