Estimation of plastic waste inputs from land into the Caspian Sea: A significant unseen marine pollution

Antibiotics in surface waters of the south caspian sea: Occurrence, spatial distribution and ecological risks

Marine environments play a crucial role in absorbing land-based pollutants. While the presence of pharmaceuticals in various marine settings worldwide is well-documented, there is a lack of data regarding pharmaceutical occurrence in the south Caspian Sea. This study examined the presence and spatial distribution of 14 antibiotics in the surface waters of the south Caspian Sea during summer of 2020. Our findings revealed that antibiotics were widespread in this region, with total concentrations reaching up to 3499.9 ng/L. The detection frequencies of the studied antibiotics ranging from 22.0% to 67.0%. Trimethoprim, ofloxacin, and sulfamethoxazole were commonly detected, with detection frequencies exceeding 56.0%. Ofloxacin (235.8 ng/L) and Erythromycin-H2O (2.3 ng/L) had the highest and lowest detected concentrations among the studied antibiotics. Furthermore, fluoroquinolones exhibited notably higher concentrations compared to other antibiotic groups. The highest concentrations of most antibiotics were found in surface waters collected from Ramsar and Chalus stations, located in the middle section of the coastline. Across all transects, the distribution of antibiotics exhibited a decreasing trend towards the sea, indicating that coastal and inland aquaculture, as well as municipal wastewaters, were probably the primary sources of antibiotics in this area. Multivariate analysis revealed that antibiotics, phosphate, nitrate, and COD were all positively correlated with stations Ram-1, Ram-20, Cha-1, Cha-20, and Tor-1, where the highest antibiotic levels were recorded. Risk assessment indicated that clarithromycin, ofloxacin and enrofloxacin posed medium to high risks to aquatic organisms. These findings offer essential baseline information and valuable insights for the comparative assessment of future antibiotic data in the south Caspian Sea.

Assessing Chlorophyll-a Variations in Caspian Sea during the COVID-19 Pandemic

The COVID-19 pandemic's disruptions to human activities prompted serious environmental changes. Here, we assessed the variations in coastal water quality along the Caspian Sea, with a focus on the Iranian coastline, during the lockdown. Utilizing Chlorophyll-a data from MODIS-AQUA satellite from 2015 to 2023 and Singular Spectrum Analysis for temporal trends, we found a 22% Chlorophyll-a concentration decrease along the coast, from 3.2 to 2.5 mg/m³. Additionally, using a deep learning algorithm known as Long Short-Term Memory Networks, we found that, in the absence of lockdown, the Chlorophyll-a concentration would have been 20% higher during the 2020-2023 period. Furthermore, our spatial analysis revealed that 98% of areas experienced about 18% Chlorophyll-a decline. The identified improvement in coastal water quality presents significant opportunities for policymakers to enact regulations and make local administrative decisions aimed at curbing coastal water pollution, particularly in areas experiencing considerable anthropogenic stress.

Sedimentary record of microplastics in coastal wetland, eastern China

Microplastic (MP) dynamics can reflect history of plastic production and waste management in nearby areas. However, the stratigraphy of MPs in coastal wetlands and their link to policy and economic pattern changes are currently unclear. Here, MP stratigraphic records in sediment core from coastal wetlands in Yancheng, China, were used to reconstruct plastic pollution history. Neural network models simulated how policy intervention and economic development affected MP accumulation over time. We showed that MP abundance curves with boundaries from 1920 to 2019 had four stages. MP growth slowed or even decreased in the mid-to-late 1980s due to improved waste management and wastewater treatment since the late 1980s. Human activities were the primary factor affecting MP abundance and shape, followed by sediment properties. We predict that the environmental impact of MPs will continue to increase in the next decade. Current plastic policy measures focus on predictable waste emissions, but hidden sources like clothing fibers and tire wear that significantly contribute to MP pollution require further attention.

