In this study, the effectiveness of subcritical water extraction (SCWE) was assessed by extracting four pesticides, namely diazinon, parathion, phenthoat, and EPN, from contaminated soil. The extraction efficiencies of different temperatures (25, 75, 100, 125, and 150 C); times (10, 20, 30, and 40 min); pressures (1, 2, and 3 MPa); and water flow rates (0.5, 0.7, 1.0, and 1.5 mL/min) were investigated. The optimum temperature, time, pressure, and flow rate were found to be 150 C, 20 min, 2 MPa, and 0.5 mL/min, respectively, in lab-scale. At this operating condition, the residual concentration of pesticide was less than 0.5 mg/kg, corresponding to an extraction efficiency of 99.9 %. The aim of this study was to also evaluate the removal efficiency on 30- and 167-fold scale-up extraction at optimum extraction condition obtained from lab-scale studies. The scale-up method considering constant ratio of the volume of water to soil mass was a feasible procedure. The results of our study suggest that SCWE is a promising option for effective disposal of pesticide- contaminated soil. © 2013 Springer Science+Business Media Dordrecht.

Land use in east China tends to change from paddy rice to vegetables or other high-value cash crops, resulting in high input rates of organic manures and increased risk of contamination with both heavy metals (HMs) and antibiotics. This investigation was conducted to determine the accumulation, distribution and risks of HMs and tetracyclines (TCs) in surface soils and profiles receiving different amounts of farmyard manure. Soil samples collected from suburbs of Hangzhou city, Zhejiang province were introduced to represent three types of land use change from paddy rice to asparagus production, vineyards and field mustard cultivation, and divided into two portions, one of which was air-dried and sieved through 2-, 0.3- and 0.149-mm nylon mesh for determination of pH and heavy metals. The other portion was frozen at -20 °C, freeze-dried and sieved through a 0.3-mm nylon mesh for tetracyline determination. HM and TC concentrations in surface soils of 14-year-old mustard fields were the highest with total Cu, Zn, Cd and ∑TCs of 50.5, 196, 1.03 mg kg(-1) and 22.9 μg kg(-1), respectively, on average. The total Cu sequence was field mustard > vineyards > asparagus when duration of land use change was considered; oxytetracycline (OTC) and doxycycline were dominant in soils used for asparagus production; OTC was dominant in vineyards and chlortetracycline (CTC) was dominant in mustard soils. There were positive pollution relationships among Cu, Zn and ∑TCs, especially between Cu and Zn or Cu and ∑TCs. Repeated and excessive application of manures from intensive farming systems may produce combined contamination with HMs and TCs which were found in the top 20 cm of the arable soil profiles and also extended to 20-40 cm depth. Increasing manure application rate and cultivation time led to continuing increases in residue concentrations and movement down the soil profile.

Many airborne and soil-borne nanoparticles (NPs) can enter plants, which are the primary producers in the food chain; recently, studies on the genotoxic effects of NPs on plants are emerging. In the present study, the phytotoxic and genotoxic effects of ZnO and CuO NPs on buckwheat (Fagopyrum esculentum) seedlings were estimated. The inhibition of root growth and biomass at the tested concentrations of NP suspensions and dissolved free ion suspensions were compared. Changes in root morphological features and localization of NPs inside the root epidermis cells were observed. Growth of root treated with ZnO NPs (84.9 and 89.6 %) and CuO NPs (75.4 and 80.1 %) at 2,000 and 4,000 mg L -1, respectively, was decreased significantly than control. The root morphological features and NP incorporation into the root epidermal cells at a high dose of NP showed completely different patterns compared to those for the controls. Through random amplified polymorphic DNA assays for comparison of the effect of ZnO and CuO NPs on DNA stability, it was shown as different DNA polymorphisms at 2,000 and 4,000 mg L-1 of ZnO and CuO NPs, compared to those for controls. Our results provide the first clue to the genotoxic effects of ZnO and CuO NPs on early growth of edible plants such as buckwheat. © 2013 Springer Science+Business Media Dordrecht.

