Occurrence,fate and effects of azoxystrobin in aquatic ecosystems: A review

The use of pesticides for crop protection may result in the presence of toxic residues in environmental matrices. In the aquatic environment, pesticides might freely dissolve in the water or bind to suspended matter and to the sediments, and might be transferred to the organisms' tissues during bioaccumulation processes, resulting in adverse consequences to non-target species. One such group of synthetic organic pesticides widely used worldwide to combat pathogenic fungi affecting plants is the strobilurin chemical group. Whereas they are designed to control fungal pathogens, their general modes of action are not specific to fungi. Consequently, they can be potentially toxic to a wide range of non-target organisms. The present work had the intent to conduct an extensive literature review to find relevant research on the occurrence, fate and effects of azoxystrobin, the first patent of the strobilurin compounds, in aquatic ecosystems in order to identify strengths and gaps in the scientific database. Analytical procedures and existing legislation and regulations were also assessed. Data gathered in the present review revealed that analytical reference standards for the most relevant environmental metabolites of azoxystrobin are needed. Validated confirmatory methods for complex matrices, like sediment and aquatic organisms' tissues, are very limited. Important knowledge of base-line values of azoxystrobin and its metabolites in natural tropical and estuarine/marine ecosystems is lacking. Moreover, some environmental concentrations of azoxystrobin found in the present review are above the Regulatory Acceptable Concentration (RAC) in what concerns risk to aquatic invertebrates and the No Observed Ecologically Adverse Effect Concentration (NOEAEC) reported for freshwater communities. The present review also showed that there are very few data on azoxystrobin toxicity to different aquatic organisms, especially in what concerns estuarine/marine organisms. Besides, toxicity studies mostly address azoxystrobin and usually neglect the more relevant environmental metabolites. Further work is also required in what concerns effects of exposure to multi-stressors, e.g. pesticide mixtures. Even though Log K_ow for azoxystrobin and R234886, the main metabolite of azoxystrobin in water, are below 3, the bio-concentration factor and the bioaccumulation potential for azoxystrobin are absent in the literature. Moreover, no single study on bioaccumulation and biomagnification processes was found in the present review.     

Stability of aquatic ecosystems and their variation under conditions of toxic pollution

The development of concepts concerning the stability of aquatic ecosystem and their variation under conditions of toxic pollution and after its reduction is considered. General trends in ecosystem transformation are explained in terms of theoretical ecology and thermodynamic mechanisms of energy ordering in living systems. Basic symptoms of disorganization in ecosystems under extreme loads and of their regenerative self-organization are discussed. It is shown that the development of a new modification of an aquatic ecosystem after a decrease in toxic pollution complies with the pattern of ecosystem succession: from a natural ecosystem, via the critical stage, to its more stable but structurally different modification.     

Diatoms in bottom sediments as indicators of pollution of urban aquatic ecosystems

Analysis of the concentrations of chemical elements and the composition of diatoms in the surface layer of bottom sediments has been performed in a small reservoir at the mouth of dammed river to evaluate the levels of pollution and the impact of toxicants on diatom communities of the river ecosystem. Data on interrelations between the concentrations of chemical elements and the relationship between inorganic pollution and accumulation of diatoms in bottom sediments as an indicator of development of the diatom assemblage have been obtained using linear correlation analysis and graphical plotting.     

Ecological half-lives of 90Sr and 137Cs in terrestrial and aquatic ecosystems

This paper describes the long-term behaviour of (90)Sr and (137)Cs in foods, feeds and a variety of environmental media. The long-term behaviour is quantified by means of the ecological half-life which integrates all processes that cause a decrease of activity in a given medium such as leaching, fixation and erosion. A large number of long-term time series of concentrations of radiocaesium and radiostrontium in these media have been identified and re-evaluated using a standardised statistical procedure to establish reference data sets of ecological half-lives. By example of undisturbed soils and marine water bodies it is shown that the ecological half-life concept is questionable if the distribution of the radionuclide of interest within the medium studied is non-uniform and if mixing and transport processes within this medium, therefore, are of considerable importance during the time period of observation.     

