Incidental losses of dissolved reactive phosphorus (DRP) to a surface waterbody originate from direct losses during land application of fertilizer, or where a rainfall event occurs immediately thereafter. Another source is the soil. One way of immobilising DRP in runoff before discharge to a surface waterbody, is to amend soil within the edge of field area with a high phosphorus (P) sequestration material. One such amendment is iron ochre, a by-product of acid mine drainage. Batch experiments utilising two grassland soils at two depths (topsoil and sub-soil), six ochre amendment rates (0, 0.15, 1.5, 7.5, 15 and 30 g kg−1 mass per dry weight of soil) and five P concentrations (0, 5, 10, 20 and 40 mg L−1) were carried out. A proportional equation, which incorporated P sources and losses, was developed and used to form a statistical model. Back calculation identified optimal rates of ochre amendment to soil to ameliorate a specific DRP concentration in runoff. Ochre amendment of soils (with no further P inputs) was effective at decreasing DRP concentrations to acceptable levels. A rate of 30 g ochre kg−1 soil was needed to decrease DRP concentrations to acceptable levels for P inputs of ≤10 mg L−1, which represents the vast majority of cases in grassland runoff experiments. However, although very quick and sustained metal release above environmental limits occurred, which makes it unfeasible for use as a soil amendment to control P release to a waterbody, the methodology developed within this paper may be used to test the effectiveness and feasibility of other amendments.

The present work discusses the startup and operation of different biotrickling filters during the simultaneous removal of NH3, H2S, and ethyl mercaptan (EM) for odor control, focusing on (a) the impact of pH control in the stability of the nitrification processes during reactor startup and (b) the crossed effects among selected pollutants and their by-products. Two biotrickling filters were packed with poplar wood chips (R1 and R2A), while a third reactor was packed with polyurethane foam (R2B). R2A and R2B presented a pH control system, whereas R1 did not. Loads of 2–10 g N–NH3 m−3 h−1, 5–16 g S–H2S m−3 h−1, and 1–6 g EM m−3 h−1 were supplied to the bioreactors. The presence of a pH control loop in R2A and R2B proved to be crucial to avoid long startup periods and bioreactors malfunctioning due to biological activity inhibition. In addition, the impact of the presence of different concentrations of a series of N species (NH 4 + , NO 2 − , and NO 3 − ) and S species (SO 4 2− and S2−) on the performance of the two biotrickling filters was studied by increasing their load to the reactors. Sulfide oxidation proved to be the most resilient process, since it was not affected in any of the experiments, while nitrification and EM removal were severely affected. In particular, the latter was affected by SO 4 2− and NO 2 − , while nitrification was significantly affected by NH 4 + . The biotrickling filter packed with polyurethane foam was more sensitive to crossed effects than the biotrickling filter packed with poplar wood chips.

The presence of synthetic dyes in industrial wastewaters may create serious environmental problems due to their mutagenicity and toxicity to aquatic life and humans. In this study, the decolourization and degradation of methylene blue (MB) by a Sphingomonas paucimobilis strain isolated from industrial wastewater was investigated under aerobic conditions. Decolourization extent of MB in medium was over 85 % when the bacterium was grown on a high concentration of the dye (1,000 mg/L) after a retention time of 5 days, while reduction in COD was 92.99 % suggesting mineralization of dyes as a result of microbial activities. The bacterium retained decolourizing activity over a wide range of pH (2–10), with peak activity obtained at pH 9. Analysis of samples extracted from decolourized culture flasks at pH 9 using UV–visible and Fourier transform infrared (FTIR) spectroscopy confirmed that the mechanism of colour removal was due to biodegradation rather than adsorption of dye on cells. Scanning and transmission electron microscopy revealed the secretion of exopolysaccharides (EPS) by S. paucimobilis cells on exposure to MB—a probable physiological defence mechanism to ensure controlled diffusion of dye molecules into cellular structures. Biokinetic coefficients, namely, growth yield, Y; specific biomass decay, K d; maximum specific substrate rate, k; saturation constant for substrate, K ₛ; and maximum specific biomass growth rate, μ ₘₐₓ, were determined by the Monod type kinetic equation. Results indicate that S. paucimobilis holds a promise as a good candidate for the biological treatment of industrial effluent containing high concentrations of synthetic dyes.

