Spatiotemporal drivers of Nature's contributions to people: A county-level study.

Nature's contributions to people (NCP) encompass both the beneficial and detrimental effects of living nature on human quality of life, including regulatory, material, and non-material contributions. Globally, vital NCPs have been deteriorating, accelerated by changes in both natural and anthropogenic drivers over recent decades. Despite the often inevitable trade-offs between NCPs due to their spatially and temporally uneven distributions, few studies have quantitatively assessed the impacts of different drivers on the spatial and temporal changes in multiple NCPs and their interrelationships. Here we evaluate the effects of precipitation, temperature, population, gross domestic product, vegetation restoration, and urban expansion on four key regulatory NCPs-habitat maintenance, climate regulation, water quantity regulation, and soil protection-in Nei Mongol at the county level. We observe increasing trends in climate regulation and soil protection from 2000 to 2019, contrasted with declining trends in habitat maintenance and water quantity regulation. We have identified the dominant positive and negative drivers influencing each NCP across individual counties, finding that natural drivers predominantly overpowered anthropogenic drivers. Furthermore, we discover significant spatial disparities in the trade-off or synergy relationships between NCPs across the counties. Our findings illustrate how the impacts of various drivers on NCPs and their interrelationships can be quantitatively evaluated, offering significant potential for application in various spatial scales. With an understanding of trade-offs and scale effects, these insights are expected to support and inform policymaking at both county and provincial levels.

Successful anti-tumor effects with two novel bifunctional chemotherapeutic compounds that combine a LAT1 substrate with cytotoxic moieties in aggressive T-cell lymphomas.

T-cell lymphomas are aggressive neoplasms characterized by poor responses to current chemotherapeutic agents. Expression of the l-type amino acid transporter 1 (LAT 1, SLC7A5) allows for the expansion of healthy T-cell counterparts, and upregulation of LAT1 has been reported in precursor T-cell acute leukemia. Therefore, the expression of LAT1 was evaluated in a cohort of cutaneous and peripheral T-cell lymphomas. The findings demonstrated that LAT1 is upregulated in aggressive variants and absent in low-grade or indolent disease such as mycosis fungoides. In addition, upregulated LAT1 expression was seen in a large proportion of aggressive peripheral T-cell lymphomas, including peripheral T-cell lymphoma not otherwise specific (PTCL-NOS) and angioimmunoblastic T-cell lymphoma (AITL). The anti-tumor effects of two novel non-cleavable and bifunctional compounds, QBS10072S and QBS10096S, that combine a potent cytotoxic chemotherapeutic domain (tertiary N-bis(2-chloroethyl)amine) with the structural features of a selective LAT1 substrate (aromatic ß-amino acid) were tested in vitro and in vivo in T-cell lymphoma cell lines. The findings demonstrated decreased survival of T-cell lymphoma lines with both compounds. Overall, the results demonstrate that LAT1 is a valuable biomarker for aggressive T-cell lymphoma counterparts and QBS10072S and QBS10096S are successful therapeutic options for these aggressive diseases.

Soil freeze-thaw cycles affect spring phenology by changing phenological sensitivity in the Northern Hemisphere.

The use of frozen soil-vegetation feedback for predictive models is undergoing enormous changes under rapid climate warming. However, the influence of soil freeze-thaw (SFT) cycles on vegetation phenology and the underlying mechanisms remain poorly understood. By synthesizing a variety of satellite-derived data from 2002 to 2021 in the Northern Hemisphere (NH), we demonstrated a widespread positive correlation between soil thawing and the start of the growing season (SOS). Our results also showed that the SFT cycles had a significant impact on vegetation phenology mainly by altering the phenological sensitivities to daytime and nighttime temperatures, solar radiation and precipitation. Moreover, the effects of SFT cycles on the sensitivity of the SOS were more pronounced than those on the sensitivity of the end of the growing season (EOS) and the length of growing season (LOS). Furthermore, due to the degradation of frozen soil, the changes in phenological sensitivity in the grassland and tundra biomes were significantly larger than those in the forest. These findings highlighted the importance of incorporating the SFT as an intermediate process into process-based phenological models.

Exploring spatial-temporal driving factors for changes in multiple ecosystem services and their relationships in West Liao River Basin, China.

