Levels Of Primary Production Research Articles

Fluctuations of continental chemical weathering control primary productivity and redox conditions during the Earliest Cambrian

The Ediacaran – Cambrian transition witnessed dramatic changes in the marine environment that are thought to have strongly influenced biological evolution. Previous studies have linked biological innovations to palaeo‐redox changes and suggested that increased productivity is the primary driver of the marine environment. However, the primary productivity and redox control mechanism still need to be clarified. Here, we present new organic carbon isotopes, total organic carbon contents, major elements, and trace and rare earth elements in drill‐core ZK107 from South China to reveal the continental chemical weathering, primary productivity, and redox control mechanism during the Earliest Cambrian (E‐C). Our studies have shown intense continental weathering, and primary productivity fluctuations that were supported by weathering (CIA, Rb/Al) and productivity (Babio, P) indicators. Additionally, the quantitative reconstructed productivity proxies (PP18, PP21, PP23) indicate a high primary productivity level in the E‐C ocean, surpassing that of the modern oceans. The strengthening of continental weathering mainly causes high primary productivity because it can alter the nutrient supply to the oceans. We suggest that changes in primary productivity closely associated with continental weathering are the leading cause of marine anoxia during the E‐C. This study establish a linkage between the land and marine system during the E‐C, confirming the terrestrial controls on the marine chemical changes and providing new insights into understanding the evolution of the Earth's surface changes during the Ediacaran – Cambrian transition.

Effect of different amino acid solutions on the oxidative stability of three different lipid emulsions in all-in-one admixtures.

Lipid peroxidation in parenteral nutrition mixtures is still a challenge. We aimed to evaluate the effect of two different amino acid solutions used in different clinical situations on lipid peroxidation of three different lipid emulsions (Intralipid, ClinOleic, and SMOFlipid) in all-in-one admixtures during 24 h of simulated infusion. The selected amino acid solutions included one used in stable patients and one used in renal insufficiency (Aminomel10E and Nephrotect, respectively). Eighteen all-in-one admixtures were prepared. The simulated infusion with light protection was conducted straight after the preparation for 24 h at room temperature. The lipid peroxidation process was evaluated in all-in-one admixtures and the original lipid emulsion by determining the malondialdehyde levels (high-performance liquid chromatography) and conjugated dienes and trienes (ultraviolet-visible spectrophotometry). Malondialdehyde in the original packaging was lower in SMOFlipid (9 µM) compared with Intralipid (27 µM, P = 0.0003) and ClinOleic (25 µM, P = 0.0001). During simulated infusion, ClinOleic showed a significantly lower rate of lipid peroxidation (26% decrease in aldehyde levels) in comparison with Intralipid and SMOFlipid (up to 39% and 31% increase in aldehyde levels, respectively) when the admixture was based on Aminomel10E. In admixtures based on Nephrotect, ClinOleic, and SMOFlipid showed better oxidative stability in comparison with Intralipid. Admixtures based on Nephrotect and Intralipid had higher levels of primary lipid peroxidation products than those based on ClinOleic (P = 0.030) or SMOFlipid (P = 0.071, not significant). Amino acid solutions influence the rate of lipid peroxidation. The observation should be confirmed in larger studies with different amino acid solutions.

Disposable e-cigarettes and cigarette butts alter the physiology of an aquatic plant Lemna minor (Lemnaceae)

Cigarette butts are one of the most littered single-use plastic items worldwide and can have ecotoxicological effects. e-Cigarettes (or ‘vapes’) have gained popularity globally as an alternative to tobacco-based cigarettes in recent years. The increased availability of disposable e-cigarettes has resulted in a rise in their littering, presenting a complex form of e-waste in the environment, yet the environmental impacts of littered e-cigarettes are largely unknown. Here Lemna minor (common duckweed) was used as a model organism to understand the effects of smoked cigarettes, vaped e-cigarettes or e-liquid. Growth-related physiological responses were measured (biomass, root development and frond chlorophyll content). After 14 days of exposure to cigarette butts there was an increase of all measured growth variables. On the contrary, exposure to e-cigarettes or e-liquid caused a decrease in root length, biomass and frond number relative to controls. The significant deviations from control conditions suggest that the presence of either cigarette butts, e-cigarettes or e-liquid caused stress to the model plant which could indicate disruption of aquatic ecosystems at the primary producer level. Disposable vapes pose a novel threat to aquatic ecosystems and it would be prudent to prevent them from becoming the next top litter item.

