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Objective: To investigate the prognosis of Chinese patients with ESCC after surgery and its correlation with genomic alterations (GAs) to identify potential prognostic markers. Methods: The clinical information, pathological specimens of 50 patients with stage II and III primary ESCC who were surgically resected. Based on overall survival, these patients were divided into the short OS group and the long OS group. Genomic alteration detection in patients with esophageal squamous cell carcinoma using next-generation sequencing. Results: There was no skew in the distribution of gender, smoking, and adjuvant therapy between the long OS group and the short OS group. A total of 372 GAs were detected in the 50 patients with ESCC, with 7 types of GAs, including insertions, deletions, and copy number variations (CNVs), and missense mutations occurred most frequently, with a frequency of >50.0%. Tumor protein 53 was the most commonly mutated gene in the entire cohort followed by cyclin D1, cyclin-dependent kinase inhibitor 2A (CDKN2A), and fibroblast growth factor 19. More CDKN2A loss were detected in the short OS group than in the long OS group. The results of the multivariate analysis after adjustment for clinical factors showed a statistically significant difference in the CDKN2A loss between the two groups. Data obtained from The Cancer Genome Atlas for surgical ESCC for surgical ESCC revealed that the CDKN2A loss may be responsible for the poorer prognosis in postoperative patients with ESCC. Conclusion: In patients with progressive primary ESCC, the poor postoperative prognosis may be epiphenomenally associated with the CDKN2A loss.

The massive use of pesticides has caused environmental problems, and it is urgent to reduce the use of pesticides. Pesticide use is closely related to social and economic activities, but few studies have quantified the contribution of socioeconomic factors to changes in pesticide use. Hence, based on the multiregional input–output (MRIO) model and structural decomposition analysis (SDA), this study quantified the contribution of pesticide use intensity, production structure, local consumption and distant consumption to changes in pesticide use in China from 2012 to 2017 and further analysed the effect of distant consumption on local pesticide use at the provincial and sectoral levels. The results showed that the total use of pesticides showed a downward trend during 2012-2017. Specifically, the intensity of pesticide use was an important factor for the decrease in pesticide use, resulting in a decrease of 4.9´105 tons of pesticide use. Nevertheless, local and distant consumption were the primary factors for the increase in pesticide use, resulting in increases of 4.37×105 and 1.21×105 tons, respectively. More importantly, provinces with high added value of primary industry bear the risk of pesticide pollution in provinces with high per capita GDP due to distant consumption. Moreover, the agriculture and food sectors are the most important sectors affected by distant consumption. Therefore, it is necessary to clarify provincial and sectoral responsibilities for pesticide use due to distant consumption and to encourage cross-regional technical support and sectoral cooperation for pesticide reduction.

Trait-based approaches are increasingly used to improve ecological restoration in degraded ecosystems. The aim of this study was to evaluate how vegetation controls soil detachment capacity (Dc) by concentrated flow based on the linkages between root traits and soil physics. We selected 60 plots along a land degradation gradient caused by long-term water erosion in a small catchment, central China. These plots consisted of woodlands, scrublands, grasslands and bare lands. And soil physical properties, root traits and Dc were measured in each plot. Fine roots (0.2 mm

Weeds and crops that grow together often confront similar types of environmental stress, especially drought stress. Weedy rice (Oryza sativa f. spontanea) and cultivated rice (O. sativa L.) provide a unique pair consisting of a weed and a conspecific model crop that can be used to study the drought tolerance of plants across a large distributional range. The investigation on weedy rice's damage to paddy fields showed that it was more serious in dry direct seeding than water direct seeding. Compared with water direct seeding, the seeds of cultivated rice and weedy rice in dry direct seeding will absorb water and germinate under the condition of insufficient soil moisture. Our hypothesis is that weedy rice seeds have evolved stronger germination ability than coexisting cultivated rice under water stress, so that they can obtain more growth space in the early stage in dry direct seeding and thus obtain higher fitness. Seeds of weedy rice populations and coexisting rice cultivars were collected from 61 sites across China and were germinated with 20% polyethylene glycol‐6000 to simulate drought stress. Two drought response indices, which assessed germination rate and germination index, plus one germination stress tolerance index, indicated significantly greater drought tolerance in weedy rice populations than in coexisting rice cultivars (P indica rice cultivars, japonica weedy rice > japonica rice cultivars, and indica weedy rice > japonica rice cultivars. These results indicate that weedy rice populations show stronger drought stress tolerance than coexisting rice cultivars at various sites, specifically during the seed germination period. Furthermore, Pearson's correlation found that drought response of weedy rice populations and coexisting rice cultivars were significantly different with these environmental factors: latitude, altitude, annual mean precipitation, mean annual temperature, mean precipitation in the sowing month, mean temperature in the sowing month, and sowing methods. Weedy rice shows different patterns of drought tolerance variation across geographical (latitude and altitude) and environmental (precipitation) gradients compared to coexisting rice cultivars. This study suggests that weedy rice might have evolved new drought tolerance and could provide a useful source of genetic resources for improving drought tolerance of crop cultivars and breeding direct seeded cultivars to reduce the usage of seeds in direct seeding.

The soil carbon (C) reservoir involves soil organic and inorganic carbon stocks. The influence of soil erosion processes on soil organic carbon (SOC) migration has been investigated in the literature, but the influence on soil inorganic carbon (SIC) remains uncertain. Variations in the proportion of SOC and SIC in eroded sediment can influence C cycling, so we conducted a detailed laboratory study to investigate the selective transport of SOC and SIC in eroded sediment in treatments with different raindrop sizes and inflow rates. We used the boosted regression trees (BRT) models to estimate the SOC and SIC contents according to the ratio of flow depth and raindrop diameter (h/D), the maximum shear stress (τ*max), the runoff rate, the stream power (ω), the sediment concentration (SC), the soil loss rate (SLR), and various particle-related factors, including D50, D[4,3], D[3,2], clay content, silt content and sand content of non-dispersed sediment. The BRT model explained 42.1% and 56.1% of the variation in the SOC and SIC contents in the sediment, respectively. The relative importance of particle-related factors was approximately 50%, demonstrating that the particle size distribution (PSD) of sediment was a crucial factor for both SOC and SIC transport. The SOC content was sensitive to the presence of fine particles, while the SIC content was largely determined by coarse particles because smaller particles with a higher specific surface area tended to adsorb more SOC whereas coarser particles contained more carbonates in the form of binding agents. In sediment under intensive rainfall on steep slopes, the SOC tended to be depleted, while the SIC was slightly enriched. Our study demonstrates that both SIC and SOC were selectively transported by water erosion and fills gaps in this field of research. Moreover, this work implies that the PSD of the sediment provides important information about the variation in SOC and SIC and should be considered when modelling the global C cycle.

