Differences of soil carbon pools and crop growth across different typical agricultural fields in China: The role of geochemistry and climate change.

Carbon storage and the aboveground biomass of farmland provide practical significance for understanding global changes and ensuring food production and quality. Based on soil carbon storage, aboveground biomass, climate, geochemistry, and other data from 19 farmland ecological stations in China, we analysed the distribution characteristics of farmland carbon storage in topsoil and aboveground biomass. We notably revealed the response direction and degree of climate and geochemical factors to farmland carbon storage in topsoil and aboveground biomass. The results indicated that the average carbon stocks of farmland in different regions ranged from 0.28 to 7.91 kg m-2, the average fresh weight of the aboveground biomass (FAB) ranged from 1370.64 to 5997.28 g m-2, and the average dry weight of the aboveground biomass (DAB) ranged from 119.95 to 852.35 g m-2. The least angle regression (LARS) and the best subsection selection regression (BSS) showed that evapotranspiration and extreme low temperatures were significant climatic factors affecting carbon sequestration and aboveground biomass on long-time scales. The linear mixed-effects model (LMM) further showed that AN and AP had significant long-term effects on carbon sequestration and aboveground biomass (p < 0.05), with AN having the highest contribution to SOC%, FAB, and DAB. The structural equation model (SEM) showed that carbon sequestration and aboveground biomass in agricultural fields were significantly positively correlated (p < 0.05). Moreover, the climate had a less direct contribution to carbon sequestration and above-ground biomass compared to geochemistry (PCc < 0.1

Distribution characteristics and integrated ecological risks evaluation modelling of microplastics and heavy metals in geological high background soil.

The microplastics (MPs), a novel pollutant, and heavy metals (HMs) significantly affect soil ecology. The study investigated HMs and MPs in Qianxi's high geological background soil, established a model for risk evaluation with MPs types and shapes, and proposed a two-dimensional comprehensive index model for MPs-HMs combined pollution and risk evaluation criterion. The results revealed a high soil Cd concentration, with a mean value of 0.38 mg·kg-1. Additionally, soils from soybean-wheat intercropping-potato-corn rotation (SWI-PCR) exhibited significantly higher concentrations of Hg, As, and Pb compared with those from soybean-wheat intercropping-corn rotation (SWI-CR). Moreover, the soil exhibited a high abundance of MPs (8667.66 ± 3864.26 items·kg-1), mainly characterized by PS and fiber. The mean of adjusted ecological risk index (ARI) for MPs in soil was 525.27, indicating a grade 3 risk. The two-dimensional combined index (TPI) was used to assess the ecological risk of MPs-HMs combined pollution, exhibiting an exceedance rate of 56 % with a mean of 445.07. The risk level of the combined pollution was graded as 6, indicating high risk. The microplastic risk evaluation model and the comprehensive evaluation method of combined pollution established in this study provide a reference for the future risk evaluation of multi-pollutant combined pollution.

Effects of soil properties and land use patterns on the distribution of microplastics: A case study in southwest China.

Microplastic pollution in the soil environment is of great concern. However, the current research on microplastics (MPs) in Southwest China mainly focuses on their distribution characteristics and sources in soil, making the understanding of the soil properties and land use patterns influencing soil MPs insufficient. In this study, the abundance and distribution characteristics of MPs in the soil of different land use patterns in Guizhou Province were determined. The results revealed that the average abundance of MPs in soils was 2936 items/kg, ranging from 780 to 9420 items/kg. The MPs were mainly small particle size (0-0.5 mm), granular, and black, accounting for 87.5%, 36.6%, and 82.2%, respectively. The most common polymer types of MPs were polypropylene, polyethylene terephthalate, and polyethylene, which accounted for 20.4%, 16.8%, and 16.4%, respectively. As soil bulk density increased, microplastic abundance and small particle size decreased. Soil microplastic abundance slightly decreased with increasing soil porosity. The abundance of MPs increased with the increase in soil pH, but no significant correlation was observed between soil organic matter content and microplastic abundance. pH was the major factor that affected the microplastic distribution, which accounted for 32.5%. This study provides insight into the distribution and influencing factors of soil MPs and also provides a theoretical basis for subsequent research on soil microplastic pollution.

Evaluation of niche, diversity, and risks of microplastics in farmland soils of different rocky desertification areas.

