Science of the Total Environment最新文献

Reservoir carbon emissions reflect greenhouse gases emitted by flooded land post-construction. However, pre-construction flooded land has been overlooked in previous assessments. Utilizing annual land cover data from 1990 to 2022 and pertinent parameters of cascade reservoirs in the Lancang River (LCR), we calculated the actual flooded areas of these reservoirs. Subsequently, the Tier1 model was employed to estimate the carbon emissions during the reservoir's life cycle and the annual carbon emissions from newly flooded land during construction. Our findings indicate that the LCR cascade reservoir's carbon emission throughout its life cycle is 4.324Tg CO_2eq (1.818-8.879Tg CO_2eq). When compared with previous results, our estimated figures (0.496-2.106 g CO_2eq/(kw·h)) fall below the global hydroelectric carbon footprint's average threshold range (IPCC: 4-14 g CO_2eq/(kW·h)). This implies that the previously estimated carbon emissions from the reservoir may be inflated due to the flooded land prior to reservoir construction. Notably, the nutrient state of the water body predominantly governs reservoir carbon emissions. This research sheds light on the intricacies of carbon emissions from cascade reservoirs and underscores the importance of accurately delineating reservoir boundaries and managing nutrient inputs to mitigate carbon emissions.

The spatial layout of the air quality monitoring network (AQMN) is crucial for objective, accurate, and comprehensive air quality assessment. The current technical standard specified the minimum quantity requirements for air quality monitoring sites, but there were no standards to specify the spatial of monitoring sites. This study proposed a novel framework to evaluate and optimize the spatial layout of AQMN. First, this study proposed three indicators to evaluate the performance of the current AQMN. They were monitoring area repetition rate, population coverage rate, and correlations. The assessment of AQMN in Beijing-Tianjin-Hebei and surroundings areas (BTHs) showed the overall monitoring area repetition rate and population coverage rate was 81.07 % and 35.5 %, respectively, which means the current AQMN in BTHs has very high monitoring repeatability and limited population coverage. Secondly, a large-scale linear programming model was built to optimize the spatial layout and determine the spatial location of 279 newly added monitoring sites in BTHs according to the Environmental Monitoring 14th Five-Year Plan of China. The optimization results showed that the optimized AQMN covered 97 million additional people, and the population coverage rate increased to 49.5 %. The proposed framework provided a valuable tool to evaluate and optimize AQMN and could be a potential solution for developing new technical standards of AQMN.

Human activities alter biomass, nutrient availability, and species dominance in grasslands, impacting their richness, composition, and biomass production. Stability (invariability in time or space) can inform the predictability of plant communities in response to human activities. However, this measure has been simplistically analyzed for temporal (interannual) changes in live biomass, disregarding their spatial stability and the temporal stability of other plant community attributes. Moreover, the simultaneous analysis of temporal and spatial stabilities of plant communities has been scarcely assessed. Here, we test how biomass removal and nutrient addition simultaneously modify the temporal and spatial stabilities of plant richness (α diversity), composition dissimilarity (β diversity), aboveground live biomass, and the role of plant species dominance in the stability responses. We conducted a factorial experiment of biomass removal (grazing, mowing, or intact -no removal-) and nutrient addition (unfertilized or fertilized with nitrogen, phosphorus, and potassium) in a temperate grassland of Argentina, South America. We replicated the experiment in 6 blocks over 10 years to estimate the temporal and spatial stabilities of the plant community. The spatiotemporal stability of plant richness and composition dissimilarity decreased in the intact grassland, while the temporal stability of live biomass increased, compared to the grazed and mowed grasslands. Nutrient addition reduced the spatiotemporal stability of live biomass and the spatial stability of plant richness. The stabilities of species richness as well as that of composition dissimilarity were negatively associated with plant dominance, while the live biomass stability was not. Our results suggest that simplifying the effect of biomass removal and nutrient addition on grassland stability is not feasible, as plant diversity stability responses are not surrogates for biomass stability. The contrasting spatiotemporal stability responses of plant diversity and biomass represent a step forward in predicting human activities' impact over time and across space in temperate grasslands.

Despite extensive efforts to understand the photodegradation of phenolic contaminants of emerging concern (PhCECs) in aquatic systems, prediction methods, especially in waters containing effluent organic matter (EfOM), remain underdeveloped. This study introduces a prediction method for p-cresol, a representative PhCECs, based on correlations between EfOM optical parameters and p-cresol kinetic parameters. We examined p-cresol photodegradation in various EfOM samples, characterized by their optical properties, and used the reaction rate coefficient between EfOM and p-cresol, α_3EfOM⁎, to quantify and predict p-cresol degradation in different wastewater effluent samples. Results showed significant correlations between p-cresol's photodegradation rate constant (0.144 to 0.441 h^-1) and EfOM characteristics, with α_3EfOM⁎ values ranging from 4 × 10¹¹ to 10 × 10¹¹ M^-1 s^-1. The method was validated with p-cresol at concentrations ranging from 25 to 100 μM and multiple EfOM samples. The method's applicability was further evaluated using propranolol, a pharmaceutical contaminant of emerging concern, demonstrating its versatility for predicting the degradation behavior of other contaminants in different wastewater samples. The method accurately predicted p-cresol and propranolol degradation across diverse wastewater samples, suggesting its potential for expansion to other classes of contaminants, aiding in water quality management, improving wastewater treatment processes, and enhancing environmental risk assessments.