Hydrological characteristics are expected to be affected by climate variability and vegetation dynamics which are interconnected and coupled in most cases. Few studies have decoupled the effects of vegetation dynamics and climate variability on hydrological characteristics, a process that benefit both water resources management and agricultural water allocation. In this study, we used partial least squares-structural equation modeling (PLS-SEM) to decouple the effects of climate variability and vegetation on the temporal variations in hydrological characteristics on a monthly scale in the Upper Du watershed (8973 km2) in subtropical China. Monthly hydrometeorological and vegetation cover data were collected from 2000 to 2010. Moderate Resolution Imaging Spectroradiometer (MODIS) derived vegetation indices were used to represent the vegetation status of the watershed. The results showed that vegetation dynamics and climate variability account for up to 67% of the temporal variation in runoff, whereas the combined effects of vegetation, climate and runoff explain 62% of the variation in sediment. Climate variability both directly affects monthly hydrological characteristics and indirectly affects these characteristics through its effects on vegetation. Vegetation is negatively correlated with both runoff and sediment, and the net effect of vegetation on the sediment load (total effect = −0.20) is greater than its effect on runoff (total effect = −0.12). Our results indicate that the direct effect of vegetation on sediment (direct effect = −0.09) is smaller than the indirect effect (indirect effect = −0.11) of vegetation on sediment through its influence on runoff; thus, vegetation reduces both the sediment concentration and the sediment load mainly by reducing runoff. Compared to conventional multivariate statistical methodologies, PLS-SEM provides additional valuable information, including the direct and indirect impacts of climatic factors and vegetation on hydrological characteristics.

Large-scale vegetation restoration generally reduces local water yield and influences river ecosystem health. Thus, scientific evaluation of vegetation restoration consequences is necessary for maintaining the stability of the surface water system and water cycle in semi-arid regions. In this study, we compared the efficiencies of different typical grasslands in regulating runoff and sediment yields and proposed feasible suggestions suiting for local environments. Four grasslands, including two Gramineae species (Elymus dahuricus and Bromus inermis) and two legume species (Medicago sativa and Trifolium repens), were tested during a two-year period with simulated rainfall experiments, and using bare land as control. Three replicates were done for each treatment, and fifteen plots with a slope of 20° were constructed. Three indices were used to assess the runoff and sediment yields reduction capacity of the grasslands, including runoff reduction benefit (RRB), sediment reduction benefit (SRB), and soil infiltration rate (SIR). The results showed that RRB and SRB were significantly different (P

The frequency of harmful algal blooms caused by eutrophication is increasing globally, posing serious threats to human health and economic development. Reservoir bays, affected by water environment and local watershed landscape, are more prone to eutrophication and algal blooms. The chlorophyll a (Chl a) concentration is an important indicator for the degree of eutrophication and algal bloom. Exploring the complex relationships between water environment and landscape background, and Chl a concentration in the reservoir bays are crucial for ensuring high-quality drinking water from reservoirs. In this study, we monitored Chl a concentrations of 66 bays in Danjiangkou Reservoir and the related water quality parameters (e.g., water temperature, turbidity, nutrients) in waterbodies of these reservoir bays in the storage and discharge periods from 2015 to 2018. Partial least squares-structural equation modeling (PLS-SEM) was used to quantify the relationship between water environmental factors and watershed landscapes, and Chl a concentrations in reservoir bays. The results showed that mean Chl a concentration was higher in storage period than that in discharge period. Two optimal PLS-SEMs explained 66.8% and 53.6% of Chl a concentration variation in the storage and discharge periods, respectively. The net effect of water chemistry on Chl a concentration was more pronounced during the discharge period (total effect = 0.61, 37% of the total effect on Chl a), while the net effect of land-use composition on Chl a concentration was more significant during the storage period (total effect = 0.57, 30% of the total effect on Chl a). The landscape pattern had significant indirect effects on Chl a concentration, especially during the discharge period (indirect effect = −0.31, 19% of the total effect on Chl a). Our results provide valuable information for managers to make rational decisions, thereby contributing to the prevention of eutrophication and algal blooms in reservoir bays.

Atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) emissions cause non-negligible damage to human health and well-being. Effective regional cooperation is urgently required to mitigate PAHs emissions to maintain satisfactory air quality. This study quantified and tracked China's PAHs emissions flows embodied in interprovincial trade. A production-based emissions inventory of 16 U.S. EPA priority PAHs based on commercial energy consumption in China in 2012 was compiled using the emissions factor approach. Then, a multiregional input-output model was constructed to reveal consumption-based emissions and to track the PAHs emissions embodied in the trade of 27 major sectors across 30 regions in China. Key structural paths were also identified using structural path analysis (SPA). In 2012, the total industrial energy-derived PAHs emissions were estimated to be 47.7 tons of BaP-toxic equivalents (8032.7 tons of mass). Shandong, Hebei, and Hubei accounted for more than 24.0% of the production-side PAHs emissions in the whole country. Approximately 30.8% of China's PAHs emissions were embodied in goods consumed outside of the province in which they were produced. PAHs flow tended to start in the western regions and ended in the eastern regions along the coast. The results of the SPA showed that critical paths, such as from the Metallurgy sector to the Construction sector, embodied a large amount of emissions and had the potential to affect the performance of the entire system. By paying attention to the consumption-based accounting as well as the production-based accounting of emissions and by focusing on vital transfer paths, policymakers can devise effective and targeted environmental protection and sustainable development policies in China.

