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 Zayandeh-Rood River (Isfahan Province, Iran) is of vital importance as a water source for various purposes, but it is facing adverse effects from human activities. This study focused on the surface sediment of 21 stations along the river to assess the concentration of potentially toxic elements (PTEs) and their environmental risk using the Geoaccumulation Index (Igeo), Enrichment Factor (EF), Pollution Load Index (PLI), and Potential Ecological Risk Index (RI). The mean concentration of the PTEs (mg/kg) was ranked as follows: Cd (0.34)< As (9.73)< Pb (10.95)< Co (11.91)< Cu (31.14)< Ni (31.90)< Zn (61.33)< Cr (96.95)< V (125.09)< Mn (707.76). Positive correlation coefficients were found among all the PTEs, while their relationships with the sediment physicochemical characteristics varied considerably, indicating that various interacting factors might influence the deposition and mobility of PTEs in the river. The river was classified as having moderate to low contamination (Igeo index) and minimal-to-moderate enrichment (EF index) except for Cd and As which exhibited extremely high enrichment and strong pollution in the upstream zone, where agricultural activities dominate. Therefore, managing agricultural practices and reducing the excessive use of PTE-containing pesticides and insecticides should be a primary focus to protect the Zayandeh-Rood River from further contamination.

The purpose of this study was to evaluate the environmental and health risk of PM2.5 microns in district 10 of Tehran. Initially, data related to the year 2019 were collected and analyzed through pollutant measurement at the regional level. Based on Kriging's interpolation the corresponding raster was produced and classified according to the minimum and maximum range. Finally, according to the air quality index, the level of importance of health safety was classified and the relevant map was prepared. Through the IO technique, the location layer of sensitive and vulnerable land uses and the carbon monoxide contaminant zoning layer were mapped. Results showed that District 10 of Tehran with the average concentration of 42µg/m3 is the most polluted area in terms of this contaminant in Tehran. Also, most of the PM2.5 pollutants belong to the northern, southern and western half of the region. Also, December was the most polluted month of the year with an average concentration of 56μg/m3. From the point of view of the air quality index based on the type of pollutants, the area had 104 days of unhealthy and unhealthy days for sensitive groups. Environmental and health risk assessment of these pollutants indicates that according to William Fine method, the risk number is 105, which indicates the average risk level. Therefore, it requires corrective and emergency risk control measures.

In this study systematic random sampling was conducted. To estimate the sample size, 100 households were selected based on the population of the city using Cochran's formula. Total generated municipal solid waste was consecutively collected, weighed and separated during a week. Then, after providing the required training through face-to-face manner and brochures regarding the economic, social, cultural and environmental importance of source separation to each of the households, once again the generated wastes were collected, weighed and separated. The difference in the composition and amount of waste generated before and after the training was compared by independent t-test. The effect of the demographic characteristics of the head of the household on reducing the amount of generated waste was determined by correlation test. The results highlighted the training as an effective intervention on the weight of produced waste from each household before and after the training (P=0.000). Education increases people's awareness about waste, recycling, harms of waste, definition of separation, benefits of separation, source separation and level of household education. The reduction in the amount of produced waste had no significant correlation with the age (P=0.89), occupation (P=0.16), income (P=0.95) and education level (P=0.36) of the heads of each household. The findings of this research showed that education, regardless of demographic characteristics, is an effective method to change specific behavior and create motivation to reduce the amount of waste at source, underlining the importance of training to improve waste recycling management.