A better understanding of the effect of anthropogenic pollution on the formation of toxic Microcystis blooms is particularly important in regions with large urban centres where rivers, lakes, and estuaries receive large quantities of contaminated domestic and industrial wastes. The response of the bloom-forming cyanobacteria Microcystis aeruginosa CALU 972 and CALU 973 from Russian Karelia to pollution was investigated. The contaminants caused compensatory-adaptive changes that led to the retention of cell viability in the cyanobacterial cells. The adaptation to metals and 1,2,4-triazole was realised due to photosystem changes and the enhanced production of organic compounds, such as proteins and exopolysaccharides. Nutrients caused a significant increase in biomass production by M. aeruginosa. The exposure of M. aeruginosa to nutrients and zinc stimulated growth and contributed to enhanced microcystin concentrations. Variants of microcystins responded differently to pollution. Contaminants had pronounced effects on microcystin RR levels but less effects on microcystin LR levels. Heavy metals, 1,2,4-triazole and nitrogen influenced microcystin concentrations by affecting both the growth of Microcystis and hepatotoxin release into the environment.

In this work, a coal combustion ash (CCA) has been tested as an alternative low-cost sorbent to commercial activated carbons (GAC) for cadmium and zinc removal from polluted water. To this aim, the effect of pH and metal concentration on CCA adsorption capacity has been investigated, and a comparative analysis with GAC has been carried out in the same experimental conditions. Furthermore, in order to improve CCA adsorption capacity, two different activation treatments of raw CCA have been tested. In particular, the CCA was subjected to a gasification process conducted with steam and to different acidic treatments, conducted either with hydrochloric acid or nitric acid at different acid concentrations. Experimental results showed that all the acid treatments determined a substantial reduction of both cadmium and zinc adsorption capacity. Differently, the steam gasification determined a substantial increase in adsorption capacity with respect to raw CCA, in particular for zinc as its adsorption capacity resulted even higher than the correspondent of GAC. Finally, a thorough analysis of sorbent physical and chemical properties and of adsorption data allowed the individuation of the main cadmium/zinc adsorption mechanism both on CCA and activated carbon, adequately described by the Freundlich model.

To evaluate cadmium (Cd) remediation capacity of gray poplar (Populus × canescens Sm. referred to the hybrid of Populus tremula L. × Populus alba L.), the glasshouse experiment was conducted in hydroponics, and the effects of Cd (0, 10, 30, 50, and 70 μM) on plant growth as well as Cd uptake and translocation were investigated. The growth rate of all tissues in P. × canescens decreased slowly with an increase in Cd concentrations. Among different tissues, the root exhibited the highest level of bio-concentration factor (BCF), followed by leaves, bark, and wood. BCFs in bark and wood significantly decreased with an increase in Cd concentrations. The translocation factor in different tissues firstly increased and then declined with an increase in Cd concentrations, respectively. The translocation factor in different tissues decreased slowly with an increase in Cd concentrations. Cd accumulation rates significantly increased and reached about sevenfold the level after 70 μM than that observed after 0 μM (control) for 28 days. These results indicated that P. × canescens have good tolerance against Cd stress, varying in Cd accumulation and translocation. These properties need to be taken into account in selecting species for the phytoremediation of orefield.

Papaya seed was used as biosorbent for removal of tannery dye (Direct Black 38) from aqueous solution. The papaya seed was characterized, and it posseses macro/mesoporous texture, large pore size, and a surface containing various organic functional groups. The initial dye concentration, contact time, and pH significantly influenced the adsorption capacity. Equilibrium data were analyzed by the Langmuir and Freundlich isotherm models. The equilibrium data were best represented by the Langmuir isotherm, with a high adsorption capacity of 440 mg g⁻¹. Adsorption kinetic data were fitted using the pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Boyd models. The adsorption kinetics for the dye onto papaya seed was best described by second-order kinetic equation. The adsorption process mechanism was found to be controlled by both external mass transfer and pore diffusion, but the external diffusion was the dominating process. Papaya seeds showed to be a promising material for adsorption of Direct Black 38 dye from aqueous solution.

