Search Results (686)

Winery wastewater (WWW), if released untreated, poses a serious environmental threat due to its high organic load. In this study, Chlorella vulgaris was cultivated in diluted WWW to assess its suitability as a culture medium. Two outdoor cultivation systems—a 270 L raceway and a 40 L bubble column—were operated over 33 days using synthetic medium (control) and WWW. A flow cytometry (FC) protocol was implemented to monitor key physiological parameters in near-real time, including cell concentration, membrane integrity, chlorophyll content, cell size, and internal complexity. At the end of cultivation, the bubble column yielded the highest cell concentrations: 2.85 × 10⁶ cells/mL (control) and 2.30 × 10⁶ cells/mL (WWW), though with lower proportions of intact cells (25% and 31%, respectively). Raceway cultures showed lower cell concentrations: 1.64 × 10⁶ (control) and 1.54 × 10⁶ cells/mL (WWW), but higher membrane integrity (76% and 36% for control and WWW cultures, respectively). On average, cells grown in the bubble column had a 22% larger radius than those in the raceway, favouring sedimentation. Heterotrophic cells were more abundant in WWW cultures, due to the presence of organic carbon, indicating its potential for use as animal feed. This study demonstrates that FC is a powerful, real-time tool for monitoring microalgae physiology and optimising cultivation in complex effluents like WWW. Full article

This study analyzes the lacustrine hydrocarbon source rocks of the Lower Cretaceous in the Erdengsumu sag of the Erlian Basin, evaluating their characteristics and identifying areas with oil resource potential, while also investigating the ancient lake environment, material source input, and controlling factors, ultimately developing a sedimentary model for lacustrine hydrocarbon source rocks. The findings suggest the following: (1) The lower Tengger Member (K₁bt₁) and the Aershan Formation (K₁ba) are the primary oil-producing strata, with an effective hydrocarbon source rock exhibiting a lower limit of total organic carbon (TOC) at 0.95%. The Ro value typically remains below 0.8%, indicating that high-maturity oil production has not yet been attained. (2) The oil generation threshold depths for the Dalestai and Sayinhutuge sub-sags are 1500 m and 1214 m, respectively. The thickness of the effective hydrocarbon source rock surpasses 200 m, covering areas of 42.48 km² and 88.71 km², respectively. The cumulative hydrocarbon generation intensity of wells Y1 and Y2 is 486 × 10⁴ t/km² and 26 × 10⁴ t/km², respectively, suggesting that the Dalestai sub-sag possesses considerable petroleum potential. The Aershan Formation in the Chagantala sub-sag has a maximum burial depth of merely 1800 m, insufficient to attain the oil generation threshold depth. (3) The research area’s productive hydrocarbon source rocks consist of organic matter types I and II₁. The Pr/Ph range is extensive (0.33–2.07), signifying a reducing to slightly oxidizing sedimentary environment. This aligns with the attributes of small fault lake basins, characterized by shallow water and robust hydrodynamics. (4) The low ratio of ∑nC₂₁₋/∑nC₂₂₊ (0.36–0.81), high CPI values (>1.49), and high C₂₉ sterane concentration suggest a substantial terrestrial contribution, with negligible input from aquatic algae–bacterial organic matter. Moreover, as sedimentation duration extends, the contribution from higher plants progressively increases. (5) The ratio of the width of the deep depression zone to the width of the depression in the Erdengsumu sag is less than 0.25. The boundary fault scale is small, its activity is low, and there is not much input from the ground. Most of the source rocks are in the reducing sedimentary environment of the near-lying gently sloping zone. Full article

