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

Ecological ditches have demonstrated the ability to filter and control nutrient transport to rivers. Few studies, however, have examined the internal loading of nitrogen (N) and phosphorus (P) in these systems due to vegetation decomposition. Most often, this concept is overlooked during evaluation of the nutrient removal rate of the ditches. Thus, the litter bag technique was used to analyze nutrient release to surface water during these processes. Mesocosm and field experiments were conducted to assess the growth characteristics and consequent nutrient accumulation by six ditch plant species. Of the six, Canna indica had the highest aboveground accumulation of N and P. About 85–95 % increase in the aboveground biomass was recorded at the end of the experimental period. The removal efficiencies of TN, TP, and NH₄-N from the sewage reached up to 72–99.4, 64–98.7, and 75 %–100, respectively. Complete removal of all NO₃-N was achieved. The amounts of N and P uptake by plant species were closely related to the biomass of plants. During the decaying process, N and P concentrations in the aboveground biomass decreased. These lost nutrients were eventually shifted to the system, which led to a deterioration of the water quality. Therefore, harvesting of aboveground biomass from inside the ditch is an appropriate intervention to prevent the release of N and P in the dormant season. The finding is important for planning an efficient eco-ditch system and predicting the influence of nutrient loading in the eco-ditches upon senescence of ditch plants.

Little research has been conducted on the occurrence of pharmaceuticals and personal care products (PPCPs) in the marine environment despite being increasingly impacted by these contaminants. This article reviews data on the occurrence of PPCPs in seawater, sediment, and organisms in the marine environment. Data pertaining to 196 pharmaceuticals and 37 personal care products reported from more than 50 marine sites are analyzed while taking sampling strategies and analytical methods into account. Particular attention is focused on the most frequently detected substances at highest concentrations. A snapshot of the most impacted marine sites is provided by comparing the highest concentrations reported for quantified substances. The present review reveals that: (i) PPCPs are widespread in seawater, particularly at sites impacted by anthropogenic activities, and (ii) the most frequently investigated and detected molecules in seawater and sediments are antibiotics, such as erythromycin. Moreover, this review points out other PPCPs of concern, such as ultraviolet filters, and underlines the scarcity of data on those substances despite recent evidence on their occurrence in marine organisms. The exposure of marine organisms in regard to these insufficient data is discussed.

In the present work, the synthesized calcium carbonate (CaCO₃) identified as fusiform aragonite was obtained through the biomimetic mineralization process for possible recovery of high concentration of phosphorus (P) within the wide range of pH. It was characterized before/after phosphate sorption by the combination of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray absorption near-edge structure (XANES) at molecular level. By batch experiments, the sorption isotherms and envelopes of the fusiform aragonite to phosphate were explored. The experimental data showed that the fusiform aragonite at pH ≥6.0 has a steep raising sorption capacity with increasing initial P (>9.0 mM) due to its unique crystalline structure and morphology. The likely mechanism is that the occurrence of fast nucleation growth of Ca-P phases (including amorphous calcium phosphate (ACP), dibasic calcium phosphate (DCP), and hydroxyapatite (HAP)) is triggered upon attainment of the stabilized crystal morphology of aragonite in solution due to phosphate sorption. These features may contribute to the fusiform aragonite as an idea adsorbent for high phosphate removal from wastewater even independent of pH.

Triclosan (TCS) is an antimicrobial agent that is extensively used in personal care products (PCPs), and its residue is frequently reported in aquatic environments. In this study, we investigated the reaction behavior of TCS during enzyme-catalyzed oxidative coupling reactions (ECOCRs) by laccase from Pleurotus ostreatus and determined how the presence of natural organic matter (NOM) influenced the formation of the products. Results indicated that the optimum pH for TCS transformation was 6.0 in laccase-mediated ECOCRs. At pH values below 5.0 and above 7.0, the pseudo first-order kinetic rate constants (k) of TCS transformation declined significantly. Moreover, the k values of TCS transformation increased as the laccase activity increased (0.1179–0.5757 h⁻¹). A total of four product peaks were generated, and they were more hydrophobic than TCS. High-resolution mass spectrometry (HRMS) analysis indicated that these products could be the oligomers resulting from TCS self-coupling reactions. The relative peak areas of these oligomers displayed strong linear correlations with the different initial TCS concentrations, and the saturation point of laccase (3.0 U mL⁻¹), when the binding with TCS was 40 μmol L⁻¹. In the presence of NOM (i.e., humates and fulvates), humates in particular strongly inhibited TCS transformation and lowered the extent of its self-coupling, which likely resulted from the cross-coupling between TCS and NOM. Our study improves a better understanding of the reaction behavior of TCS in the natural aquatic environment during laccase-mediated ECOCRs.

