Soil is a primary resource used by mankind to ensure its needs mainly through agriculture. Its sustainability is regulated by the indigenous organisms it contains such as microorganisms. Current agricultural practices employ mixtures of pesticides to ensure the crops yield and can potentially impair these non-target organisms. However despite this environmental reality, studies dealing the susceptibility of microorganisms to pesticide mixtures are scarce. In this context, we designed a 3-month microcosm study to assess the ecotoxicity of realistic herbicide mixtures of formulated S-metolachlor (Dual Gold Safeneur®), mesotrione (Callisto®), and nicosulfuron (Milagro®) on the abundance, the diversity, and the activities of microorganisms from a “clay/organic matter-rich” soil, with a particular attention given to N-cycle communities. These communities appeared to be quite resistant to realistic mixtures even if transient effects occurred on the N-cycle-related communities with an increase of ammonification and an inhibition of nitrification as a short-term effect, followed by an increase of denitrification and an accumulation of nitrates. As nitrates are known to be highly leachable with a strong pollution potential, intensive studies should be carried out at field level to conclude on this potential accumulation and its consequences. Moreover, these data now need to be compared with other agricultural soils receiving these herbicide mixtures in order to bring general conclusion on such practices.

This study investigated drivers of denitrification and overall NO₃ ⁻ removal in an agricultural riparian area in central New York. Denitrification was measured using an in situ “push-pull” method with ¹⁵N–NO₃ ⁻ as a tracer during summer and fall 2011 at a pair of riparian sites characterized by different hydrologic regimes. Median denitrification rates were 1347 and 703 μg N kg soil⁻¹ day⁻¹ for the two study sites. These rates are higher than those reported for other riparian areas, emphasizing the role of some riparian areas as hotspots of NO₃ ⁻ removal. N₂O production was significantly higher at one site, demonstrating that riparian areas can be a greenhouse gas source under certain conditions. Denitrification was negatively correlated with groundwater flux, suggesting that slower flushing of water, and thus longer residence time, promotes denitrification. A mass balance of NO₃ ⁻ loss revealed that denitrification only accounted for 5–12 % of total NO₃ ⁻ loss, and production of NH₄ ⁺ indicated that dissimilatory NO₃ ⁻ reduction to NH₄ ⁺ (DNRA) may be occurring at both sites. While both sites were characterized by high NO₃ ⁻ removal, differences in denitrification rates and NO₃ ⁻ removal processes demonstrate the need to improve our ability to capture spatial and process heterogeneity in landscape biogeochemical models.

This study compares the efficiency of a synthetic chelate (ethylenediaminetetraacetic acid-EDTA), a natural low-molecular-weight organic acid (citric acid), and their combination for phytoremediation of Cu-pyrene co-contaminated soils. Zea mays was grown in each soil and amended with citric acid and/or EDTA to understand the effect of chelates during phytoremediation of contaminated soils. In Cu or pyrene-contaminated soil, plant growth was negatively affected by EDTA (43 %) and citric acid (44 %), respectively, while EDTA + citric acid promoted (41 %) plant growth in co-contaminated soil. EDTA and EDTA + citric acid increased the phytoextraction of Cu in Cu-contaminated and co-contaminated soils, respectively. In pyrene-contaminated soil, all tested chelates increased the dissipation of pyrene reaching 90.4 % for citric acid, while in co-contaminated soil, only citric acid or EDTA + citric acid enhanced pyrene dissipation. These results show that Z. mays can be effective with the help of chelates in phytoextraction of Cu and dissipation of pyrene in co-contaminated soil.

Drainage water from acid sulfate soils with sulfuric material has high concentrations of protons and dissolved metals which can have detrimental effects on the surrounding ecosystems. Liming is expensive; therefore, alternative methods are needed. Organic materials such as plant residues, compost or biochars can bind protons and metals but have not been evaluated with respect to remediation of acid drainage water from acid sulfate soils. In this study, eight organic materials (compost, two straws and five biochars differing in feed stock and production temperature) were placed in small PVC cores at 1.5 g C/core and synthetic acid drainage water (pH 3, 28 mg Fe/l and 2 mg Al/l, properties based on long-term averages of drainage water from sulfuric acid sulfate soils) was applied in four leaching events. Mallee biochar produced at 550 °C and wheat biochar produced at 450 °C had high retention capacity for protons, Fe and Al. Retention was low in compost and wheat straw. Retention of protons was positively correlated with organic C concentration of the materials. Retention of Fe and Al was correlated with percentage alkyl, aryl and ketone groups. Other properties such as release of native Fe and Al and amount of material per core could explain differences in ability of organic materials to retain protons, Fe and Al. We conclude that some organic materials such as mallee biochar produced at 550 °C and wheat biochar produced at 450 °C could be used to remediate acidic drainage water.

To treat PCP-contaminated soil, abiotic methods for PCP degradation have been developed, where heme or powder hemoglobin acts as a catalyst and hydrogen peroxide as an oxidant. Degradation of PCP had the first-order kinetics, and rate coefficients, k, were 0.073 and 0.104/day for heme and hemoglobin, respectively, indicating that the hemoglobin was a more efficient catalyst than heme. Approximately 96 % of the initial PCP was degraded at day 35. Thus, hemoglobin might be recommended as the catalyst of choice, since it is much less expensive than heme.