Recycling facemasks into civil construction material to manage waste generated during COVID-19

Growing plastic pollution in the context of COVID-19 has caused significant challenges, exacerbating this already out-of-control issue. The pandemic has considerably boosted the demand for personal protective equipment (PPE), such as facemasks and gloves, all over the globe, and mismanaging this growing plastic pollution has harmed the environment and wildlife significantly. To mitigate negative environmental impacts, it is necessary to develop and implement effective waste management strategies. This present study estimated the daily facemask generation throughout the pandemic in Iran based on the distribution of urban and rural populations and, likewise, the daily generation of hand gloves in the COVID-19 era and the amount of medical waste generated by COVID-19 patients were calculated. In the next step, the quantities of discarded facemasks dumped into the Caspian Sea, the Persian Gulf, and the Gulf of Oman from the coastal cities were determined. Finally, the innovative alternatives for repurposing discarded facemasks in civil construction materials such as concrete, pavement, and partition wall panel were discussed.

Adverse effects of microplastics and nanoplastics on the reproductive system: A comprehensive review of fertility and potential harmful interactions

In recent years, microplastics (MPs) and nanoplastics (NPs) have caused ubiquitous environmental pollution and raised widespread concern about their potential toxicity to human health, especially in the reproductive system. Moreover, infertility affects >15 % of couples worldwide, and the birth rate is decreasing. Environmental factors are some of the most important causes of infertility. However, little is known about the effects of MPs and NPs on the testes and ovaries. These particles can enter the body primarily via ingestion, inhalation, and skin contact, target the reproductive system in a size-dependent manner and disturb germ cell and other somatic cell development. Our study systematically reviewed the adverse effects of plastic particles on reproductive function and offers valuable insights into the different stages of germ cells and the potential mechanisms. Moreover, the synergistic reproductive toxicity of these particles and carried contaminants was summarized. Given the limited research scale, a shift toward innovative technologies and the adoption of multiple omics are recommended for advancing related studies. Further study is needed to explore the reproductive toxicity of MPs and NPs based on their size, polymer type, shape, and carried toxins, establish effective protective measures, and develop precision medicine for targeted reproductive damage.

Incidence and exposure to microplastics in table salt present in the Iran market

Plastics and microplastics (MPs) are toxic, pervasive and threatening the biotic and abiotic components of the earth, and they threaten food safety and food security by moving in the food chain. In this study, the amounts and characteristics of 40 table salt samples with different brands, including sea salt (No = 13), rock (No = 13), bulk (No = 8) and non-standard (No = 6), were investigated with a combination of sieving, filtration, observation and FTIR, Micro-Raman and SEM techniques. The results showed that all the salts were contaminated with MPs. In general, the abundance range of detected particles was 700-5470 MPs/kg. The abundance of MPs was higher in counterfeit and non-standard salts (1825 ± 1808 MPs/kg). Investigating the relationship between the effect of the purification process (Kruskal-Wallis Test, P = 0.841), the type of packaging (Kruskal-Wallis Test, P = 0.609), and the type of salt (Kruskal-Wallis Test, P = 0.942), on the abundance of MPs using a comparison test Kruskal-Wallis was not significant. However, the numerical difference was recognizable. The most identified polymer in the salts was cellulose acetate, which probably causes by unmanaged plastic litter in the environment (especially cigarette butts). The dominant form of particles was fragment-shaped, which is the most abundant form of identified MPs in the environment. Both environmental pollution and secondary pollution (during production and packaging), respectively, contribute to the contamination of salts with MPs. The estimated human dietary intake (EDI) and the amount of estimated annual intake (EAI) for different ages in Iran were obtained EDI = 5-59 MPs/capita/day and EAI = 1967-21563 MPs/capita/year. The surface morphology of the particles showed that the MPs were affected by continuous weathering, mechanical fracture and oxidation. MPs are a threat to human health due to the absorption and transmission of dangerous pollutants and their inherent toxicity. Therefore, a solution must be thought of to prevent the contamination of the food chain through salts by MPs, (with protective measures at the salt source, and by improving its production processes.