Terracing and rainfall characteristics notably influence the water erosion processes. However, an extensive long term in situ quantitative evaluation of the approaches to control the water erosion in different orchard terraces has not yet been performed, especially considering the increasing frequency and severity of extreme rainfall events due to the global climate change. In this study, six types of orchard terraces, including slope land as the control (SLck), level terrace with bare (LTb) and vegetation taluses (LTv), outward (OTv) and inward terrace (ITv) with vegetation taluses and level terrace having front mounds and back ditches with vegetation taluses (MDLTv), were used to analyze the effects of extreme and ordinary rainfall events on the surface runoff and soil erosion. According to the measured data for twelve consecutive years, 356 natural rainfall events were divided into extreme and ordinary rainfall, based on the World Meteorological Organization standard. The results indicated that more severe surface runoff and sediment loss occurred under extreme rainfall: the runoff coefficient and soil loss under extreme rainfall were 2.6 and 11.5 times those under ordinary rainfall, respectively. The sediment yield (contribution rate, 42.9%) exhibited a higher sensitivity to extreme rainfall events compared to that of the surface runoff generation (contribution rate, 16.4%). Moreover, the reduction in the surface runoff and sediment in the extreme rainfall case differed for different orchard terraces. The average surface runoff coefficient and soil loss amount decreased in the following order: SLck>LTb>OTv>LTv>ITv>MDLTv. Nevertheless, the highest and lowest contributions of the extreme rainfall to the sediment yield occurred in the LTb (64.8%) and MDLTv (21.7%) plots, respectively. Therefore, severe talus erosion caused by extreme rainfall should be monitored, and a combination of vegetation taluses and front mounds and back ditches on the platforms is recommended as a sustainable strategy to prevent extreme water erosion when transforming slope land into orchard terraces.

The continuous afforestation has led to significant changes in soil moisture (SM) dynamics on the Loess Plateau, China (LPC). However, evaluating the spatio-temporal distributions and driving factors of the SM changes following afforestation is challenging because of the difficulty of accessing areas and the lack of long-term series records. Here, we evaluated the accuracy of Global Land Evaporation Amsterdam Model (GLEAM) SM product by comparing with in-situ SM data in LPC, and quantified the spatio-temporal variations of SM in different periods from 1982 to 2015 under the ‘Grain for Green’ program (GGP). The results showed that the Normalized Difference Vegetation Index (NDVI) was well matched with the SM variations in more than 46% area of LPC from 1982 to 2015, which mainly located at the vegetated areas. The variations of SM responding to revegetation displayed obvious southeast-negative and northwest-positive patterns, which was the wet region (annual precipitation >450 mm) to be dry and dry region (annual precipitation ≤450 mm) to be wet. Path coefficient value revealed that the positive effect of vegetation activity for grassland on SM was ascribed to its promotion on the occurrence of rainfall (mean path coefficient = 0.278). Precipitation played vital impact on the SM in bareland and sparsely vegetated area, and evapotranspiration played a dominant role in the SM dynamic of the forestland, especially at the early stage of GGP (From 2000 to 2010), while precipitation and NDVI had stronger effects than evapotranspiration on the SM dynamics of grassland. Our study suggests that in arid and semi-arid areas, vegetation achieves the optimal water retention capacity when the vegetation fractions are 1.4%–3.7% and 3.8%–7.2%, respectively. Hence, vegetation should not be further expanded in semi-humid areas, but should be further restored in arid and semi-arid areas with sparse or excessively sparse vegetation cover (especially in desert).

Check dams are very important structures for torrent control areas throughout the world. Measuring the sediment deposition behind check dams is thought to be an effective method of estimating the sediment yield of small catchments. In this study, we employed a high-density electrical resistivity system to detect sediment at six check dams distributed in the hilly and gully area of the Loess Plateau. A total of 11 lines were arranged, with 60 electrodes along each line. The resultant resistivity data were inverted into subsurface structures using least-squares inversion techniques. The results indicate that the sediment bottom can been identified using an electrical resistivity contour method. Using trenches, boreholes and drillings to calibrate the calculated values, the accuracy of the high-density electrical resistivity tomography method was found to be quite high (95.7%). The bulk density increases with the sediment deposit depth and can reach a maximum of 1.6 g cm−3. Geometric methods considering three shapes (V-shaped, U-shaped and trapezoidal) were used to estimate the profile area of the check dams; the V-shaped geometric method showed high accuracy. This study provides a four-step approach based on high-density electrical resistivity tomography and a geometric method to estimate sediment yield for check dam-controlled catchments. This methodology enables the measurement of the total sediment yield, including both the suspended and bedload sediment transport, from an ungauged catchment.

Socioeconomic factors are key driving forces for the occurrence and development of soil erosion, but their effects are not well understood. To analyse the relationship between the socioeconomic system and soil erosion, a framework was proposed and validated with structural equation modelling. Population pressure, economic development, agricultural inputs and outputs and soil erosion are latent variables of the framework. A case study was conducted in Jiangxi Province. The results showed that economic development was the key controlling factor and that agricultural output was the main promoting factor for soil erosion, with path coefficients of -1.321 and 1.609 in 1995 and -0.624 and 0.453 in 2010, respectively. This implied that the contradiction between socioeconomic development and ecological protection was alleviated during the study period. Agricultural input controlled severe soil erosion (-‍0.322) while promoting mild soil erosion (0.095), which indicated that more attention should be paid to the adverse impact of excessive agricultural inputs on soil erosion control. The identification of the socioeconomic driving forces of regional soil erosion could help adjust the development strategy and mitigate the negative effects of economic development on soil erosion control and ecological conservation.

This paper aims to investigate the hydrological response of a large-scale (8973 km2) mountainous watershed to different rainstorm spatial patterns and reforestation. Based on 32 years of observations, measurements of 184 rainstorm events and 125 sediment-producing events with complete hydrographs were analyzed. The K-means clustering method was used to classify the spatial patterns of rainstorm events in accordance with their event-based spatial rainfall characteristics. The 184 rainstorm events were classified into four spatial patterns, among which the spatial features differ significantly: (I) Spatial Pattern I (SPI) includes rainstorms with a low amount of cumulative areal rainfall (27.4 mm), the highest spatial variability (0.986), and the highest frequency; (II) Spatial Pattern II (SPII) includes rainstorms of high spatial variability (0.759) and the largest amount of local maximum daily rainfall (106.8 mm); (III) Spatial Pattern III (SPIII) includes rainstorms with a medium amount of cumulative areal rainfall (58.7 mm) and low spatial variability (0.362); and (IV) Spatial Pattern IV (SPIV) includes rainstorms with the largest amount of cumulative areal rainfall (117.2 mm) and the lowest spatial variability (0.313). Vegetation cover in the upper Du watershed was significantly improved after the implementation of the Grain-for-Green project. The average area-specific sediment yields (SSY) for the four SPs were 15.4, 65.5, 55.8, and 286.2 t km−2 before reforestation and decreased to 6.0, 59.3, 43.7 and 89.9 t km−2, respectively, after reforestation. ANOVA (analysis of variance) indicated that reforestation resulted in a significant reduction in runoff coefficient under SPIII and SPIV and a significant reduction in SSY under SPI and SPIV. A hysteresis analysis suggested that the proportion of events with a clockwise loop increased from 64.9% before reforestation to 82.1% after reforestation and that complex loops became less common during 2000–2010 under SPIV, thereby implying a reduced sediment supply.