Ecosystem services (ES) are the direct and indirect benefits people obtain from ecosystems, serving as a bridge linking ecological systems and social-economic systems. The quantitative assessment of the dynamic changes in ES and their relationships and the identification of the driving forces behind them have recently become a research hotspot. However, several research gaps remain challenging, such as the lack of an analytical framework for selecting relevant driving factors and the need for an innovative approach that integrally estimates the impacts of driving factors on the changes in ES and the relationships between ES. In this study, we modify the social-ecological system framework as the analytical basis and suggest a series of principles for selecting relevant driving factors, we then adopt the path analysis model to simultaneously and consistently quantify the contributions of driving factors to ES changes and their relationships. Using the West Liao River Basin (WLRB) as a case study, the results show the spatial-temporal variations in three ES and six driving factors from 2000 to 2020, divided into four periods. The estimation of path analysis model confirm two hypotheses that different driving factors exerted differential effects on changes in multiple ES in four periods for the whole WLRB and in three sub-basins for the period 2015-2020. In addition, the path analysis exhibits the quantitative relationships between food production, water yield, and soil conservation, which vary temporally and spatially in different periods and different sub-basins. The identification of driving factors is helpful for supporting policy-making to construct a coupled self-adjusted social-ecological for the benefit of the public.

Effects of species mixtures on soil water storage in the semiarid hilly gully region.

Mixed-species plantations are promoted to restore degraded ecosystems and improve soil quality worldwide. However, differences of soil water conditions between pure and mixed plantations are still controversial and how species mixtures affect soil water storage (SWS) was not well quantified. In this study, vegetation characteristics, soil properties and SWS were continuously monitored and quantified in three pure plantations (Armeniaca sibirica (AS), Robinia pseudoacacia (RP) and Hippophae rhamnoides (HR)) and their corresponding mixed plantations (Pinus tabuliformis-Armeniaca sibirica (PT-AS), Robinia pseudoacacia-Pinus tabuliformis-Armeniaca sibirica (RP-PT-AS), Platycladus orientalis-Hippophae rhamnoides plantation (PO-HR), Populus simonii-Hippophae rhamnoides (PS-HR)). The results found that SWS of 0-500 cm in RP (333.60 ± 75.91 mm) and AS (479.52 ± 37.50 mm) pure plantations were higher than those in their corresponding mixed plantations (p > 0.05). SWS in the HR pure plantation (375.81 ± 81.64 mm) was lower than that in its mixed plantation (p > 0.05). It is suggested that the effect of species mixing on SWS was species specific. Additionally, soil properties exerted more contributions (38.05-67.24 %) to SWS than vegetation characteristics (26.80-35.36 %) and slope topography (5.96-29.91 %) at different soil depths and the whole 0-500 cm soil profile. Furthermore, by excluding the effects of soil properties and topographic factors, plant density and height were particularly important to SWS (with standard coefficients 0.787 and 0.690 respectively). The results implied that not all the mixed plantations exhibits the better soil water conditions than the compared pure plantations, which was tightly related to species selected for mixing. Our study provides scientific support for revegetation technique improvement (structural adjustment and species optimization) in this region.

Streamflow and sediment load changes from China's large rivers: Quantitative contributions of climate and human activity factors.

Riverine water and sediment discharge drive global material circulation and energy transfer, and they are crucial to the biogeochemical cycle. We investigated the changes in water-sediment fluxes in six major rivers from north to south in China from the mid-1950s to 2020 under the influence of climate change and human activities, and quantified the contributions of these specific influencing factors to water-sediment flux changes. Results showed that streamflow of the Songhua, Liao and Yellow rivers decreased significantly (p < 0.05). The sediment load of all rivers reduced significantly (p < 0.01) except the Songhua River. Streamflow or sediment fluxes to the oceans have increased or stabilized since around 2000, and the terrestrial sediment yielding center in China has shifted southward from the Yellow River to the Yangtze and Pearl rivers. The contribution of precipitation to the streamflow and sediment load changes decreased from north to south across the six rivers. From the mid-1950s to 2020, the underlying land surface change was the dominant contributor (>70 %) to reducing streamflow in the Songhua and Yellow rivers, while climate change (>50 %) was responsible for decreased streamflow in the Liao and Huai rivers. The sediment load reduction of the six rivers was attributed mainly to human activities. Among them, dam construction, human water consumption and catchment land surface change have reduced the total sediment load into the sea by 49 %, 25 % and 19 %, respectively. These results highlight that north-south variability in water and sediment flux are driven by both natural and anthropogenic forcing agents.