Removal of most frequent microplastic types and sizes in secondary effluent using Al2(SO4)3: choosing variables by a fuzzy Delphi method

Microplastics (MPs) as an emerging pollutant can affect aquatic organisms through physical ingestion, chemical problems and possible creation of biological layers on their surfaces in the environment. One of the significant ways for MPs to enter the aquatic environment is through the effluent discharge of wastewater treatment plants (WWTPs). In this study, first, the concentration and characteristics of MPs in secondary wastewater effluent, and the influential variables related to the coagulation process, for MPs removal were identified using systematic reviews of previous studies. Then, the most proper MPs characterization and coagulation variables were chosen by experts' opinions using a fuzzy Delphi method. Therefore, the experiment tested in conditions close to the full-scale wastewater treatments. Finally, in the laboratory removal of MPs by coagulation of polyamide (PA), polystyrene (PS), and polyethylene (PE), < 125 and 300-600 μm in size, was tested by a jar test applying Al2(SO4)3 in doses of 5 to 100 mg/L plus 15 mg/L polyacrylamide as a coagulant aid. Using R and Excel software, the results were analyzed statistically. It was concluded that the maximum and minimum removal efficiency was 74.7 and 1.39% for small PA and large PE, respectively. Smaller MPs were found to have higher removal efficiency. The MPs type PA achieved greater removal efficiency than PS, while PE had the least removal efficiency.

Distribution of microplastics in upstream and downstream surface waters of the Iranian rivers discharging to the southern Caspian Sea

Microplastic pollution in the riverine ecosystems has caught many attentions in the scientific literatures. However, little information is available about the abundance and distribution of microplastics of the rivers discharging to the Caspian Sea. The aim of this study was to assess the spatial and seasonal distribution of microplastics in the surface waters of thirteen rivers discharging to the southern Caspian Sea. Microplastics were found in all stations with uneven distributions. The average concentrations of microplastics in the stations during snowmelt and dry seasons were 1.406 ± 0.1380 microplastics/m3 and 0.4070 ± 0.01500 microplastics/m3, respectively. Positive gradients of the rivers microplastics concentration from upstream to downstream were found. White/transparent polyethylene (PE) particles with the shape of fragment/film and the length (L) of ≤ 1 mm were the most common microplastics in the surface waters of the rivers discharging to the southern Caspian Sea. Also, the mean concentration of microplastics in spring snowmelt and runoff period was 3.45 times higher than in dry period. Factors such as sewage and household wastes; landfills; and recreational-tourism, fishing and agricultural activities along the rivers may contribute to microplastic contamination in downstream stations. Our data provide baseline information of microplastics in surface waters of rivers discharging to the southern Caspian Sea.

Sources, distribution, and incipient threats of polymeric microplastic released from food storage plastic materials

The present study aimed to find out the source, distribution, quantity, and incipient threats of the microplastics (MPs) released by food-packing plastic materials, plastic bags, bottles, and containers on human health, biodiversity, water bodies, and atmosphere. For this purpose, 152 articles about MPs (0.1 to 5000 µm) and nanoplastics (NP) 1 to 100 nm) were reviewed and interpreted their results in the present articles about microplastics. The highest plastic waste is generated by China (⁓ 59 Mt), the USA (⁓ 38 Mt), Brazil (⁓ 12 Mt), Germany (⁓ 15 Mt), and Pakistan (⁓ 6 Mt). The count of MPs (MPs/kg) in Chinese salt was 718, UK 136, Iran 48, and USA 32, while MPs in bivalves, i.e., in Chinese bivalves was 2.93, UK 2.9, Iran 2.2, and Italy 7.2 in MPs/kg, respectively. The MPs count in Chinese fish was 7.3, Italy's 23, the USA's 13, and UK's 1.25 in MPs/kg, respectively. The MP concentrations in the water bodies, i.e., USA, were 15.2, Italy 7, and UK 4.4 in mg/L, respectively. It was critically reviewed that MPs can enter the human body causing various disorders (neurotoxic, biotoxic, mutagenic, teratogenic, and carcinogenic disorders) because of the presence of various polymers. The present study concluded that MPs were released from processed and stored food containers, either through physical, biological, or chemical means, which harshly affect the surrounding environment and human health. The study recommended that alternatives to plastic containers are glass and bioplastic containers, papers, cotton bags, wooden boxes, and tree leaves need to use to avoid direct consumption of MPs from food.