Metal nanoparticles such as Ni, Cu, and Co were prepared within polyethyleneimine (PEI) microgels and were used in the reduction of 4-nitrophenol (4-NP) and 2-nitrophenol (2-NP) to 4-aminophenol (4-AP) and 2-aminophenol (2-AP). The metal nanoparticle content of the prepared PEI-M composite catalyst system (M = Co, Ni, and Cu) was increased by multiple loading and reduction cycles into PEI microgels to provide faster and better reduction of 4-NP and 2-NP. The TOF value increased to 1.48 from 0.353 (mol 4-NP (mol catalyst min)⁻¹) for 4-NP reduction catalyzed by PEI-Ni after three cycles of metal loading and reduction. The effect of temperature on 4-NP and 2-NP reductions catalyzed by PEI-M illustrated that higher temperature resulted in very fast reductions, e.g., at 70 °C 4-NP and 2-NP reduction by PEI-Ni resulted in very fast reduction times of 1.2 and 0.67 min to 4-AP and 2-AP, respectively. The activation parameters, such as energy, entropy, and enthalpy, were also calculated and mild activation energies of 38.8 and 46.0 kJ mol⁻¹for 4-NP and 2-NP catalyzed by PEI-Ni were found, respectively, in comparison to similar studies in the literature. Moreover, it was demonstrated that PEI-Ni microgels are reusable five times consecutively, with almost 100 % conversion and 100 % of their catalytic activity.

Concentrated animal feeding operations (CAFOs) are the principal means of livestock production in the USA and Europe, and these industrial-scale facilities have a high potential to pollute nearby waterways. Chemical and biological stream water quality of a swine and poultry CAFO-rich watershed was investigated on 10 dates during 2013. Geometric mean fecal coliform counts were in the thousands at five of seven sites, especially in locations near swine waste sprayfields. Nitrate concentrations were very high and widespread throughout the watershed, with some individual samples yielding >10 mg-N/L. Ammonium concentrations were likewise high, but greatest near swine waste sprayfields, ranging up to 38 mg-N/L. Five-day biochemical oxygen demand (BOD5) concentrations exceeded 10 mg/L in 11 of 70 stream samples, reaching as high as 88 mg/L. BOD5 concentrations were significantly correlated with components of animal waste including total organic carbon, ammonium, and phosphorus, as well as the nutrient response variable chlorophyll a. The degree of nutrient and fecal contamination did not significantly differ between rainy and dry periods, indicating that surface and groundwater pollution occurs independently of stormwater runoff. This research shows that industrial-scale swine and poultry production leads to chronic pollution that is both a human health and ecosystem hazard. There are approximately 450,000 CAFOs currently operating in the USA, with the majority located in watersheds feeding major riverine and estuarine systems with known water quality problems. Current US waste management protocols for this widespread system of livestock production fail to protect freshwater and estuarine ecosystems along the US Mid-Atlantic, Southeast and Gulf coasts, and expansion into industrializing nations will likely bring severe pollution with it.

Wastewater from textile industry contains a number of pollutants which are hazardous in nature. The direct discharge of the wastewater into the environment affects its ecological status by causing various undesirable changes. As environmental fortification becomes a global anxiety, industries are finding novel solutions for mounting low-cost and environmental-friendly technologies for the dye removal from the waste. The presence of the dyes hinders sunlight penetration and disturbs the ecosystem of water. However, the treatment of wastewater with biodegradable polymer attains a vital importance as they are environmental friendly. The main objective of the work was to make an effort to develop a feasible process for the removal of dyes/color from the textile wastewater by using potato starch, which is a plant-based bio-polymer. A three-level, full-factorial design was selected, and experiments were conducted using a jar test apparatus. The main effects and interactions of dosage, pH, and temperature on the percentage color removal were analyzed. Reduction in color was analyzed using UV-2800 spectrophotometer. A three-way significant interaction was observed. However, dosage is found to be the most important parameter for dye removal using potato starch.

The scarcity of clean water affecting many parts of the world encourages efforts to improve water reclamation processes, which rely on their capability to remove diverse types of water pollutants and contaminants. Thus, this study reports the application of bamboo fiber powders as potential low-cost sorbent for removal of noxious organic compounds in aqueous solution. Bisphenol A, a biorefractory endocrine disruptor compound, was chosen as model compound in order to easily follow the separation process. Principal component analysis of the FTIR spectra and BET surface area measurements were performed on treated bamboo fiber powders. Treatment of the raw powders with alkali, ionic and non-ionic surfactants appeared to improve the bisphenol A removal performance of the bamboo fiber powders with the best removal efficiency reached at 39 % for a sorbent dosage of 4 g L⁻¹ gained after a bamboo treatment using the cationic surfactant. Effects of contact time, sorbent dosage, and particle sizes (55, 300, and 1000 μm) of cationic surfactant-treated bamboo fiber powders towards removal of bisphenol A were further assessed in a batch system with an optimum removal observed for 55 μm in particle size.