The presence of lead (Pb) and cadmium (Cd) can have considerable effects on the environment and on humans. The present study examines their levels in two lakes with different trophic levels located in northwestern Poland; their concentrations were determined in water and the bottom sediments, in common reed and in the organs of pike, bream and roach. The work also evaluates Pb and Cd bioavailability in bottom sediments, their potential for biomagnification, their bioaccumulation in the food chain and risk to human consumers. Metal concentrations were determined by graphite furnace atomic absorption spectrometry (GFAAS). The geochemical fractions of the metals were isolated by sequential extraction. Both Pb and Cd demonstrated low bioavailability, with the carbonate fraction playing a key role in their bioconversion. The concentrations of Pb and Cd in some organs and tissue types of fish and reeds correlated with their levels in water and sediments. No biomagnification was observed between the studied fish species. Calculations based on BMDL, TWI and THQ concentrations found Pb and Cd levels in the edible parts of fish to be within permissible limits and not to pose any threat to consumer health. Full article

The growing mismatch between ecosystem service (ES) supply and demand underscores the importance of thoroughly understanding their spatiotemporal patterns and key drivers to promote ecological civilization and sustainable development at the regional level in China. This study investigates six key ES indicators across mainland China—habitat quality (HQ), carbon sequestration (CS), water yield (WY), sediment delivery ratio (SDR), food production (FP), and nutrient delivery ratio (NDR)—by integrating a suite of analytical approaches. These include a spatiotemporal analysis of trade-offs and synergies in supply, demand, and their ratios; self-organizing maps (SOM) for bundle identification; and interpretable machine learning models. While prior research studies have typically examined ES at a single spatial scale, focusing on supply-side bundles or associated drivers, they have often overlooked demand dynamics and cross-scale interactions. In contrast, this study integrates SOM and SHAP-based machine learning into a dual-scale framework (grid and city levels), enabling more precise identification of scale-dependent drivers and a deeper understanding of the complex interrelationships between ES supply, demand, and their spatial mismatches. The results reveal pronounced spatiotemporal heterogeneity in ES supply and demand at both grid and city scales. Overall, the supply services display a spatial pattern of higher values in the east and south, and lower values in the west and north. High-value areas for multiple demand services are concentrated in the densely populated eastern regions. The grid scale better captures spatial clustering, enhancing the detection of trade-offs and synergies. For instance, the correlation between HQ and NDR supply increased from 0.62 (grid scale) to 0.92 (city scale), while the correlation between HQ and SDR demand decreased from −0.03 to −0.58, indicating that upscaling may highlight broader synergistic or conflicting trends missed at finer resolutions. In the spatiotemporal interaction network of supply–demand ratios, CS, WY, FP, and NDR persistently show low values (below −0.5) in western and northern regions, indicating ongoing mismatches and uneven development. Driver analysis demonstrates scale-dependent effects: at the grid scale, HQ and FP are predominantly influenced by socioeconomic factors, SDR and WY by ecological variables, and CS and NDR by climatic conditions. At the city level, socioeconomic drivers dominate most services. Based on these findings, nine distinct supply–demand bundles were identified at both scales. The largest bundle at the grid scale (B3) occupies 29.1% of the study area, while the largest city-scale bundle (B8) covers 26.5%. This study deepens the understanding of trade-offs, synergies, and driving mechanisms of ecosystem services across multiple spatial scales; reveals scale-sensitive patterns of spatial mismatch; and provides scientific support for tiered ecological compensation, integrated regional planning, and sustainable development strategies. Full article