Sedimentary Mn Metallogenesis and Coupling among Major Geo-Environmental Events during the Sturtian Glacial–Interglacial Transition

The Sturtian (720–670 Ma) glacial–interglacial transition period was an important interval for sedimentary manganese metallogenesis, including the Mn oxide deposit in the Otjosondu region in Namibia and Mn carbonate deposits in the Datangpo Formation in the south-eastern Yangtze Platform, South China. During this period, Earth experienced the breakup of Rodinia, the Sturtian glaciation, and the Neoproterozoic oxygenation event. In this study, we investigate scenarios that might have provided geologically and geochemically favorable conditions for Mn metallogenesis. In these scenarios, the global recovery of microorganisms enhanced marine primary productivity and O2 levels of the hydrosphere and atmosphere during the Sturtian glacial–interglacial transition. However, the water column was not completely oxidized, maintaining redox stratification. Transgression–regression cycles or O2-rich downwelling drove the exchange of oxygenated topwater and anoxic deep water in rift-related basins that developed due to Rodinia’s breakup. The coupling of these processes precipitated existing dissolved Mn(II) at the margins of basins (Otjosondu region) or at their centers (Yangtze Platform). In the latter case, precursor Mn oxides were further converted into Mn carbonates via the reduction of Mn oxides coupled with organic matter oxidation during early diagenesis. A brief review of Mn metallogenesis in the geological record reveals that Mn metallogenic processes typically occur under geo-environmental conditions that, in concert, produce favorable conditions for Mn sourcing, concentration, and sedimentation.

Development of subsurface chlorophyll maximum layer and its contribution to the primary productivity of water column in a large subtropical reservoir

The phenomenon of subsurface chlorophyll maximum (SCM) layer emerging at a certain water depth is commonly found in stratified water bodies. Also, it is a crucial contributing region to the primary productivity of the water column. Currently, there is a lack of concern about the occurrence of SCM phenomena in studies targeting inland water bodies such as natural lakes and artificial reservoirs. This led to a significant underestimation of the level of primary productivity in these water bodies and their trophic state. In this study, a subtropical reservoir (the Xinanjiang Reservoir, XAJR) was investigated, to understand the characteristics of SCM layer in deep-large reservoir and its contribution to the primary productivity of the water column. Water sampling were conducted from September 2020 to August 2021, and in September 2022. Buoy station data for this reservoir between 2019 and 2021 were also collected. Based on the detailed observations of the water column profile in riverine area (X1), transitional area (X2), and central area (X3 and X4) of this reservoir, it was found that there was an obvious SCM phenomenon, which was closely related to the characteristics of seasonal thermal stratification. The SCM layer of XAJR appeared at depth around 3–5 m underwater from May to August, and as the thermal stratification strength increased, so did the depth and thickness of the SCM layer. It was estimated that gross primary productivity of euphotic layer of XAJR ranged from 347.9 to 4508.6 mgC·m−2·d−1. The average primary productivity level of the SCM layer reached 1411.7mgC·m−2·d−1, accounting for about 40–90% of the gross primary productivity of euphotic layer. This study contributes to a better understanding of the factors influencing changes in the development of the SCM layer in large reservoirs, as well as its critical role in the inland water carbon cycle.

Detection of Atypical Salmonella Infantis Phenotypes in Broiler Environmental Samples.