Ammonia emission from broiler houses is a major concern because of its impacts on the environment. To reduce ammonia emissions, it is necessary to understand the fate of ammonia/um in the broiler waste. In broiler waste, uric acid and urea hydrolyze to ammonia (NH₃) and a fraction of NH₃ converts to ammonium (NH₄ ⁺) depending on pH and temperature. Further, NH₄ ⁺ undergoes solid–liquid partitioning and the ammonia fraction is partitioned among the solid, liquid, and gas phases in the waste. Ammonium partitioning between solid and liquid phases in broiler cake and litter were measured at pH of 4, 6, and 7. Ammonium adsorption increased with pH in both broiler litter and cake. Adsorption capacity of the litter was much lower than broiler cake. Six NH₄ ⁺ adsorption/desorption isotherms (linear, Langmuir, Freundlich, Temkin, Redlich–Peterson, and Toth) were evaluated. The isotherm that provided the best fit for partitioning NH₄ ⁺ in litter or cake for each pH value was selected by comparing up to six sets of parameters modeled using linear and nonlinear (with five error functions) regressions. Despite high R ² values obtained using linear regression, linearizing the models introduced an offset into the model reducing their accuracy. The sum of normalized error was used to select the most suitable parameter set for each isotherm. While the nonlinear error functions were the more suitable for developing parameter sets in broiler litter, for cake, linear regression generally provided the most optimum parameter sets. Whereas the Freundlich, linear, and Temkin isotherms were the most suitable for broiler litter for pH of 4, 6, and 7, respectively, for the cake, the linear isotherm was the most suitable for the entire range of pH evaluated. Overall, due to its simplicity, the linear isotherm seems suitable for partitioning NH₄ ⁺ in the adsorbed and dissolved phases for simulating nitrogen fate and dynamics in broiler waste more accurately.

Stormwater is a potential and readily available alternative source for potable water in urban areas. However, its direct use is severely constrained by the presence of toxic pollutants, such as heavy metals (HMs). The presence of HMs in stormwater is of concern because of their chronic toxicity and persistent nature. In addition to human health impacts, metals can contribute to adverse ecosystem health impact on receiving waters. Therefore, the ability to predict the levels of HMs in stormwater is crucial for monitoring stormwater quality and for the design of effective treatment systems. Unfortunately, the current laboratory methods for determining HM concentrations are resource intensive and time consuming. In this paper, applications of multivariate data analysis techniques are presented to identify potential surrogate parameters which can be used to determine HM concentrations in stormwater. Accordingly, partial least squares was applied to identify a suite of physicochemical parameters which can serve as indicators of HMs. Datasets having varied characteristics, such as land use and particle size distribution of solids, were analyzed to validate the efficacy of the influencing parameters. Iron, manganese, total organic carbon, and inorganic carbon were identified as the predominant parameters that correlate with the HM concentrations. The practical extension of the study outcomes to urban stormwater management is also discussed.

Rewetting of agriculturally used peatlands has been proposed as a measure to stop soil subsidence, conserve peat and rehabilitate ecosystem functioning. Unintended consequences might involve nutrient release and changes in the greenhouse gas (GHG) balance towards CH₄-dominated emission. To investigate the risks and benefits of rewetting, we subjected soil columns from drained peat- and clay-covered peatlands to different water level treatments: permanently low, permanently inundated and fluctuating (first inundated, then drained). Surface water and soil pore water chemistry, soil-extractable nutrients and greenhouse gas fluxes were measured throughout the experiment. Permanent inundation released large amounts of nutrients into pore water, especially phosphorus (up to 11.7 mg P-PO₄ l⁻¹) and ammonium (4.8 mg N-NH₄ l⁻¹). Phosphorus release was larger in peat than in clay soil, presumably due to the larger pool of iron-bound phosphorus in peat. Furthermore, substantial amounts of phosphorus and potassium were exported from the soil matrix to the surface water, risking the pollution of local species-rich (semi-)aquatic ecosystems. Rewetting of both clay and peat soil reduced CO₂ emissions. CH₄ emissions increased, but, in contrast to the expectations, the fluxes were relatively low. Calculations showed that rewetting reduced net cumulative GHG emissions expressed as CO₂ equivalents.