Iron (Fe) oxides in wetland soils are crucial for stabilizing soil organic carbon (SOC) by forming stable Fe-OC complexes, thus protecting SOC from microbial breakdown and aiding its preservation. This study delves into the response of Fe (hydr-)oxides to salt stress, a relatively unexplored area, by examining Kandelia obovata, a key mangrove species. Through controlled climate chamber experiments, we investigated how salt stress affects the interactions between Fe (hydr-)oxides and SOC in root exudates (REs) and rhizosphere soils. Our results demonstrate that salinity at 30 ppt significantly increases the release of sugars, amino acids, inorganic nutrients (NH₄⁺, NO₃^-), and phosphorus in K. obovata's REs, while reducing crystalline and amorphous Fe (hydr-)oxides and increasing complexed Fe (hydr-)oxide levels, thereby reducing their crystallinity in rhizosphere soils. Importantly, at elevated salinity (30 ppt), the Fe-OC bond in the rhizosphere shows greater stability, indicating enhanced resilience to salt stress compared to bulk soil. Salt stress also raises the carbon to nitrogen (C/N) ratio in REs. Testing artificial REs (AREs) with different C/N ratios showed that Fe (hydr-)oxide content decreases at C/N ratios of 10 and 30 compared to the control, whereas Fe-OC content increases with higher C/N ratios. Introduction of AREs with a C/N ratio of 20 significantly affected rhizosphere crystalline Fe (hydr-)oxide and Fe-OC content, highlighting AREs' impact on the binding of Fe (hydr-) oxides and OC. The presence of soil microorganisms was critical for the binding of Fe (hydr-) oxides and OC, as sterilized soil exhibited significantly lower levels of Fe (hydr-) oxides and Fe-OC compared to unsterilized soil. This research reveals that under salt stress, mangrove plants play a crucial role in stabilizing rhizosphere SOC by influencing Fe (hydr-) oxide crystallinity and promoting the formation of stable Fe-OC complexes, highlighting the complex interactions between plant REs, salt stress, and soil minerals.

Ligand-specific binding interactions of xenobiotics with receptor proteins form the basis of cytotoxicity-based hazard assessment. Computational approaches enable predictive hazard assessment for a large number of chemicals in a high-throughput manner, minimizing the use of animal testing. However, in silico models for predicting mechanisms of toxic actions and potencies are difficult to develop because toxicity datasets or comprehensive understanding of the complicated kinetic process of ligand-receptor interactions are needed for model development. In this study, a directional reactive binding factor (DRBF) model based on first principles was used to predict cytotoxicity potencies of agonists of the aryl hydrocarbon receptor (AhR) for 16 different polycyclic aromatic hydrocarbons (PAHs). Molecular dynamics were simulated by accounting for the directional configuration factor toward receptor protein and the factor of binding to the Per-Arnt-Sim (PAS) domain. When comparing the experimental results of toxic potencies from in vitro bioassays with the predictions among two different in silico models, including quantitative structure-activity relationship (QSAR) and molecular docking models, the DRBF model exhibited the highest model performance (R² = 0.90 and p < 0.01). Our results showed that the DRBF model based on first principles and molecular and computational structural biology could serve as a novel framework to advance next generation hazard assessment for high-throughput screening of chemical substances.

Constructed wetlands (CWs) have been proven to effectively remove antibiotic resistance genes (ARGs) at different experimental scales; however, there is still a lack of researches on the removal and monitoring of ARGs during the actual operation of full-scale CWs. To fill this gap, this study selected the Annan constructed wetland in Beijing as a case study and utilized quantitative sequencing, metagenomic analysis, and other technical methods to determine characteristics of ARGs in CWs during different operating periods. Furthermore, we analysed the overall removal characteristics of ARGs in the CW during different operating periods and differences of ARG distribution in three media. The dominant ARGs in the CW were quinolone, β-lactam and tetracycline, with subtypes of tufA and fusA. ARG distributions are significantly influenced by anthropic activities and seasonal changes. Three periods of the CW had good removal effects on special ARGs, but there were differences in the removal characteristics of different types and subtypes of ARGs. The CW had removal effects on four types of ARGs (such as multidrugs), 16 types of fusidic acid, and nine types of ARGs (such as bleomycin) during the dormancy, start-up, and operation periods, respectively. Among ARG subtypes, the CW had removal effects on 37, 53, and 51 subtypes during the dormancy, start-up, and operation periods, respectively. The subtypes that were removed mainly included those containing tetracycline, efflux pump, and β-lactam, mcr-1, and mcr-5 (colistin ARGs). For individual parts of CWs, the removal effects on the total abundance of ARGs were as follows: forebay > surface flow wetland > subsurface flow wetland. These findings provide insights for optimizing the purification efficiency of CWs for ARGs.

