Understanding the biogeochemistry of metal-contaminated peatlands is important for predicting the impact of mining and industrial activities on peatlands and downstream surface waters and for predicting recovery of previously impacted sites. The objective of this work was to characterize the factors controlling spatial and temporal variability in surface peat (0–15 cm) and pore water chemistry of 18 regionally representative peatlands in Sudbury, Ontario, Canada. The pollution gradient is clearly evident as Cu and Ni concentrations in surface peat are elevated close to the main Copper Cliff smelter. Surface peat also differs greatly in acidity (pH) and organic matter content among sites, and dissolved organic carbon (DOC) concentrations in pore water are positively correlated with peat carbon content. In addition, sites having surface peat that is more decomposed also have pore water DOC that is more humified. Pore water chemistry varies seasonally; samples taken in late summer and fall were characterized by higher SO₄, and lower pH and higher concentrations of base cations and metals such as Ni, Co, and Mn compared with those in late spring that had higher DOC, higher pH, and higher concentrations of metals such as Cu and Fe. Despite the large spatial and temporal variability in pore water chemistry, soil-solution partitioning (K d) of some metals (Ni, Co, and Mn) can be explained by pH alone. Modeling soil-solution partitioning for these metals and Cu, Al, and Fe is significantly improved with the addition of SO₄; dissolved organic matter quality and quantity and/or the δ¹⁸O signature of the pore water in regression models indicating several factors other than acidity has an influence on pore water chemistry.

A novel magnetic pyridinium-functionalized mesoporous silica adsorbent (Fe₃O₄@SiO₂@Py-Cl) was synthesized for nitrate removal from aqueous solutions. The adsorption performances were investigated by varying experimental conditions such as pH, contact time, and initial concentration. The adsorbent was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, and magnetic hysteresis loops. The results showed that the adsorption equilibrium could be reached within 30 min and the kinetic data were fitted well by pseudo-second-order and intra-particle diffusion model. The adsorbent exhibited a favorable performance, and its maximum adsorption capacity calculated by the Langmuir isotherm model was 1.755 mmol/g. The nitrate adsorption mechanism was mainly controlled by the material through ion exchange of nitrate with chloridion, as determined by XPS. This study indicated that this novel pyridinium-functionalized mesoporous material had excellent adsorption capacity. Meanwhile, compared with other adsorbents, it could remove nitrate fast and easy to be collected by magnetic separation, showing great potential application for nitrate removal from aqueous solution.

The biodegradation of organic compounds present in water at trace concentration has become a critical environmental problem. In particular, enzymatic oxidation by fungal laccases offers a promising alternative for efficient and sustainable removal of organic pollutants in water. In this work, the biocatalytic ability of laccases from the Pycnoporus sanguineus CS43 fungus was evaluated. A filtered culture supernatant (laccase cocktail) evidenced an enhanced biotransformation capability to remove common endocrine-disruptor compounds (EDCs), such as bisphenol A, 4-nonylphenol, 17-α-ethynylestradiol and triclosan. A biodegradation of around 89–100 % was achieved for all EDCs using synthetic samples (10 mg L⁻¹) and after the enzymatic treatment with 100 U L⁻¹ (50.3 U mg ⁻¹). The biodegradation rates obtained were fitted to a first order reaction. Furthermore, enzymatic biocatalytic activity was also evaluated in groundwater samples coming from northwestern Mexico, reaching biotransformation percentages between 55 and 93 % for all tested compounds. As far as we know this is the first study on real groundwater samples in which the enzymatic degradation of target EDCs by a laccase cocktail from any strain of Pycnoporus sanguineus was evaluated. In comparison with purified laccases, the use of cocktail offers operational advantages since additional purification steps can be avoided.

During the extraction of coal bed methane (CBM), entrapped in the deep layers of different coal beds, large amount of coal bed water (CBW) is also simultaneously released. The quality of this water is generally very poor which may often contaminate the adjoining soil environment adversely. In the present study, some major changes occurring in CBW-contaminated soils were assessed with relation to nearby non-affected soils. The CBW was found to be moderately saline and highly alkaline in nature with high sodium absorption ratio (SAR) values. Contamination with this water affected the soil environments substantially resulting in significantly increased pH and exchangeable sodium percentage (ESP) in the affected soils thus rendering the soils unsuitable for undertaking common agricultural practices. However, in spite of moderately high electrical conductivity values of this contaminating water, the resultant increments in salinity status of the soils were not observed to reach near the critical level. This behaviour was attributed to light texture of these soils which probably helped in leaching of a part of the soluble salts. Some microbial properties as well as availability of nitrogen and phosphorus were also found to decline in these CBW-affected soils. The study showed that utmost care needs to be exercised before release of CBW during extraction of CBM. In case of any contamination to nearby arable soils, suitable amendment practices for alkaline soils need to be adopted to mitigate the adverse effects of such water on soil environment.