Stronger Geographic Limitations Shape a Rapid Turnover and Potentially Highly Connected Network of Core Bacteria on Microplastics

Core microbiota is shared microbial taxa within the same habitat, which is important for understanding the stable and consistent components of the complex microbial assembly. However, information on the microplastic core bacteria from the river ecosystems is poor. Here, we investigated the composition and function of microplastic core bacteria from the Three Gorges Reservoir area along the approximate 662 km of the Yangtze River via full-length 16S rRNA gene sequencing, compared with those in water, sediment, and soil. The results showed that the spatial turnover of bacterial communities in four habitats supported deterministic processes dominated by niche differentiation, which shaped their core bacteria. The composition and function of microplastic core bacteria were significantly different from those in the other three habitats. Rhodobacteraceae was the main component of microplastic core bacteria, while the main component of core bacteria in water, sediment, and soil were Burkholderiaceae (21.90%), Burkholderiaceae (5.01%), Nitrosomonadaceae (4.61%), respectively. Furthermore, microplastic core bacteria had stronger geographic limitations along the Yangtze River in the Three Gorges Reservoir area. Stronger geographic limitations shaped the rapid community turnover and a potentially more connected network for the microplastic core bacteria than water, sediment, and soil. More importantly, microplastic core bacteria had strong potential functions of drug resistance and could cause risks to ecosystems and human health. Microplastic core bacteria were mainly influenced by sediment core bacteria, although the bacteria colonizing on microplastics could be from all the contact environments and original sources. These findings provide important insights into the composition, function, and association of microplastic core bacteria with their surrounding environment.

Characteristics and fluxes of plastic debris based on socio-economic data for Patos Lagoon-a choked coastal Lagoon in South Brazil

Patos Lagoon, located in southern Brazil, is the world's largest choked coastal lagoon. Studies have revealed that plastic pollution affects lagoons; however, to date, they have only focused on a few limited regions of the lagoon. Top-down quantification methods based on socio-economic data from 2010 to 2017 were used to measure the amount of plastic reaching Patos Lagoon, thus broadening the perspective of plastic pollution in this area. According to the findings, Patos Lagoon's hydrographic regions produced an average of 4.54 Mton of plastic during the studied period. 1.86 Mton was consumed on average. High- and low-density polyethylene (HDPE and LDPE, respectively), polypropylene (PP), and polyvinyl chloride (PVC) were the main resins produced. Food-related activities were the largest consumer of plastic (17.98%), indicating a higher amount of single-use plastics being used in the basin. The preforms for plastic bottles, bags, and packaging were the most commonly manufactured plastic utensils. An estimated 8 to 14% of all plastics used to end up as mismanaged waste in the Patos Lagoon hydrographic basin. This resulted in 1.73 and 10.72 Kton, or 0.5 and 3.2 g/per person/per day, of plastic waste flowing into the waters of Patos Lagoon throughout the study period. These findings can help focus on management efforts by providing managers and policymakers with information for better plastic pollution mitigation in this environment.

Satellite-Based Monitoring of Eutrophication in the Earth's Largest Transboundary Lake