The Jurassic Tamulangou Formation in the Hongqi Depression has favorable hydrocarbon generation conditions and great resource potential. This study systematically analyzes the geochemical characteristics and thermal evolution history of the source rocks using data from multiple key wells. The dark mudstone of the Tamulangou Formation has a thickness ranging from 50 to 200 m, with an average total organic carbon (TOC) content of 0.14–2.91%, an average chloroform bitumen “A” content of 0.168%, and an average hydrocarbon generation potential of 0.13–3.71 mg/g. The organic matter is primarily Type II and Type III kerogen, with an average vitrinite reflectance of 0.71–1.36%, indicating that the source rocks have generally reached the mature hydrocarbon generation stage and are classified as medium-quality source rocks. Thermal history simulation results show that the source rocks have undergone two major thermal evolution stages: a rapid heating phase from the Late Jurassic to Early Cretaceous and a slow cooling phase from the Late Cretaceous to the present. There are differences in the thermal evolution history of different parts of the Hongqi Depression. In the southern part, the Tamulangou Formation entered the hydrocarbon generation threshold at 138 Ma, reached the hydrocarbon generation peak at approximately 119 Ma, and is currently in a highly mature hydrocarbon generation stage. In contrast, the central part entered the hydrocarbon generation threshold at 128 Ma, reached a moderately mature stage around 74 Ma, and has remained at this stage to the present. Thermal history simulations indicate that the Hongqi Depression reached its maximum paleotemperature at 100 Ma in the Late Early Cretaceous. The temperature evolution pattern is characterized by an initial increase followed by a gradual decrease. During the Late Jurassic to Early Cretaceous, the Hongqi Depression experienced significant fault-controlled subsidence and sedimentation, with a maximum sedimentation rate of 340 m/Ma, accompanied by intense volcanic activity that created a high-temperature geothermal gradient of 40–65 °C/km, with paleotemperatures exceeding 140 °C and a heating rate of 1.38–2.02 °C/Ma. This thermal background is consistent with the relatively high thermal regime observed in northern Chinese basins during the Late Early Cretaceous. Subsequently, the basin underwent uplift and cooling, reducing subsidence and gradually lowering formation temperatures. Full article

Potamogeton crispus (P. crispus), with strong nitrogen uptake capacity, plays an important ecological role during winter and early spring when most aquatic plants are inactive. Its presence can also influence microbial denitrification in sediments by regulating oxygen levels and organic carbon availability. In this study, an indoor hydroponic simulation system was used to systematically evaluate the effects of P. crispus under different nitrogen-loading conditions on nitrogen removal from water, changes in sediment carbon and nitrogen fractions, microbial community structure, and greenhouse gas fluxes. The results showed that P. crispus effectively removed TN, NH₄⁺-N, NO₃⁻-N, and NO₂⁻-N, maintaining strong denitrification capacity even under high-nitrogen loading. Under all nitrogen conditions, TN removal exceeded 80%, while NH₄⁺-N and NO₃⁻-N removal efficiencies surpassed 90%, with effective suppression of NO₂⁻-N accumulation. Rhizosphere-mediated regulation by P. crispus enhanced the transformation and stabilization of DOC and NO₃⁻-N in sediments, while also mitigating nitrogen-induced disturbances to carbon–nitrogen balance. The plant also exhibited strong CO₂ uptake capacity, low CH₄ emissions with a slight increase under higher nitrogen loading, and N₂O fluxes that were significantly affected by nitrogen levels—showing negative values under low nitrogen and sharp increases under high-nitrogen conditions. Correlation analyses indicated that CO₂ and N₂O emissions were mainly regulated by microbial taxa involved in carbon and nitrogen transformation, while CH₄ emissions were primarily driven by methanogenic archaea and showed weaker correlations with environmental factors. These findings highlight the importance of water restoration during low-temperature seasons and provide a theoretical basis for integrated wetland management strategies aimed at coordinated pollution reduction and carbon mitigation. Full article

Pyrite-based autotrophic denitrification is an effective method for nitrate removal. However, pyrite does not exist alone and is inevitably accompanied by the presence of organic matter in nature, and thus the influence of organic co-substrates on pyrite-based denitrification should be taken into consideration. Even in a circumstance where no addition of an exogenous organic carbon source is implemented, the introduction of pyrite into groundwater and sediment is capable of stimulating both autotrophic and heterotrophic denitrifying bacteria. In this study, the impact of the initial addition of organic co-substrates on the performance and dynamics of bacterial communities in pyrite-based denitrification processes was evaluated under low-concentration conditions. The findings suggest that the initial addition of organic co-substrates at low concentrations (6–48 mg L⁻¹) could enhance the efficiency of pyrite-based autotrophic denitrification. In contrast, the competitive effects of organic co-substrates became positive with increasing additions of initial organic co-substrates. When an organic co-substrate was added at an initial concentration of 96 mg L⁻¹, the competition between heterotrophic denitrification and pyrite-based autotrophic denitrification was found to be more pronounced than their promotion role as the majority of nitrate was consumed by heterotrophic denitrification. Thiobacillus was the most dominant bacterium in the denitrification system, where pyrite served as the sole electron donor. At the same time, the addition of organic co-substrate under low initial concentration, led to a different microorganism composition. Full article