In numerous countries, strict and targeted measures concerning Salmonella monitoring and control are implemented and high quality of surveillance is ensured by obligatory investigation of samples from the primary production level of animals according to EN/ISO standards. Here, 2 phenotypic characteristics of Salmonella exhibited on compulsory media are crucial, namely, motility demonstrated on modified semisolid Rappaport Vassiliadis agar (MSRV), and production of hydrogen sulfide (H2S) on xylose lysine deoxycholate agar (XLD). In the present study, we describe the detection of Salmonella Infantis variants found in broiler environmental samples with major alterations in their growth characteristics on MSRV, XLD, and brilliant green-phenol red-agar (BPLS). The variants proved to be non-motile on MSRV and displayed non-confirming colony appearances on the previously mentioned selective agars. The growth spectrum comprised pinhead sized yellow colonies with small black centers, but also pinpoint sized colorless colonies, both colony types of regular shape. Our work contributes to highlight the finding of S. Infantis variants which possess more than one phenotypic deviation from the "typical" growth characteristics and by this limit the detection power of the actual obligatory used media. IMPORTANCE Salmonellosis caused by non-typhoidal Salmonella serovars is the second most frequently reported zoonotic disease in humans in the EU. The transmission of these agents is mainly via contaminated food of animal origin. In this context, poultry products are the main source of infection. Therefore, continuous and standardized surveillance of the prevalence of such Salmonella serovars at the primary production level is essential. Our findings show the phenotypic heterogeneity of the serovar Infantis and provide growth characteristics of atypical variants. Such variants pass unnoticed official screening methods, resulting in incorrect identification and being underrepresented in epidemiological surveillance programs.

Depositional conditions of siliceous microfossil-rich shale during the Ordovician–Silurian transition of south China: Implication for organic matter enrichment

Knowledge of the paleoenvironment is crucial to understand organic matter enrichment and shale gas development. Like organic matter, siliceous microfossils such as radiolarians and sponge spicules are widely distributed in Late Ordovician to early Silurian shales. However, there are few characterizations of the depositional conditions of siliceous microfossil-enriched layers. Here siliceous microfossil-rich shales from the Ordovician–Silurian transition in South China were selected for this study. We used major/trace element geochemistry to determine the sedimentary environment of siliceous microfossil-rich shale and to strengthen the understanding of the effect of siliceous microorganisms on organic matter enrichment. Our results show that most siliceous microfossils were deposited in anoxic reducing conditions with the presence of free hydrogen sulfide and accompanied by a moderately to weakly restricted seawater circulation. In addition, the nutrient-rich water bodies could upwell from the deep sea into the Yangtze Sea, and siliceous microfossil-rich shale was deposited during a period of high primary productivity. The shale layers of siliceous microfossils generally correspond to high gas-producing intervals and high organic matter abundance. The accumulation and preservation of organic matter in siliceous microfossil-rich shales is attributed to anoxic benthic conditions, high levels of primary productivity and flourishing of siliceous microorganisms. This study addresses the knowledge gap of the depositional conditions in siliceous microfossil-rich shale, and can help better understand the history of organic matter accumulation.

A comparison of Echium, fish, palm, soya, and linseed oil supplementation on pork quality.

Long chain n-3 polyunsaturated fatty acids (PUFA) exert positive effects on human health. The long chain n-3 PUFA of pork can be increased by adding fish oil to the diet. Due to the cost and availability of fish oil an alternative source must be found. This study evaluated the effect of five dietary oils on meat quality, fatty acid composition and lipid stability. The five diets contained 1% palm oil (Control), 1% soya oil, 1% linseed oil, 1% fish oil, and 1% Echium oil, respectively. The trial consisted of 60 gilts, randomly allocated to five groups. All color parameters, extractable fat content, fat free dry matter, and moisture content of the m. longissimus muscle were unaffected by dietary treatment. Consumers and a trained sensory panel could not detect a difference between the control samples and the Echium oil sample during sensory analysis. Samples containing higher levels of PUFA (soya, linseed, fish, and Echium oil) had higher levels of primary and secondary lipid oxidation products after refrigerated and frozen storage. However, these values were still well below the threshold value where off flavors can be detected. The Echium oil treatment had significantly higher levels of long chain PUFA than the linseed oil treatment, but it was still significantly lower than that of the fish oil treatment. Echium oil supplementation did not increase the levels of n-3 to the same extent as fish oil did. The result did however suggest that Echium oil can be used in pig diets to improve muscle long chain n-3 fatty acid content without any adverse effects on meat quality when compared to linseed, soya, and palm oil.

