Although the effects of plastic residues on soil organic carbon (SOC) have been studied, variations in SOC and soil carbon-enzyme activities at different plant growth stages have been largely overlooked. There remains a knowledge gap on how various varieties of plastics affect SOC and carbon-enzyme activity dynamics during the different growing stages of plants. In this study, we conducted a mesocosm experiment under field conditions using low-density polyethylene and poly (butylene adipate-co-terephthalate) debris (LDPE-D and PBAT-D, 500–2000 μm (pieces), 0%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%), and low-density polyethylene microplastics (LDPE-M, 500–1000 μm (powder), 0%, 0.05%, 0.1%, 0.5%) to investigate SOC and C-enzyme activities (β-xylosidase, cellobiohydrolase, β-glucosidase) at the sowing, seedling, flowering and harvesting stages of soybean (Glycine Max). The results showed that SOC in the LDPE-D treatments significantly increased from the flowering to harvesting stage, by 12.69%–13.26% (p 0.05), but significantly decreased in the 0.05% and 0.1% LDPE-M treatments from the sowing to seedling stage (p 0.05). However, PBAT-D had no significant effect on SOC during the whole growing period. For C-enzyme activities, only LDPE-D treatments inhibited GH (17.22–38.56%), BG (46.7–66.53%) and CBH (13.19–23.16%), compared to treatment without plastic addition, from the flowering stage to harvesting stage. Meanwhile, C-enzyme activities and SOC responded nonmonotonically to plastic abundance and the impacts significantly varied among the growing stages, especially in treatments with PBAT-D (p 0.05). These risks to soil organic carbon cycling are likely mediated by the effects of plastic contamination and degradation soil microbe. These effects are sensitive to plastic characteristics such as type, size, and shape, which, in turn, affect the biogeochemical and mechanical interactions involving plastic particles. Therefore, further research on the interactions between plastic degradation processes and the soil microbial community may provide better mechanistic understanding the effect of plastic contamination on soil organic carbon cycling.

The influence of algae presence in surface water on the settling velocities of microplastics is unknown, and determining it is challenging due to the turbidity of algal suspensions. Measuring the settling velocity of microplastics has traditionally relied on either manual measurement techniques or 2D Particle Tracking Velocimetry (PTV). This study introduces a 3D-PTV method tailored to determine the effects of algae (Synechoccocus sp.) on microplastic settling speeds in semi-large columns. We demonstrated that 3D PTV produces much more accurate results than 2D particle tracking. Testing the method in six experiments with varying algae concentrations revealed consistent results across the experiments and alignment with some theoretical approximations. The results were concurrent with calculated 2D speeds. No influence of algal density on settling velocities was found, which is highly relevant for microplastic fate modeling in eutrophic systems. We highlight the applicability and accuracy of 3D particle tracking velocimetry in further understanding microplastic settling behavior.

The widespread and extensive use of pesticides in European crop production to reduce losses from weeds, diseases, and insects may have serious consequences on the ecosystem and human health. This study aimed to identify 20 active substances of high health risk, based on their detection frequency within and across the environmental matrices (soil, crop, water, and sediment) and to identify their associated hazardous effects. A sampling campaign was conducted across 10 case study sites in Europe and 1 in Argentina and included conventional and organic farming systems. In 31% of cases, the detected substances were found at a higher concentration in the soil than in the corresponding crops, 93% of the compounds were fungicides, and the remainder were insecticides. 43% of the substances, 57% of which were insecticides, were detected only in soil. There was a clear relationship between soils and crops in terms of contamination, but not between water and sediment. Portuguese soil (wine grapes) had the highest number of substances (12) with average concentrations (AC) varying between 1 and 162 μg/kg, followed by French (11 substances in wine grapes) (1≤AC≤64 μg/kg) and Spanish soils (9 substances in vegetables) (3≤AC≤59 μg/kg). The crops corresponding to these soils contained a relatively high number of detected substances and several in high average concentrations (AC). The risk quotient was consistently higher for conventional farms than for organic farms. For the soils from conventional farms, 5 active substances (chlorpyrifos, glyphosate, boscalid, difenoconazole, lambda-cyhalothrin, and one metabolite: AMPA) were considered high risk. For water samples, 2 substances (dieldrin and terbuthylazine) found were high risk, and for sediment, there were 3 substances (metalaxyl-M, spiroxamine, and lambda-cyhalothrin). There were 6 substances detected in crops that are suspected to cause human health effects. Uncontaminated soil is a prerequisite for the adoption of sustainable alternatives to pesticides. Efforts are needed to elucidate the unknown effects of mixtures, including biocides and banned compounds in addition to the substances used in agriculture.