The world's large lakes and their life-supporting services are rapidly threatened by eutrophication in the warming climate during the Anthropocene. Here, MODIS-Aqua level 3 chlorophyll-a data (2018-2021) were used to monitor trophic state in our planet's largest lake, that is, the Caspian Sea that accounts for approximately 40% of the total lacustrine waters on Earth. We also used the in situ measurements of chlorophyll-a data (2009-2019) to further verify the accuracy of the data derived from the MODIS-Aqua and to explore the deep chlorophyll-a maxima (DCMs) in the south Caspian Sea. Our findings show an acceptable agreement between the chlorophyll-a data derived from the MODIS-Aqua and those measured in situ in the coast of Iran (coefficient of determination = 0.71). The oligotrophic, mesotrophic, and eutrophic states cover 66%, 20%, and 13% of the sea surface area, respectively. The DCMs are dominantly regulated by water transparency and they generally observe at depths of less than 20 and 30 m during the cold (autumn and winter) and warm (spring and summer) seasons, respectively. Our results suggest an ever-increasing chlorophyll-a in the shallow zones (i.e., coasts) and even in deep regions of the sea, mainly due to nutrient inputs from the Volga river delta. Alarming increase of chlorophyll-a in this transboundary lake can amplify eutrophication under the lens of global warming and further threaten the lake ecosystem's health, where almost all legal agreements have not yet been implemented to protect the lake environment and its rich resources.

Sources and hotspots of microplastics of the rivers ending to the southern Caspian Sea

The occurrence of microplastics (MPs) in beach sediments of the southern Caspian Sea was well documented, however, there are still many unknowns about the abundances and distributions of MPs in the rivers ending to the Caspian Sea. Here, bank sediments of 26 sites in the thirteen rivers were surveyed in two seasons. However, there was not any significant difference (p > 0.05) between the concentrations of MPs during the two seasons. MPs were detected in all samples with mean concentrations of 214.08 ± 14.35 MPs/kg. The most common size, shape, color, and polymer types of MPs were L < 300 μm, fragment/film, white/transparent, and polystyrene (PS), respectively. In all rivers, positive MP gradients from upstream to downstream were observed. Maximum concentrations of MPs were found in the downstream parts of Chalus, Haraz, and Safarud rivers. Recreational-tourism and fishing activities had significant positive relationships (p < 0.05) with concentration of MPs in the rivers.

Valorization of lignocellulosic biomass for polyhydroxyalkanoate production: Status and perspectives

With the increasing concerns regarding climate, energy, and plastic crises, bio-based production of biodegradable polymers has become a dire necessity. Significant progress has been made in biotechnology for the production of biodegradable polymers from renewable resources to achieve the goal of zero plastic waste and a net-zero carbon bioeconomy. In this review, an overview of polyhydroxyalkanoate (PHA) production from lignocellulosic biomass (LCB) was presented. Having established LCB-based biorefinery with proper pretreatment techniques, various PHAs could be produced from LCB-derived sugars, hydrolysates, and/or aromatic mixtures employing microorganisms. This provides a clue for addressing the current environmental crises because "biodegradable polymers" could be produced from one of the most abundant resources that are renewable and sustainable in a "carbon-neutral process". Furthermore, the potential future of LCB-to-non-natural PHA production was discussed with particular reference to non-natural PHA biosynthesis methods and LCB-derived aromatic mixture biofunnelling systems.

A spatial decision support system for municipal solid waste landfill sites (case study: The Mazandaran Province, Iran)

Landfilling is an inevitable step for the municipal solid waste (MSW) management system in developing countries. This article presents a Spatial Decision Support System (SDSS) that was developed for the monitoring of municipal landfills and siting the new places for waste disposal at Mazandaran province, south of Caspian Sea, Iran. The effective criteria and evaluation constraints were chosen according to the Iran waste management law. The ArcGIS 10.4.1 software was used for creating a geospatial database and the analytic hierarchy process (AHP) was used for ranking the criteria. By integrating the criteria, a suitability map was generated into four categories: high suitability, moderate suitability, low suitability and illegal areas. Using ArcGIS online, the maps were shared on a website that was specifically designed for this purpose. The decision-makers can check online the laws, the effective criteria and the results of spatial analysis for optimal siting. Also, the results of environmental evaluations for active landfills have been provided. Given the characteristics of active landfills and the optimal sites for the possible development, the SDSS can provide a mutually beneficial relationship between the experts, decision-makers and stakeholders to decide about the priority of actions required for the relocation of landfills, site closure or emergency care.