Previous studies have made some progress with the use of microbial community properties as assessment criteria for rehabilitation success of post-mining areas. Currently, there is a need for reference ranges of specific properties in rehabilitated post-mining sites to make this approach more practical. The aim of this investigation was to compare assessment parameters indicative of microbial community function (enzymatic assays) and structure (phospholipid fatty acid (PLFA) analysis) in rehabilitated asbestos and coal discard sites and to establish ranges of minimum and maximum values for these parameters in both types of sites. The range established for dehydrogenase activity in coal discard sites was 24.3–339.5 μg INF g−1 2 h−1 and for asbestos 44.5–544.6 μg INF g−1 2 h−1. Ranges were also established for β-glucosidase, urease, acid phosphatase and alkaline phosphatase. Complete PLFA profiles were determined and ranges established for major PLFA groups and ratios in both types of discard. From the PLFA profiles, viable microbial biomass was determined as 6,080–29,851 and 8,128–47,242 pmol g−1 dry weight for the coal and asbestos discard sites, respectively. While similar ranges were observed for both types of discard, a canonical correspondence analysis that accounts for functional and structural characteristics showed that sites clustered according to the origin of the samples.

Most previous studies investigating controls on nitrous oxide (N2O) emissions have relied on plot-scale experiments and focused on relative homogeneous biotic and abiotic factors such as soil, vegetation, and moisture. We studied soil N2O flux at 11 chamber sites along a 620 m topographic gradient in upstate New York, USA, aiming at identifying patterns of N2O flux and correlating them to hydrological factors and soil substrate properties along the gradient. The topographic gradient is a complex slope with an overall gradient of 8%, covering plant communities of pasture, forest, alfalfa field, and riparian area from the top to the bottom. Mean fluxes of N2O measured from late March to May ranged from 4.45 to 343 μg N m−2 h−1, and these fluxes were not significantly different among chamber sites located in different communities. With the descending of the slope, N2O fluxes increased with the increase of soil water content, except for the riparian site. Statistically, N2O fluxes were not strongly correlated with soil temperature, soil bulk density, and water filled pore space (p > 0.05). Instead, strong correlations (p < 0.05) were found between N2O fluxes and soil C and N content including NO 3 − , NH 4 + , total organic carbon, and C/N ratio. Multiple linear regression analyses including both soil physical and substrate properties highlighted the significance of soil NO 3 − content and C/N ratio in regulating N2O fluxes along the gradient.

Biochar is a carbon-rich product derived from biomass through pyrolysis. Fluoride adsorption potential of the biochar derived from orange peel (OP) and water treatment sludge (WS) at different pyrolytic temperatures (400, 600, and 700 °C) was investigated in a batch mode as a function of pH. With respect to adsorption, two types were considered, i.e., actual and apparent adsorption where fluoride combined with metal complexes in solution were counted and not counted, respectively. The highest actual fluoride adsorption was observed in the pH range of 2.0 to 3.9 for OP biochar and 5.1 to 6.2 for WS biochar, respectively. For the WS biochar, apparent fluoride adsorption showed nearly 100 % in the pH range of 2.0 to 4.5, and then the adsorption capacity diminished drastically as the pH increased from 5.0 to 10.0. There was no significant difference between apparent and actual fluoride adsorption for OP biochar. In the Fourier-transform infrared spectroscopic analysis of WS biochar, a strong and sharp band was observed at around 2,364 cm⁻¹ after adsorption of fluoride. Elemental content analysis by the energy-dispersive X-ray method revealed that the fluorine content was higher at pH 6.0 than at pH 3.0 and 9.0 as the results of actual fluoride adsorption. From these results, we may conclude that the biochar derived from OP and WS can be reused as an economical and effective adsorbent for fluoride removal in acidic aqueous phase.

