When released into natural aquatic systems, cerium oxide (CeO₂) nanoparticles (NPs) may have toxic effects to the ecosystems and public health; it is thus important to understand their environmental fate and transport. This work studied the effects of humic acid (HA) concentrations (0–10 mg L⁻¹) and solution chemistry (ionic strength (IS) and pH) on the retention and transport of CeO₂NPs in water-saturated porous media under environmental relevant conditions. HA and IS showed remarkable effect on the retention and transport of CeO₂NPs in the porous media. Even at low concentrations (i.e., 5 and 10 mg L⁻¹), HA stabilized CeO₂NPs in the suspensions by introducing both negative surface charge and steric repulsion and thus enhanced their mobility in the porous media. When solution HA concentration increased or ionic strength decreased, mobility of CeO₂NPs in the porous media enhanced dramatically. Solution pH, however, had little influence on the mobility of the CeO₂NPs under the tested experimental conditions, and increasing solution pH only slightly increased the transport of the NPs. Mathematical models were applied to describe the experimental data. Predictions from the extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory and advection–dispersion–reaction (ADR) model matched the experimental data well.

Studying the toxic risk of pesticide exposure to ladybird beetles is important from an agronomical and ecological perspective since larval and adult ladybirds are dominant predators of herbivorous pest insects (e.g., aphids) in various crops in China. This article mainly deals with the long-term effects of a single application of the insect growth regulator hexaflumuron on Coccinella septempunctata. A 72- h and a 33-day toxicity test with hexaflumuron (single application) were performed, starting with the second instar larvae of C. septempunctata. Exposure doses in the long-term experiment were based on the estimated 72-h acute LR50 (application rate causing 50 % mortality) value of 304 g active ingredient (a.i.) ha-1 for second instar larvae of C. septempunctata. The long-term test used five hexaflumuron doses as treatment levels (1/50, 1/100, 1/200, 1/400, and 1/800 of the 72-h acute LR50), as well as a solvent control and blank control treatment. The measurement endpoints used to calculate no observed effect application rates (NOERs) included development time, hatching, pupation, adult emergence, survival, and number of eggs produced. Analyzing the experimental data with one-way analysis of variance showed that the single hexaflumuron application had significant effects on C. septempunctata endpoints in the 33-day test, including effects on development duration (NOER 1.52 g a.i. ha-1), hatching (NOER 3.04 g a.i. ha-1), pupation (NOER 3.04 g a.i. ha-1), and survival (NOER 1.52 g a.i. ha-1). These NOERs are lower than the reported maximum field application rate of hexaflumuron (135 g a.i. ha-1) in cotton cultivation, suggesting potential risks to beneficial arthropods.

In this study, we simulated heterotrophic CO₂(Rh) fluxes at six European peatland sites using the ECOSSE model and compared them to estimates of Rh made from eddy covariance (EC) measurements. The sites are spread over four countries with different climates, vegetation and management. Annual Rh from the different sites ranged from 110 to 540 g C m⁻². The maximum annual Rh occurred when the water table (WT) level was between −10 and −25 cm and the air temperature was above 6.2 °C. The model successfully simulated seasonal trends for the majority of the sites. Regression relationships (r²) between the EC-derived and simulated Rh ranged from 0.28 to 0.76, and the root mean square error and relative error were small, revealing an acceptable fit. The overall relative deviation value between annual EC-derived and simulated Rh was small (−1 %) and model efficiency ranges across sites from −0.25 to +0.41. Sensitivity analysis highlighted that increasing temperature, decreasing precipitation and lowering WT depth could significantly increase Rh from soils. Thus, management which lowers the WT could significantly increase anthropogenic CO₂, so from a carbon emissions perspective, it should be avoided. The results presented here demonstrate a robust basis for further application of the ECOSSE model to assess the impacts of future land management interventions on peatland carbon emissions and to help guide best practice land management decisions.

Corn cob silica (CCS), produced via a modification of the sol-gel method, can reduce heavy metal availability and stabilize contaminated soil on abandoned mining sites. Adding 5 % (w/w) CCS to mining site soil increased pH from 4.0 to 7.7, and cation exchange capacity increased from 94.5 to 100.3 cmol+/kg. Sequential extraction showed that adding CCS decreased heavy metal availability in the soil. Mobility factor (MF) values indicated that CCS reduced Pb mobility more than that of Zn or Cu in all fractions. Pb concentrations in leachate from all fractions using the toxicity characteristic leaching procedure (TCLP) were greatly decreased by adding 3 % (w/w) CCS. CCS similarly reduced Zn concentrations in TCLP leachate. CCS addition did not impact Cu concentrations in leachate, likely because concentrations were much lower than those of the other metals. As was generally less mobile than the heavy metals; however, As mobility and leachability tended to increase with CCS addition because its oxyanions arsenite and arsenate have low affinity for negatively charged surfaces on the CCS. Shoot and root growth of Spinacia oleracea L. (spinach) was much greater in CCS-treated soil than in unamended soil. Results demonstrate the utility of CCS to stabilize heavy metals in contaminated mining site soil, but this treatment may not be ideal for As-contaminated soils.