Microcystins (MCs) are a class of toxic secondary metabolites produced by some cyanobacteria strains that endanger aquatic and terrestrial organisms in various freshwater systems. Although patterns in MC occurrence are being recognized, divergences in the global data still hamper our ability to predict the toxicity of cyanobacterial blooms. This study aimed (i) to determine the dynamics of MCs and other cyanopeptides in a tropical reservoir, (ii) to investigate the correlation between peptides and potential cyanotoxin producers (iii) identifying the possible abiotic factors that influence the peptides. We analyzed, monthly, eight MC variants (MC-RR, -LA, -LF, -LR, -LW, -YR, [D-Asp3]-RR and [D-Asp3]-LR) and other peptides in 47 water samples collected monthly, all season long, from two sampling sites in a tropical eutrophic freshwater reservoir, in southeastern Brazil. The cyanopeptides were assessed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The biomass of potential cyanobacterial producers and water quality variables were measured. MCs were detected in both sampling sites year-round; the total MC concentration varied from 0.21 to 4.04 μg L−1, and three MC variants were identified and quantified (MC-RR, [D-Asp3]-RR, -LR). Additionally, we identified 28 compounds belonging to three other cyanopeptide classes: aeruginosin, microginin, and cyanopeptolin. As potential MC producers, Microcystis spp. and Dolichospermum circinalis were dominant during the study, representing up to 75% of the total phytoplankton. Correlational and redundancy analysis suggested positive effects of dissolved oxygen, nitrate, and total phosphorus on MC and microginins concentration, while water temperature appeared to favor aeruginosins. A comparison between our results and historical data showed a reduction in total phosphorus and cyanobacteria, suggesting increased water quality in the reservoir. However, the current MC concentrations indicate a rise in cyanobacterial toxicity over the last eight years. Moreover, our study underscores the pressing need to explore cyanopeptides other than MCs in tropical aquatic systems.

The present study was conducted to determine the effects of source separation training for municipal solid waste on the quality of compostable organic waste at District 8 of Karaj Municipality, Iran. This was an experimental study, the tools of which were  sampling and conducting experiments. The research data were collected using cluster sampling. To determine the chemical properties of wet waste, samples were taken from 480 households in 7 neighborhoods of District 8 of Karaj Municipality, followed by laboratory analysis. To measure the quality of compostable organic materials, first, waste from the studied households was received once without providing training and subjected to physical analysis (separation of wet and dry materials). Once again, after providing training, the waste of the studied households was collected separately, wet and dry, from the doorsteps of the homes. From the total wet waste samples taken from each neighborhood, after complete mixing, one sample was taken for chemical  analysis and transported to the laboratory. The measured parameters included total nitrate, organic carbon, electrical conductivity  (EC), pH, calcium, cadmium, copper, iron, potassium, magnesium, phosphorus and lead. A t-test was used to obtain the difference  between the physical and chemical properties of the wet waste before and after source separation training to households. Data  were analyzed using SPSS27 software. Based on the results, there was a statistically significant difference between the values of EC,  pH, cadmium, and iron at the level of 5%, as well as between the parameters of copper, potassium, magnesium, and phosphorus at  the level of 1%, in the pre- and post-training stages. The EC value in the pre-training phase was 9914 μs/cm, which decreased to  7350 μs/cm after training. Calcium levels were 19,674 and 30,898 mg/kg, potassium levels were 24,006 and 18,225 mg/kg,  phosphorus levels were 1987 and 3019 mg/kg, and the iron levels were 1804 and 466 before and after training, respectively. The concentration of magnesium in compostable organic waste increased significantly in the post-training phase compared to the pre-training phase. The findings of this study revealed the effectiveness of source separation of municipal solid waste in maintaining  the amounts of elements present in compostable organic materials at appropriate levels.

The use of copper (Cu) and silver (Ag) nanoparticles in coatings can eliminate surface microbial contamination. This study compared antibacterial activity of Cu- (Cu/CNTs) and Ag-coated carbon nanotubes (Ag/CNTs) synthesized by plasma-enhanced chemical vapor deposition (PECVD) against Escherichia coli and Staphylococcus aureus. Initially, the PECVD technique was applied to deposit the CNTs on high-resistivity silicon wafers previously decorated by nickel catalyst using an Electron Beam Gun. Then, the nanotubes were coated by Cu and Ag thin films in a vacuum evaporator using the Direct Current (DC) Magnetron Sputtering method. Finally, the antibacterial effects were determined by Standard Plate Count (SPC, with film thicknesses of 0, 10, 30 and 60 nm) and Disk Diffusion Test (based on zone of inhibition (ZOI) with nanoparticle concentrations of 5, 10 and 15 µg/mL). According to the SPC findings, the highest antibacterial activity of Cu/CNTs was found for the film thickness of 60 nm against E. coli (66%), and the lowest activity was related to the film thickness of 19 nm against S. aureus (28.8%). The antibacterial activity of Ag/CNTs was about 70% against E. coli with the highest thickness and about 34.12% against S. aureus. The lowest ZOI was measured for the bare CNTs at a concentration of 5 µg/mL (12 mm), and the highest ZOI was related to Ag/CNTs with a concentration of 15 µg/mL against S. aureus (18 mm). To conclude, the carbon nanotube composites coated with copper or silver nanoparticles can be used to control bacterial growth in aqueous solutions.