Effect of Shrub Components on Soil Water and Its Response to Precipitation at Different Time Scales in the Loess Plateau.

Water shortages have become the major limiting factor for ecological protection and sustainable development in the Loess Plateau. Few studies have focused on the effects of different plant components on soil water and its response to precipitation at different time scales. This study conducted an observation of shrub plants with three treatments (natural condition (NC), canopy + roots after removing the litter (CR), and only roots (OR)) to monitor the dynamics of soil water during the rainy season of an extreme drought year in 2015. The results showed that the soil moisture content (SMC) and soil water storage (W) had a trend of OR > CR > NC. The response of the SMC to precipitation was gradually decreased and delayed for longer with increasing soil depth. Daily precipitation >10 mm was the threshold to trigger an SMC response below 20 cm of depth. The thresholds of precipitation to increase W were 2.09-2.54 mm at the daily scale and 29.40-32.56 mm at the monthly scale. The effect of precipitation on W and its change (∆W) also depended on the time scales. At the daily scale, precipitation only explained 1.6%, 0.9%, and 2.4% of the W variation in NC, CR, and OR, respectively. However, precipitation was more important for ∆W, making a contribution of 57.6%, 46.2%, and 56.6%, respectively, and the positive ∆W induced by precipitation happened more easily and frequently at deeper depths in OR. At the monthly scale, the contribution of precipitation to ∆W increased to 75.0%, 85.0%, and 86%, respectively. The ∆W of the whole rainy season was OR > NC > CR. Precipitation of the monthly scale displayed higher contributions to soil water than that of the daily scale. Plant components had different influences on soil water and its response to precipitation, which was strengthened by the roots, weakened by the canopy, and neutralized by the litter. Regular cutting of the canopy at the single-shrub scale may help increase water storage, which is useful for vegetation management and hydrologic regulation.

Spatial Heterogeneity of Root Water Conduction Strategies of Zygophyllaceae Plants in Arid Regions of China.

Desert plants are the main component of species diversity in desert ecosystems, and studying the anatomy and function of desert plant xylem is of great significance for understanding climate sensitivity and adaptation mechanisms to arid ecosystems. In this study, 11 sampling points were selected in the region starting from the Loess Plateau to the Jungar Basin, the taproot anatomy materials of 9 samples of Zygophyllaceae plants were collected, and the water conduction strategies and spatial distribution characteristics of these species were analyzed. The age, growth rate, vessel number, vessel fraction, vessel area within a fixed measurement range (TVA), MVA, water conductivity (TKp, MKp) and vessel diameter ranged between 1 and 27 years, 43.67 and 678.10 µm/year, 20 and 1952, 4.43 and 26.58%, 8009.62 and 192069.12 µm², 27.63 and 2164.33 µm², 0.417 and 364.97 kg m−1 MPa−1 s−1, 0.000624 and 7.60 kg m−1 Mpa−1 s−1, and 5.57 and 73.87 µm, respectively. The number of root vessels (R = 0.27, p > 0.05) of Zygophyllaceae plants decreased with the decrease in precipitation, and the average vessel area (R = −0.28, p > 0.05) and hydraulic diameter (R = −0.29, p > 0.05) showed an upward trend. This shows that the water hydraulic efficiency priority strategy may be adopted in the root system of Zygophyllaceae plants in severe drought stress condition, and the water hydraulic safety priority strategy may be used in mild drought stress conditions. With the increase in temperature, the root age of Zygophyllaceae plants showed an increasing trend, and the growth rate showed a downward trend, indicating that the radial growth of the roots of Zygophyllaceae plants is mainly affected by temperature. Altitude influences plant growth by affecting temperature and precipitation in arid habitats. The findings of the present study on root xylem anatomical characteristics and life history strategies provides a scientific basis for the ecological restoration of vegetation in arid and semi-arid areas of China.

Spatiotemporal changes and driving forces of ecosystem vulnerability in the Yangtze River Basin, China: Quantification using habitat-structure-function framework.

