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A colorimetric assay based on an enzyme-inhibition strategy is promising for the on-site detection of pesticide residues. Due to the high cost and low stability of enzymes, nanozymes (nanomaterials with enzyme-like activities) are widely developed as substitutes of enzymes. However, the inhibition of pesticides toward enzymes and nanozymes generally lacks selectivity. It is of great significance and challenge to design a specific pesticide assay based on an activity-inhibition strategy. Here, we discovered that iridium nanoparticles possess both peroxidase-like and oxidase-like activities under the same conditions, and their catalytic mechanisms are different. The synergistic effect of dual enzyme-like activities enhanced the colorimetric signal. Interestingly, the dual enzyme-mimicking activities could be simultaneously inhibited, and the inhibition effect exhibited high selectivity toward malathion. Considering the popularity and the hazards of malathion, a malathion assay method based on activity inhibition was established without enzymes and a redundant process. The synergistic effect of the selective inhibition of dual enzyme-like activities enhanced the selectivity and sensitivity. The proposed assay strategy opens up an avenue for specific assay of various pesticides.

Photosynthetically carbon (C) allocation largely determines yield and C sequestration of agroecosystem. However, how C allocation of crops responses to climate change at the long-time scale is poorly defined. Combining thirteen years of eddy covariance and inventory measurements, we comprehensively investigated C allocation mechanism in a winter-wheat and summer-maize double cropping field. Significantly increased gross primary production (GPP) was benefited from CO2 fertilization, and 35% of increased GPP transferred to strengthening C sequestration. However, elevated temperature and drying surface soil moisture stimulated the partitioning of GPP to autotrophic respiration, resulted in conservative net primary production and grain yield. Maize faced a greater risk of C loss and yield reduction than wheat to warming and drying. By synthesizing published long-term data of agroecosystems, we further highlight that the GPP partitioning cannot be simply predicted by allometric theory, particularly for grains, which should be considered in predicting C budget and crop yield.

DNase-catalyzed hydrolysis of extracellular DNA (eDNA) have been widely employed to eradicate intractable biofilms. Although aggregation-induced emission (AIE) has become the ideal tool for killing planktonic bacteria, AIE luminogens (AIEgens) often lack DNase-mimetic activity, in order to suffer from poor anti-biofilm capacity. Here, an “AIEzyme”, a kind of AIE nanomaterial with enzyme-like activity, is designed and synthesized, where the AIEgens are used as the ligands of Zr-based coordination polymer nanoparticles. Not only do AIEzyme have enduring DNase-mimetic activity with high substrate affinity and low activation energy, but also structural rigidity-stabilized fluorescence. Due to the long-acting hydrolysis for eDNA in biofilm, AIEzyme can efficiently disorganize the established biofilms with good penetrability and realize the healing of superbugs-infected wound for at least seven days under only one dose of AIEzyme. Moreover, AIEzymes can be observed by virtue of their own AIE character, facilitating the study on self-positioning and residual amount of AIEzymes in wound. On the support of AIEzyme, we expect to explore an idea for the application development of AIEgen.

Al–MgAl2O4–MgO refractories were prepared using fused magnesia, metal Al, fused spinel and sintered high purity magnesia as raw materials. The phase composition and microstructure of Al–MgAl2O4–MgO refractories treated at 1400 °C under N2 atmosphere were investigated by means of XRD, SEM and EDS. The results showed that magnesia (MgO) whiskers and MgAlON whiskers were formed on the surface and in the inner area of the Al–MgAl2O4–MgO refractories, respectively. The MgO whiskers grew preferentially along the axial direction, forming cylindrical shape MgO whiskers. Then the cylindrical MgO whiskers further absorbed Mg(g) and O2(g), and grew along the radial direction to form the square columnar shape MgO whiskers. The MgAlON whiskers firstly grew in one-dimensional direction, forming whisker shape MgAlON, then some whisker shape MgAlON gradually developed and grew into two-dimensional flake shape MgAlON. The sintering and thermal shock resistance was significantly improved by the whiskers. The growth process of magnesia whiskers and MgAlON whiskers were dominated by a vapor-solid (VS) mechanism.

