This study primarily focused on the performance of 1,1,1-trichloroethane (1,1,1-TCA) and trichloroethylene (TCE) degradation involving redox reactions in zeolite-supported nanozerovalent iron composite (Z-nZVI)-catalyzed sodium percarbonate (SPC) system in aqueous solution with five different chelating agents (CAs) including oxalic acid (OA), citric acid monohydrate (CAM), glutamic acid (GA), ethylenediaminetetraacetic acid (EDTA), and L-ascorbic acid (ASC). The experimental results showed that the addition of OA achieved almost 100 % degradation of 1,1,1-TCA and TCE. The addition of CAM and GA also significantly increased the contaminant degradation, while excessive addition of them inhibited the degradation. In contrast, EDTA and ASC showed negative impacts on 1,1,1-TCA and TCE degradation, which might be due to the strong reactivity with iron and OH● scavenging characteristics. The efficiency with CA addition on 1,1,1-TCA and TCE degradation decreased in the order of OA > CAM > GA > no CAs > EDTA > ASC. The extensive investigations using probe compound tests and scavenger tests revealed that both contaminants degraded primarily by OH● and O₂ –● in chelated Z-nZVI-catalyzed SPC system. The significant improvement in 1,1,1-TCA and TCE degradation efficiency was accredited due to the (i) increase in concentration of Fe²⁺ and (ii) continuous generation of OH● radicals and maintenance of its quantity, ensuring more stability in the aqueous solution. Finally, the complete mineralization of 1,1,1-TCA and TCE in the OA-chelated, Z-nZVI-catalyzed SPC system was confirmed without any chlorinated intermediate by-products detected, demonstrating a great potential of this technique in the application of groundwater remediation. Graphical Abstract Schematic representation of the reactive oxygen species in the chelated Z-nZVI-catalyzed percarbonate system for the degradation of 1,1,1-TCA and TCE

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.

Agricultural drainage plays a vital role in the discharge of non-point source pollutants into surface-receiving waters. Sustainable drainage management to mitigate nitrogen losses from cultivated land is needed. Many factors influence nitrogen removal in agricultural drainage ditches. However, existing research has not fully considered parameter sensitivity analysis of nitrogen removal. Therefore, in this study, an ecological ditch model containing a permeable dam was built, in which the influent nitrogen concentration, suspended solid concentration, influent flow, and water level were examined as influencing factors. An orthogonal test was conducted to explore the significance of these four factors and their impacts on nitrogen removal as well as the nitrogen transport characteristics along the ditch. The results revealed that the ditches had an interception effect on nitrogen pollutants, and according to importance, the four factors are influent nitrogen concentration, water level, water flow, and suspended solid concentration in descending order. The plants and permeable dam in the ditch also played an important role in nitrogen removal.

Dutch fens, subjected to high nitrogen (N) deposition levels with reduced N (NHy) highly dominating over oxidised N (NOₓ), have since the second half of the past century seen a significant decline of Scorpidium and other characteristic brown moss species, while several Sphagnum species have increased rapidly. This promotes acidification and the transition from rich to poor fens. In line with the outcomes of previous short-term water culture experiments, we hypothesised that Scorpidium growth is negatively affected by NHy due to ammonium toxicity, but not by NOₓ deposition, and that Sphagnum grows equally well on both N forms. To test this hypothesis under field conditions, we carried out a 4-year N addition experiment (5.0 g N m⁻² year⁻¹, applied either as NO₃ ⁻-N or as NH₄ ⁺-N) on natural mixed Scorpidium revolvens–Sphagnum contortum stands in a rich fen with relatively low background N deposition. After 4 years, ammonium addition had significantly reduced Scorpidium growth, while Sphagnum had not significantly been affected by N additions. Increased ammonium levels were directly toxic to Scorpidium, while Sphagnum was not affected. Furthermore, N addition (in particular nitrate) also indirectly influenced moss growth through promoting vascular plants. Our study confirms that it is ecologically relevant to consider the specific form in which N enrichment occurs, i.e. the ratio of NHy vs. NOₓ. We conclude that in rich fens, the risk of rapid transition of the moss layer to dominance of poor-fen species is strongly promoted by increased deposition of reduced N.

Information on the phytotoxicity of nanoparticles (NPs) at low concentrations (e.g., ppb to low ppm) is scarce. Therefore, this study was conducted to assess the effects of laboratory-prepared Cu, Zn, Mn, and Fe oxide NPs in low concentrations (<50 ppm) on the germination of lettuce (Lactuca sativa) seeds in a water medium. The data showed that CuO NPs were slightly more toxic than Cu ions while the toxicity of ZnO NPs was similar to that of Zn ions, and MnOx NPs and FeOx NPs were not only less toxic than their ionic counterparts but also significantly stimulated the growth of lettuce seedlings by 12–54 %. This study showed that manufactured NPs were not always more toxic than other chemical species containing the same elements. Instead, Mn or Fe NPs can significantly enhance plant growth and have the potential to be effective nanofertilizers for increasing agronomic productivity.

Standardized measurement protocols are required to reduce ammonia (NH₃) emissions. In vitro measurement of NH₃ emissions consists in trapping the emission from an emitting source in an acidic solution under controlled conditions. The objective of this study was to assess the in vitro NH₃ measurement method from pig slurry with acid wet traps, as regards to the following: (i) the variation between replicates of NH₃ emissions measured in vitro, (ii) the relationships between partial and accumulated emissions, and (iii) the reduction of measurement frequency. For this study, a total of 60 pig slurry samples from different animal types (sows and growing animals) were collected from commercial farms. The coefficient of variation among replicates of accumulated NH₃ emission during 15 days was 6.73 %. Emissions tended to decrease with time, and an average reduction of NH₃ emissions about 16 % was found in the period 96–240 h with respect to the 0–96-h period. However, samples continued emitting considerable amounts of NH₃ after 360 h. Linear regression models allowed predicting emissions accumulated for 15 days using only the first 8 days (R ² > 0.90). Reducing NH₃ measurement frequency (from 24 to 48 h) did not significantly affect measured emissions (P > 0.05). The results of this study confirm that replication of measurements is required and a coefficient of variation of 10 % may be established as quality control requirement. The study also suggests that reducing the duration and frequency of measurements is a tangible option to simplify this methodology.

