Thermokarst landslide (TL) activity in the Qinghai-Tibet Plateau (QTP) is intensifying due to climate warminginduced permafrost degradation. However, the mechanisms driving landslide formation and evolution remain poorly understood. This study investigates the spatial distribution, annual frequency, and monthly dynamics of TLs along the Qinghai-Tibet engineering corridor (QTEC), in conjunction with in-situ temperature and rainfall observations, to elucidate the interplay between warming, permafrost degradation, and landslide activity. Through the analysis of high-resolution satellite imagery and field surveys, we identified 1298 landslides along the QTEC between 2016 and 2022, with an additional 386 landslides recorded in a typical landslide-prone subarea. In 2016, 621 new active-layer detachments (ALDs) were identified, 1.3 times the total historical record. This surge aligned with unprecedented mean annual and August temperatures. The ALDs emerged primarily between late August and early September, coinciding with maximum thaw depth. From 2016 to 2022, 97.8 % of these ALDs evolved into retrogressive thaw slumps (RTSs), identified as active landslides. Landslides typically occur in alpine meadows at moderate altitudes and on gentle northward slopes. The thick ice layer near the permafrost table serves as the material basis for ALD occurrence. Abnormally high temperature significantly increased the active layer thickness (ALT), resulting in melting of the ice layer and formation of a thawed interlayer, which was the direct causing factor for ALD. By altering the local material, micro-topography, and thermal conditions, ALD activity significantly increases RTS susceptibility. Understanding the mechanisms of ALD formation and evolution into RTS provides a theoretical foundation for infrastructure development and disaster mitigation in extreme environments.
Soil reinforcement using eco-friendly biopolymer and vegetation has been increasingly popular in geotechnical engineering. However, research is still in its early stages due to complex biochemical interactions between biopolymers and plants. Moreover, under the increasing climate change, extreme weather poses severe challenges to the effectiveness of biopolymer-vegetation on soil treatment. Therefore, this paper provides a comprehensive review and summary of recent research on the influence of biopolymer and biopolymervegetation interaction on soil properties. First, this paper evaluates the various hydraulic and mechanical properties of soils after biopolymer treatment, including compaction characteristics, Atterberg limits, unconfined compressive strength, shear strength, tensile strength, permeability, water holding capacity, slaking behavior, and erosion resistance, as well as the influence of climate change. Then, the application of biopolymer-vegetation measure in the current field of soil treatment is summarized, and the biopolymer-vegetation interaction is discussed, including the influence of biopolymers on plant germination rate, growth conditions, wilting rate, and other indicators. Under drought and water scarcity conditions, biopolymers can improve soil mechanical strength and water retention, reducing plant wilting rate, and enhancing the survival ability of plants under extreme climate changes. Appropriate biopolymers can increase soil strength by >50 %, reduce strength and mass losses from dry-wet cycles to within 10 %, enhance grass seed germination rates by over 60 %, and reduce wilting rates under drought stress by 80 %. Finally, the research gaps and deficiencies in this field are highlighted, and potential research hotspots that can be strengthened and studied in the future are proposed. This review demonstrates the biopolymer-vegetation measure to be a new ecological restoration technology with widespread application prospects.