Evolutionary stasis during the Mesoproterozoic Columbia-Rodinia supercontinent transition

The transition between the supercontinents Columbia and Rodina coincided with a delay in eukaryote expansion during the Mesoproterozoic, however, the cause for this association is uncertain. Here, we use statistical geochemical analyses of igneous and fine-grained siliciclastic rocks to demonstrate that extensive crustal differentiation occurred during this transition interval. The results show a relative increase in abundance of phosphorus-poor felsic volcanic and plutonic rocks and a prevailing low weathering intensity between ∼ 1.8 and 1.2 Ga (billion years ago). The decelerated weathering of phosphorus-poor felsic volcanic and plutonic rocks could have maintained the low flux of bio-essential nutrients to the oceans that sustained low primary productivity and atmospheric O2 levels, which inhibited biologic radiation during the Columbia-Rodinia supercontinent transition period.

Trivial gain of downscaling in future projections of higher trophic levels in the Nordic and Barents Seas

AbstractDownscaling physical forcing from global climate models is both time consuming and labor demanding and can delay or limit the physical forcing available for regional marine ecosystem modelers. Earlier studies have shown that downscaled physics is necessary for capturing the dynamics of primary production and lower trophic levels; however, it is not clear how higher trophic levels respond to the coarse resolution physics of global models. Here, we apply the Nordic and Barents Seas Atlantis ecosystem model (NoBa) to study the consequences of using physical forcing from global climate models versus using that from regional models. The study is therefore (i) a comparison between a regional model and its driving global model to investigate the extent to which a global climate model can be used for regional ecosystem predictions and (ii) a study of the impact of future climate change in the Nordic and Barents Seas. We found that few higher trophic level species were affected by using forcing from a global versus a regional model, and there was a general agreement in future biomass trends and distribution patterns. However, the slight difference in temperature between the models dramatically impacted Northeast Arctic cod (Gadus morhua), which highlights how species projection uncertainty could arise from poor physical representation of the physical forcing, in addition to uncertainty in the ecosystem model parameterization.

Spatial insurance against a heatwave differs between trophic levels in experimental aquatic communities.

Climate change-related heatwaves are major threats to biodiversity and ecosystem functioning. However, our current understanding of the mechanisms governing community resistance to and recovery from extreme temperature events is still rudimentary. The spatial insurance hypothesis postulates that diverse regional species pools can buffer ecosystem functioning against local disturbances through the immigration of better-adapted taxa. Yet, experimental evidence for such predictions from multi-trophic communities and pulse-type disturbances, like heatwaves, is largely missing. We performed an experimental mesocosm study to test whether species dispersal from natural lakes prior to a simulated heatwave could increase the resistance and recovery of plankton communities. As the buffering effect of dispersal may differ among trophic groups, we independently manipulated the dispersal of organisms from lower (phytoplankton) and higher (zooplankton) trophic levels. The experimental heatwave suppressed total community biomass by having a strong negative effect on zooplankton biomass, probably due to a heat-induced increase in metabolic costs, resulting in weaker top-down control on phytoplankton. While zooplankton dispersal did not alleviate the negative heatwave effects on zooplankton biomass, phytoplankton dispersal enhanced biomass recovery at the level of primary producers, providing partial evidence for spatial insurance. The differential responses to dispersal may be linked to the much larger regional species pool of phytoplankton than of zooplankton. Our results suggest high recovery capacity of community biomass independent of dispersal. However, community composition and trophic structure remained altered due to the heatwave, implying longer-lasting changes in ecosystem functioning.

Partial intermediary value-chain coordination and its effects on productivity of sweet potato in Tanzania

