Laboratory toxicity testing is the primary tool used for surface water environmental risk assessment; however, there are critical information gaps regarding the sublethal effects of pesticides. In 10-day exposures, we assessed the lethal and sublethal (motility and growth) toxicities of four commonly used pesticides, bifenthrin, permethrin, cyfluthrin, and chlorpyrifos, on two freshwater invertebrates, Chironomus dilutus and Hyalella azteca. Pyrethroids were more toxic than the organophosphate chlorpyrifos in both species. Bifenthrin was most toxic to H. azteca survival and growth. Cyfluthrin was most toxic to C. dilutus. However, cyfluthrin had the greatest effect on motility on both H. azteca and C. dilutus. The evaluated concentrations of chlorpyrifos did not affect C. dilutus motility or growth, but significantly impacted H. azteca growth. Motility served as the most sensitive endpoint in assessing sublethal effects at low concentrations for both species, while growth was a good indicator of toxicity for all four pesticides for H. azteca. The integration of sublethal endpoints in ambient water monitoring and pesticide regulation efforts could improve identification of low-level pesticide concentrations that may eventually cause negative effects on food webs and community structure in aquatic environments.

The recycling of reclaimed wastewater for irrigation and road cleaning is an important strategy to minimize water scarcity in megacities. However, little is known regarding the potential accumulation of antibiotics contained in reclaimed wastewater in urban soil. We investigated the occurrence and distribution of eight quinolones (QNs), nine sulfonamides (SAs), and five macrolides (MLs) antibiotics in urban surface soil in Beijing and Shanghai, China. QNs, especially norfloxacin (NOR), ofloxacin (OFL), and ciprofloxacin (CIP) were the predominant antibiotics in urban surface soil, and NOR revealed the highest average concentration of 94.6 μg kg⁻¹. The antibiotic concentrations in urban soil in our study were higher than those detected in agricultural soils after long-term wastewater irrigation and manure fertilization. The concentrations of antibiotics in Shanghai urban soil showed a significant negative correlation with soil pH and a positive correlation with total organic carbon (TOC), reflecting the effect of speciation and soil organic matter content on sorption and retention. In addition, antibiotic concentrations in the urban soil were positively correlated with heavy metal contents, likely due to their coexistence in reclaimed wastewater and the promoting effect of metals on the sorption of antibiotics. In several soil samples, NOR, OFL, CIP, enrofloxacin (ENR), and fleroxacin (FLE) showed higher concentrations than the trigger value of 100 μg kg⁻¹ in soil, indicating a potential risk for the environment.

Relatively limited attention has been given to the presence of fungi in the aquatic environment compared to their occurrence in other matrices. Taking advantage and recognizing the biodegradable capabilities of fungi is important, since these organisms may produce many potent enzymes capable of degrading toxic pollutants. Therefore, the aim of this study was to evaluate the potential ability of some species of filamentous fungi that occur in the aquatic environment to degrade pesticides in untreated surface water. Several laboratory-scale experiments were performed using the natural microbial population present in the aquatic environment as well as spiked fungi isolates that were found to occur in different water matrices, to test the ability of fungi to degrade several pesticides of current concern (atrazine, diuron, isoproturon and chlorfenvinphos). The results obtained in this study showed that, when spiked in sterile natural water, fungi were able to degrade chlorfenvinphos to levels below detection and unable to degrade atrazine, diuron and isoproturon. Penicillium citrinum, Aspergillus fumigatus, Aspergillus terreus and Trichoderma harzianum were found to be able to resist and degrade chlorfenvinphos. These fungi are therefore expected to play an important role in the degradation of this and other pollutants present in the aquatic environment.

Diesel represents a common environmental contaminant as a result of operation, storage, and transportation accidents. The bioremediation of diesel in a contaminated soil is seen as an environmentally safe approach to treat contaminated land. The effectiveness of the remediation process is usually assessed by the degradation of the total petroleum hydrocarbon (TPH) concentration, without considering ecotoxicological effects. The aim of this study was to assess the efficacy of two bioremediation strategies in terms of reduction in TPH concentration together with ecotoxicity indices and changes in the bacterial diversity assessed using PCR-denaturing gradient gel electrophoresis (DGGE). The biostimulation strategy resulted in a 90 % reduction in the TPH concentration versus 78 % reduction from the natural attenuation strategy over 12 weeks incubation in a laboratory mesocosm-containing diesel-contaminated soil. In contrast, the reduction in the ecotoxicity resulting from the natural attenuation treatment using the Microtox and earthworm toxicity assays was more than double the reduction resulting from the biostimulation treatment (45 and 20 % reduction, respectively). The biostimulated treatment involved the addition of nitrogen and phosphorus in order to stimulate the microorganisms by creating an optimal C:N:P molar ratio. An increased concentration of ammonium and phosphate was detected in the biostimulated soil compared with the naturally attenuated samples before and after the remediation process. Furthermore, through PCR-DGGE, significant changes in the bacterial community were observed as a consequence of adding the nutrients together with the diesel (biostimulation), resulting in the formation of distinctly different bacterial communities in the soil subjected to the two strategies used in this study. These findings indicate the suitability of both bioremediation approaches in treating hydrocarbon-contaminated soil, particularly biostimulation. Although biostimulation represents a commercially viable bioremediation technology for use in diesel-contaminated soils, further research is required to determine the ecotoxicological impacts of the intervention.