As the use of biodegradable plastics becomes increasingly widespread, their environmental behaviors and impacts warrant attention. Unlike conventional plastics, their degradability predisposes them to fragment into microplastics (MPs) more readily. These MPs subsequently enter the terrestrial environment. The abundant functional groups of biodegradable MPs significantly affect their transport and interactions with other contaminants (e.g., organic contaminants and heavy metals). The intermediates and additives released from depolymerization of biodegradable MPs, as well as coexisting contaminants, induce alterations in soil ecosystems. These processes indicate that the impacts of biodegradable MPs on soil ecosystems might significantly diverge from conventional MPs. However, an exhaustive and timely comparison of the environmental behaviors and effects of biodegradable and conventional MPs within soil ecosystems remains scarce. To address this gap, the Web of Science database and bibliometric software were utilized to identify publications with keywords containing biodegradable MPs and soil. Moreover, this review comprehensively summarizes the transport behavior of biodegradable MPs, their role as contaminant carriers, and the potential risks they pose to soil physicochemical properties, nutrient cycling, biota, and CO2 emissions as compared with conventional MPs. Biodegradable MPs, due to their great transport and adsorption capacity, facilitate the mobility of coexisting contaminants, potentially inducing widespread soil and groundwater contamination. Additionally, these MPs and their depolymerization products can disrupt soil ecosystems by altering physicochemical properties, increasing microbial biomass, decreasing microbial diversity, inhibiting the development of plants and animals, and increasing CO2 emissions. Finally, some perspectives are proposed to outline future research directions. Overall, this study emphasizes the pronounced effects of biodegradable MPs on soil ecosystems relative to their conventional counterparts and contributes to the understanding and management of biodegradable plastic contamination within the terrestrial ecosystem.
Salinization is very detrimental to photosynthetic processes and plant growth, while nanoparticles (NPs) are considered to be the emerging materials to improve plant adaptability to salt stress. Cyclocarya paliurus is being planted on saline-alkali soils to meet the growing demand for its leaves and medicinal products. However, this species exhibits low salt tolerance and little information is available on whether NPs application would mitigate the salt-induced effects. This study explored the influence of three oxide NPs and their application doses on improving salt tolerance in C. paliurus under simulated natural conditions. The results showed that these oxide NPs could modify the salt tolerance in C. paliurus seedlings, but the alleviating effects varied in the NPs types and their application doses. Under the salt stress, foliar applications of SiO2-NPs with 500 mg L-1 and MnO2-NPs with 50 mg L-1 significantly increased net photosynthetic rate and seedling height by 52.0-59.5 %, and reduced the salt injury index by 67.6-70.7 %. Transcriptomic analysis revealed that the genes related to photosynthesis pathway were well responsive to both salt stress and NPs application, while the applications of high-dose SiO2- and MnO2-NPs up-regulated the expression of 50 photosynthesis-related genes. Weighted gene co-expression network analysis (WGCNA) indicated there existed a close relationship between physiological parameters and gene expression patterns, and the nine key genes in mitigating salt stress in C. paliurus were identified after the NPs application. Our findings suggested that the effects of NPs on mitigating salt-induced damages depending on the NP type and applied dose. The applications of SiO2-NPs and MnO2-NPs with an appropriate dose hold great promise for mitigating the salt-induced photosynthetic dysfunction via regulation of related key genes, and ultimately promoting plant growth and ameliorating the salt-tolerance.
Terrestrial enhanced rock weathering (ERW) is a promising carbon dioxide removal technology that consists in applying ground silicate rock such as basalt on agricultural soils. On top of carbon sequestration, ERW has the potential to raise the soil pH and release nutrients, thereby improving soil fertility. Despite these possible co-benefits, concerns such as heavy metal pollution or soil structure damage have also been raised. To our knowledge, these contrasted potential effects of ERW on soil fertility have not yet been simultaneously investigated. This field trial aimed at assessing the impact of ERW on biological, physical, and chemical soil properties in a temperate agricultural context. To do so, three vineyard fields in Switzerland were selected for their distinct geochemical properties and were amended with basaltic rock powder at a dose of 20 tons per hectare (2 kg.m(-2)). On each field, basaltic rock powder was either applied one year before the sampling campaign, one month before the sampling campaign, or not applied (control) for a total of 27 plots with 9 repetitions of each level. Overall, basaltic rock powder addition had a predominantly positive to neutral effect on soil fertility. Most soil properties showed no significant change either 1 month or 1 year post application. Nevertheless, our study highlighted a significant increase in earthworm abundance (+71 % on average), soil respiration (+50 %) and extractable sodium concentration (+23 %) as early as 1 month post application. The higher soil respiration raises the question of CO2 losses from organic matter mineralization that could limit ERW's efficiency. The increase in sodium raises concerns about a sodification risk potentially damaging soil fertility. These elements now require further investigation before enhanced rock weathering can be considered a viable and secure carbon dioxide removal technology.