Identifying the contribution of different land uses plays a crucial role in preventing erosion and prioritizing land management activities. This research aimed to assess the impacts of various land use scenarios on mitigating soil erosion in the North West Urmia region of Iran. In addition to the current scenario, 12 land use management scenarios were identified based on the observed trend in changes in land use patterns throughout the study area utilizing GIS. The RUSLE was used, and the necessary input parameters of the RUSLE model, were prepared. The erosion mapping has been done using overlaying the input layers. The baseline scenario (current condition) resulted in an erosion amount of 17.22 (t/ha/yr). Introducing soil conservation techniques in dry farming on steep terrain, as depicted in scenario 6 (conservation and restoration of plowed rangelands), resulted in a reduction of the erosion rate from 17.22 to 9.75 (t/ha/yr). On the other hand, scenario 20, characterized by severe rangeland degradation and overgrazing, exhibited the highest estimated erosion rate at 30.42 (t/ha/yr). In contrast, the most substantial erosion reduction of 43.37% was evident in scenario 6 (conservation and restoration of plowed rangelands). It was observed that the P-factor (support practice factor) had a more pronounced impact than the C-factor (crop/vegetation and management factor) in mitigating erosion. These findings suggest the potential for utilizing a scenario-based framework to evaluate the impact of management scenarios on erosion and prioritize soil and water management measures and strategies.

Novel technologies and subsequent pollutions are serious threats to the environment and public health. The environmental pollutions, especially air pollution, are currently leading environmental concerns in developing countries, including Iran. In the present study, the air quality and meteorological data were employed to achieve potent models based on an Artificial Neural Network (ANN) for the prediction of air pollution in Tehran, Iran. The developed models manage to predict daily concentrations of various air pollutants such as O3, PM10, NO2, CO, and PM2.5. The required data were collected daily through the Air Quality Organization from all air quality stations of Tehran within a four-year period (from 2012 to 2015). Training the models was on the basis of Multi-Layer Perceptron (MLP) with the Back Propagation (BP) algorithm using MATLAB program. The results indicated appropriate agreement between the observed and predicted concentrations, as the values of the coefficient of multiple determinations (R2) for all models were more than 0.83. In conclusion, the studied meteorological parameters are effective on all pollutants concentrations.

Water security problems are becoming more and more challenging in Iran for several reasons such as population growth, urbanization, land-use change, unsustainable water use and climate change. All the mentioned reasons result in an increase in the human exploitation of water resources and consequently increasing anthropogenic impacts on rivers, flood plains, and fresh groundwater. Therefore, assessment of the human pressures on rivers is particularly important to find areas where water resources are threatened and subjected to rapidly increasing anthropogenic effects. By this integrated approach, a successful Integrated Water Resources Management will be achieved to guide policy makers for best protection, restoration and management. In this regard, Southern Caspian Sea Basin Rivers (including Kura-South Caspian and Caspian Highland ecoregions) were studied in terms of human pressure types. Human pressures were analyzed at different spatial scales, and finally seven main pressure types (i.e. Land use, Hydrology, Morphology, Connectivity, Water quality, Biology) were defined in which the abundance and distributions of each pressure type was different. According to this study, most areas were impacted by land use pressure type followed by water quality. Moreover, most areas were threatened by multiple pressures.

Silver nanoparticles (Ag-NPs) are potentially toxicant substances whose widespread use has raised considerations regarding environmental risks caused by the discharge of those nanoparticles (NPs) into aquatic ecosystems. The aim of this study was to analyze the impact of Ag-NPs on the hematologic parameters Rainbow trout, Oncorhynchus mykiss juvenile. Hematological toxicities of Ag-NPs to rainbow trout juveniles were assessed in four treatment groups: Control (without Ag-NPs), 0.1gr/L Ag-NPs solution (T1), 0.25gr/l Ag-NPs (T2) and 0.5gr/l Ag-NPs (T3). Blood samples were collected from fish after 5 and 10 days of exposure. Analysis of blood parameters in the 5th and 10th days of the experiment showed that the values white blood cells (WBCs) were higher in all treatments than those in the control group (p < /p>