Environmental Management Plan (EMP) is regarded as a guidance document to attain and measure compliance with the mitigation requirements and environmental protection of projects, which are normally requirements for project approvals. The study mainly aims to present an Environmental Management Plan for dams whose construction was suspended by opposing stakeholders for the harmful impacts on the environment in forested areas. As a case study, the Hyrcanian forests (Caspian forests) are located in western Asia and were inscribed on the United Nations Educational Scientific and Cultural Organization (UNESCO) World Heritage List in 2019. The construction of the hydropower Shafarood dam began in these forests in 1990. Because of budget deficits and the suspensions incurred by opposing activists in 2013, dam construction has only advanced by 23% ever since. To meet that aim, the research data was collected through analysis of documents, letters, articles, field visits to the construction site, and interviews. The semi-structured interviewing method was employed in holding interviews with governmental and environmental NGOs, local people, specialists, and academics because of their good cooperation. The results indicate that the most negative effects in the construction phase have been produced by deforestation and degradation of vegetation, source of material supply, settlement and livelihood of migrants impacted by dam impoundment, water, air and sound quality. Ultimately, an Environmental Management Plan was proposed for this dam and those under construction or suspended in forested areas to minimize the negative environmental effects of the Hydropower Shafarood dam, which technically concentrates on mitigating measures.

Remediation of residually contaminated soils remains a widespread problem. Biochar can immobilize polycyclic aromatic hydrocarbons (PAH). However, studies on its ability to immobilize PAH and N, S, and O substituted PAH (hetero-PAH) in real soils, and benchmarking with commercial activated carbon are missing. Here, we compared the ability of pristine biochar (BC), steam-activated biochar (SABC), and commercial activated carbon (AC) to immobilize PAH and hetero-PAH. The three carbons were tested on soils from four different contaminated sites in Austria. Different amendment rates (w/w) of the carbons were investigated (BC: 1.0, 2.5, and 5%; SABC: 0.5, 1.0, and 2.0%; AC: 1%) in batch experiments to cover meaningful ranges in relation to their performance. SABC performed better than AC, removing at least 80% PAH with the lowest application rate of 0.5%, and achieving a complete removal at an application rate of 1.0%. BC performed slightly worse but still acceptable in residually contaminated soils (40 and 100% removal at 1 and 5% amendment, respectively). The ability of BC and SABC to immobilize PAH decreased as the PAH-molar volume increased. PAH with three or more rings were preferentially removed by AC compared to SABC or BC. This can be explained by the difference in pore size distribution of the carbons which could limit the accessibility of PAH and hetero-PAH to reach sorption sites for π- π electron donor-acceptor interactions, which drive PAH and hetero-PAH sorption to carbons. Column percolation tests confirmed the results obtained in batch tests, indicating, that decisions for soil remediation can be derived from simpler batch experiments. In soil samples with 1% BC, a reduction of over 90% in the total concentration of PAH in the leached water was observed. Overall, BC and SABC were demonstrated to be valid substitutes for AC for stabilizing residually contaminated soils.

Nowadays, marine ecosystems are under severe threat from the simultaneous presence of multiple stressors, including microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (B[a]P). In addition to their presence in various marine compartments, there are increasing concerns on the potential capacity of MPs to sorb, concentrate and transfer these pollutants in the environment. Although their ecotoxicological impacts are currently evident, few works have studied the combined effects of these contaminants. Therefore, the major purpose of this work was to assess the toxicity of environmental relevant concentrations of MPs (<30 μm) and B[a]P, alone and in mixture, in the seaworm Hediste diversicolor by exploring their accumulation and hazardous biological effects for 3 and 7 days. Environmental MPs were able to increase B[a]P in a time-dependent manner. The obtained results showed that individual treatments, as well as co-exposure to contaminants, caused cytotoxicity and genotoxicity in the cœlomic fluid cells, while oxidative stress effects were observed at tissue and gene levels associated with alteration in neurotransmission. Overall, our findings provide additional clues about MPs as organic pollutant vectors in the marine environment, and contribute to a clearer understanding of their toxicological risk to aquatic invertebrates.