Although soil erosion and land use change have long been focuses in carbon research, the combined influence of soil erosion and vegetation rehabilitation on aggregate stability and the associated soil organic carbon (SOC) and total nitrogen (TN) remains unclear. The current study evaluated the effects of soil erosion on aggregate stability and the associated SOC and TN dynamics in relation to vegetation rehabilitation after the implementation of the “Grain-for-Green” project in the hilly Loess region. A check dam sediment sequence was dated using 137Cs activity and erosive rainfall events. The SOC and TN in the bulk soil and aggregate fractions were measured in soils from rehabilitated grasslands and sloping croplands and in sediments retained by the check dam. The results showed that vegetation rehabilitation led to 78%, 27% and 9% average increases in the macroaggregate amount, mean weight diameter (MWD) and mean geometric diameter (MGD), respectively. In addition, rehabilitation resulted in the highest SOC and TN concentrations and contents in macroaggregates among all the aggregate size fractions. Soil erosion facilitated the modification of the aggregate size distributions along with soil mineralization and induced the incorporation of deeper SOC-poor soils during transport. These processes resulted in the aggregate-associated SOC and TN concentrations and contents in the sediments being significantly lower than those in the eroding sloping cropland soils. The highest reductions were found in microaggregates, which exhibited decreases of 48% and 44% for SOC and TN, respectively. Moreover, reaggregation and gully soils incorporated during soil erosion led to higher values of macroaggregate amount and aggregate stability at depositional sites than those at eroding sloping cropland sites in this study. Our study contributes to the understanding of the effects of soil erosion and vegetation rehabilitation on SOC and TN dynamics, which is crucial for understanding the restoration efficiency in soil erosion control and ecosystem security evaluation.

Neonicotinoids pollution poses a serious threat to aquatic ecosystems. However, there is currently little knowledge about how neonicotinoids are transferred from the agricultural environment to the aquatic environment. Here, we conducted in situ high-frequency monitoring of neonicotinoids in soil-water systems along the hydrological flow path during rainfall to explore the horizontal and vertical transport mechanisms of neonicotinoids. The collected samples included 240 surface runoff, 128 subsurface runoff, 60 eroded sediment, 120 soil and 144 soil solution, which were used to analyse neonicotinoids concentrations. Surface runoff, subsurface runoff and eroded sediment were the three main paths for the horizontal migration of neonicotinoids. In the CK (citrus orchards without grass cover) and grass-covered citrus orchards, there are 15.89% and 2.29% of the applied neonicotinoids were transported with surface runoff, respectively. While in the CK and grass-covered citrus orchards, there are only 1.23% and 0.19% of the applied neonicotinoids were transported with eroded sediment and subsurface runoff. Although the amount of neonicotinoids lost along with eroded sediment was small, the concentration of neonicotinoids in eroded sediment was two orders of magnitude higher than the concentration of neonicotinoids in sediments of the surface water. Meanwhile, neonicotinoids migrated vertically in soil due to water infiltration. In the CK and grass-covered citrus orchards, there are 57.64% and 24.36% of the applied neonicotinoids were retained in soil and soil solution, respectively, and their concentration decreased as soil depth increased. Another noteworthy phenomenon is that more neonicotinoids migrated to deeper soil layers under grass cover compared with no grass cover because grass roots promoted the formation of cracks and vertical preferential flow. Our results are expected to improve the accuracy of neonicotinoids pollution prediction by considering migration paths, including surface and subsurface runoff and eroded sediment.

The rapid expansion of citrus orchards and their increased cultivation intensity have accelerated soil erosion, which has impeded the achievement of Sustainable Development Goals. In citrus orchards, the benefits of soil and water conservation measures for alleviating soil erosion have been widely tested at the plot scale. These studies provide crucial information, but they inevitably involve considerable uncertainty and cannot fully characterize the efficacy of soil and water conservation measures. Given the seriousness of soil erosion in citrus orchards and the uncertain factors in the efficiency of soil and water conservation measures, data published in the literature were collected. A meta-analysis of 346 plots (representing 4443 events) for runoff and 307 plots (representing 3596 events) for soil loss was conducted to evaluate the effectiveness of soil and water conservation measures in citrus orchards. This study aims to (i) summarize the level of soil erosion in citrus orchards worldwide, (ii) explore the influence of soil and water conservation measures on soil erosion control in citrus orchards and (iii) identify the trade-offs between runoff reduction and soil loss reduction. The results showed that the citrus orchards without soil and water conservation measures had a probability of approximately 80% of exceeding tolerable levels of soil loss. The effectiveness of soil and water conservation measures in reducing soil erosion decreased in the order biological measures + engineering measures > engineering measures > biological measures. The trade-off between runoff reduction and soil loss reduction showed that soil and water conservation measures provide better soil loss control than runoff control. Overall, besides considering the ecological benefits of soil and water conservation measures, decision maker should also consider the economic benefits to obtain an optimal citrus orchard management for farmers.