Distribution of PCB congeners in aquatic ecosystems: A case study

Polychlorinated biphenyls (PCB) congeners were determined in water samples, sediments, and animal species in the frame of a survey of the River Arrone (Central Italy, near Rome) after a major contamination episode. Animal species were selected on the basis of their living and feeding habits and evaluated as candidate bioindicators of PCB pollution in this lotic ecosystem. Total PCB concentrations in water were found to be low (ng/L level), and in sediments, ranged from about 10 to 200 μg/kg dry weight, depending on the distance from the contamination source. PCB patterns in sediments showed a prevalence of higher chlorinated congeners over time. Concentrations in macroinvertebrates (Calopteryx splendens and Anax imperator) ranged from 60 to 400 μg/kg dry weight, showing significantly different species to species patterns. PCB concentrations were almost parallel in sediments for different sampling stations, while differences in patterns among species can be explained in terms of bioaccumulation/excretion mechanisms. Freshwater shrimps (Palaemonetes antennarius) were not found close to the contamination source, as a consequence of their extreme sensitivity to chemicals, and showed a peculiar pattern (almost exclusively determined by congeners 153, 138, and 180) probably originating from biodegradation mechanisms. Fish samples (Rutilus erythrophthalmus) showed the highest concentrations, as a combination of feeding habit, lipid content, and, probably, less effective biodegradation/excretion pathways. Congener patterns closely match those of Aroclor 1260, which originates from the contamination source. This study confirms that congener physical and chemical parameters, different degradation rates, feeding habits, and mobility of the analysed aquatic organisms, metabolism, and excretion mechanisms, are to be considered to explain the distinctive PCB patterns of different samples.     

Impacts of atrazine in aquatic ecosystems

A portion of all herbicides applied to forests, croplands, road sides, and gardens are inevitably lost to water bodies either directly through runoff or indirectly by leaching through groundwater into ephemeral streams and lakes. Once in the aquatic environment, herbicides may cause stress within aquatic communities and radically alter community structure. Atrazine is one of the most effective and inexpensive herbicides in the world and is consequently used more frequently than any other herbicide. Atrazine is frequently detected in aquatic waters, and has been known to affect reproduction of aquatic flora and fauna, which in turn impacts on the community structure as a whole. This paper presents a summary of the reported direct and indirect impacts of atrazine on aquatic organisms and community structure. The information can be used for developing improved management guidelines and legislation. It is concluded that a single universal maximum limit on the atrazine application in catchments, as suggested by many regulatory authorities, does not provide adequate protection of the aquatic environment. Rather, it is advocated that flexible limits on the application of atrazine be developed in line with the potential risk of contamination to surface and subsurface water and fragility of the aquatic environment.     

Interacting environmental and chemical stresses under global change in temperate aquatic ecosystems: stress responses,adaptation, and scaling

Regional Environmental Change - Unfavorable environmental conditions—abiotic stress—constitute one of the key drivers of evolution leading to environmental adaptation. Since the start...     

A global assessment of phthalates burden and related links to health effects

Phthalates are ubiquitous environmental contaminants which are used in industry as plasticizers and additives in cosmetics. They are classified as Endocrine Disrupting Chemicals (EDCs) which impair the human endocrine system inducing fertility problems, respiratory diseases, childhood obesity and neuropsychological disorders. The aim of this review is to summarize the current state of knowledge on the toxicity that phthalates pose in humans based on human biomonitoring studies conducted over the last decade. Except for conventional biological matrices (such as urine and serum), amniotic fluid, human milk, semen, saliva, sweat, meconium and human hair are also employed for the estimation of exposure and distribution of pollutants in the human body, although data are not enough yet. Children are highly exposed to phthalates relative to adults and in most studies children's daily intake surpasses the maximum reference dose (RfD) set from US Environmental Protection Agency (US EPA). However, the global trend is that human exposure to phthalates is decreasing annually as a result of the strict regulations applied to phthalates.     