The conventional multicriteria decision analysis (MCDA) methods used for pollution control generally depend on the data currently available. This could limit their real-world applications, especially where the input data (e.g., the most cost-effective remediation cost and eventual contaminant concentration) might vary by scenario. This study proposes an optimization-based MCDA (OMCDA) framework to address such a challenge. It is capable of (1) capturing various preferences of decision-makers, (2) screening and analyzing the performance of various optimized remediation strategies under changeable scenarios, and (3) compromising incongruous decision analysis results. A real-world case study is employed for demonstration, where four scenarios are considered with each one corresponding to a set of weights representative of the preference of the decision-makers. Four criteria are selected, i.e., optimal total pumping rate, remediation cost, contaminant concentration, and fitting error. Their values are determined through running optimization and optimization-based simulation procedures. Four sets of the most desired groundwater remediation strategies are identified, implying specific pumping rates under varied scenarios. Results indicate that the best action lies in groups 32 and 16 for the 5-year, groups 49 and 36 for the 10-year, groups 26 and 13 for the 15-year, and groups 47 and 13 for the 20-year remediation.

Crop irrigation with heavy metal-contaminated effluents is increasingly common worldwide and necessitates management strategies for safe crop production on contaminated soils. This field study examined the phytoavailability of three metals (Cd, Cu, and Zn) in two cereal (wheat, maize) and legume (chickpea, mungbean) crops in response to the application of either phosphatic fertilizer or sewage-derived water irrigation over two successive years. Five fertilizer treatments, i.e. control, recommended nitrogen (N) applied alone and in combination of three levels of phosphorus (P), half, full and 1.5 times of recommended P designated as N₀P₀, N₁P₀, N₁P₀.₅, N₁P₁.₀, and N₁P₁.₅, respectively. Tissue concentrations of Cd, Cu, Zn, and P were determined in various plant parts, i.e., root, straw, and grains. On the calcareous soils studied while maximum biomass production was obtained with application of P at half the recommended dose, the concentrations of metals in the crops generally decreased with increasing P levels. Tissue metal concentrations increased with the application of N alone. Translocation and accumulation of Zn and Cu were consistently higher than Cd. And the pattern of Cd accumulation differed among plant species; more Cd being accumulated by dicots than monocots, especially in their grains. The order of Cd accumulation in grains was maize > chickpea > mungbean > wheat. Mungbean and chickpea straws also had higher tissue Cd concentration above permissible limits. The two legume species behaved similarly, while cereal species differed from each other in their Cd accumulation. Metal ion concentrations were markedly higher in roots followed by straw and grains. Increasing soil-applied P also increased the extractable metal and P concentrations in the post-harvest soil. Despite a considerable addition of metals by P fertilizer, all levels of applied P effectively decreased metal phytoavailability in sewage-irrigated soils, and applying half of the recommended dose of P fertilizer was the most feasible solution for curtailing plant metal uptake from soils. These findings may have wide applications for safer crop production of monocot species when irrigating crops with sewage effluent-derived waters.

Poyang Lake is a unique wetland system that has evolved in response to natural seasonal fluctuations in water levels. To better characterize the response of water quality to hydrological variation, historical data were analyzed in combination with dissolved organic matter (DOM) fluorescence samplings conducted in situ. Historical data showed that long-term changes in water quality are mainly controlled by the sewage inputs to Poyang Lake. Monthly changes in water quality recorded during 2008 and 2012 suggest that water level may be the most important factor for water quality during a hydrological year. DOM fluorescence samples were identified as three humic-like components (C1, C2, and C3) and a protein-like component (C4). These obvious compositional changes in DOM fluorescence were considered to be related to the hydrodynamic differences controlled by water regimen. Principal component analysis (PCA) showed higher C1 and C2 signals during a normal season than the wet season, whereas C3 was lower, and C4 was higher in the dry season than in the wet or normal seasons. From the open lake to the Yangtze River mouth, increased C3 component carried by backflows of the Yangtze River to the lake resulted in these unique variations of PCA factor 2 scores during September. These obvious compositional changes in DOM fluorescence were considered to be related to the hydrodynamic differences controlled by water regimen. DOM fluorescence could be a proxy for capturing rapid changes in water quality and thereby provide an early warning signal for the quality of water supply.