Changes in natural rainfall regimes have taken place and are expected to become more pronounced in future decades. These changes are also likely to be accompanied by changes in crop management practices. The main purpose of this study was to analyze runoff and soil loss in relation to rainfall regimes and terracing in the Three Gorges area, China. Based on 10 years of field observation and k-mean clusters, 101 rainfall events were grouped into three rainfall regimes. Rainfall regime I was the group of events with strong rainfall intensity, high frequency, and short duration. Rainfall regime III consisted of events with low intensity, long duration, and high rainfall amount. Rainfall regime II was the aggregation of events of high intensity and amount, and less frequent occurrence. The results showed that event runoff coefficients were not significantly different among rainfall regimes. However, the average soil erosion rates in rainfall regimes I and II were significantly higher than that in regime III. The average erosion rates under rainfall regimes I, II, and III were 21.6, 39.7, and 9.8 g m−2, respectively. The effect of rainfall regime on soil erosion also was changed by terracing. On unterraced cropland, soil erosion rate in rainfall regime I is significantly higher than that in regime III. However, the situation did not exist in unterraced orchard. Terracing significantly reduced runoff and soil erosion, and compensated the effects of rainfall regime on soil erosion, which indicated that runoff and erosion in terraced system may be little influenced by climate change. Based on these results, it was suggested more attention should be paid to the timing of rainfall events in relation to crop development and the high erosion on unterraced citrus orchard to control soil erosion in this area.

Soil erosion not only affects the redistribution of soil materials but also changes soil respiration (Rs) and its temperature sensitivity (Q10), which plays a significant role in the carbon cycle of terrestrial ecosystem. To explore the stoichiometric regulations of Rs and Q10 under erosion and deposition conditions, typical eroded (croplands) and deposited sites (check dams) were selected in the Luoyugou watershed of the Chinese Loess Plateau. In situ Rs, soil temperature and moisture were monitored. The results showed that soil deposition decreased soil organic carbon, total nitrogen, heavy fraction organic carbon and dissolved organic nitrogen by 20.0%, 26.7%, 20.1% and 49.1%, respectively. However, the higher ratios of carbon:nitrogen and labile carbon:organic carbon were observed in the deposited sites due to the accelerated loss of dissolved nitrogen and the selective transport of light fraction organic matter. The Rs displayed a decreasing trend from July to December, and soil temperature explained 69.5–93.6% of the temporal variation in Rs. The mean Rs was 2.18 and 2.89 μmol m−2 s−1 in the eroded and deposited sites, respectively, and the average Q10 was 2.49 and 3.38. Multiple stepwise regression analysis showed that soil organic carbon:total nitrogen and light fraction organic carbon totally explained 48.9% of the Rs variation, and the main control factors for Q10 were dissolved organic carbon: total organic carbon (34.6%), soil temperature (17.0%) and dissolved organic carbon (10.0%). Our results suggested that the ratios of carbon:nitrogen and labile carbon:organic carbon play an important role in regulating Rs and Q10, and the increase in carbon:nitrogen ratios induced by sediment deposition contributes to increasing Rs and Q10. We believe that the effects of erosion and deposition on Rs and Q10 revealed in the study will contribute to a better understanding of the terrestrial ecosystem carbon cycle.

Assessing the impacts of land use on soil respiration (Rs) and its temperature sensitivity (Q10) is of vital significance for understanding regional carbon cycles. In this study, the regulation of Rs and Q10 by soil biotic and abiotic factors under different land-use types, i.e., cropland, apple orchard, abandoned land, Coronilla varia grassland, and Robinia pseudoacacia woodland, were examined in the Luoyugou watershed on the Chinese Loess Plateau. We monitored Rs, soil temperature, and moisture in situ from July to December 2018 and evaluated soil microbial abundance, root biomass, carbon and nitrogen nutrient levels. The results showed that soil organic carbon, total nitrogen, available nitrogen, dissolved organic carbon, and microbial biomass carbon decreased by the following order: grassland > woodland > abandoned land > cropland > orchard. The high amounts of plant residues and the low levels of human disturbance in grassland and woodland contributed to higher soil carbon and nitrogen nutrient levels in these land-use types than in cropland and orchard. Rs decreased from July to December, with soil temperature and moisture being the key explanatory factors. The mean Rs in grassland (3.68 μmol m−2 s−1) and woodland (3.81 μmol m−2 s−1) was significantly higher than that in cropland, orchard, and abandoned land. Q10 ranged from 1.77 to 5.87 across all land-use types, and orchard, abandoned land, grassland, and woodland had Q10 values 1.91, 1.37, 1.47, and 3.32 times higher, respectively, than the Q10 of cropland. The variable importance in the projection (VIP) values from the partial least squares regression model showed that soil temperature (VIP = 1.41), pH (VIP = 1.22), microbial biomass nitrogen (VIP = 1.13), microbial biomass carbon (VIP = 1.12), bacterial abundance (VIP = 1.12), available nitrogen (VIP = 1.01), and soil moisture (VIP = 1.01) were the most important predictors of Rs. Our study suggests that soil temperature and labile organic matter exert stronger impacts on Rs than do microbial abundance and root biomass. Our results contribute to a better understanding of ecosystem carbon cycles.

Anthropogenic pressure coupled with strong precipitation events and a mountainous landscape have led to serious soil erosion and associated problems in the subtropical climate zone of China. This study analyzes 1576 rainfall-runoff-soil loss events at 36 experimental plots (a total of 148 plot-years of data) under a wide range of conditions in subtropical mountainous areas of China where slope farming is commonly practiced. The plots, which have standardized dimensions, represent five common types of land use and have four different slopes. Event-based analyses show that almost half of the total rainfall caused soil erosion in the study area. The dominant factor controlling the runoff coefficient is the slope gradient rather than the land use type. The maximum soil lossfor crop plots under steep tillage (35°) is 5004 t km−2 for a single event. Among the common local crops, the average soil loss values increase in the following order: buckwheat cropland (1179 t km−2 year−1) > terraced cropland (1083 t km−2 year−1) > orchard land (1020 t km−2 year−1) > grassland (762 t km−2 year−1) > terraced orchard land (297 t km−2 year−1) > forest and grassland (281 t km−2 year−1).