The occurrence, sources, effects, and risks of microplastics (MPs) in farmland soils have attracted considerable attention. However, the pollution and ecological characteristics of MPs in farmland soils at different levels of rocky desertification remain unclear. We collected and analyzed farmland soil samples from rocky desertification areas in Guizhou, China, ranging from no to heavy risks. We explored differences and migration of MPs across these areas, unveiled the relationship between diversity, niche, and risks of MPs, and determined influencing factors. The average abundance of soil MPs was 8721 ± 3938 item/kg, and the abundance and contamination factor (CF) of MPs escalated with the increase in rocky desertification level. Diversity, niche, and risk of soil MPs in different rocky desertification areas were significantly different. Rocky desertification caused both MP community differences and linked MP communities at different sites. Diversity and niche significantly affected MP risk (p < 0.05). Environmental factors with significant correlations (p < 0.05) with the abundance and ecological characteristics of MPs varied significantly in soils of different rocky desertification areas. This study advances our comprehension of MP pollution in farmland soils within rocky desertification areas, offering essential data and theoretical insights for the development of control strategies.

Impact of soil structure and texture on occurrence of microplastics in agricultural soils of karst areas.

The impact of microplastics (MPs) on soil ecosystems has attracted widespread attention; however, the effects of soil structure and texture on the occurrence of MPs are not fully understood. In this study, we investigated the effects of soil structure and texture on the abundance of MPs and their potential mechanisms in agricultural soils of karst areas in Guizhou, China. The results showed the average abundance of MPs was 2948 items/kg. The soil texture in the study area can be categorized into seven types such as powdered-light clay, the range of total soil porosity was 39.05-69.22 % and the range of soil bulk density was 0.66-1.51 g/cm3. Soils with a powdered-light clay, low soil porosity, and low soil bulk density showed higher MPs pollution. The percentage of pellet MPs in agricultural soils with a powdered-light clay was 84 %, which was higher than that of the other soil textures. The direct effects of soil texture, soil porosity, and soil bulk density on MPs abundance were much lower than the indirect effects, with soil texture having the highest effect on MPs abundance. We speculated that karst geology may affect the accumulation and distribution of MPs in soil by affecting soil texture and structure, which, in turn, affects the fragmentation and migration of MPs. These findings will help to better understand the mechanisms of soil MPs pollution and provide a scientific basis for the development of relevant control strategies.

Study of soil microplastic pollution and influencing factors based on environmental fragility theory.

Soil microplastics (MPs) pollution is a global concern, but the distribution of MPs and the factors affecting the distribution of MPs in different ecologically fragile karst areas remain poorly understood. Here, we investigated the spatial distribution, characteristics, and composition of MPs in different ecologically fragile karst areas of Guizhou Province and explored the relationship between ecosystem fragility and MPs. Structural equation models combined with robust random forest (RF) models were used to clarify the effects of karst soil properties on MPs and quantify their relative contributions. The abundance of soil MPs in ecologically fragile karst areas was 2949 item kg-1, and the risk of MPs contamination was highest in medium-fragile areas. The robust RF models precisely predicted the abundance of soil MPs in different fragile areas, and the mean root mean square error and R2 were 0.21 and 0.93, respectively. The contribution of karst soil properties to the abundance of MPs was estimated. Some soil chemical properties had a significant effect (p < 0.05) on MPs pollution in ecologically fragile karst areas. The results of our study suggest that the fragile ecological environment may exacerbate MPs pollution. Our study also contributes to establish a scientific theoretical foundation for the utilization of plastics and the prevention and control of microplastics pollution in karst ecosystems.

Soil Heavy Metal Content and Enzyme Activity in Uncaria rhynchophylla-Producing Areas under Different Land Use Patterns.

