Flow cytometry was applied to assess the microbiological impact of treated sewage effluent discharge into a small brook carrying surface runoff water. Increases in dissolved organic carbon and soluble reactive phosphorous were accompanied by increases in counts of intact bacteria by up to eightfold. Effluent ingress furthermore resulted in a pronounced shift of bacterial clusters. Whereas brook water upstream of the discharge point was characterised by a bacterial cluster with low nucleic acid (LNA) content, downstream water showed a shift to bacteria with high nucleic acid (HNA) content. Changes in the LNA/HNA ratio were largely maintained along the course of the brook. Results suggest that the LNA/HNA ratio can under certain conditions serve as an indicator of anthropogenic nutrient impact. Measuring impact on this low trophic level might be more sensitive and straightforward than measuring macroindicators. More evidence will however be required to assess the usefulness of LNA/HNA measurements to assess the ecological nutrient status of natural waters and the impact of nutrient pollution.

Impacts of subsurface biogeochemical processes over time have always been a concern for the long-term performance of zero valent iron (Fe⁰)-based permeable reactive barriers (PRBs). To evaluate the biogeochemical impacts, laboratory experiments were performed using flow-through glass columns for 210 days at controlled temperature (20 °C). Two different particle sizes of Fe⁰ were used in the columns, and to simulate indigenous microbial activity, extra carbon source was provided in the two columns (biotic columns) and the remaining two columns were kept abiotic using gamma radiations. Heavy metals (Zn, As) were removed efficiently in all the columns, and no exhaustion of treatment capability or clogging was observed during our experimental duration. Newly formed Fe mineral phases and precipitates were characterized using X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and micro-XRF techniques in solid phase at the end of the experiment. In addition, 16S rRNA gene extraction was used for microbial community identification in biotic columns. During the incubation, microbial population shifted in favor of Desulfosporosinus species (sulfate-reducing bacteria) from initial dominance of Acidithiobacillus ferrooxidans in sediments. Dominant mineral phases detected in biotic columns were mackinawite (FeS) and sulfate green rust, while in abiotic columns, magnetite/maghemite phases were more prevalent.

The primary goal of this research was to evaluate the effect of a ternary mixture of toluene, methanol, and trichloroethylene (TCE) on the elimination of TCE in a biotrickling filter. Two biotrickling filters—Biofilter I and Biofilter II—were run in parallel, each with a different toluene/methanol/TCE loading ratio of 3:2.7:1 and 1.9:0.9:1, respectively. Both systems were seeded with fungal strains grown on diatomaceous earth media and were run at pH 4 maintained by formate buffer. To control excess biomass growth, the systems were “starved” for 2 days a week and run continuously for the rest of the week. TCE loading rates for each system ranged from 1.61 to 6.44 g/m³ h⁻¹ across three phases while toluene and methanol were loaded at rates corresponding to the influent composition ratios. More than 95 % methanol was removed from the gaseous streams throughout, while TCE removal was a function of the influent organic ratio and the corresponding concentrations. At and above loading rates of 3.22 g/m³ h⁻¹, elimination capacities obtained from Biofilter II surpassed those from Biofilter I due to a lower feed of bio-accessible carbon (toluene and methanol) offering reduced competition to TCE removal. While over 90 % toluene was removed from both systems, its elimination capacities dropped as the phases progressed due to competition and TCE cytotoxicity. Most carbon was converted to CO₂ and biomass, and no TCE oxidation by-products were detected.

To demonstrate the variation and affecting factors of dissolved oxygen under different aeration strategies in polluted urban river sediment, simulation systems constructed with collected sediment and in situ overlaying water were aerated up or beneath the sediment-water interface 6 h day⁻¹ for 15 days. The results showed that aeration greatly altered the spatial pattern of DO in overlying water regardless of the way of treatment. Within the first 5 min of aeration, DO in overlying water increases rapidly from 0.86–3.13 mg L⁻¹ to the saturated range of 6.12–8.14 mg L⁻¹. During the first 5 days, aeration to water costed 5 min to reach the highest DO, while aeration to sediment costed 30 min to reach a lower highest level of DO in overlaying water. Analysis showed that DO was significantly negatively correlated with NO₂ ⁻-N and COD Mₙ , suggesting that DO was synergistically consumed by biochemical processes of organic matter degradation and nitrification. Aeration to sediment (ES group) and aeration to water (EW group) differently influenced nitrification and organic matter degradation. After daily aeration treatment, nitrification was the main oxygen-depleting process in EW group, especially after the action of the second stage of nitrification, where organic matter was probably largely degraded during aeration. However, in ES group, DO was consumed by both organic matter oxidation and nitrification processes.