Soil erosion affects the redistribution of soil and associated soil organic carbon (SOC) from different landforms, and it has significant implications regarding the fate of eroded SOC and terrestrial carbon sequestration. Despite the importance of soil erosion, few studies have evaluated the sources and budget of eroded SOC in the Loess Plateau region, which suffers from severe soil erosion. Based on an 11.3 m check dam sediment profile, we used the 137Cs activity and extreme rainfall events as dating methods to date sediment sequences. In addition, the natural abundance levels of the stable carbon isotope (δ13C) of bulk organic matter and a two-end-member mixing model were used to discriminate the sources of eroded SOC from different siltation stages retained by the check dam in an intensive agricultural catchment of the Loess Plateau, China. The eroded SOC captured by the check dam was compared to potential source materials from different landscape units, which included sloping cropland and gully surface soils (0–5 cm). The results showed that the check dam intercepted 98.5 Gg of eroded soil and 172.6 Mg of SOC. The eroded SOC was primarily sourced from sloping cropland, which contributed to 81.3% of the total SOC retained by the check dam, whereas the gully soils contributed to 18.7% during the entire siltation stage. Additionally, the contribution of sloping cropland to eroded SOC increased from 1960 to 1990 as a result of rainfall and anthropogenic activities. A total of 89.7 Mg SOC was lost during soil erosion processes at a rate of 0.17 Mg ha−1 yr−1 and accounted for approximately 30% of the total eroded SOC exported from the eroding areas. Our results indicate that the soil erosion process has been an important net source of SOC in the study catchment. The check dam served as a carbon storage and sequestration structure for the hilly loess region due to its beneficial conditions for carbon sequestration over broad temporal and spatial distributions.

In the soil environment, iron oxides co-occur commonly with different types of organic constituents to produce iron oxide–organic composites that play an important role in the biogeochemical cycling of trace metals. We investigated copper (Cu) adsorption on synthetic goethite, Pseudomonas putida (CCTCC M209319) bacterial cells, humic acid (HA) and their binary and ternary composites with batch adsorption experiments coupled with isothermal titration calorimetry (ITC). Morphological characterizations show that the three components can form closely combined and heterogeneous aggregates with one another. The kinetics of sorption of Cu to these composite materials conforms to the pseudo-second-order model, whereas the Cu sorptivities deviate from linear additivity. Specifically, Cu sorptivities on the binary goethite–P. putida and P. putida–HA and ternary goethite–P. putida–HA composites are less than expected assuming additivity, whereas the opposite is seen for the binary goethite–HA composite. There is considerable masking of adsorption sites in the ternary goethite–P. putida–HA system, but the binding sites on bacteria are not completely covered, as shown by the adsorption enthalpy and entropy (19.60 kJ mol−1 and 120.9 J mol−1 K−1, respectively) for the ternary composite. We conclude that the binding affinity of Cu for the binary goethite–humic acid composite is larger than that for the bacterial composites with goethite or humic acid, or both. This research indicates that bacteria, iron oxide and humic substances exhibit different behaviour in the sequestration of heavy metals when they form various binary and ternary complexes in natural environments. Highlights How does mineral–organic interaction affect the binding behaviour of trace elements? First investigation of Cu sorption to goethite–bacteria–humic acid composites. Goethite–HA shows enhanced Cu adsorption, whereas the opposite is true for bacterial complexes. Various bacteria–iron oxide–humic substance composites behave differently in metal sequestration.

Although the fallout radionuclide 137Cs technique has been widely used to provide soil redistribution estimates in recent decades, some researchers have recently challenged the usefulness of this technique. Thus, it is necessary to evaluate the usefulness of the 137Cs technique to study soil redistribution, especially in areas that suffer from severe soil erosion and where the 137Cs inventory distributions vary. This study analyses the abundance of 137Cs deposited in sediment trapped by a check dam over 31 years in a small agriculture catchment in the Loess Plateau, which has experienced some of the most extensive agricultural soil erosion in the world. The 137Cs inventory and soil loss were evaluated, and the results indicated that the sediment deposition rate behind the check dam was approximately 38 cm/year. The specific soil erosion rate of the catchment is estimated to be 178 t ha−1 year−1. A geochemical properties fingerprinting method indicated that the ratio of the inter-gully erosion from cropland to gully erosion was 0·46:0·54 during the investigated period of 31-year period. Our results suggest that the 137Cs technique cannot be directly used in the study catchment. Gully erosion is the main type of soil erosion that occurs in the loess catchment, and the amount of gully erosion changes from year to year. Therefore, the abundance of 137Cs cannot be used to estimate soil redistribution where gully erosion is severe. However, after calibration, the inter-gully soil loss was consistently related to 137Cs abundance, which means that the 137Cs technique can be used at the plot or slope scale on the Loess Plateau. Our results also reveal the particle-size selectivity of soil detachment and sediment deposition during runoff-erosion events. The average 137Cs content of the fine group couplets is 63% greater than the 137Cs content of the coarse group. When the studied section spans more than 15 years, the 137Cs inventory is consistent (R2 = 0·95, p

Nitrate exports from diffuse sources constitute a major cause of eutrophication and episodic acidification in inland aquatic systems, and remedial action requires the identification of the influencing factors associated with these nitrate exports. This paper examines the combined effects of watershed complexity on nitrate concentration and flux in terms of the hydrological and environmental factors in heterogeneous nested subwatersheds in the Danjiangkou Reservoir Area (DRA), China. We established 15 sampling sites in the main stream and tributaries and conducted biweekly sampling in 2008–2012 to monitor the nitrate exports. The hydrological and environmental indices within the watershed were divided into subwatersheds and considered as potential influencing factors. In consideration of the high co-linearity of these influencing factors, we used partial least squares regression (PLSR) to determine the associations between the stream nitrate concentration or flux and 26 selected watershed characteristics. The number of components was unequal for the nitrate concentration and flux models. The optimal models explained 66.4%, 60.0% and 59.9% of the variability in nitrate concentration and 74.7%, 67.1% and 58.0% of the variability in nitrate flux annually, in the dry season, and in the wet season, respectively. According to the variable importance in the projection (VIP) values, the dominant first-order factors for the nitrate concentration were as follows: the areal percentages of agricultural, forest and residential areas; followed by the slope; the largest patch index (LPI); the flow path gradient (FPG); the slope gradient variance (SGV); and the splitting index (SPLIT). In addition to these factors, the runoff coefficient (RC), flashiness index (FI), and patch density (PD) affected the changes in the nitrate flux. This study illustrates the influence of hydrological and environmental factors on seasonal water quality and can serve as guidelines for better watershed modeling and effective water quality management.