We reported previously that okadaic acid (OA) and dinophysistoxin-1 (DTX1) were responsible for diarrhetic shellfish poisoning (DSP) incidents due to consuming cultivated mussels (Mytilus galloprovincialis) in coastal cities near the East China Sea in May 2011. Pectenotoxin-2 (PTX2) and its seco acids were also present in these mussels. Causative species of microalgae were not identified because detailed information on the location of the contaminated shellfish was not recorded. In order to explore potential causes for these poisoning events, the lipophilic toxin profiles in picked cells of Dinophysis and in shellfish samples collected from two mariculture zones in the East China Sea were analyzed in the present study. Single-cell isolates (100 cells total for each location) of Dinophysis were collected from the aquaculture zones of Gouqi Island (Ningbo City, Zhejiang Province) and Qingchuan Bay (Ningde City, Fujian Province) in July and September 2013, respectively, for lipophilic toxin profiling. Shellfish samples collected over the course of a year from the Gouqi Island aquaculture zone and mussels (M. galloprovincialis) collected four times from the Qingchuan Bay aquaculture zone were tested for lipophilic toxins by LC-MS/MS. The Dinophysis cells isolated from both sampling sites were identified under the light microscope as Dinophysis caudata. Average quota of PTX2, the predominant toxin in D. caudata isolated from the coastal waters of Gouqi Island and Qingchuan Bay, was 0.58 and 2.8 pg/cell, respectively. Only trace amounts of OA and DTX1 were detected in D. caudata. PTX2, PTX2sa, 7-epi-PTX2sa, OA, and/or DTX1 were found in samples of mussels (M. galloprovincialis and Mytilus coruscus) collected in the Gouqi Island aquaculture zone from the end of May to the beginning of July 2013. PTX2, PTX2sa, and 7-epi-PTX2sa were also detected in oyster (Crassostrea gigas) during that period, but almost no OA and DTX1 were present. Gymnodimine (GYM) was detected in almost all mussel (M. coruscus) samples, with the highest levels occurring in winter. Trace amounts of pectenotoxins (PTXs) and OAs were also found in mussels (M. galloprovincialis) collected from Qingchuan Bay. D. caudata is suggested as an important source of PTXs in shellfish cultivated in the East China Sea. This is the first report of toxin profiles for single-cell isolates of Dinophysis in the East China Sea.

The emergent plants Acorus calamus, Lythrum salicaria, and Scirpus tabernaemontani were exposed to atrazine for 15, 30, 45, and 60 days in a hydroponic system. Effects were evaluated investigating plant growth, chlorophyll (Chl) content, peroxidase (POD) activity, and malondialdehyde (MDA) content. Results showed that selected plants survived in culture solution with atrazine ≤8 mg L⁻¹, but relative growth rates decreased significantly in the first 15-day exposure. Chla content decreased, but MDA increased with increasing atrazine concentration. S. tabernaemontani was the most insensitive species, followed by A. calamus and L.salicaria. The growth indicators exhibited significant changes in the early stage of atrazine exposure; subsequently, the negative impacts weakened and disappeared. Plant growth may be more representative of emergent plant fitness than physiological endpoints in toxicity assessment of herbicides to emergent plants.

The determination of bioaccessible metal concentrations and/or fractions is a prerequisite for reliable assessment of the hazardous potential of toxic trace metals present in airborne particulate matter (APM). For this purpose, the use of various leaching agents has been reported in literature. The applied reagents reveal severe differences in composition. Therefore, variations in the amounts of trace metals released from APM samples could be expected with the use of these agents, hampering comparison of literature data. In this work, bioaccessible metal fractions were determined in PM10 samples from Graz, Austria, and Karachi, Pakistan, using synthetic gastric juice (SGJ), artificial lysosomal fluid (ALF), Gamble’s solution, aqueous solutions of sodium chloride, ammonium acetate, ammonium citrate, and water for sample extraction. Investigated trace metals showed distinct differences in extractable fractions for the same extractant. For example, bioaccessible contents ranged from 34.8 ± 13.3 % for Ni (n = 12) to 77.9 ± 14.8 % for Cd (n = 12) when SGJ was used for extraction. Furthermore, extraction yields for the applied leaching agents were determined, indicating for all investigated elements two to four times more efficient extraction with SGJ, ammonium citrate buffer, and ALF as compared to water and simple inorganic salt solutions, indicating that ammonium citrate buffer could be used as an alternative for synthetic body fluids with rather complex composition.