Personal protective equipment (PPE) pollution in the Caspian Sea, the largest enclosed inland water body in the world

The COVID-19 pandemic led to a still ongoing international health and sanity crisis. In the current scenario, the actions taken by the national authorities and the public prioritized measures to control the transmission of the virus, such as social distancing, and face mask-wearing. Unfortunately, due to the debilitated waste management systems and incorrect disposal of single-use face masks and other types of personal protective equipment (PPE), the occurrence of these types of items has led to the exacerbation of marine plastic pollution. Although various studies have focused on surveying marine coasts for PPE pollution, studies on inland water are largely lacking. In order to fill this knowledge gap, the present study assessed PPE pollution in the Iranian coast of the Caspian Sea, the largest enclosed inland water body in the world by following standard monitoring procedures. The results concerning the density (1.02 × 10-4 PPE/m2) composition (face masks represented 95.3% of all PPE) of PPE are comparable to previous studies in marine waters. However, a notable decrease in the occurrence of PPE was observed, probably to behavioral and seasonality reasons. The possible consequences of PPE pollution were discussed, although much more research is needed regarding the ecotoxicological aspects of secondary PPE contaminants, such as microplastics and chemical additives. It is expected that face mask mandates will be eventually halted, and PPE will stop being emitted to the environment. However, based on the lessons learned from the COVID-19 scenario, several recommendations for coastal solid waste management are provided. These are proposed to serve during and after the pandemic.

A Systematic Literature Review on Environmental Sustainability Issues of Flexible Packaging: Potential Pathways for Academic Research and Managerial Practice

The purpose of this review is to investigate environmental sustainability issues of the flexible packaging (FP) segment of the packaging industry. Increasingly, waste and pollution caused by FP have become a significant challenge for global sustainable development. Prior research studies have examined a diverse set of environmental challenges associated with FP, albeit, in a fragmented way. There is a paucity of research exploring and synthesizing the environmental burden of FP in an integrated fashion. To bridge this knowledge gap, we conducted a systematic literature review (SLR) to identify, synthesize, and analyze the environmental sustainability issues of FP utilizing the SCOPUS database. Based on an in-depth critical analysis of selected articles, this paper provides novel insights to scholars, practitioners, and policymakers for developing an improved understanding of environmental issues of the FP sector. This paper promotes academic scholarship and strengthens managerial practice in addressing the environmental sustainability challenges of FP.

Microplastic pollution in inshore and offshore surface waters of the southern Caspian Sea

In this study, as the first comprehensive monitoring, the occurrence of microplastics (MPs) in inshore and offshore surface waters of the southern Caspian Sea was investigated. Our data indicated that MPs, which were detected in all the samples, were widely distributed in the thirteen studied stations. Non-normally distribution of the MPs was observed among the studied stations (p<0.05). The average concentration of microplastics in the selected stations was 0.246 ± 0.020 MP/m³. In most of the transects, negative gradients of MPs from coastal waters to deeper waters were observed. The dominant size and color of MPs in the inshore and offshore water samples was 1000-5000 μm and white-transparent, respectively. Films and fibers constituted about 50% and 40% of the total number of MPs of the water samples, respectively. Also, polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) were the three main polymer types of microplastics in the inshore and offshore surface waters. Our data provide valuable evidence for the comparative assessing of future data regarding decreases or increases of MPs in the southern Caspian Sea.

Spatial distribution of microplastics in sandy beach and inshore-offshore sediments of the southern Caspian Sea

The occurrence of microplastics (MPs) in nearshore zones of the southern Caspian coasts is well documented; however, no data are available on MP occurrence in offshore sediments. In this study, six sandy beach stations and 18 inshore-offshore stations (six transects) were surveyed. MPs were detected in all sediment samples. The mean abundances of MPs in the beach and inshore-offshore stations were 196.67 ± 11.58 and 103.15 ± 7.21 MPs/kg, respectively. Fibers constituted the most common shape of MPs. Polystyrene (PS) and polyethylene terephthalate (PET) were the major polymer types found in the beach and inshore-offshore sediments, respectively. In most transects, negative MP gradients were observed from nearshore to offshore, which showed that coastal fishing, tourism, and rivers were the main sources of MPs in this area. These results will improve our understanding on MPs pollution in the marine ecosystem. We recommend further MP studies in different parts of the Caspian Sea to develop appropriate management programs.