Molecular motion is related to the structures and properties of the molecules and their aggregates. Owing to both weak intermolecular interactions and complicated interplay between molecules, the manipulation of inter-molecular motion to realize specific structures and properties as well as applications, is challenging but attractive. Here, we reported that the photoluminescence property of luminogens could be tuned by the manipulation of the inter-molecular motion based on the dynamic ionic bond between the cation of acridinium and the anion of tetraphenyl boron. The free inter-molecular motion and the strong attraction of the ionic bond in the non/less polar solvents enabled the formation of a dark state in the excited state with faint emission. In contrast, multiple ionic bonds between cation and anion together with non-covalent interactions were observed in the crystalline state. This directly contributed to the restriction of the inter-molecular motion (RIMM), and eventually gave rise to bright aggregation-induced emission. Such a RIMM model for efficient solid-state emission can be validated by several organic ionic species. More importantly, this type of “multicomponent luminogens” showed remarkable reactive oxygen species generation, which enabled them to kill bacteria even superbugs upon white-light irradiation. This study not only provided fundamental insights into the molecular motion-structure-property relationship, but also opened up the possibility of constructing highly efficient luminogens in aggregates via RIMM for advanced applications.

Background Emerging studies have reported that long non-coding RNAs (lncRNAs) were crucial regulators in the progression of colorectal cancer (CRC). LncRNA susceptibility 9 (CASC9) was involved in several cancers; however, its role in CRC remains unknown. Methods RT-PCR was done to probe the expression of CASC9 and miR-193a-5p in CRC samples. CRC cell lines (HCT116 and SW480) were used as cell models. The biological influence of CASC9 on cancer cells was studied using CCK-8 assay, Transwell assay and TUNEL assay in vitro, and subcutaneous xenotransplanted tumor model in vivo. Interaction between CASC9 and miR-193a-5p was investigated by bioinformatics analysis, RT-PCR, and luciferase reporter assay. The expression level of the downstream gene of miR-193a-5p, erb-b2 receptor tyrosine kinase 2 (ERBB2), was tested by Western blot. Results CASC9 was significantly up-regulated in CRC samples, while miR-193a-5p was markedly down-regulated. Overexpression of CASC9 promoted viability, migration and invasion of CRC cells, while overexpression of miR-193a-5p had the opposite effect. CASC9 could down-regulate miR-193a-5p via sponging it, and there was a negative relevancy between CASC9 and miR-193a-5p in CRC samples. CASC9 also enhanced the expression levels of ERBB2, while this effect could be reversed by co-transfection with miR-193a-5p. Conclusion CASC9, an oncogenic lncRNA, was abnormally up-regulated in CRC tissues, and it could indirectly modulate the expression of ERBB2 via reducing the expression level of miR-193a-5p.

Photocatalytic hydrogen evolution from water is a valid method to face the challenge of energy shortage. TiO2, as the most well-known and investigated semiconductor photocatalyst, has been extensively applied in this field. However, the hydrogen evolution performance of TiO2 suffer from low efficiency due to the high combination of photo-induced carries and the narrow light utilization range resulting from wide band gap. In this work, we use the commercial TiO2 (P25) and fullerene (C60) as precursors to construct an efficient photocatalyst via a mild mixed method. The introduction of C60 not only effectively broaden light absorption, but also suppressed the recombination of photo-generated carriers on TiO2. The photocatalytic water splitting property of the optimum sample achieve 597.2 μmol g−1 h−1, which is 31 times higher than pure P25.

Drought is one of the most damaging and complicated disasters in the world. Timely monitoring of droughts over agro-ecosystem is important for reducing yield loss. The potential of satellite-borne solar-induced chlorophyll fluorescence (SIF) for drought detection and assessment were explored in this study. As denoted by the significant negative anomalies of standardized precipitation evapotranspiration index (SPEI), precipitation (PPT), soil moisture (SM) and positive anomalies of land surface temperature (LST) and air temperature difference (DT), a severe drought event was detected at summer maize growth period in 2014 over the North China Plain. In the duration of this drought, the anomalies of SIF and SIFyield (SIF normalized by absorbed photosynthetically active radiation) were negative. The regional averaged SIF and SIFyield declined 9.0% and 9.3% in July, and 11.9% and 12.5% in August, respectively, higher than those of normalized difference vegetation index (NDVI) (4.8% in July and 3.5% in August) and land surface water index (LSWI) (8.2% in July and 4.9% in August). In addition, the linear relationship between gross primary productivity (GPP) and SIF (R2 = 0.85) was more significant than that between GPP and NDVI (R2 = 0.60). The GPP estimated by SIF decreased by 10.6% in counties with severe drought in 2014, which was consistent with the yield reduction (9.1%) estimated by county statistical yield data. It is concluded that satellite SIF is more reliable and effective for regional drought monitoring and assessment, which can help policy-makers or farmers implement appropriate measures to mitigate the drought disasters.