Health effects of indoor air pollution: Synergistic effects of nitrogen dioxide and a respirable aerosol

Comparative studies of the effects of various air pollutants on lung collagen biosynthesis have been performed. A hitherto unexpected synergism between the oxidant air pollutants ozone or nitrogen dioxide and a respirable-sized aerosol of ammonium sulfate was observed during controlled exposures of rats to these substances. In an assay system, measuring collagen biosynthesis by lung minces prepared from rats exposed for 1 week to either filtered air or to these pollutants gases, dose-response curves to either O₃ or NO₂ are altered in the presence of 5 mg/m³ of (NH₄)₂SO₄ aerosol. These observations may have broad implications for the appropriate evaluation of laboratory data in the setting of ambient air quality standards and/or the setting of threshold limit values for maintenance of occupational health and safety.     

Distribution of leeches in aquatic ecosystems of the city of Yekaterinburg and its vicinity

Ecological features and species composition of leeches were studied in 25 water bodies located in the city of Yekaterinburg and its vicinity. Specific features of their occurrence and distribution in water bodies of various types were analyzed. Dominant, mass, common, and rare species were distinguished.     

Ecological effects of various toxic agents on the aquatic microcosm in comparison with acute ionizing radiation

The purpose of this study was an evaluation of the effect levels of various toxic agents compared with acute doses of ionizing radiation for the experimental model ecosystem, i.e., microcosm mimicking aquatic microbial communities. For this purpose, the authors used the microcosm consisting of populations of the flagellate alga Euglena gracilis as a producer, the ciliate protozoan Tetrahymena thermophila as a consumer and the bacterium Escherichia coli as a decomposer. Effects of aluminum and copper on the microcosm were investigated in this study, while effects of gamma-rays, ultraviolet radiation, acidification, manganese, nickel and gadolinium were reported in previous studies. The microcosm could detect not only the direct effects of these agents but also the community-level effects due to the interspecies interactions or the interactions between organisms and toxic agents. The authors evaluated doses or concentrations of each toxic agent which had the following effects on the microcosm: (1) no effects; (2) recognizable effects, i.e., decrease or increase in the cell densities of at least one species; (3) severe effects, i.e., extinction of one or two species; and (4) destructive effects, i.e., extinction of all species. The resulting effects data will contribute to an ecological risk assessment of the toxic agents compared with acute doses of ionizing radiation.     

Silver nanoparticles: behaviour and effects in the aquatic environment

This review summarises and evaluates the present knowledge on the behaviour, the biological effects and the routes of uptake of silver nanoparticles (Ag NPs) to organisms, with considerations on the nanoparticle physicochemistry in the ecotoxicity testing systems used. Different types of Ag NP syntheses, characterisation techniques and predicted current and future concentrations in the environment are also outlined. Rapid progress in this area has been made over the last few years, but there is still a critical lack of understanding of the need for characterisation and synthesis in environmental and ecotoxicological studies. Concentration and form of nanomaterials in the environment are difficult to quantify and methodological progress is needed, although sophisticated exposure models show that predicted environmental concentrations (PECs) for Ag NPs in different environmental compartments are at the range of ng L(-1) to mg kg(-1). The ecotoxicological literature shows that concentrations of Ag NPs below the current and future PECs, as low as just a few ng L(-1), can affect prokaryotes, invertebrates and fish indicating a significant potential, though poorly characterised, risk to the environment. Mechanisms of toxicity are still poorly understood although it seems clear that in some cases nanoscale specific properties may cause biouptake and toxicity over and above that caused by the dissolved Ag ion. This review concludes with a set of recommendations for the advancement of understanding of the role of nanoscale silver in environmental and ecotoxicological research.     