Aquatic natural colloids are closely related to the environmental behavior of pollutants, which may affect their bioavailability in aquatic organisms. This study explored the potential mechanisms of the natural colloids at environmentally relevant concentrations affecting the bioaccumulation process of benzophenone-3 (BP3) in zebrafish (Danio rerio). The results of kinetic model fitting showed that the natural colloids decreased the uptake and loss rate of BP3 by zebrafish but prolonged the time to reach the cumulative equilibrium, eventually resulting in a higher cumulative concentration in zebrafish. According to the tissue concentration at equilibrium and the results of toxicokinetic analysis, the presence of high molecular colloids could enhance the bioaccumulation of freely dissolved BP3 due to its high desorption rate with BP3 in the intestines of fish, increasing the freely dissolved BP3 concentrations to which zebrafish were exposed. Both natural colloids and BP3 could enhance the cell permeability of zebrafish, which allowed colloid-bound BP3 to directly enter the fish and accumulate in its muscle. Besides, although both natural colloids and BP3 could cause the metabolic disorders in adult zebrafish, they affected the physiological and biochemical activities of zebrafish through different pathways. The disturbance of glutathione metabolism in zebrafish induced by natural colloids may be the reason for the diminished ability of zebrafish to clear and transform BP3 in the mixture system. The carrier effect of natural colloids and reduced clearance ability of zebrafish eventually increased the bioaccumulation of BP3 in zebrafish. This study highlights the significance of natural colloids at environmentally relevant concentrations on the biological effects of emerging contaminants in actual waters, however, natural colloids are always ignored in most field investigation of pollutants, which would ultimately lead to an underestimation of the true ecological risk of pollutants.

Biochar-oxalic acid composite application (BCOA) have shown to be efficient in the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil, but the functional degraders and the mechanism of improving biodegradation remains unclear. In this study, with the help of stable isotope probing technology of phenanthrene (Phe), we determined that BCOA significantly improved Phe mineralization by 2.1 times, which was ascribed to the increased numbers and abundances of functional degraders. The BCOA increased contents of dissolved organic carbon and available nutrients and decreased pH values in soil, thus promoting the activity, diversity and close cooperation of the functional Phe-degraders, and stimulating their functions associated with Phe degradation. In addition, there is a relay activity among more and diverse functional Phe-degraders in the soil with BCOA. Specifically, Pullulanibacillus persistently participated in Phe-degradation in the soil with BCOA throughout the incubation period. Moreover, Pullulanibacillus, Blastococcus, Alsobacter, Ramlibacter, and Mizugakiibacter were proved to be potential Phe-degraders in soil for the first time. The specific Phe degraders and their relay and cooperation activity in soils as impacted by BCOA were first identified with DNA-stable isotope probing technology. Our findings provided a novel perspective to understand the efficient degradation of PAH in the BCOA treatments, revealed the potential of soil native microbes in the efficient bioremediation of PAH-contaminated natural soil, and provided a basis for the development of in-situ phytoremediation technologies to remediate PAH pollution in future.

Epidemiological studies have demonstrated a strong association of ambient fine particulate matter (PM₂.₅) exposure with the increasing mortality by ischemic heart disease (IHD), but the involved mechanisms remain poorly understood. Herein, we found that the chronic exposure of real ambient PM₂.₅ led to the upregulation of hypoxia-inducible factor-1 alpha (HIF-1α) protein in the myocardium of mice, accompanied by obvious myocardial injury and hypertrophy. Further data from the hypoxia-ischemia cellular model indicated that PM₂.₅-induced HIF-1α accumulation was responsible for the promotion of myocardial hypoxia injury. Moreover, the declined ATP level due to the HIF-1α-mediated energy metabolism remodeling from β-oxidation to glycolysis had a critical role in the PM₂.₅-increased myocardial hypoxia injury. The in-depth analysis delineated that PM₂.₅ exposure decreased the binding of prolyl hydroxylase domain 2 (PHD2) and HIF-1α and subsequent ubiquitin protease levels, thereby leading to the accumulation of HIF-1α. Meanwhile, factor-inhibiting HIF1 (FIH1) expression was down-regulated by PM₂.₅, resulting in the enhanced translocation of HIF-1α to the nucleus. Overall, our study provides valuable insight into the regulatory role of oxygen sensor-mediated HIF-1α stabilization and translocation in PM-exacerbated myocardial hypoxia injury, we suggest this adds significantly to understanding the mechanisms of haze particles-caused burden of cardiovascular disease.