In this study, we investigated the content of soil heavy metals, the level of heavy metal pollution and the characteristics of soil enzyme activity under three different land use patterns of Uncaria rhynchophylla base, forestland and wasteland in Jianhe County, Qiandongnan Prefecture, Guizhou Province, revealing the intrinsic correlation between heavy metal content and soil enzyme activity to reveal the relationship between soil enzyme activity and heavy metal content under different land use patterns in the Uncaria rhynchophylla production area. The results showed that soil Cd and Hg contents in Uncaria rhynchophylla base both exceeded the national soil background value. The single pollution index indicated that Cd had the greatest contribution to Pn, and the comprehensive pollution index (Pn) demonstrated no heavy metal pollution in the soil of Uncaria rhynchophylla-producing areas. Under different land use patterns, the enzyme activity was forestland > wasteland > Uncaria rhynchophylla base, and catalase and acid phosphatase activities presented significant spatial differences (p < 0.05). The correlation between soil enzyme activity and heavy metal content was uncertain due to the changes in land use patterns and heavy metal species. The proportions of positive correlation and negative correlation between soil enzyme activity and heavy metals in Uncaria rhynchophylla base were 50%, respectively. In the forestland, soil enzyme activity was positively correlated with heavy metals, while in the wasteland, soil enzyme activity was negatively correlated with heavy metals. This study revealed that the changes in heavy metal content should be focused on for the soil quality in Uncaria rhynchophylla-producing areas under different land use patterns. The results of the study provide some basic theoretical references for the improvement of soil quality in the production area of Uncaria rhynchophylla under different land use practices.

Evaporation Dynamics of Sessile Droplets: The Intricate Coupling of Capillary, Evaporation, and Marangoni Flow.

A single-component droplet placed on a completely wetting substrate shows a pseudostable apparent contact angle (θapp) during evaporation. We propose a simple theory to explain the phenomenon accounting for the liquid evaporation and the internal flow induced by the capillary and Marangoni effects. The theory predicts that when evaporation starts, the contact angle approaches to θapp in a short time τs, remains constant for most of the time of evaporation, and finally increases rapidly when the droplet size becomes very small. This explains the behavior observed for alkane droplets. Analytical expressions are given for the apparent contact angle θapp and the relaxation time τs, which predict how they change when the evaporation rate, droplet size, and other experimental parameters such as thermal conductivity of the substrate are changed.

LncRNA SNHG11 aggravates cell proliferation and migration in triple-negative breast cancer via sponging miR-2355-5p and targeting CBX5.

Triple-negative breast cancer (TNBC) is one of the most common malignances worldwide. Concurrently, the incidence of TNBC has continued to rise in recent years. It is reported that long non-coding RNAs (lncRNAs) are involved in biological processes in numerous cancers including TNBC. Small nucleolar RNA host gene 11 (SNHG11) has already been studied and reported in some cancers. However, the role of SNHG11 in TNBC remains unknown. RT-qPCR was used to measure gene expression in the current study. CCK-8, colony formation, flow cytometry, Transwell and western blotting experiments were also performed to determine the biological function of SNHG11 in TNBC cells. Luciferase reporter and RIP assays were performed to measure relationship between genes. In the present study, the results indicated SNHG11 was highly expressed in TNBC tissues and cell lines. Moreover, SNHG11 aggravated cell proliferation and migration, and whereas it attenuated cell apoptosis in TNBC. Furthermore, SNHG11 sponged microRNA 2355-5p (miR-2355-5p) in TNBC. Silencing SNHG11 increased miR-2355-5p expression. In addition, chromobox 5 (CBX5) was identified to be targeted by miR-2355-5p in TNBC. It was also suggested that CBX5 silencing suppressed cell proliferation and migration. Furthermore, overexpressed CBX5 recovered the inhibitive influence of SNHG11 silencing on proliferative and migrative abilities of TNBC cells. Overall, SNHG11 acted as a tumor promoter in TNBC and regulated TNBC cell growth by modulating the miR-2355-5p/CBX5 axis, which indicated that it may be used as a biomarker for TNBC treatment.

Thermal effects on arsenic emissions during coal combustion process.

In this study, the rate of emission of arsenic during the burning process of different kinds of coal is examined in order to study the volatile characteristics of arsenic during coal combustion which have negative effects on the ecological environment and human health. The results show that the emission rate of arsenic gradually increases with increased burning temperature, with a threshold of approximately 700°C to 800°C in the process of temperature increase. Then, the relationships among the arsenic emission rate and combustion environment, original arsenic content, combustion time, burning temperature, air flow and amount of arsenic fixing agent are discussed, and it is found that except for the original arsenic content, the rest of the factors have a nonlinear relationship with the emission rate of arsenic. That is, up to a certain level, they all contribute to the release of arsenic, and then their impact is minimal. The original arsenic content in coal is proportional to the arsenic emission rate. Therefore, taking into consideration the nonlinear relationships between factors that affect the arsenic emission rate can reduce contamination from arsenic.