Microorganisms are abundant in many surface and near-surface geochemical environments. They interact with arsenic through a variety of mechanisms, including sorption, mobilisation, precipitation and redox and methylation transformation; sometimes, this is to their benefit, while other times it is to their detriment, substantially affecting the fate and transport of arsenic in the environment. Here, an attempt was made to review the current state of knowledge concerning microbial influences on arsenic transformation and retention processes at the water–solid interface with the goal to elucidate the ability of microorganisms to react with arsenic, and to quantify the role of microorganisms in the biogeochemical arsenic cycle. Such knowledge is indispensable for comprehensive understanding arsenic behaviour in the environment and support accurate assessment of the threat of arsenic contamination to human and environmental health, as well as for the development of novel technologies for arsenic bioremediation.

This paper reports on the effect of activating agents such as the impregnation ratio of phosphoric acid (1:1–1:5) at constant activation temperature on the performance of porous activated carbon from waste residues (maize tassel). The variation in the impregnation ratio of the produced activated carbon (AC) from 1:1 to 1:5 enabled the preparation of a high surface area (1,263 m²/g) and a large pore volume (1.592 cm³/g) of AC produced from maize tassel (MT) using a convectional chemical activating agent (phosphoric acid). Impregnation ratios (IR) of the precursors were varied between 1:1 and 1:5 in which it was found that the ratio of 1:4 was optimal based on the high surface area, while 1:5 has the optimal pore volume value for the produced activated carbon.

Pyrene, a four-ring polycyclic aromatic hydrocarbon that is highly resistant to degradation, persists in the environment and exerts its harmful effects toward humans, flora, and fauna when accumulated to a certain level. The ineffectiveness of conventional physical–chemical treatment methods has urged the emergence of biological treatments to degrade pyrene that persists in the environment. In this study, Pleurotus eryngii F032 was originally isolated from our laboratory due to its ability to degrade pyrene. Optimum conditions for pyrene degradation were determined using five different parameters, including pyrene concentration, incubation temperature, pH, agitation, and rhamnolipid concentration. The culture was incubated for 7, 15, 23, and 30 days, respectively, followed by pyrene extraction for degradation analysis. Results show that lower pyrene concentration requires less time for degradation by P. eryngi F032. Moreover, more time is needed for degradation when higher concentration is used, resulting in slower degradation. Optimum pyrene degradation conditions by P. eryngii F032 have been recorded at 40 °C incubation temperature, pH 3, and 2.5 % of rhamnolipid concentration with an agitation speed of 120 rpm. The capability of P. eryngii F032 to utilize pyrene as carbon and energy source depends on the presence of ligninolytic enzymes. The formation of protocatechuic acid resulting from pyrene degradation was detected via GC-MS analysis, which was further confirmed through spectrophotometric analysis.

The Wetland Classification and Risk Assessment Index (WCRAI) is based on manifestations of ecological processes in natural wetland ecosystems. The index is hierarchical in structure and is designed to allow identification and rapid assessment at the broadest levels by non wetland experts in different disciplines to manage natural wetlands. From previous studies, landscape ecology has demonstrated the importance of considering landscape context in addition to local site attributes when explaining wetland ecological processes and ecological integrity. The pressures that land uses and activities exert on wetlands generate impacts that affect both the biotic and abiotic characteristics of the surface water column and the surrounding riparian zone. Therefore, human-altered land in a catchment and spatial patterns of surrounding wetlands provide a direct way to measure human impacts and can be correlated with indicators such as water chemistry and biotic variables. The objective of this study was to develop and test the WCRAI so that the index can be used to classify different types of wetlands and to assess their ecological condition (also known as “Eco-status”) under different ecological conditions. The results obtained from the WCRAI were indicative of the integrity of these wetlands when compared to the status of the abiotic and biotic variables measured at each sampling site. From an economical perspective, the WCRAI can play a crucial role in preventing unnecessary degradation of wetlands, hence reducing financial loss through management, restoration, or rehabilitation efforts. The methodology can be applied very easily (due to its simplistic nature) by industry stakeholders to continually monitor these wetlands.

Cytostatic drugs are pharmaceutically active compounds used in chemotherapy to prevent or disrupt cell division. Only a few environmental studies have been focused on cytostatic drugs, in spite of their toxicity, their increasing consumption, and their discharge into municipal sewage. This fact can be mainly due to the lack of methods for their simultaneous analysis. This research describes the occurrence of 14 cytostatic drugs in influent and effluent wastewater from four wastewater treatment plants located in Seville (Spain) during 1-year period. A preliminary environmental risk assessment was also carried out. Five cytostatic drugs (cytarabine, etoposide, gemcitabine, iphosphamide, and methotrexate) were detected in influent wastewater at concentration levels up to 464 ng L⁻¹(cytarabine). Six of them (cytarabine, doxorubicin, gemcitabine, iphosphamide, paclitaxel, and vinorelbine) were detected in effluent wastewater at concentration levels up to 190 ng L⁻¹(cytarabine). Most of the detected cytostatic drugs are not significantly removed during wastewater treatment. Nevertheless, neither ecotoxicological nor genotoxical risks are expected to occur at the measured concentrations on the aquatic environment.