Long-term sedimentary sequence research can reveal how human activities and climate interact to affect catchment vegetation, flooding, soil erosion, and sediment sources. In this study, a biomarker sediment fingerprinting technique based on n-alkanes was used to identify long timescale (decadal) sediment sources in a small agricultural catchment. However, the highly saline carbonate environment and bacterial and algal activities elevated the levels of even-chain n-alkanes in the sediments, leading to an obvious even-over-odd predominance of short and middle components (C 15 -C 26 ). Therefore, by analyzing three odd, long-chain n-alkanes (C 27 , C 29 and C 31 ) in 27 source samples from cropland, gully, and steep slope areas and one sediment sequence (one cultivated horizon and 47 flood couplets), a composite fingerprinting method and genetic algorithm optimization were applied to find the optimal source contributions to sediments. The biomarker fingerprinting results demonstrated that the primary sediment source is gullies, followed by cropland and steep slope areas. The average median source contributions associated with 47 flood couples collected from sediment core samples ranged from 0 ± 0.1% to 91.9 ± 0.4% with an average of 45.0% for gullies, 0 ± 0.4% to 95.6 ± 1.6% with an average of 38.2% for cropland, and 0 ± 2.1% to 60.7 ± 0.4% with an average of 16.8% for steep slopes. However, because farmers were highly motivated to manage the cropland after the 1980s, over half the sediments were derived from cropland in the 1980s. Biomarkers have significant advantages in the identification of sediments derived from different landscape units (e.g., gully and steep slope areas), and n-alkanes have considerable potential in high-resolution research of environmental change based on soil erosion in the hilly Loess Plateau region.

6 Pags.- 4 Figs.- Suppl. Data., The application of ecological restoration programs, related to water resources protection and soil erosion control, may have some undesirable outcomes. An important example is the effect that vegetation restoration may have in reducing surface water resources. After searching peer-reviewed articles, we selected 38 publications from 16 countries in comparable areas - semiarid conditions (aridity index 50% and fine soil texture - to evaluate the effectiveness of different types of vegetation (i.e., forestland, scrubland and grassland) in regulating runoff and sediment transport. In particular, we used three indices: the runoff reduction effect, the sediment reduction effect and the ratio between runoff and sediment reduction. These indices were calculated from measured data reported in the original articles. Results showed that scrubland had higher runoff reduction effect (59% in gentle slopes; 65% in steep slopes) than in grassland (39% on gentle slopes; 43% on steep slopes) and forestland (33% on gentle slopes; 51% on steep slopes). For the three types of vegetation, the sediment reduction effect was >70%. Concerning the ratios between runoff and sediment reduction, grassland showed the lowest ratios (56% on gentle slopes; 53% on steep slopes) compared to forestland (63% on gentle slopes; 65% on steep slopes) and scrubland (93% on gentle slopes; 81% on steep slopes). Our results indicate that low values of ratios between runoff and sediment reduction are the most suitable because they indicate an effective soil erosion and sediment delivery reduction but maintaining surface runoff. Overall, our study demonstrates that grassland may be the best choice for optimizing the trade-off between catchment water yield and soil conservation during the implementation of ecological restoration programs in semi-arid regions., This study was funded by Projects of the National Natural Science Foundation of China (NSFC41722107, 41525003, 41977063, 41930755), and the Youth Talent Plan Foundation of Northwest A & F University (2452018025).

Increasing resistance to aging is conducive to seed storage and germination rate of crop. Meanwhile, the resistance to aging is one of the important adaptive mechanisms of weed to thrive in farmland. Weedy rice (Oryza sativa f. spontanea) and cultivated rice (Oryza sativa L.) provide a unique pair demonstrating a weed and conspecific model crop that can be used to study the aging resistance of plants across a diverse geographical range. Chinese weedy rice derived from de-domestication of cultivated rice has rapidly risen to malignant weeds, though the hazard has only been reported for about 20 years. Whether weedy rice rapidly evolves higher seed aging resistance than cultivated rice during the process of dedomestication, which is conducive to its persistence in rice fields, is still unclear. In this experiment, the seeds of weed rice populations and their co-existing rice varieties were collected from 61 regions of China and germinated under normal and high temperatures for consecutive four years (2013–2016). Our study found that the aging resistance of weedy rice was higher than that of the co-existing rice cultivars, and weedy rice may have evolved a different aging resistance mechanism than rice cultivars and could be used as a germplasm resource to cultivate aging-resistant rice. The indica-type has strong aging resistance and no dormancy, while the japonica type has weak aging resistance and a little weak dormancy. Thus, by introducing indica-type aging-resistant alleles into japonica rice, cultivation of aging-resistant japonica rice could be possible.

Soil erosion on cropland is a result of the interaction between nature and human activities. The socioeconomic influencing factors of soil erosion have been less studied than the biophysical processes and previous studies have mainly focused on the impacts of local socioeconomic factors on soil erosion in the same region. However, since agricultural activities are densely connected to other socio-economic activities, the need for agricultural products from distant regions could potentially drive local soil erosion accompanying agricultural production. To the best of our knowledge, these telecoupling effects have not been studied. Here, we combined the Revised Universal Soil Loss Equation (RUSLE) and multiregional input-output analysis (MRIO) models to quantify the contribution of China's cross-provincial economic demand to local soil erosion at the provincial, sectoral, and supply chain levels. Our results show that a large amount of soil erosion in the southwest, northeast, and central regions is linked to the economic needs across provinces. Agriculture and food processing are the most important distant driving sectors. The driving effect of household consumption on soil erosion mainly occurs on shorter supply chains, while exports and capital formation drive soil erosion through longer chains. Our results indicate that local soil erosion management must consider the impact of distant agricultural product needs and coordinate food production and supply on a national scale to protect the ecological function of the land.