This study investigates the effect of partial intermediary coordination on Tanzania sweet potato productivity. A cross-sectional research design was used, and a sample of 100 small-scale farmers from Kilosa and Gairo Districts were surveyed using both purposive and simple random sampling techniques. Data analysis tools included the Statistical Package for Social Sciences, Microsoft Excel and Ethnographic Content Analysis. Three key value chain actors primary, secondary, and tertiary were identified by the study, along with their roles and linkages. The majority of farmers identified three main factors that affected crop productivity in the research area: Lack of improved cultivars, restricted access to cash, and small parcels cultivated. Coordination between the horizontal and vertical chain is critical for productivity and efficiency. The study also discovered that weak institutional frameworks exist among key participants in value chain nodes. Farmers and buyers conducted the majority of their business on the spot, and all agreements were unwritten. Meanwhile, only 6% of respondents reported that extension officers had notified them of market price offers and demands from profitable markets. Growers are unable to use innovative production techniques that could lead to economies of scale in shared services and collaborative ventures because of current production practices. It was noticed that rather than raising production, the existing intermediate corporations have contributed to lowering transaction costs. Despite these challenges, there is a lot of potentials for the sweet potato crop to transform rural livelihoods and turn into a valuable commodity. Governance needs to be supported by policies that improve market information flow and necessary infrastructures. While intermediate organizations are essential for improving market connections and lowering transaction costs for dispersed smallholders, it is critical for increasing productivity at the primary production level. Last but not least, the local government should put into effect a strategy designed to promote a climate suitable to the crop. Key words: Partial, Productivity, Coordination, Sweet potatoes, Value-Chain, Smallholders, Actors, Farmers

Sector-level estimates for global future copper demand and the potential for resource efficiency

We evaluate the effectiveness of resource efficiency strategies for copper by quantifying the effect of technological and behavioral changes on primary copper demand. We assess multi-product sector-level estimates based on service needs under the Shared Socioeconomic Pathway 2 with Representative Concentration 2.6 W/m2 (SSP2-RCP2.6) in a baseline and eight different resource efficiency strategies. Our results show that final global copper demand will increase under the SSP2-RCP2.6 scenario from 24.3 Mt in 2015 to 44.4 Mt in 2050. Copper demand for vehicles and transportation infrastructure will quadruple. Improved scrap sorting and higher collection rates can decrease primary copper production (from copper ore) in 2050 by 2.3 and 2.2 Mt, respectively. The largest copper losses occur through hibernating stocks in the appliances sector. With ambitious material efficiency and demand-side sufficiency, it is possible to return to the primary copper production levels of 2020, despite growing service needs.

Oxidative Stress Reactions in Women of Reproductive Age with Metabolic Syndrome.

We analyzed the levels of LPO products and antioxidant defense components in women with the metabolic syndrome. Women with the metabolic syndrome had higher values of substrates with unsaturated double bonds and final TBA-reactive substances in comparison with the control group and higher levels of unsaturated double bonds, primary and end products of LPO, and retinol in comparison with the reference group (women with less than 3 signs of metabolic syndrome). No statistically significant differences between the groups were revealed while estimating the coefficient of oxidative stress; however, there was a tendency to an increase in the median value of this parameter in the group with metabolic syndrome. Thus, the results of the study indicate the activity of LPO reactions at different stages in women of reproductive age with the metabolic syndrome, which points to the necessity to evaluate and monitor the content of these metabolites in the patients of this cohort for the purpose of prevention and treatment.

Simulation and Key Physical Drivers of Primary Productivity in a Temperate Lake during the Ice-Covered Period: Based on the VGPM Model

The primary productivity of seasonal ice-covered water bodies is an important variable for understanding how temperate lake ecosystems are changing due to global warming. But there have been few studies on the complete change process of primary productivity during the ice-covered period, and the connection between ice physical and associated biological production has not been fully understood. In this study, a Vertically Generalized Production Model (VGPM) suitable for the ice-covered period was used to calculate the primary productivity of a temperate lake, and the key physical controlling factor was analyzed in the process of primary productivity change in the ice-covered period. The results showed that there was a high level of primary productivity, (189.1 ± 112.6) mg C·m−2·d−1, under the ice in the study site, Hanzhang Lake. The phytoplankton production under the ice was not as severely restricted by light as commonly thought. The water temperature played a more crucial role in the changes of primary productivity than the light beneath the ice. The study highlighted the variability in primary productivity covering the whole ice-covered age, and provided a better understanding of how the aquatic environment of lakes in seasonal ice-covered areas was affected by warmer temperatures.