Ecosystem vulnerability is the degree to which an ecosystem is susceptible to adverse effects of external disturbances. Exploring the pattern of ecosystem vulnerability and its driving mechanism is important for regional ecological protection and management. A little study has conducted the ecosystem vulnerability assessment from the perspective of multiple ecosystems characteristics, and the spatial heterogeneity impacts of climate change and human activities on ecosystem vulnerability variation need to be further explored. In this study, a habitat-structure-function framework was proposed to evaluate ecosystem vulnerability pattern of the Yangtze River Basin (YRB) in China from 1990 to 2018. Then, the spatial heterogeneity impacts of various factors on ecosystem vulnerability changes were examined utilizing the Geographically Weighted Regression model. Results show that the ecosystem vulnerability index (EVI) pattern in the YRB decreased from upstream to downstream. There was 63.85% of the basin area experiencing a decline in EVI from 1990 to 2018, which was primarily found in the source, southwest and north regions, while the southeast and east regions have suffered an increase in EVI. The impact of climate change on EVI changes increased as time scales increase, while, human activities were still the dominant factor leading EVI changes. Overall, areas with great impact of climate change on EVI variation were concentrated in the source region and upper reaches, while the remarkable impact of human activities occurred in the whole basin. The enhancement of climate warming and humid trend and the strengthen of ecological protection were benefit to the decline of EVI. The proposed framework can be extended to assess vulnerability in other areas or specific ecosystem types, and the findings are expected to provide policy recommendations for ecosystem conservation and management in the YRB.

Effects of land-use patterns on soil carbon and nitrogen variations along revegetated hillslopes in the Chinese Loess Plateau.

In water-limited areas, revegetation of abandoned croplands may lead to extensive land-use changes and considerable variations on soil carbon (C) and nitrogen (N). However, the impact of land-use patterns (i.e., the spatial combinations of different land-use types) on soil C and N variations following revegetation remains unclear. In this study, we measured soil organic carbon (SOC), total carbon (TC), and total nitrogen (TN) stocks to a depth of 200 cm in grassland (GL), shrubland (SL), young forestland (YF), and mature forestland (MF) under four land-use patterns in a catchment located in the Chinese Loess Plateau. The highest SOC, TC and TN stocks occurred in MF and the lowest was found in GL. Compared to every single land-use type, soil C and N stocks significantly increased under different land-use patterns. The highest SOC stock (6.51 kg m-2) was found in the GL-YF-SL pattern, and the highest TC stock (47.25 kg m-2) and TN stock (0.70 kg m-2) were both observed in the MF-YF pattern. SOC stocks showed significantly positive correlations with TC and TN stocks under different land-use patterns (p < 0.05), except for the GL-MF. The soil C-N interactions were stronger in the MF-SL and GL-YF-SL patterns compared to the GL-MF and MF-SL. Redundancy analysis indicated that the SOC, TC, and TN variations were well explained by aboveground biomass and land-use patterns, with accumulated variance of 41.6% and 54.2% in Axis 1 and Axis 2, respectively. The differences of soil C and N accumulation among land-use patterns were mostly related to different vegetation coverage and the intensity of soil erosion. This study indicates that creating proper spatial distribution of land-use types on hillslopes could benefit soil C and N sequestrations and ecosystem restoration in semi-arid environments.

Identification of climate variables dominating streamflow generation and quantification of streamflow decline in the Loess Plateau, China.

Precipitation-extremes-driven floods, which compose an important proportion of streamflow but cause severe adverse impacts in the Loess Plateau of China, urged the progressive implementation of ecological restoration (ER) strategies in the Loess Plateau (LP) of China. Knowledge of the linkage between climate variables (especially precipitation extremes) and streamflow generation become more essential for advanced catchment management as ER and climate variability have resulted in reduced streamflow and freshwater stress. Here, a partial least squares regression (PLSR) approach was used to investigate this issue at 16 main catchments of the LP over a reference period (1961-1979). Then, we quantified streamflow decline during the "Integrated Soil and Water Conservation" (1980-1999) and the "Grain for Grain" (2000-2015) strategies by PLSR modeling. We found that the dominant climatic variables controlling annual streamflow include heavy precipitation amount and heavy precipitation days, maximum precipitation event amount, number of consecutive wet days, annual total precipitation (daily precipitation ≥1 mm), and effective precipitation amount (daily precipitation ≥5 mm). Further, the effect of precipitation extremes on streamflow generation is stronger in drier catchments. The impacts of precipitation extremes on streamflow generation can be strengthened by agricultural cultivation and weakened by revegetation (especially reforestation). Overall, we found that climate-driven annual streamflow decreased by 7.5 mm during 1980-1999 and by 5.6 mm during 2000-2015, in comparison to 1961-1979. The dominant cause of streamflow reduction was ER, with the contribution increasing from 59% in 1980-1999 to 82% in 2000-2015. The PLSR approach enables the identification of linkages between climate variables and streamflow generation, and the prediction of climate-driven streamflow. This study yields a greater understanding of the influences of climate variability and ER on streamflow change, and is helpful to identify hydroclimatological trends and projections.