Purpose: Dredging of sediments, a requirement for harbor maintenance, removes millions of tons of mineral wastes, contaminated at varying degrees with trace metals, from the water. In previous investigations, Cu and Zn have been identified as highly concentrated trace metals associated to sulfides, mineral phases sensitive to oxidation. In order to ensure their sustainable management, the solidification/stabilization (S/S) and/or the valorization of contaminated sediments as secondary raw materials is a way to be promoted. Indeed, their reuse as a substitute of sand in cemented mortar formulation would allow combining both treatment and valorization of such wastes. Methods: In the present study, the environmental assessment of mortars formulated with raw and weathered marine sediments (in particular contaminated with Cu, Pb and Zn), compared to sand reference mortars, was conducted through two kinetic leaching tests: weathering cell tests (WCTs), in which mortars were crushed and leached twice a week, and a tank monolith leaching test (MLT), in which leaching was performed on monolithic mortars with increasing leachate renewal time. Results: In both leaching tests, calcium and sulfur were released continuously from sediment mortars, showing the oxidation-neutralization processes of sulfides and carbonates. In the MLT, Cu was released by sediment mortars through diffusion, particularly by weathered mortars, at low concentrations during 60 days of the test duration. With the more aggressive WCT, Cu concentrations were higher at the beginning but became negligible after 7 days of testing. Pb was released through diffusion mechanisms until depletion in both tests, whereas Zn was particularly well immobilized in the cemented matrices. Conclusions: The S/S process applied using hydraulic binders proved to be efficient in the stabilization of Cu, Pb, and Zn highly presents in studied sediments, and further valorization in civilian engineering applications could be considered.

Biogas slurry is a product of anaerobic digestion of manure that has been widely used as a soil fertilizer. Although the use for soil fertilizer is a cost-effective solution, it has been found that repeated use of biogas slurry that contains high heavy metal contents can cause pollution to the soil-plant system and risk to human health. The objective of this study was to investigate effects of biogas slurry on the soil-plant system and the human health. We analyzed the heavy metal concentrations (including As, Pb, Cu, Zn, Cr and Cd) in 106 soil samples and 58 plant samples in a farmland amended with biogas slurry in Taihu basin, China. Based on the test results, we assessed the potential human health risk when biogas slurry containing heavy metals was used as a soil fertilizer. The test results indicated that the Cd and Pb concentrations in soils exceeded the contamination limits and Cd exhibited the highest soil-to-root migration potential. Among the 11 plants analyzed, Kalimeris indica had the highest heavy metal absorption capacity. The leafy vegetables showed higher uptake of heavy metals than non-leafy vegetables. The non-carcinogenic risks mainly resulted from As, Pb, Cd, Cu and Zn through plant ingestion exposure. The integrated carcinogenic risks were associated with Cr, As and Cd in which Cr showed the highest risk while Cd showed the lowest risk. Among all the heavy metals analyzed, As and Cd appeared to have a lifetime health threat, which thus should be attenuated during production of biogas slurry to mitigate the heavy metal contamination.

Accurately measuring air concentrations of agricultural fumigants is important for the regulation of air quality. Understanding the conditions under which sorbent tubes can effectively retain such fumigants during sampling is critical in mitigating chemical breakthrough from the tubes and facilitating accurate concentration measurements. Using laboratory experiments, we studied the effects of air flow rate (100–1000 mL min⁻¹) and sampling time (2–16 h) on the breakthrough of co-applied chloropicrin (CP) and 1,3-dichloropropene (1,3-D) from 600-mg XAD-4 sorbent tubes. Due to the reversible adsorption of the chemicals, it was not possible to determine a tube adsorption capacity that was true across all flow and sample time conditions. Flow rate exerted the stronger influence on breakthrough, particularly for CP, with flow rates in excess of 200 mL min⁻¹ resulting in significant system losses even at the shortest sampling time (2 h). A flow rate of 200 mL min⁻¹ should therefore not be exceeded, irrespective of flow rate. With the use of a single tube (no backup), sampling times up to 4 h showed no system losses (100 % retention). Using a primary and backup tube, sampling periods up to 16 h also resulted in retention of all the added chemical masses. The information will be useful in establishing effective air quality monitoring programs following fumigation events.

Global warming and pollution are the twin crises experienced globally. Biological offset of these crises are gaining importance because of its zero waste production and the ability of the organisms to thrive under extreme or polluted condition. In this context, this review highlights the recent developments in carbon dioxide (CO₂) capture from flue gas using microalgae and finding the best microalgal remediation strategy through contrast and comparison of different strategies. Different flue gas microalgal remediation strategies discussed are as follows: (i) Flue gas to CO₂ gas segregation using adsorbents for microalgal mitigation, (ii) CO₂ separation from flue gas using absorbents and later regeneration for microalgal mitigation, (iii) Flue gas to liquid conversion for direct microalgal mitigation, and (iv) direct flue gas mitigation using microalgae. This work also studies the economic feasibility of microalgal production. The study discloses that the direct convening of flue gas with high carbon dioxide content, into microalgal system is cost-effective.