Cetaceans in the Mediterranean Sea: Encounter Rate, Dominant Species, and Diversity Hotspots

We investigated the presence and diversity of cetaceans in the Mediterranean Sea, analysing the data collected by 32 different research units, over a period of 15 years (2004–2018), and shared on the common web-GIS platform named Intercet. We used the encounter rate, the species prevalence, and the Shannon diversity index as parameters for data analysis. The results show that cetacean diversity, in the context of the Mediterranean basin, is generally quite low when compared with the eastern Atlantic, as few species, namely the striped dolphin, the bottlenose dolphin, the fin whale, and the sperm whale, dominate over all the others. However, some areas, such as the Alboran Sea or the north-western Mediterranean Sea, which includes the Pelagos Sanctuary (the Specially Protected Area of Mediterranean Interest located in the northern portion of the western basin), show higher levels of diversity and should be considered hotspots to be preserved. Primary production and seabed profile seem to be the two main drivers influencing the presence and distribution of cetaceans, with the highest levels of diversity observed in areas characterized by high levels of primary production and high bathymetric variability and gradient. This collective work underlines the importance of data sharing to deepen our knowledge on marine fauna at the scale of the whole Mediterranean Sea and encourages greater efforts in the networking process, also to accomplish the requirements of the Marine Strategy Framework Directive, with particular reference to Descriptor 1: biological diversity is maintained.

Mapping amorphous SiO2 in Devonian shales and the possible link to marine productivity during incipient forest diversification

Silica cycling in the world’s oceans is not straightforward to evaluate on a geological time scale. With the rise of radiolarians and sponges from the early Cambrian onward, silica can have two depositional origins, continental weathering, and biogenic silica. It is critical to have a reliable method of differentiating amorphous silica and crystalline silica to truly understand biogeochemical and inorganic silica cycling. In this study, opal-A is mapped across the Western Canada Sedimentary Basin in the Late Devonian Duvernay Formation shales using longwave hyperspectral imaging alongside geochemical proxies that differentiate between crystalline and amorphous SiO2, during the expansion of the world’s early forests. Signaled by several carbon isotope excursions in the Frasnian, the punctata Event corresponds to the expansion of forests when vascular land plants develop seeds and deeper root networks, likely resulting in increased pedogenesis. Nutrients from thicker soil horizons entering the marine realm are linked to higher levels of primary productivity in oceans and subsequent oxygen starvation in deeper waters at this time. The results of this study reveal, for the first time, the spatial distribution of amorphous SiO2 across a sedimentary basin during this major shift in the terrestrial realm when forests expand and develop deeper root networks.

Diet of deep-sea holothurians in theVolcanologists Massif, Bering sea, as inferred from stable isotope and fatty acid analyses

Holothurians are one of the key components of the deep-sea megabenthos, often forming significant aggregations with high abundance and biomass. The crucial factors determining the pattern of their spatial distribution might be their food strategies, as well as the quantity and quality of available food. Using the set of trophic markers (analysis of fatty acid (FA) composition and stable nitrogen and carbon isotope signatures), we studied the trophic preferences of four common species of deep-sea holothurians (Paelopatides sp., Pannychia henrici, Psolidium sp., and Scotoplanes kurilensis) inhabiting the Volcanologists Massif, Bering Sea, at depths from 984 m to 3395 m. The δ13С values in tissues of all four species varied slightly (from −16.2 to −16.6‰) and were significantly higher than those in sediment organic matter (SOM) (on average, −21.5‰), which indicates the use of organic matter of the same origin by all species. The δ15N values (10.1–12.9‰) were also significantly higher than in SOM (on average, 4.4‰). The lowest average δ15N value was recorded for the deepest-dwelling species (Scotoplanes kurilensis), and the highest value from the shallowest-dwelling ones (Psolidium sp.). All the species differed significantly in FA composition. Psolidium sp. was distinguished by the highest saturated FA content (45.5%) and the lowest polyunsaturated FA (PUFA) content (18.7%). In the rest of the species, PUFAs dominated (>35%). The ratios of major PUFAs varied among the four species studied but all holothurians species were rich in phytoplankton derived FA suggesting tight trophic coupling to phytodetritus. However, for Psolidium sp., bacteria could constitute a substantial portion in the diet. The high level of 20:4n-6 might indicate a significant contribution of protozoans to the diet of Pannychia henrici. Paelopatides sp. and Scotoplanes kurilensis were characterized by a high level of 20:5n-3 and a high value of the 20:5n-3/20:4n-6 ratio, which indicates the predominance of fresh phytodetritus in their diet. The high level of primary production in the upper layers of the Bering Sea provides the high quality of the sedimentary OM and food supply of deposit feeders even at the greatest depths.