Relative contributions of wind and water erosion to total soil loss and its effect on soil properties in sloping croplands of the Chinese Loess Plateau.

Wind and water erosion are two dominant types of erosion that lead to soil and nutrient losses. Wind and water erosion may occur simultaneously to varying extents in semi-arid regions. The contributions of wind and water erosion to total erosion and their effects on soil quality, however, remains elusive. We used cesium-137 (137Cs) inventories to estimate the total soil erosion and used the Revised Universal Soil Loss Equation (RUSLE) to quantify water erosion in sloping croplands. Wind erosion was estimated from the subtraction of the two. We also used 137Cs inventories to calculate total soil erosion and validate the relationships of the soil quality and erosion at different slope aspects and positions. The results showed that wind erosion (1460tkm-2a-1) on northwest-facing slope was responsible for approximately 39.7% of the total soil loss, and water erosion (2216tkm-2a-1) accounted for approximately 60.3%. The erosion rates were 58.8% higher on northwest- than on southeast-facing slopes. Northwest-facing slopes had lower soil organic carbon, total nitrogen, clay, and silt contents than southeast-facing slopes, and thus, the 137Cs inventories were lower, and the total soil erosions were higher on the northwest-facing slopes. The variations in soil physicochemical properties were related to total soil erosion. The lowest 137Cs inventories and nutrient contents were recorded at the upper positions on the northwest-facing slopes due to the successive occurrence of more severe wind and water erosion at the same site. The results indicated that wind and water could accelerate the spatial variability of erosion rate and soil properties and cause serious decreases in the nutrient contents in sloping fields. Our research could help researchers develop soil strategies to reduce soil erosion according to the dominant erosion type when it occurs in a hilly agricultural area.

Effects of revegetation and precipitation gradient on soil carbon and nitrogen variations in deep profiles on the Loess Plateau of China.

Precipitation is one of the most important factors affecting the variations in soil carbon (C) and nitrogen (N) following revegetation. However, the effects of revegetation and precipitation gradients on soil organic carbon (SOC), total nitrogen (TN) and C-N interactions in deep profiles over large scales are poorly understood. This study measured the SOC and TN stocks to depth of 300 cm in three revegetation types (grassland, shrubland and forestland) and paired cropland stands at seven sites along a precipitation gradient with mean annual precipitation (MAP) from 280 to 540 mm yr-1 in the Loess Plateau of China. The results showed that the SOC and TN stocks in the 0-300 cm profile increased along the precipitation gradient. Revegetation did not always result in accumulation of SOC and TN stocks, which depended on the precipitation condition and varied among different vegetation types. Grassland restoration resulted in more SOC and TN accumulation than shrubland and forestland in areas with MAP < 510 mm, whereas there were losses in SOC and TN following grass plantation in sites with MAP > 510 mm. The changes in SOC and TN stocks following revegetation (∆SOC and ∆TN) were significantly correlated with MAP in only the 0-20 cm layer, whereas the changes in the C/N ratio of each depth were significantly and negatively correlated with MAP. The correlations between ∆SOC and ∆TN were stronger in the 0-60 cm layer than that in the 60-300 cm layer, and an accumulation of 1 g TN was associated with approximately 7.9 g increase of SOC in the 0-300 cm profile following revegetation. This study indicated that the changes in soil C and N stocks following revegetation had different patterns along precipitation gradient and among depths, and grassland restoration and N fertilizer input benefitted soil C and N sequestration in drier areas.

Ecological effects and potential risks of the water diversion project in the Heihe River Basin.