Radionuclides and heavy metals pose potential risks to marine ecosystems and human health. Daya Bay, the site of China’s first commercial nuclear power plant, has experienced significant anthropogenic impacts, yet the extent of radionuclide and heavy metal contamination remains unclear. Nineteen surface sediment samples were collected in January 2024 and analyzed for natural (²¹⁰Pb, ²²⁸Th, ²²⁶Ra, ²²⁸Ra, and ⁴⁰K) and anthropogenic (¹³⁷Cs) radionuclides, heavy metals (Cu, Pb, Zn, Cd, Cr, Mn, Hg, and As), grain size, and total organic carbon (TOC). The surface sediments of Daya Bay were predominantly fine-grained, with TOC levels ranging from 0.41% to 1.83%, influenced significantly by riverine input from the Dan’ao River. Natural radionuclides exhibited distinct spatial patterns: ²¹⁰Pb and ²²⁸Th activity levels were higher in fine-grained sediments, and correlated with TOC, indicating adsorption and sedimentation controls. In contrast, anthropogenic ¹³⁷Cs activity was low and showed no significant impact from the nuclear power plant. Notably, the absence in the samples of key anthropogenic radionuclides typically associated with nuclear power plant operations further confirmed the negligible impact of the power plant on local sediment contamination. The results indicated that the baseline levels of both natural and anthropogenic radionuclides and heavy metals were predominantly influenced by natural processes and local anthropogenic activities rather than the operation of the nuclear power plant. This study establishes critical baselines for radioactivity and heavy metals in Daya Bay, underscoring effective pollution control measures and the resilience of local ecosystems despite anthropogenic pressures. Full article

Lake eutrophication, often driving harmful algal blooms (HABs) and ecosystem degradation, involves complex biogeochemical shifts within sediments. Changes in the sedimentary dissolved organic matter (DOM) composition during transitions from macrophyte to algal dominance are thought to critically regulate internal phosphorus (P) loading, yet the underlying mechanisms, especially in vulnerable plateau lakes like Qilu Lake, require further elucidation. This study investigated the coupled cycling of carbon (C) and P in response to historical ecosystem succession and anthropogenic activities using a 0–24 cm sediment core from Qilu Lake. We analyzed the total organic carbon (TOC), total phosphorus (TP), sequential P fractions, and DOM fluorescence characteristics (EEM-PARAFAC), integrated with chronological series data. The results revealed an asynchronous vertical distribution of TOC and TP, reflecting the shift from a submerged macrophyte-dominated, oligotrophic state (pre-1980s; high TOC, low TP, stable Ca-P dominance) to an algae-dominated, eutrophic state. The eutrophication period (~1980s–2010s) showed high TP accumulation (Ca-P and NaOH85 °C-P enrichment), despite a relatively low TOC (due to rapid mineralization), while recent surface sediments (post-2010s) exhibited a high TOC, but a lower TP following input controls. Concurrently, the DOM composition shifted from microbial humic-like dominance (C1) in deeper sediments to protein-like dominance (C3) near the surface. This study demonstrates that the ecosystem shift significantly regulates P speciation and mobility by altering sedimentary DOM abundance and chemical characteristics (e.g., protein-like DOM correlating negatively with Ca-P), reinforcing a positive feedback mechanism that sustains internal P loading and potentially exacerbates HABs. DOM molecular characteristics emerged as a key factor controlling the internal P cycle in Qilu Lake, providing critical insights for managing eutrophication in plateau lakes. Full article