A high-dimensional driving function for Microcystis bloom warning was developed, in which both the inhibition and promotion impacts on Microcystis growth activation energy are integrally considered. Five factors, including flow disturbance, temperature, light intensity, nutrient concentration, and biological inhibition, are embedded in the equation, which results in a high-dimensional problem. The projection pursuit principle was applied for dimension reduction to resolve the numerical problem, and an integrated hydro-environmental model was established. Jinshan Lake, a typical riverside lake, was selected as the research area, and six bloom grades were determined for warning analysis. Based on the established model, the processes of Microcystis growth under varied hydrodynamic conditions were simulated. It was found that the established warning model could well reveal the Microcystis bloom processes in Jinshan Lake. The low-water year was characterized by the largest number of days on which Microcystis bloom might occur for its poor water exchange frequency; The areas where Microcystis bloom might occur in the flood seasons of high-water year, common-water year, and low-water year varied with the uneven-distributed dynamic conditions, which were respectively 0.15, 0.91, and 1.26 km².

We evaluated the biogeochemical processes occurring in the rhizosphere of different native plants growing spontaneously in a copper-contaminated soil in an abandoned mine site in NE Brazil. We also assessed the effects that these processes have on copper mobility and toxicity and discuss the potential use of the plants as pioneer species in restoration programs. For these purposes, we determined chemical (pH, macronutrients, % TOC, and % TIC) and mineralogical (XRD) properties in both rhizosphere and nonrhizosphere soils (bulk soil), and we used the sequential extraction method (SEM) to extract copper from both soils. The study findings show that the plants have greatly altered the physicochemical characteristics of the soil that is directly influenced by their roots. Different plant species appear to act through different processes, thus altering various soil components and affecting the biogeodynamic cycling of essential nutrients and copper. The changes in the physical-chemical characteristics of the rhizosphere affected copper dynamics, mainly manifested as significantly lower concentrations of potentially bioavailable copper, i.e., exchangeable and carbonate-associated copper, in this soil fraction. The concentration of copper associated with noncrystalline Fe oxides was also higher in the rhizosphere, thus enhancing the immobilization and probably minimizing the risks of copper toxicity and mobility. The biogeochemical processes observed in the rhizosphere of the species under study seem to indicate that the plants promote phytostabilization of copper in their rhizosphere zone, and they thus show desirable characteristics for use in phytoremediation programs.

Numerous carbon dioxide mineralization (CM) processes have been proposed to overcome the slow rate of natural weathering of silicate minerals. Ten of these proposals are mentioned in this article. The proposals are described in terms of the four major areas relating to CM process design: pre-treatment, purification, carbonation, and reagent recycling operations. Any known specifics based on probable or representative operating and reaction conditions are listed, and basic analysis of the strengths and shortcomings associated with the individual process designs are given in this article. The processes typically employ physical or chemical pseudo-catalytic methods to enhance the rate of carbon dioxide mineralization; however, both methods have its own associated advantages and problems. To examine the feasibility of a CM process, three key aspects should be included in the evaluation criteria: energy use, operational considerations as well as product value and economics. Recommendations regarding the optimal level of emphasis and implementation of measures to control these aspects are given, and these will depend very much on the desired process objectives. Ultimately, a mix-and-match approach to process design might be required to provide viable and economic proposals for CM processes.