To curb the severe ecological deterioration in the lower Heihe River Basin (HRB) in northwest China, a water diversion project was initiated in 2000. A comprehensive analysis of the ecological effects and potential risks associated with the project is needed. We assessed the hydrological and ecological achievements, and also analyzed the potential problems after the project was completed. We found that since the project began the hydrological regime has changed, with more than 57.82% of the upstream water being discharged to the lower reaches on average. As a result, the groundwater level in the lower reaches has risen; the terminal lake has gradually expanded to a maximum area in excess of 50km2 since 2010, and there has been a significant recovery of vegetation in the riparian zone and the Ejin core oases, which represents the initial rehabilitation of the degraded downstream environment. Additionally, the economy of Ejin has developed spectacularly, with an annual growth rate of 28.06%. However, in the middle reaches, the average groundwater level has continuously declined by a total of 5.8m and significant degradation of the vegetation has occurred along the river course. The discrepancy in the water allocation between the middle and lower reaches has intensified. This highlights the inability of the current water diversion scheme to realize further ecological restoration and achieve sustainable development throughout the whole basin. In future water management programs, we recommend that water allocation is coordinated by considering the basin as an integrated entity and to scientifically determine the size of the midstream farmland and downstream oasis; restrict non-ecological water use in the lower reaches, and jointly dispatch the surface water and groundwater.

River flow is critical for vegetation dynamics: Lessons from multi-scale analysis in a hyper-arid endorheic basin.

Knowledge of the spatio-temporal responses of vegetation dynamics to hydro-climatic factors is important to assess ecological restoration efforts in arid and semiarid areas. In this study, the vegetation dynamics during 2000-2015 were investigated in the downstream area of the Heihe River Basin (HRB) in Northwest China where an ecological water diversion project (EWDP) commenced in 2000. The spatio-temporal relationships between vegetation cover and climatic factors (precipitation and temperature) and available water resources (river flow and groundwater) were determined. The results indicated that the mean growing season NDVI increased significantly during the period of 2000-2015, and the area of East Juyan Lake (EJL) enlarged to 36.4km2 in 2010. The scale effect of the relationships between NDVI and hydro-climatic factors was obvious. At the catchment scale, changes of NDVI were not significantly correlated with climatic factors, but significantly related with the antecedent 1-year river flow. River flow played an important role in vegetation growth within approximately 2000m distance from the river bank. At the pixel scale, the changes of NDVI were significantly positive with temperature and river flow in 17.40% and 7.14% of the study area, respectively, whereas significant relationship between NDVI and precipitation occurred in only 0.65% of study area. The suitable water table depth for vegetation growth was between 1.8 and 3.5m. The increased river flow and recovered groundwater due to the EWDP were critical for the improvement of vegetation cover, whereas the riparian vegetation degraded along some parts of the river bank. It is important to improve integrated watershed management with consideration of spatio-temporal lagged hydro-ecological connections in the study area.

Determining the hydrological responses to climate variability and land use/cover change in the Loess Plateau with the Budyko framework.

Understanding and quantifying the impacts of land use/cover change and climate variability on hydrological responses are important to the design of water resources and land use management strategies for adaptation to climate change, especially in water-limited areas. The elasticity method was used to detect the responses of streamflow and runoff coefficient to various driving factors in 15 main catchments of the Loess Plateau, China between 1961 and 2009. The elasticity of streamflow (Q) and runoff coefficient (Rc) to precipitation (P), potential evapotranspiration (E0), and catchment characteristics (represented by the parameter m in Fu's equation) were derived based on the Budyko hypothesis. There were two critical values of m=2 and E0/P=1 for the elasticity of Q and Rc. The hydrological responses were mainly affected by catchment characteristics in water-limited regions (E0/P>1), and in humid areas (E0/P<1), climate conditions played a more important role for cases of m>2 whereas catchment characteristics had a greater impact for cases of m<2. The annual Q and Rc in 14 of the 15 catchments significantly decreased with average reduction of 0.87mmyr(-1) and 0.18%yr(-1), respectively. The mean elasticities of Q to P, E0 and m were 2.66, -1.66 and -3.17, respectively. The contributions of land use/cover change and P reduction to decreased Q were 64.75% and 41.55%, respectively, while those to decreased Rc were 75.68% and 32.06%, respectively. In contrast, the decreased E0 resulted in 6.30% and 7.73% increase of Q and Rc, respectively. The contribution of land use/cover changes was significantly and positively correlated with the increase in the percentage of the soil and water conservation measures area (p<0.05). The Rc significantly and linearly decreased with the vegetation coverage (p<0.01). Moreover, the Rc linearly decreased with the percentage of measures area in all catchments (eight of them were statistically significant with p<0.05).

Linking the soil moisture distribution pattern to dynamic processes along slope transects in the Loess Plateau, China.