Based on the MODIS NDVI data and Landsat TM/ETM data of 2002 and 2012, this paper extracts the planting area of winter wheat—summer maize, single spring maize, cotton and forest/fruit trees, vegetable and paddy, and made the agricultural land use map of the North China Plain (NCP). Agricultural land use area accounted for 63.32% compared to the total area of the NCP in 2002. And it increased to 65.66% in 2012, which mainly caused by the vegetables and forest/fruit trees increasing. Planting areas of winter wheat—summer maize, cotton, single spring maize, forest/fruit trees, vegetables and paddy were 5031.21×103, 865.90×103, 1226.10×103, 1271.17×103, 648.02×103, 216.51×103 ha in 2012. Rank of changes was: vegetables (+45%) > forest/fruit trees (+27.4%) > paddy (−23.7%) > cotton (−20.4%) > single spring maize (+17.3%) > winter wheat—summer maize (−0.6%). In developed region like Beijing and Tianjin, planting area of crops with high economic benefit (such as fruit trees and vegetables) increased significantly. Government policies for groundwater protection caused obvious decline of winter wheat cultivation in Hebei Province. Cotton planting in Shandong Province decreased more than 200,000 ha during 2002–2012. The data products will be published in the website: http://hydro.sjziam.ac.cn/Default.aspx . To clarify the agricultural land use in the NCP will be very helpful for the regional agricultural water consumption research, which is the serious problem in the NCP.

The North China Plain is one of the most water-stressed areas in China. Irrigation of winter wheat mainly utilizes groundwater resources, which has resulted in severe environmental problems. Accurate estimation of crop water consumption and net irrigation water consumption is crucial to guarantee the management of agricultural water resources. An actual crop evapotranspiration (ET) estimation model was proposed, by combining FAO Penman-Monteith method with remote sensing data. The planting area of winter wheat has a significant impact on water consumption; therefore, the planting area was also retrieved. The estimated ET showed good agreement with field-observed ET at four stations. The average relative bias and root mean square error (RMSE) for ET estimation were −2.2% and 25.5 mm, respectively. The results showed the planting area and water consumption of winter wheat had a decreasing trend in the Northern Hebei Plain (N-HBP) and Southern Hebei Plain (S-HBP). Moreover, in these two regions, there was a significant negative correlation between accumulated net irrigation water consumption and groundwater table. The total net irrigation water consumption in the N-HBP and S-HBP accounted for 12.9×109 m3 and 31.9×109 m3 during 2001–2016, respectively. Before and after 2001, the decline rate of groundwater table had a decreasing trend, as did the planting area of winter wheat in the N-HBP and S-HBP. The decrease of winter wheat planting area alleviated the decline of groundwater table in these two regions while the total net irrigation water consumption was both up to 28.5×109 m3 during 2001–2016 in the Northwestern Shandong Plain (NW-SDP) and Northern Henan Plain (N-HNP). In these two regions, there was no significant correlation between accumulated net irrigation water consumption and groundwater table. The Yellow River was able to supply irrigation and the groundwater table had no significant declining trend.

Stable oxygen and hydrogen isotopic compositions (δ18O and δD) of plant xylem water and its potential water sources can provide new information for studying water sources, competitive interactions and water use patterns of plants. The contributions of different water sources to three plants, Hedysarum scoparium (HS), Caragana Korshinskii (CK) and Artemisia ordosica(AO), were investigated in the artificial sand-fixed vegetation of Shapotou, the southeastern margin of the Tengger Desert of northwestern China, based on meteorological data and δ18O and δD values of precipitation, groundwater, soil water and xylem water of HS, CK and AO. Our results indicated that water content throughout the soil profile and their competition balance for water uptake during different growth season. The results indicate that these sand-fixed plants have developed into a relatively stable stage and they are able to regulate their water use behavior as a response to the environmental conditions, which reinforces the effectiveness of plantation of native shrubs without irrigation in degraded areas.

Clarifying the relationship between meteorological factors and ozone can provide scientific support for ozone pollution prediction, but the effects of boundary layer meteorology, especially boundary layer height and turbulence, on ozone pollution are rarely studied. Here, ozone and its related meteorological factors were observed in summer in Shijiazhuang, a city with the most serious ozone pollution on the North China Plain. The forced and free convection boundary layers were classified using ground remote observations. After eliminating the forced convection condition, strong free convection conditions, exhibiting a high boundary layer height, high wind speed, strong turbulence and large-scale free convection velocity, were found to be beneficial for the aggravation of ozone pollution. Combined with the ozone profile detected by a tethered balloon, the ozone chemical budget was calculated using the differences in the column ozone concentrations between the morning and afternoon, and the results confirmed the impact of free convection intensity on ozone pollution. The change in ozone sensitivity from VOCs sensitivity to NOx sensitivity driven by strong free convection was the main reason for the deterioration of ozone pollution. This study clarified the impact of boundary layer meteorology on ozone and its sensitivity and has important practical significance for ozone pollution prevention and early warning.