Lakes are important sinks for antibiotics as suspended particulate matters (SPMs) in lakes have become significant carriers of antibiotic adsorption and migration. The light and heavy fractions of SPM are involved in the process of suspension and sedimentation in the aqueous environment. Combined with the adsorption behaviors of antibiotics onto SPM, a basis for the risk of antibiotic migration in lakes will be provided. In this study, SPM from Lake Taihu was collected and grouped according to density as light fraction (LF) and heavy fraction (HF), with heavy fraction including loosely bound humus (WLH) and tightly bound humus (TH). Adsorption studies were carried out with three typical antibiotics: tetracycline hydrochloride (TC), norfloxacin (NOR), and trimethoprim (TMP). The adsorption processes of all particulate fractions towards antibiotics were fast, which is consistent with pseudo-second-order kinetics. The adsorption in the TC and NOR groups was much higher than that in the TMP group, which was mainly related to the properties of the antibiotics. The LF group was the special component with the fastest adsorption rate, the largest adsorption amount, and the lowest desorption ratio, regardless of antibiotics, which is related to the organic matter content and the rich-carbon-containing functional groups in the LF group, such as -C=O. These findings highlight the need for further attention to the high adsorptive transport effect of LF on antibiotics in lake ecosystems. Full article

Arid regions face multiple challenges such as population expansion, water scarcity, land degradation, and biodiversity reduction. Understanding temporal and spatial patterns of ecosystem service trade-offs and synergies is critical for sustainable development and effective ecosystem service management in arid regions under environmental stress. Taking the Tarim River Basin in China as an example, five ecosystem services (carbon sequestration, water yield, sediment delivery ratio, habitat quality, and food production) were studied at different scales in 1990, 2000, 2010, and 2020 in the inland arid region. Spearman correlation, geographical weighted regression, and self-organizing mapping were used to analyze the ecosystem service trade-offs and synergies. The results showed that the ecosystem services in the basin increased gradually; in particular, the water yield increased from 15.38 × 10⁹ m³ to 29.8 × 10 m³, and the food production increased from 11.03 × 10⁶ t to 29.26 × 10⁶ t. There was a significant positive correlation between carbon sequestration, water yield, and habitat quality, but a negative correlation between sediment delivery ratio and food production. The spatial distribution of trade-offs and synergies of ecosystem services varies in different years and on different scales. The area change in ecosystem service bundles at the pixel scale is relatively small, while the area change at the sub-basin scale is relatively large. This paper provides policy suggestions for the ecological management and sustainable development of the Tarim River Basin through the analysis of ecosystem service trade-offs and synergies. Full article

The aim of the conducted research was to assess the impact of gypsum deposit development on changes in the radiation levels of the abiotic components of the environment. For this purpose, a study of the radioactivity of water, bottom sediment, soil, gypsum and loam samples was performed. Ground-based studies of the distribution of the values of the ambient dose equivalent rate of gamma radiation and radon flux density were also carried out. It was shown that due to the high solubility of gypsum, the degree of karstification of the territory increases under the influence of meteoric waters, and as a result of the intensification of anthropogenic impact, the degree of chemical weathering of rocks increases. This leads to a coordinated change in not only the chemical but also the radiation conditions. In particular, radioactive contamination of quarry waters and areas of increased radon flux density in soil air were established. In bottom sediments, the significant correlations of ¹³⁷Cs, ²³⁸U and ²³⁴U activity concentrations with carbonates, organic matter and soluble salts contents, as well as Fe, Zn, Cu, Cr, Pb, Ni, Mo, Cd, Co, Ti and V, indicate a significant role of the anthropogenic factor in the accumulation in bottom sediments. This factor is associated with both regional atmospheric transport (¹³⁷Cs) and the activity of the mining enterprise in the study area (²³⁸U and ²³⁴U). Full article