The insufficient taking into account of groundwater as a basis for implementing protection measures for coastal wetlands can be related to the damage they are increasingly exposed to. The aim of this study is to demonstrate the pertinence of combining hydrogeological tools with assessment of pollutant fluxes and stable isotopes of O, H and N, as well as groundwater time-tracers to identify past and present pollution sources resulting from human activities and threatening shallow groundwater-dependent ecosystems. A survey combining physico-chemical parameters, major ions, environmental isotopes (O-18, H-2, N-15 and H-3), with emerging organic contaminants including pesticides and trace elements, associated with a land use analysis, was carried out in southern Italy, including groundwater, surface water and lagoon water samples. Results show pollution of the shallow groundwater and the connected lagoon from both agricultural and domestic sources. The N-isotopes highlight nitrate sources as coming from the soil and associated with the use of manure-type fertilizers related to the historical agricultural context of the area involving high-productivity olive groves. Analysis of EOCs has revealed the presence of 8 pesticides, half of which have been banned for two decades and two considered as pollutant legacies (atrazine and simazine), as well as 15 molecules, including pharmaceuticals and stimulants, identified in areas with human regular presence, including rapidly degradable compounds (caffeine and ibuprofen). Results show that agricultural pollution in the area is associated with the legacy of intensive olive growing in the past, highlighting the storage capacity of the aquifer, while domestic pollution is sporadic and associated with regular human presence without efficient modern sanitation systems. Moreover, results demonstrate the urgent need to consider groundwater as a vector of pollution to coastal ecosystems and the impact of pollutant legacies in planning management measures and policies, with the aim of achieving 'good ecological status' for waterbodies.
The accumulation of heavy metal in circulating TCMs has attracted widespread attention because the security and therapeutic efficacy are inevitably imperiled by the survival ecological environment and human production activities. How to reduce the pollution level and improve the toxicity damage becomes an urgent issue. This article provides a comprehensive overview of the current status of heavy metal contamination over a thousand types of single herbal (botanical, animal and mineral medicines) and TCM preparations published over nearly two decades. The survey revealed that growth ecosystems (soil, water sources), anthropogenic factors (harvesting, processing, storage), specific varieties and medicinal parts utilized as well as the inherent resistance capacity are the key factors that affect the accumulation of heavy metals in TCMs. And Pb, Cu and Cr are the major cumulative elements for botanicals, while mineral and animal medicines are dominated by As and Cu elements, respectively. Ongoing efforts aimed at mitigating the level and translocation rate of heavy metals by optimized cultivation processes, appropriate processing methodologies and advanced adsorption techniques are effective removal strategies. And the prospects of TCMs as a detoxifying agent for heavy metal toxicity damage posed development potential. Besides, the correlation between the speciation of arsenic (As) and chromium (Cr) and their toxicity should also be elaborated in order to provide effective references for standardizing drug dosage and cycle. And the imperative from the perspective of improving limitations standards of HMs for animal medicines, external preparations and folk medicines as well as exploring the interaction mechanisms between heavy metals and active ingredients of TCMs provides the direction for the follow-up study.
In heavy metal-contaminated areas, the simultaneous occurrence of increasing microplastic pollution and persistent acid rain poses a serious threat to food security. However, the mechanisms of combined exposure to microplastics (MP) and acid rain (AR) on the toxicity of cadmium (Cd) in rice seedlings remain unclear. Our study investigated the combined effects of exposure to polyvinyl chloride microplastics and AR (pH 4.0) on the toxicity of Cd (0.3, 3, and 10 mg/L) in rice seedlings. The results showed that at low Cd concentrations, the combined exposure had no significant effect, but at high Cd concentrations, it alleviated the effects of Cd stress. The combined application of MP and AR alleviated the inhibitory effects of Cd on seedling growth and chlorophyll content. Under high Cd concentrations (10 mg/L), the simultaneous addition of MP and AR significantly reduced the production of reactive oxygen species (ROS), the content of malondialdehyde (MDA), and the activity of the superoxide dismutase (SOD). Compared with AR or MP alone, the combination of MP and AR reduced root cell damage and Cd accumulation in rice seedlings. Transcriptomic analysis confirmed that under high Cd concentrations, the combination of MP and AR altered the expression levels of genes related to Cd transport, uptake, MAPK kinase, GSTs, MTs, and transcription factors, producing a synergistic effect on oxidative stress and glutathione metabolism. These results indicate that co-exposure to MP and AR affected the toxicity of Cd in rice seedlings and alleviated Cd toxicity under high Cd concentrations to some extent. These findings provide a theoretical basis for evaluating the toxicological effects of microplastic and acid rain pollution on crop growth in areas contaminated with heavy metals, and are important for safe agricultural production and ecological security.