The changes of soil bacterial biomass and community composition were monitored in a simulated nitrogen (N) deposition experiment during 4 years of Cunninghamia lanceolata growth in a plantation site in southern China. The experimental design included two N forms (NH₄Cl and KNO₃) and five levels of N deposition (0, 20, 40, 60, 80 kg N ha⁻¹) for 2 years. Research into the bacterial population was conducted using plate count, phospholipid fatty acid (PLFA) composition, and 16Sr DNA gene-based high-throughput pyrosequencing methods. The results of plate count and PLFA analysis indicated that ammonium (NH₄⁺) addition increased bacterial number and biomass, whereas nitrate (NO₃⁻) addition decreased these values. The high-throughput sequencing showed that N deposition of the two N forms inhibited the growth of bacteria compared with control plots, and the changing trend was related to the NH₄⁺-N/NO₃⁻-N ratio of soil. When the N deposition dose exceeded 20 kg N ha⁻¹, there was a significant effect on cultured bacteria counts and bacterial biomass. When examining the bacterial community, we observed 22 bacterial phyla of which Proteobacteria, Acidobacteria, and Actinobacteria were dominant. Acidobacteria abundance was higher in NH₄⁺ treatments than NO₃⁻ treatments. When the rates of NH₄⁺ deposition increased, Acidobacteria abundance decreased; however, it showed a positive correlation in NO₃⁻ treatments. The bacterial cluster structures were significantly different between different N addition rates in the NO₃⁻-treated plots. This research will provide data support to addressing the negative influences of nitrogen deposition and provide reference for soil management.

Heavy metal extraction from soils is one of the functions of plants which is widely studied and applied worldwide. However, little is known to what extent medicinal plants can accumulate these metals and cause problems to human health. This study aimed to evaluate the accumulation of heavy metal/loid in plant tissues, nutritional imbalance, and the effect of heavy metal concentrations in soil on the medicinal plants. The experiment was conducted in a factorial scheme with three contaminated soil samples and a soil sample from an uncontaminated field and three medicinal species: Cynara scolymus, Ocimum basilicum, and Rosmarinus officinalis. The heavy metal content in the biomass increased with increasing soil samples concentration. Biomass production, nutritional imbalance by nutrients did not show consistent results according to soil contamination criteria and are not good indicators of heavy metals presence in plant tissues, since they did not allow predicting the presence of metal in the plants, due to the different behavior of elements and plant species. There was a high concentration of Cd, Cr, Pb, and As and micronutrients Fe, Zn, and Cu in the plant tissues, above the limits recommended by the World Health Organization. Therefore, as the components of C. scolymus, O. basilicum, and R. officinaliss are used to prepare teas, condiments, or consumed raw, coupled with the ability of such species to concentrate toxic metals, the continued use of these plant products containing these metals can pose a potential health concern.

Fibrous mats of polymer/clay were obtained by electrospinning method, and their capacity for heavy metals removal from water was evaluated. Four different fibrous mats were prepared from a corresponding polymer/clay solutions. The precursor materials employed were poly-ε-caprolactone, polyvinyl alcohol polymers, kaolin, and metakaolin clays. Raw materials and the prepared fiber mats characterization were carried out using scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, termogravimetric analysis, differential thermal analysis, and differential scanning calorimetry. Elemental composition of the materials was obtained using energy-dispersive X-ray spectroscopy. The environmental applications of polymer/clay materials were tested for water treatment by heavy metals (cadmium (Cd⁺²), chromium (Cr⁺³), copper (Cu⁺²), and lead (Pb⁺²)) sorption. Kinetic adsorption studies were conducted employing heavy metal solutions with initial concentration of 200 mg/L, and the amount of heavy metal adsorbed and kinetics parameters was determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES). According to the kinetic data, the adsorption process of Cd⁺², Cr⁺³, Cu⁺², and Pb⁺² onto polymer/clay is favorable for the prepared materials and they follow a pseudo-first-order model according to the kinetic analysis. Additionally, the intraparticle diffusion was evaluated by applying the Morris and Weber model; in order to investigate the contribution of film resistance to the kinetics of the heavy metals adsorption, the adsorption kinetic data was further analyzed by Boyd’s film-diffusion model.