Abundance and distribution of microplastics in the sediments of the estuary of seventeen rivers: Caspian southern coasts

Given the increase in plastic production, persistence, and toxicity in the environment, understanding the probability of microplastics (MPs) accumulation in the sediments of the rivers' estuary is urgently needed. In this study, sediments of the estuary of 17 rivers, ending to the Caspian Sea, were evaluated at two depths (0-5 cm and 5-15 cm). Plastic particles were categorized into two groups in terms of size: small MPs and large MPs. The combination of observational techniques, FTIR, and SEM analysis was applied to identify MPs. The mean of MPs in 17 rivers was obtained at a depth of 0 to 15 cm of sediments 350.6 ± 232.6 MP/kg. The fiber was identified as the predominant particles in sediments, and foam-shaped particles were the least amount in the sediment. In terms of polymer structure, polyethylene (PE) (20%) and polyvinyl chloride (PVC) (2%) showed the highest and lowest prevalence, respectively. In the current study, the number of MPs was higher than the average of MPs in sediments of recreational-tourist areas and non-tourist areas of the southern Caspian coast. Results from this study indicate that sediments of the rivers' estuary are a hotspot of plastic particle pollution. Therefore, plastic management in the path of the Caspian catchment area of Iran, and cleaning rivers coast and rivers mouth from plastic is recommended.

Intra and extracellular effects of benzo [α] pyrene on liver, gill and blood of Caspian White fish (Rutilus frissi kutum): Cyto-genotoxicity and histopathology approach

Southern parts of the Caspian Sea have been faced with a diverse range of oil pollutants. Therefore, this study was designed to evaluate the effects of relevant environmental concentrations of benzo[α]pyrene (BαP) on liver, gill, and blood of Caspian White fish. To this end, 150 fingerling fish (6.5 ± 0.8 g) were exposed to under, near and over environmental concentrations of BαP (i.e. 50, 100, and 200 ppb, respectively) and two control groups for 21 days. Following exposure to BαP, generally, DNA damage increased in the liver and gill cells as well as the frequency of micro- and bi-nucleated erythrocytes in a time and concentration-dependent pattern. In addition, the liver and gill tissues displayed several histopathological lesions. Together, the findings are warning the health status of the Caspian Sea due to an ever-increasing concentration of BαP through using Caspian White fish as an ecological model.

Systematic Analysis of the Relative Abundance of Polymers Occurring as Microplastics in Freshwaters and Estuaries

Despite growing interest in the environmental impact of microplastics, a standardized characterization method is not available. We carried out a systematic analysis of reliable global data detailing the relative abundance of polymers in freshwaters and estuaries. The polymers were identified according to seven main categories: polyethylene terephthalate, polyethylene, polyvinyl chloride, polypropylene, polystyrene, polyurethane and a final category of miscellaneous plastic. The results show that microplastics comprised of polyvinyl chloride and polyurethane are significantly less abundant than would be expected based on global production, possibly due to their use. This has implications for models of microplastic release into the environment based on production and fate. When analysed by matrix (water, sediment or biota) distinct profiles were obtained for each category. Polyethylene, polypropylene and polystyrene were more abundant in sediment than in biota, while miscellaneous plastics was more frequent in biota. The data suggest that environmental sorting of microplastic particles, influenced by physical, chemical and biological processes, may play a key role in environmental impact, although partitioning among matrices based on density was not realized. The distinct profile of microplastics in biota raises an important question regarding potential selectivity in uptake by organisms, highlighting the priority for more and better-informed laboratory exposure studies.