Prognostic simulation of alpine ecosystems in view of global climate change

Experience in predicting the state of alpine ecosystems on the basis of empirical-statistical simulation is described using the example of the Central Caucasus. Two types of analytical and cartographic prognostic models, chorometric and chronometric, are presented. They are used to obtain probabilistic estimates of alpine meadows and forests in the vicinity of Mount Elbrus in view of the forthcoming global climate warming for the period until the year 2100 (by means of GISS Model E for climate prediction).     

Status and characteristics of ambient PM2.5 pollution in global megacities

Ambient PM_2.5 pollution is a substantial threat to public health in global megacities. This paper reviews the PM_2.5 pollution of 45 global megacities in 2013, based on mass concentration from official monitoring networks and composition data reported in the literature. The results showed that the five most polluted megacities were Delhi, Cairo, Xi'an, Tianjin and Chengdu, all of which had an annual average concentration of PM_2.5 greater than 89 μg/m³. The five cleanest megacities were Miami, Toronto, New York, Madrid and Philadelphia, the annual averages of which were less than 10 μg/m³. Spatial distribution indicated that the highly polluted megacities are concentrated in east-central China and the Indo-Gangetic Plain. Organic matter and SNA (sum of sulfate, nitrate and ammonium) contributed 30% and 36%, respectively, of the average PM_2.5 mass for all megacities. Notable seasonal variation of PM_2.5 polluted days was observed, especially for the polluted megacities of China and India, resulting in frequent heavy pollution episodes occurring during more polluted seasons such as winter. Marked differences in PM_2.5 pollution between developing and developed megacities require more effort on local emissions reduction as well as global cooperation to address the PM_2.5 pollution of those megacities mainly in Asia.     

Ecological pressures on grassland ecosystems and their conservation strategies in Northern China

In this study,we identified ecological pressures on grassland ecosystems and adaptive countermeasures in Northern China.Our research revealed that the main sources of these pressures included population growth,economic development,resources exploitation,and global climate change,with human-related activities being overriding factors.Overgrazing was an important reason for grassland imbalance,causing soil erosion and desertification,especially during the sensitive spring greening phase.In steppe zones,commercial coal mining was destructive to the ecological environment.Regarding long-term strategies,we recommend that policy-makers devote more consideration to a new conceptual approach for transforming grasslands through shifting the focus from die grassland’s traditional production functions to meir ecological functions.Applying this concept,adaptive countermeasures should be developed to reduce human impacts based on the environmental capacities of grasslands.Moreover,we recommend the development of environment-friendly industries and reduction of pressures from human activities as effective measures for maintaining the balance between sustainable economic development and grassland conservation.Lastly,we suggest that restoration of degraded grasslands should conform to the principle of natural vegetation to further improve the ecological adaptability of plants and ecosystem stability.This study is expected to provide scientific support for policy-makers engaged in grassland protection.     

A review of traffic-related air pollution exposure assessment studies in the developing world

Exposure assessment studies in the developing world are important. Although recent years have seen an increasing number of traffic-related pollution exposure studies, exposure assessment data on this topic are still limited. Differences among measuring methods and a lack of strict quality control in carrying out exposure assessment make it difficult to generalize and compare findings between studies. In this article, exposure assessment studies carried out in the developing world on several traffic-related air pollutants are reviewed. These pollutants include particulate matter (PM), carbon monoxide (CO), nitrogen dioxide (NO(2)), volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs). In addition, it discusses advantages and disadvantages of various monitoring methods (ambient fixed-site monitoring, microenvironment monitoring, and personal exposure assessment using portable samplers) for these pollutants in exposure assessment studies. Also included in this paper is a brief introduction of standards for these pollutants in ambient air or in occupational settings established by the United States Environmental Protection Agency (USEPA), the United States Occupational Safety and Health Administration (OSHA) and the World Health Organization (WHO). The review ends with a summary of the limitations and gaps in recent studies and suggestions for future research in the developing world.     