Reservoirs play a crucial role in the drinking water supply for solving the uneven distribution of water resources. Reservoir bays, which serve as direct source areas and initial collection areas of pollutants, are crucial areas for drinking water safety. Systematic observations of heavy metal pollution in reservoir bays are required and urgent under different hydrological regulation. Water samples were collected from 65 bays in the Danjiangkou Reservoir which is the water source of the world’s longest trans-basin water diversion project during the storage and flood discharge period from 2015 to 2019. We investigated the temporal and spatial variation in eight dissolved heavy metals, chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), and lead (Pb), and assessed their human health risks. The driving factors of high-risk metals were identified by constructing a structural equation model (SEM). The results showed that the concentrations of heavy metals decreased after 5 years of reservoir operation and varied significantly (p

Water erosion induces a wide variation in organic carbon (OC) loss in orchard agroecosystems due to high anthropogenic disturbance. Grass cover, a common agricultural practice, can both suppress OC transport by reducing erosive rainfall and runoff, and enhance the amount of OC in soil by increasing OC inputs. These different effects on OC loss call for a deeper understanding of the process and drivers of OC loss under grass cover during water erosion processes. Hence, we conducted a simulated rainfall experiment under bare land (BL) and grass cover in orchards to analyse the direct and indirect effects of grass cover, soil aggregate properties, runoff and sediment yield on OC loss using structural equation modelling (SEM). The results demonstrated that grass cover reduced sediment and runoff by 97.84–98.81 % and 47.28–82.12 %, respectively, and correspondingly reduced the loss of 97.21–99.24 % soil organic carbon (SOC) and 83.55–92.76 % dissolved organic carbon (DOC) compared to BL. The SEM results showed that sediment, as opposed to runoff, was the main pathway of OC loss and grass cover regulated total organic carbon (TOC) loss by varying soil aggregate properties rather than by changing erosive forces. Specifically, the total effect of the soil aggregate stability and SOC content in aggregates under grass cover on TOC loss was negative (-0.21 and -1.14, respectively). Moreover, the increasing percentage of >5 mm soil aggregates contributed to reducing SOC and DOC losses, while the increasing percentage of 0.5−0.25 mm soil aggregates aggravated SOC and DOC losses. The results from this study emphasize that grass cover is a convenient and effective measure for reducing OC loss in orchards; moreover, studying the effect of multiple-factor interactions on OC loss will provide insights and improve predictions of the global carbon cycle.

The shrub patch pattern has important influence on the ecosystems in the arid water-wind erosion crisscross regions. The objective of this study was to examine the effects of vegetation pattern of shrub spot patch on species diversity and soil water content at the sand in slopes in water-wind erosion crisscross region on the Loess Plateau. In this study, the shrub patch size was classified to four size classes, contrasting with bare land patch, and herbaceous plants, and soil water content of the shrub patch were measured in each patch. The Shannon–Wiener indices were 0.364 and 1.074 respectively in small and large patches, which were higher than 0.231 in the bare land patch. The Richness index was 1.41 in bare land patch, which was lower than 1.704 in small shrub patch and 4.370 in large shrub patch. The above- and below-ground biomass and surface soil water content were also significantly (p < 0.05) higher in the shrub patch than that in the bare land patch. These results suggest that the shrub patch could significantly increased species diversity, the above- and below-ground biomass, and surface soil water content. Based on these results, the soil was aggregated in shrub patch and the vegetation pattern was successive and each cycle of vegetation pattern was benefited by its previous stage in the water-wind erosion crisscross region on the Loess Plateau.

Community composition strongly affected the soil C and N storages. However, the influences of community composition on native grassland remain poorly understood. The purpose of this study is to investigate the ability of plant communities including how legumes affect the soil C and N storages in the semi-arid grassland. Experimental grassland communities were separated by whether or not containing legumes. We measured soil C and N storages and determined above-ground and below-ground biomass, litter biomass, plant species richness, and species diversity to understand the mechanisms underlying the changes of soil C and N storages and to determine the relationship of species diversity and productivity. The results showed that legumes increased above-ground and below-ground biomass and C and N storages. Soil C and N storages were significantly and positively related to above-ground and below-ground biomass, litter biomass, plant species richness, and diversity in the presence of legumes. The presence of legumes increased soil C and N simultaneously but not synchronously, which resulting in a higher C:N ratio. This study indicated that legumes increased soil C and N storages possibly through increasing biomass and soil C and N inputs. The increases are mediated by plant diversity and plant functional complementarity. We suggest that the combination of legumes-grass species may greatly enhance ecosystem services such as soil C and N storages, productivity, and diversity in semi-arid grassland. Copyright © 2016 John Wiley & Sons, Ltd.

Summary Theoretical explanations for vegetation pattern dynamic emphasized on banded pattern-forming systems on the dynamics of the spot pattern. In this context, we explore the patch pattern forming and development in the desertification land. We hypothesized that spatial heterogeneity of microtopography and soil properties with different patch sizes would determine vegetation pattern dynamics theory. The spatial heterogeneity of microtopography and soil properties with different patch sizes were studied. Differences between the inside and outside of the canopy of soil carbon content and soil total nitrogen content were significantly increasing with patches sizes. Sampling location across vegetation patch was the main factor controlling soil properties. Soil nutrient content and saturated hydraulic conductivity were the largest, while bulk density and the coarse sand content were the lowest at the sampling location of half-way between taproot and downslope edge of the canopy. The height of the mound relative to the adjacent soil interspace between shrubs increased as patches diameter increased at the upslope of the taproot. Hydrological and aeolian processes resulted in spatial distributions of soil moisture, nutrition properties, which lead to patch migrated to downslope rather than upslope. A conceptual model was integrated hydrological and nutrient facilitation and competition effects among the plant-soil in mosaic-pattern patch formation and succession process.

The trade-off between plant community structure and function is an important issue during grassland restoration. It is essential to assess changes of structure and function after converting farmland to grassland. Three restoration stages (5, 15, and 30 years) were studied to determine the optimum time when the trade-off between diversity and productivity occurs. The results showed that the vegetation coverage, height, and productivity significantly increased, but the species richness, diversity, and density significantly decreased along the restoration time. Grassland community presented a succession from small individuals and high density to larger individuals and lower density. The community changed from being dominated by grass and forb functional groups to being dominated only by the grass functional group. The dominant grass functional group plays a decisive role on community structure and function (productivity, diversity, and density) during grassland succession. Our results suggest that community structure and function were mainly driven by the dominant grass functional group during the long-term succession. Grassland should be utilized to suppress the leading role of the dominant functional groups in the 20th year for keeping the trade-off of diversity and productivity. We suggest that the restoration grassland should be considered to use appropriately in the 20th year. Our study could provide a key guidance for maintaining the community structure and function trade-off for cropland-converted grassland management in the semi-arid areas. Copyright (C) 2016 John Wiley & Sons, Ltd.