Evapotranspiration (ET) is an important water budget term for understanding the recovery of stormwater retention in green roof systems (GRs). However, ET evaluations, particularly in full-scale GRs, remain challenging. This study investigated ET dynamics within a GR in the City of Pittsburgh, USA, using a water balance based on continuously monitored soil moisture from moisture sensors over 15 months. Results suggest under well-watered soil conditions, daily moisture loss correlated with solar radiation, temperature, and humidity, in decreasing order of correlation strength, while wind speed had limited effects. Compared to sensor-informed moisture loss (using moisture-based water balance), the Hargreaves and FAO-56 Penman-Monteith equations predicted cumulative ET that was 1.8 and 2.1 times higher, respectively. When soil moisture declined and approached the temporary wilting points, a noticeable reduction in daily moisture loss was observed. This suggests the necessity of using a water stress coefficient alongside a crop coefficient to represent actual ET based on FAO-56 Penman-Monteith estimates. Seasonal crop coefficients from dominant native plant species present at our monitored location, eastern bluestar (Amsonia tabernaemontana) and creeping woodsorrel (Oxalis corniculata), had mean values of 0.48, 0.62, and 0.65 for fall, spring, and summer, respectively. The impact of water stress on ET could be characterized by a linear relationship with moisture content. Our results highlight the importance of soil moisture in regulating ET processes and demonstrate the utility of soil moisture data for evaluating ET in GRs and informing irrigation practices.
Arctic fjords are hotspots of marine carbon burial, with diatoms playing an essential role in the biological carbon pump. Under the background of global warming, the proportion of diatoms in total phytoplankton communities has been declining in many high-latitude fjords due to increased turbidity and oligotrophication resulting from glacier melting. However, due to the habitat heterogeneity among Svalbard fjords, diatom responses to glacier melting are also expected to be complex, which will further lead to changes in the biological carbon pumping and carbon sequestration. To address the complexity, three short sediment cores were collected from three contrasting fjords in Svalbard (Krossfjorden, Kongsfjorden, Gronfjorden), recording the history of fjord changes in recent decades during significant glacier melting. The amino acid molecular indicators in cores K4 and KF1 suggested similar organic matter degradation states between these two sites. In contrast to the turbid Kongsfjorden and Gronfjorden, preserved fucoxanthin in Krossfjorden indicated a continuous increase in diatoms since the mid-1980s, corresponding to a 59 % increase in biological carbon pumping, as quantified by the delta C-13 of sedimentary organic carbon. The increasing biological carbon pumping in Krossfjorden is further attributed to its hard rock types in the glacier basin, compared to Kongsfjorden and Gronfjorden, which are instead covered by soft rocks, as confirmed by a one-dimensional model. Given the distribution of rock types among basins in Svalbard, we extrapolate our findings and propose that approximately one-fifth of Svalbard's fjords, especially those with hard rock basins and persistent marine-terminated glaciers, still have the potential for an increase in diatom fractions and efficient biological carbon pumping. Our findings reveal the complexity of fjord phytoplankton responses and biological carbon pumping to increasing glacier melting, and underscore the necessity of modifying Arctic marine carbon feedback to climate change based on results from fjords underlain by hard rocks.