Community effects of carbon nanotubes in aquatic sediments

Aquatic sediments form an important sink for manufactured nanomaterials, like carbon nanotubes (CNT) and fullerenes, thus potentially causing adverse effects to the aquatic environment, especially to benthic organisms. To date, most nanoparticle effect studies used single species tests in the laboratory, which lacks ecological realism. Here, we studied the effects of multiwalled CNT (MWCNT) contaminated sediments on benthic macroinvertebrate communities. Sediment was taken from an unpolluted site, cleaned from invertebrates, mixed with increasing levels of MWCNTs (0, 0.002, 0.02, 0.2 and 2g/kg dry weight), transferred to trays and randomly relocated in the original unpolluted site, which now acted as a donor system for recolonization by benthic species. After three months of exposure, the trays were regained, organic (OC) and residual carbon (RC) were measured, and benthic organisms and aquatic macrophytes were identified. ANOVA revealed a significantly higher number of individuals with increasing MWCNT concentrations. The Shannon index showed no significant effect of MWCNT addition on biodiversity. Multivariate statistics applied to the complete macroinvertebrate dataset, did show effects on the community level. Principal Component Analysis (PCA) showed differences in taxa composition related to MWCNT levels indicating differences in sensitivity of the taxa. Redundancy Analysis (RDA) revealed that MWCNT dose, presence of macrophytes, and spatial distribution explained 38.3% of the total variation in the data set, of which MWCNT dose contributed with 18.9%. Still, the net contribution of MWCNT dose was not statistically significant, indicating that negative community effects are not likely to occur at environmentally relevant future CNT concentrations in aquatic sediments.     

Fate and effects of amphoteric surfactants in the aquatic environment

Amphoteric surfactants form part of specialty surfactants available for formulators to improve or design new formulations in response to environmental, toxicity, safety and performance demands. Nevertheless, limited information on the ecological properties of amphoterics is available. In the present work, the aerobic and anaerobic biodegradability and the aquatic toxicity of different types of amphoteric surfactants (three alkyl betaines, one alkylamido betaine and three alkyl imidazoline derivatives) were studied. The amphoteric surfactants tested were readily biodegradable under aerobic conditions (CO(2) headspace test) and alkylamido betaines and alkyl imidazoline derivatives were also easily biodegradable under anaerobic conditions (test based on the ECETOC method). Toxicity to Photobacterium phosphoreum and Daphnia magna increased with the fatty chain length of the surfactant. The EC(50) toxicity values of the amphoterics tested were higher than 5 mg/L, and alkyl imidazoline derivatives, with EC(50) values from 20 to >200 mg/L, showed the lowest aquatic toxicity.     

Forest ecosystems of the volga basin under conditions of global climate warming: Local ecological prediction

Prediction based on one of the latest extreme prognostic models, the Hadley Centre Model HadCM3 (version A2) has been performed using an original method of discrete empirical statistical modeling of ecosystems. Probabilistic scenarios of the expected changes in summer soil moisture content until the mid-22nd century and corresponding structural and functional changes in forest ecosystems for different zonal/regional conditions of the Volga basin are described.     

Soil respiration of forest ecosystems in gradients of environmental pollution by emissions from copper smelters

The effect of industrial pollution on soil respiration measured in situ has been studied along two gradients formed by emissions from large copper smelters: the Middle Ural Copper Smelter (spruce-fir forests) and Karabash Copper Smelter (birch forests). Pollution has proved to have a slight effect on soil respiration: its rate drops only in the zone of industrial barren. There is no correlation between soil respiration and distance to the emission source, metal contents in the litter, or litter acidity. A hypothesis is proposed that this may be due to a shift in the ratio of the root and microbial components of respiration in the pollution gradient.