Soil moisture pulses are a prerequisite for other land surface pulses at various spatiotemporal scales in arid and semi-arid areas. The temporal dynamics and profile variability of soil moisture in relation to land cover combinations were studied along five slopes transect on the Loess Plateau during the rainy season of 2011. Within the 3 months of the growing season coupled with the rainy season, all of the soil moisture was replenished in the area, proving that a type stability exists between different land cover soil moisture levels. Land cover combinations disturbed the trend determined by topography and increased soil moisture variability in space and time. The stability of soil moisture resulting from the dynamic processes could produce stable patterns on the slopes. The relationships between the mean soil moisture and vertical standard deviation (SD) and coefficient of variation (CV) were more complex, largely due to the fact that different land cover types had distinctive vertical patterns of soil moisture. The spatial SD of each layer had a positive correlation and the spatial CV exhibited a negative correlation with the increase in mean soil moisture. The soil moisture stability implies that sampling comparisons in this area can be conducted at different times to accurately compare different land use types.

Contaminant transport in soil with depth-dependent reaction coefficients and time-dependent boundary conditions.

Predicting the fate and movement of contaminant in soils and groundwater is essential to assess and reduce the risk of soil contamination and groundwater pollution. Reaction processes of contaminant often decreased monotonously with depth. Time-dependent input sources usually occurred at the inlet of natural or human-made system such as radioactive waste disposal site. This study presented a one-dimensional convection-dispersion equation (CDE) for contaminant transport in soils with depth-dependent reaction coefficients and time-dependent inlet boundary conditions, and derived its analytical solution. The adsorption coefficient and degradation rate were represented as sigmoidal functions of soil depth. Solute breakthrough curves (BTCs) and concentration profiles obtained from CDE with depth-dependent and constant reaction coefficients were compared, and a constant effective reaction coefficient, which was calculated by arithmetically averaging the depth-dependent reaction coefficient, was proposed to reflect the lumped depth-dependent reaction effect. With the effective adsorption coefficient and degradation rate, CDE could produce similar BTCs and concentration profiles as those from CDE with depth-dependent reactions in soils with moderate chemical heterogeneity. In contrast, the predicted concentrations of CDE with fitted reaction coefficients at a certain depth departed significantly from those of CDE with depth-dependent reactions. Parametric analysis was performed to illustrate the effects of sinusoidally and exponentially decaying input functions on solute BTCs. The BTCs and concentration profiles obtained from the solutions for finite and semi-infinite domain were compared to investigate the effects of effluent boundary condition. The finite solution produced higher concentrations at the increasing limb of the BTCs and possessed a higher peak concentration than the semi-infinite solution which had a slightly long tail. Furthermore, the finite solution gave a higher concentration in the immediate vicinity of the exit boundary than the semi-infinite solution. The applicability of the proposed model was tested with a field herbicide and tracer leaching experiment in an agricultural area of northeastern Greece. The simulation results indicated that the proposed CDE with depth-dependent reaction coefficients was able to capture the evolution of metolachlor concentration at the upper soil depths. However, the simulation results at deep depths were not satisfactory as the proposed model did not account for preferential flow observed in the field.

Dual inhibitors of inosine monophosphate dehydrogenase and histone deacetylase based on a cinnamic hydroxamic acid core structure.

Small molecules that act on multiple biological targets have been proposed to combat the drug resistance commonly observed for cancer chemotherapy. By combining the structural features of known inhibitors of inosine monophosphate dehydrogense (IMPDH) and histone deacetylase (HDAC), dual inhibitors of IMPDH and HDAC based on the scaffold of cinnamic hydroxamic acid (CHA) have been designed, synthesized, and evaluated in biological assays. Key features, including the linker length, linker functionality, substitution position, and interacting groups, have been explored. Their individual contribution to the inhibitory activities against human IMPDH1 and IMPDH2 as well as HDAC has been assessed.

Cobalt-catalyzed asymmetric olefin aziridination with diphenylphosphoryl azide.

The cobalt(II) complexes of D2-symmetric chiral porphyrins, such as 3,5-Di(t)Bu-ChenPhyrin P5, can catalyze asymmetric olefin aziridination with diphenylphosphoryl azide (DPPA) as a nitrene source. Acceptable asymmetric inductions were observed for the [Co(P5)]-based catalytic system, forming the desired N-phosphorus-substituted aziridines in moderate to high yields and good enantioselectivities.