Urban greenspace soils can store equal amount of carbon, or even more, compared to agricultural and forest soils, and play an important role in carbon sequestration. Despite its importance, the patterns and drivers of the priming effect-a key and complex process in soil organic matter decomposition-in urban ecosystems remain poorly understood. Here, we sampled soils in urban lawns, suburban lawns, and forests, and conducted a 30-day microcosm incubation with ¹³C-labelled glucose and nitrogen additions to explore whether and how the intensity of soil organic matter priming effect differs between urbanized and forest ecosystems. We found that lawn soils in urban (7.01 mg C g^-1 SOC) and suburban (5.86) areas had a significantly higher intensity of priming effect than forest soils (1.34), with further enhancement observed in urban lawn soils through simulated nitrogen deposition. Moreover, the alpha diversity of soil bacteria and fungi was found to play a crucial role in modulating the priming effect, exhibiting a positive correlation with its intensity. These findings advance our understanding of the potential mechanisms behind the soil priming effect in urban greenspaces, providing crucial insights for predicting soil carbon stocks and environmental impacts of urban development.

Tris (1-chloro-2-propyl) phosphoric acid (TCPP), a widely used organophosphate flame retardant, has been detected in various aquatic environments due to its extensive industrial application. TCPP is well-known to negatively impact large aquatic organisms. However, the effects of TCPP on zooplankton remain poorly understood. This study explored the ecological risk of TCPP in low-trophic marine organisms by evaluating the marine rotifer Brachionus plicatilis at the molecular, biochemical, individual, and population levels after exposure to TCPP concentrations of 14.79, 44.37, and 73.94 μM. Results showed that exposure to TCPP inhibited body size, feeding behavior, life expectancy, generation time, net reproductive rate, reproduction rate, and population growth rate of rotifers, thus impairing their growth, survival, reproduction, and population expansion. Environmental concentrations surpassing 0.031 μM and 0.23 μM adversely impact rotifer reproduction and survival, respectively. Biochemically, TCPP induced oxidative stress, increased amylase activity, decreased lipase activity, and total protein content. Transcriptome analysis revealed that TCPP could induce abnormal mitochondrial function, impaired energy metabolism, programmed cell death by generating excessive reactive oxygen species, and affect cellular DNA replication. Results indicate that TCPP disrupts homeostasis in rotifers by inducing oxidative stress, significantly suppressing individual and population parameters. These findings provide critical insights for assessing the ecological risk posed by TCPP to zooplankton and the stability of aquatic ecosystems.

Fluvial ecosystems are among the main drivers of microparticles (MPC) in the form of both synthetic polymers (i.e. microplastics; MPs) and natural-based textile fibers (MF_TEX) to the seas. A wide dimensional range of MPC (5 to 5000 μm, hereafter MPC_TOT) were investigated for the first time in the Arno River waters, one of the principal rivers of Central Italy, crossing a highly anthropized landscape. Fluxes of MPC_TOT discharging to the Mediterranean Sea, one the most polluted Sea worldwide, were estimated as well. A specific sampling and analytical protocol was set up to distinguish between microplastics (MPs) and natural-based textile fibers (MF_TEX) contribution for MPC larger than 60 μm (MPC_>60), and investigate MPC smaller than 60 μm (MPC_<60) as well. Results suggest extreme MPC_TOT contamination all along the river (up to 6 × 10⁴ particles/L), strongly driven by MPC_<60, which account for >99 % of total particles found and whose abundance increases inversely with particle size. The MPC_>60 fraction (<0.5 % of MPC_TOT) highlighted a predominance (76 % of the total) of MF_TEX and synthetic polymers microfibers (e.g., PET) suggesting strong contributions from laundry effluents. Specifically, MF_TEX represent around 70 % of all MPC_>60. The metropolitan area of Florence was identified as an MPC_TOT hotspot as a consequence of the intense urbanization and possibly of over-tourism phenomenon affecting the city. The Arno River discharges approximately 4.6 × 10¹⁵ MPC_TOT annually to the Mediterranean Sea. Fluxes are highly dependent on the seasonality, with a MPC_TOT delivery of 2.4 × 10¹³ particles/day and 1.2 × 10¹² particles/day during wet and dry season, respectively. The total mass of discharged MPC_TOT is estimated at about 29 tons/year (t/y); the MPC_>60 fraction amounts to about 8 t/y, and MF_TEX to about 1 t/y.