Mangrove forests, vital coastal ecosystems that provide critical biodiversity habitats and carbon sequestration services, face increasing heavy metal pollution that threatens their ecological functions through bioaccumulation and toxicity to marine organisms. However, existing studies lack dynamic insights into temporal and spatial variations of heavy metals in mangrove sediments. This study systematically analyzed two mangrove reserves in Hainan Island, China (Hainan Dongzhaigang National Nature Reserve [DZG] and Hainan Qinglan Provincial Nature Reserve [QL]), by collecting sediment samples in 2014 and 2022, analyzing metals (Cr, Cu, Zn, As, Cd, and Pb) via ICP-MS, and applying the geo-accumulation index, potential ecological risk index, Markov transition matrix, and statistical analyses. Results showed that DZG exhibited rising Cu and Zn levels but declining Cr, As, Cd, and Pb, with Cd showing the most significant decrease (66.83%). In contrast, QL saw only a 42.7% reduction in Cd, while other heavy metals increased. Spatial heterogeneity linked higher concentrations to anthropogenic hotspots, DZG’s southeast (industrial/aquaculture inputs), and QL’s northwest (urban/industrial discharges). Although ecological risks were generally low, Cd in QL reached a moderate risk level (E_Cd = 46.44, 40 ≤ E_i < 80). The large-scale pond-to-mangrove conversion significantly increased vegetation cover, which enhanced sedimentation rates and exerted a “dilution effect” on sediment heavy metals. These findings underscore anthropogenic activities as the dominant driver of heavy metal contamination. We recommend (1) stringent wastewater control near QL, (2) enhanced shipping regulation, and (3) the establishment of mangrove buffers in heavy metal accumulation zones to improve ecological status. Full article

The third member of the Shahejie Formation (Es₃) in Dongying Sag is noteworthy for its abundance of laminated shale, considerable thickness, and high organic matter content, with carbonate interbeds playing a crucial role in reservoir properties. The salinity and pH of water influence the change of sedimentary environment and the mineral composition of sediment, thereby affecting the distribution characteristics of carbonate interbeds. Based on geochemical data from 8721 samples in the Dongying Sag, this study systematically analyzed the salinity and pH characteristics. This study is the first to develop an environmental zoning framework based on aqueous medium characteristics of aqueous media, and the favorable shale oil enrichment areas in Es₃ were identified by integrating carbonate mineral content analysis. The results showed that the lower part of Es₃ is dominated by a zone with high salinity–middle pH, and middle salinity–high pH with rich carbonate. Combining the development of carbonate interbeds, it is speculated that the sweet spots in Es₃ are high salinity–middle pH and middle salinity–high pH. The favorable areas are concentrated in the lower part of Es₃, including the western and northeastern parts of the Lijin Sub-Sag and the northern gentle slope of Guangrao. It provides a novel perspective on shale oil exploration through lacustrine environmental zonation. Full article

To address the critical challenges of wind erosion mitigation and sustainable soil management in the fragile agroecosystem of the black soil region in the foothills of the Daxing’anling Mountains, this study evaluated five tillage practices—conventional ridge tillage (CP), no tillage with straw removal (NT), no tillage with straw mulching (R+NT), autumn strip tillage with straw mulching (R+ST_A), and spring strip tillage with straw mulching (R+ST_S)—across two landforms: gently sloped uplands and flat depressions. The results demonstrated that R+ST_S achieved superior performance across both landscapes, exhibiting a 42.99% reduction in the wind erosion rate, a 48.88% decrease in soil sediment discharge, and a 52.26% reduction in the soil creep amount compared to CP. These improvements were mechanistically linked to the enhanced surface microtopography (aerodynamic roughness increased by 1.8–2.3 fold) and optimized straw coverage (68–72%). R+ST_S also enhanced the topsoil fertility, increasing the total nitrogen (TN), soil organic carbon (SOC), alkaline nitrogen (AN), available phosphorus (AP), and rapidly available potassium (AK) by 22.07%, 12.94%, 14.92%, 32.94%, and 9.52%, respectively. Furthermore, it improved maize emergence and its yield by 10.04% and 9.99% compared to R+NT. Mantel tests and SEM revealed strong negative correlations between erosion and nutrients, identifying nitrogen availability as the key yield driver. R+STS offers a sustainable strategy for erosion control and productivity improvement in the black soil region. Full article