A greenhouse experiment was accomplished to investigate the feasibility of excess sludge modified by coal fly ash pretreatment and γ-ray irradiation in soil application for cultivation of Artemisia ordosica. The results showed that modified excess sludge provided a positive effect on the growth of Artemisia ordosica. The modified excess sludge and aeolian sandy soil at the volume ratio of 1:2 was optimal, and nutrient concentrations of Artemisia ordosica reached the highest. In the aeolian sandy soil, the bio-concentration factor values of most heavy metals were less than 1.0 except for Cu, Zn, and Ni. The average bio-concentration factor values of heavy metals in Artemisia ordosica increased in a sequence of Mo < Cd < Fe < V < Cr < Co < Mn < Pb < Cu < Zn < Ni for all samples. Artemisia ordosica could be used to decrease the bioavailability and eco-toxicity of Ni, V, and Mo in all cultivation experiments of artificial soil, and Artemisia ordosica could also reduce the bioavailability and eco-toxicity of Cu, Cd, Cr, and Mn in the artificial soil of modified excess sludge and aeolian sandy soil at the volume ratio of 1:2.

The removal of As(V) from aqueous solutions by leonardite loaded with ferric ions (Fe-leonardite) has been investigated. The influence of pH, contact time, and arsenate concentration on the adsorption process were evaluated. Batch kinetic studies showed that equilibrium time was reached at 24 h of contact time. Equilibrium data obtained with low initial arsenate concentrations (10–400 ppb) were fitted to both Langmuir and Freundlich models, and the maximum adsorption capacity was estimated to be 322 μg g⁻¹. Arsenic sorption was evaluated in continuous mode to reproduce industrial applications and to determine the conditions where the process was controlled by either mass transfer or reaction rate. A maximum sorption capacity of 905 μg g⁻¹ was obtained in continuous experiments. These results indicate that Fe-leonardite is a great potential material for removing arsenate at low initial concentrations from contaminated water.

Along the southeastern coast of Costa Rica, a variety of pesticides are intensively applied to produce export-quality plantains and bananas. In this region, and in other agricultural areas, fish kills are often documented by local residents and/or in the national news. This study examines principal exposure pathways, measured environmental concentrations, and selected toxicity thresholds of the three most prevalent pesticides (chlorpyrifos, terbufos, and difenoconazole) to construct a deterministic risk assessment for fish mortality. Comparisons of observed pesticide concentrations, along with estimated biological effects and observations during actual fish kills, highlight gaps in knowledge in correlating pesticide environmental concentration and toxicity in tropical environments. Observations of fish kill events and measured pesticide concentrations in the field, along with other water quality indicators, suggest that a number of environmental conditions can interact to cause fish mortality and that current species toxicity datasets may not be applicable for estimating toxicological or other synergistic effects, especially in tropical environments.

The olive oil industry produces a highly complex wastewater, known as olive oil mill wastewater (OOMW), which represents a relevant environmental problem for the Mediterranean region. Several physicochemical, biological and combined treatments have been tested to deal with this industrial externality but none was totally effective in reducing its toxicity for species inhabiting the receiving freshwater systems. Within this framework, nanotechnology appears as a promising research area, offering new approaches for the treatment of wastewaters based on the enhanced physical and chemical properties of nanomaterials (NMs). In this context, this work aimed to investigate the treatability of OOMW through several treatments involving advanced oxidation processes plus the use of two nanomaterials as catalysts (UV/H₂O₂, UV/TiO₂, UV/Fe₂O₃, UV/TiO₂/H₂O₂ and UV/Fe₂O₃/H₂O₂). The concentrations of the catalyst and of the oxidant agent were also investigated. The results obtained showed that photodegradation treatments combining TiO₂ or Fe₂O₃ NMs with H₂O₂ were the most efficient. Regarding the OOMW toxicity to Vibrio fischeri, it was significantly reduced with the following treatments: UV/TiO₂/H₂O₂ and UV/Fe₂O₃/H₂O₂. However, the highest reduction recorded for this parameter was obtained in the treatment with UV/H₂O₂. The use of NMs combined with H₂O₂ showed a great potential for removing phenols from OOMW, which have been pointed out as the major toxic compounds of this wastewater.