Nitrogen inputs to coastal watersheds have been linked to eutrophication. However, the role that domestic sources of wastewater play in contributing nitrogen to coastal watersheds is not well known in the southeastern USA. In a yearlong study (2011–2012), nitrogen concentrations were compared in watersheds served by septic systems and a centralized sewer system in the Coastal Plain of North Carolina. Surface and groundwater samples from septic systems and sewer watersheds were analyzed for total dissolved nitrogen (TDN), total nitrogen, and nitrogen and oxygen isotopes in nitrate. Groundwater beneath the drainfield and adjacent to streams had median concentrations of TDN at 5.9 and 4.4 mg/L, respectively. Additionally, median groundwater-transported loads of TDN to the stream from septic systems sites (0.6 kg-TDN/year) were significantly greater than sites in sewer watersheds (0.2 kg-TDN/year). Isotopic analyses revealed that effluent from septic systems was the primary source of nitrate in watersheds served by septic systems, while fertilizer and/or soil organic matter were dominant sources of nitrate in sewer watersheds. Nitrogen exported from septic systems contributed to elevated nitrogen concentrations in groundwater and streams throughout the watershed, whereas nitrogen exports from sewers were focused at a single point source and affected surface water concentrations. Based on watershed TDN exports from septic systems minus TDN exports from sewers watersheds, it was estimated that septic systems contributed 1.6 kg TDN/ha/year to watershed exports of TDN. Overall, septic systems and sewers contributed to elevated nitrogen loading and should be considered in nutrient-sensitive watershed management.

Plant peroxidases have strong potential utility for decontamination of phenol-polluted wastewater. However, large-scale use of these enzymes for phenol depollution requires a source of cheap, abundant, and easily accessible peroxidase-containing material. In this study, we show that potato pulp, a waste product of the starch industry, contains large amounts of active peroxidases. We demonstrate that potato pulp may serve as a tool for peroxidase-based remediation of phenol pollution. The phenol removal efficiency of potato pulp was over 95 % for optimized phenol concentrations. The potato pulp enzymes maintained their activity at pH 4 to 8 and were stable over a wide temperature range. Phenol solutions treated with potato pulp showed a significant reduction in toxicity compared with untreated phenol solutions. Finally we determined that this method may be employed to remove phenol from industrial effluent with over 90 % removal efficiency under optimal conditions.

Soil salinization is a worldwide problem of which secondary salinization is increasingly more frequent, threatening agricultural production. Salt accumulation affects not only plants but also the physio-chemical characteristics of the soil, limiting its potential use. Climate change will further increase the rate of salinization of soil and groundwater as it leads to increased evaporation, promotes capillary rise of saline groundwater as well as increased irrigation with brackish water. Episodic seawater inundation of coastal areas is likely to increase in frequency as well. This work analyzed three types of salinization: seawater inundation (by irrigating soils with a 54 dS m⁻¹NaCl solution), saline groundwater capillary rise (soil contact with a 27 dS m⁻¹NaCl solution), and irrigation with two types of brackish water with different residual sodium carbonate (RSC). Two soils were used: a mineral soil (7.0 % clay; 0.7 % organic matter) and an organic soil (2.7 % clay; 7.4 % organic matter). The tested soils had different resilience to salinization: The mineral soil had higher sodium adsorption ratio (SAR) due to low levels of calcium + magnesium but had higher leaching efficiency and more limited effects of RSC. The organic soil however was more prone to capillary rise but seemingly more structurally stable. Our results suggest that short-term inundation with seawater can be mitigated by leaching although soil structure may be affected and that capillary rise of brackish groundwater should be carefully monitored. Also, the impact of irrigation with brackish water with high RSC can be inferior in soils with higher exchangeable acidity.

Dielectric barrier discharges (DBDs) were utilized for the remediation of soil contaminated with p-nitrophenol (PNP). The effect of treatment time, applied discharge voltage, initial PNP concentration, pH of contaminated soil, and airflow rate were investigated in this study. The results showed that 63.2 % of the PNP in the contaminated soil was degraded in 50 min with a voltage of 38.2 kV with no airflow. This degradation reaction followed the first order reaction kinetics. The degradation by ozone alone was compared with the plasma treatment to identify the role of ozone. Chromatographic analysis was applied to monitor the intermediates produced during the oxidation process, and the main byproducts were maleic acid, p-benzoquinone, 4-nitrocatechol, methanoic acid, acetic acid, oxalic acid, NO₂ ⁻, and NO₃ ⁻. Possible pathways for the degradation of PNP in this system were deduced, which would provide evidence for the researches about the remediation of soils polluted by organic pollutants.

Before and after an intense wildfire in a forested area of Colorado in June 2012, river water and sediment samples were collected to study temporal and spatial trends related to the event. Water quality and soil properties were disturbed by the fire, but the magnitude was relatively small without precipitation. After precipitation, in-stream total nitrogen and total phosphorus (TP) concentrations significantly increased in the upstream section located within 10 km of the burned area. Large amounts of particulate P associated with highly correlated total suspended solids were introduced to the upstream section. Along with significantly increased in-stream concentrations of soluble reactive P (SRP) and dissolved organic P (DOP) after rain events, SRP dominated dissolved P in the river replacing DOP that was the main dissolved species before the fire event. In the riverbank, TP load increased significantly after the fire, and silt-clay and organic matter mass concentrations increased after precipitation. Riverbed TP mass concentrations decreased due to a reduced sorption capacity leading to a considerable P release from the sediments. The results indicate that fire-released P species will impact the downstream area of the watershed for a considerable time period as the bank erosion-sorption-desorption cycles in the watershed adjust to the fire-related loading.