This study presents the application of multivariate statistical tools for the evaluation of spatial variations and the interpretation of water quality data obtained in a monitoring program of Lis river basin surface water, Portugal. Twenty-seven physicochemical and microbiological parameters were determined in six water sampling campaigns at 16 monitoring sites during the period from September 2003 to November 2006. Correlation analysis, principal component analysis, and cluster analysis were performed to evaluate the main water pollution sources and to characterize the spatial distribution of water pollution profiles in river basin. The results achieved with the statistical methodologies led to distinguish natural and anthropogenic pollution sources. Additionally, monitoring sites with similar water pollution profile were identified, indicating that some monitoring locations can be changed to improve the spatial characterization of water quality in the river basin. CBO, CQO, P, and N were identified as significant variables affecting spatial variations, namely in the Lis river middle reach. Besides the identification of main pollution sources, the applied statistical tools were able to identify spatial patterns of water pollution in Lis river basin, which further helps in the reassessment of the number and location of monitoring sites.

The fate of N-15-labeled potassium nitrate (8.5% N-15 excess) was determined in 3-year-old Valencia orange trees grown in 1-m(3) containers filled with different textured soils (sandy and loamy). The trees were fertilized either in spring (24 March) or summer (24 July). Spring fertilized trees gave higher fruit yields in sandy than in loamy soils, which exceeded summer fertilized trees in both cases. Summer fertilized trees had greater leaf biomass than spring fertilized trees. Fibrous root weight was 1.9-fold higher in sandy than in loamy soil. At the end of the cycle, tree N recovery from spring application was 45.7% for sandy and 37.7% for loamy soil; from summer fertilization, N recovery was 58.9% and 51.5% for sandy and loamy soils, respectively. The N-15 recovered in the inorganic soil fraction (0-90 cm) was higher for loamy (1.3%) than for sandy soil (0.4%). Fertilizer N immobilized in the organic matter was lower in sandy (2.5%) than in loamy soil (6.0%). Potential nitrate leaching from fertilizer ((NO)-N-15 (3) (-) -N in the 90-110-cm soil layer plus (NO)-N-15 (3) (-) -N in drainage water) was 34.8% higher in sandy than in loamy soil. The low N levels in sandy soil resulted from both higher NO (3) (-) -N leaching losses and higher N uptake of plants grown in the former. The great root mass and higher soil temperatures could account for raised plant N uptake in sandy soil and in summer, respectively.

The industrial wastewater from resin production plants contains as major components phenol and formaldehyde, which are traditionally treated by biological methods. As a possible alternative method, electrochemical treatment was tested using solutions containing a mixture of phenol and formaldehyde simulating an industrial effluent. The anode used was a dimensionally stable anode (DSA®) of nominal composition Ti/Ru₀.₃Ti₀.₇O₂, and the solution composition during the degradation process was analyzed by liquid chromatography and the removal of total organic carbon. From cyclic voltammetry, it is observed that for formaldehyde, a small offset of the beginning of the oxygen evolution reaction occurs, but for phenol, the reaction is inhibited and the current density decreases. From the electrochemical degradations, it was determined that 40 mA cm⁻² is the most efficient current density and the comparison of different supporting electrolytes (Na₂SO₄, NaNO₃, and NaCl) indicated a higher removal of total organic carbon in NaCl medium.

The goal of our study was to identify pharmaceuticals, their potential sources and consumption level in two different socioeconomic and geographical regions—Bordeaux, France and Kharkiv, Ukraine. These substances were monitored in rivers water during contrasted seasonal conditions with application of passive samplers. The 21 pharmaceuticals (psychiatric drugs: alprazolam, amitriptyline, diazepam, fluoxetine, nordiazepam, carbamazepine, bromazepam; analgesics: aspirin, paracetamol; broncholidator: clenbuterol, salbutamol, terbutaline; non-steroidal anti-inflammatory drug: diclofenac, ibuprofen, ketoprofen, naproxen; lipid regulator: gemfibrozil; stimulants: caffeine, theophylline) were identified in sites upstream and downstream of urban areas and discharge of wastewaters. Caffeine, carbamazepine, and diclofenac were relatively abundant into the surface water and could be considered as potential anthropogenic markers of wastewater discharges into rivers. A mass balance modeling has been applied to calculate approximate consumption rates for carbamazepine, diclofenac, and caffeine in both regions to assess socio-economic factors linked with pharmaceuticals behavior.