Using Single-Species and Whole Community Stream Mesocosm Exposures for Identifying Major Ion Effects in Doses Mimicking Resource Extraction Wastewaters.

Wastewaters and leachates from various inland resource extraction activities contain high ionic concentrations and differ in ionic composition, which complicates the understanding and effective management of their relative risks to stream ecosystems. To this end, we conducted a stream mesocosm dose-response experiment using two dosing recipes prepared from industrial salts. One recipe was designed to generally reflect the major ion composition of deep well brines (DWB) produced from gas wells (primarily Na+, Ca2+, and Cl-) and the other, the major ion composition of mountaintop mining (MTM) leachates from coal extraction operations (using salts dissociating to Ca2+, Mg2+, Na+, SO42- and HCO3-)-both sources being extensive in the Central Appalachians of the USA. The recipes were dosed at environmentally relevant nominal concentrations of total dissolved solids (TDS) spanning 100 to 2000 mg/L for 43 d under continuous flow-through conditions. The colonizing native algal periphyton and benthic invertebrates comprising the mesocosm ecology were assessed with response sensitivity distributions (RSDs) and hazard concentrations (HCs) at the taxa, community (as assemblages), and system (as primary and secondary production) levels. Single-species toxicity tests were run with the same recipes. Dosing the MTM recipe resulted in a significant loss of secondary production and invertebrate taxa assemblages that diverged from the control at all concentrations tested. Comparatively, intermediate doses of the DWB recipe had little consequence or increased secondary production (for emergence only) and had assemblages less different from the control. Only the highest dose of the DWB recipe had a negative impact on certain ecologies. The MTM recipe appeared more toxic, but overall, for both types of resource extraction wastewaters, the mesocosm responses suggested significant changes in stream ecology would not be expected for specific conductivity below 300 µS/cm, a published aquatic life benchmark suggested for the region.

ПРОГНОЗ ДИНАМИКИ ПЕРВИЧНОЙ ПРОДУКЦИИ ОРГАНИЧЕСКОГО ВЕЩЕСТВА И ЗАГРЯЗНЕНИЯ ПРИОРИТЕТНЫМИ ТОКСИКАНТАМИ АЗОВСКОГО МОРЯ НА КРАТКОСРОЧНУЮ ПЕРСПЕКТИВУ

Background. Modern climate changes and increasing anthropogenic water withdrawal in the Azov Sea river basins have led to a reduction in freshwater runoff and a record increase in the sea salinity. Relevance. Salinization of the Azov Sea leads to a transformation of the structure of biological communities and a decrease in primary productivity, which inevitably has a negative impact on fish productivity. Another important factor in the stock formation of aquatic biological resources is the quality of their habitat. Aim of this work is to make a short-term forecast of the hydrochemical foundation of biological productivity and toxicological status of the Azov Sea up to 2030. Methods. This study was based on the long-term data on the level of primary production, hydrochemical regime and accumulation of priority toxicants in the Azov Sea ecosystem. Results. In the present period, adaptation of the Azov Sea ecosystem to increasing water salinity is manifested in a decrease in the level of primary production. In recent years, during the summer season, an unfavorable physiological state of phytoplankton has been observed due to the high content of pheophytin in the cells. In the Azov Sea, from 1986 (the peak of industrial development and anthropogenic load) up to the present, in the water, bottom sediments and muscles of commercial fish species, has been observed a decrease in the average annual concentration of the majority of monitored toxicants. Conclusions. Under the most likely forecasted scenario for the river flow and water salinity (14.5–16.5 ‰), a further decrease in the level of primary production is expected. It is possible that the ecosystem will adapt to the increase in water salinity; phytoplankton will be characterized by a more favorable physiological state in the summer. No deficiency of biogenic elements is predicted. If the existing anthropogenic load remains unchanged (the most likely scenario), the level of sea pollution by anthropogenic toxicants is predicted to be low, and in certain areas—Taganrog Bay, the waters of the Yeysk and Temryuk Sea Ports—it is expected to be moderate. The quality and safety of aquatic biological resources as a food product will meet regulatory requirements.