Contamination of the Caspian Sea Southern coast sediments with microplastics: A marine environmental problem

Marine ecosystem pollution with microplastics (MPs) is a global problem. The current study aimed to assess the occurrence of MPs in the sediments of the Caspian Sea southern coasts. For sampling, two distinct areas were selected including recreational-tourism areas (No = 24), and non-tourist areas (No = 24). MPs were studied in 5 and 5-15 cm from the top sediment surface. All 96 samples were taken and analyzed according to the methodology provided by the US national oceanic and atmospheric administration (NOAA). The combination of observational techniques, FTIR, and SEM analysis was applied to identify MPs. MPs were classified into two categories in terms of size: small MPs and large MPs. The average, maximum, and minimum abundance of MPs (based on dry weight) in sediments of the southern coast of the Caspian Sea was 183.5 ± 154.4 MP/kg, 542 MP/kg, and 13 MP/kg, respectively. On the basis of morphology, fragment-shaped (30.3%) MPs showed the highest prevalence, while film-shaped (18.7%) MPs were the least contributory. Polyethylene (PE) and polyethylene terephthalate (PET), each of them with a 20% share, were the most common MPs found in the studied samples. The distribution of MPs on the southern coasts of the Caspian Sea revealed a sporadic and irregular spatial pattern. Correspondingly, it can be concluded that probably environmental factors (the current of the sea surface water from west to east), enclosed environment of the Caspian Sea, anthropogenic activities (e.g., industrialization and urbanization, improper waste management, fishing, and tourism activity, residential wastewater), and also discharging of rivers (which can carry plastics) into the sea, have all influenced the abundance and polymer diversity of MPs in the sediments of the southern coast of the sea. More attention should be paid to the health and environmental effects of MPs and to the protection of this sensitive marine ecosystem through implementing proper waste management system by all surrounding littoral countries.

Estimation of plastic waste inputs from land into the Persian Gulf and the Gulf of Oman: An environmental disaster, scientific and social concerns

It has been reported that, the huge amount of plastic waste is present in marine environments. This study evaluated solid waste generation, management, disposal approaches, and the amount of plastic waste entered into the Persian Gulf and the Gulf of Oman in 2016. The findings showed that waste in the Persian Gulf and the Gulf of Oman regions has been mismanaged by 65% and 81%, respectively. According to our estimates, about 1634.9 k-tons (Kt) and 204.6 Kt of plastic waste have been, respectively, generated by the Persian Gulf and the Gulf of Oman littoral states in 2016. Most likely, the mass of plastic waste entering the Persian Gulf and the Gulf of Oman in 2016 was ranged from 155 to 413.4 Kt and 29.2-77.9 Kt, respectively. Without implementation of effective waste management strategies, it is estimated that by 2030, the mass of plastic waste entering the Persian Gulf will increase to 199.4-531.6 Kt, while in the Gulf of Oman it would be about 40.4-107.7 Kt. The entry of plastic waste into the Persian Gulf and the Gulf of Oman has been expected to increase by 29% and 38% in 2030, respectively. As a result, the related cumulative environmental and health effects can be more intensive. It can be emphasized that all countries located in the coastal areas of the Persian Gulf and the Gulf of Oman need to modify their solid waste management, plastic waste in particular, policies to conserve sensitive marine ecosystems.

Seawater-Degradable Polymers-Fighting the Marine Plastic Pollution

Polymers shape human life but they also have been identified as pollutants in the oceans due to their long lifetime and low degradability. Recently, various researchers have studied the impact of (micro)plastics on marine life, biodiversity, and potential toxicity. Even if the consequences are still heavily discussed, prevention of unnecessary waste is desired. Especially, newly designed polymers that degrade in seawater are discussed as potential alternatives to commodity polymers in certain applications. Biodegradable polymers that degrade in vivo (used for biomedical applications) or during composting often exhibit too slow degradation rates in seawater. To date, no comprehensive summary for the degradation performance of polymers in seawater has been reported, nor are the studies for seawater-degradation following uniform standards. This review summarizes concepts, mechanisms, and other factors affecting the degradation process in seawater of several biodegradable polymers or polymer blends. As most of such materials cannot degrade or degrade too slowly, strategies and innovative routes for the preparation of seawater-degradable polymers with rapid degradation in natural environments are reviewed. It is believed that this selection will help to further understand and drive the development of seawater-degradable polymers.