Monitoring vegetation change and their potential drivers are important to environmental management. Previous studies on vegetation change detection and driver discrimination were two independent fields. Specifically, change detection methods focus on nonlinear and linear change behaviors, i.e., abrupt change (AC) and gradual change (GC). But driver discrimination studies mainly used linear coupling models which rarely concerned the nonlinear behaviors of vegetation. The two diagnoses need be treated as sequential flow because they have inner causality mechanisms. Furthermore, ACs concealed in time series may induce over/under-estimate contributions from human. We chose the Yangtze River Basin of China (YRB) as a study area, first separated ACs from GCs using breaks for additive and seasonal trend method, then discriminated drivers of GCs using optimized Restrend method. Results showed that (1) 2.83% of YRB were ACs with hotspots in 1998 (30.2%), 2003 (10.4%), and 2002 (7.6%); 66.7% of YRB experienced GC with 94.8% of which were positive; and (2) climate induced more area but less dramatic GCs than human activities. Further analysis showed that temperature was the main climate driver to GCs, while human-induced GCs were related to local eco-policies. The widely occurring ACs in 1998 were related to the flooding catastrophe, while the dramatic ACs in sub-basin 12 in 2003 may result from urbanization. This paper provides clear insights on the vegetation changes and their drivers at a relatively long perspective (i.e., 34 years). Sequential combination of specifying different vegetation behaviors with driver analysis could improve driver characterizations, which is key to environmental assessment and management in YRB.

Considering DNA-based homogeneous electrochemical assay allows identification of targets to be carried out in a homogeneous solution, it would be of significance to develop the successive homogeneous assay system in dynamic solution for rapid disease diagnosis and high-throughput bioanalysis. In homogeneous assay, the work electrodes generally have capability of DNA capture but lack signal amplification, restricting its sensitivity. Here, a flow-homogeneous sensing system was proposed to realize the successive assay of microRNA, a model biomarker. Ultrathin 2D metal-organic framework (MOF) nanozymes with thickness of about 1 nm were facilely prepared by ultrasonic approach. Due to the excellent enzyme-like activity and adsorption capacity towards single-strand DNA (ssDNA), MOF nanozymes adsorbed on electrode simultaneously played two roles of ssDNA collector and signal-amplifier. To adapt the recoverable electrode to on-line monitoring, duplex-specific nuclease-assisted circle reaction was conducted to produce the turn-on amplified signal. Flow injection device was employed to realize the recycling of electrodes and the successive microRNA assay. The assay strategy showed low limit of detection (0.12 pM, S/N = 3) for microRNA, excellent renewability and acceptable reliability for real sample assay. The established system exerts the advantages of DNA-based homogeneous electrochemical sensing strategy. This work would not only expand homogeneous electrochemical assay to successive bioassay, but also provide the possibility for practical application of homogeneous sensing strategy.

The North China Plain (NCP) has a severe water shortage. About 70% groundwater has been exploited for irrigation. Winter wheat – summer maize and pears are typical representative cereal crops and commercial fruit trees in this area, respectively. Water budget for the typical cropland and orchard ecosystems has a significant importance for agricultural production, especially in the NCP. Therefore, evapotranspiration (ET) and water balance were studied in the annual winter wheat – summer maize rotation (cropland) and pear orchard. Latent and sensible heat fluxes were measured by eddy covariance. Annual ET for pear trees was 764 mm and for both crops was 690 mm. The difference of ET between these two ecosystems was about equal to one irrigation. Transpiration was the main loss with the mean proportion of 63% for crops and 76% for pear trees. Wheat growth period is in the dry season and requires much more irrigation than maize. Mainly transpiration (80%) occurred from April through September in the both ecosystems which was also the growing period for pear trees. The annual precipitation was 469 mm and 444 mm in the pear orchard and cropland, respectively, although 80% of it occurred from June to September. Compared with the precipitation, annual mean water deficit was 294 mm for the pear trees and 244 mm for crops. The water shortage was severe in May while surplus water presented in July and August. Energy and ET fluxes were determined by atmospheric demand and the response of plants as controlled by plant phenology and crop selection. As the water shortage situation becomes more serious in the NCP, sustainability of the agricultural ecosystems could be improved by changing crop planting patterns, specifically, increasing the area ratio of maize to pear trees.

Irrigation of the conventional double cropping system of winter wheat and summer maize has caused serious problems regarding water resources and the environment on the Beijing-Tianjin-Hebei plain (HP), China. Reducing or replacing high water consumption crops (such as winter wheat) is the most impactful way to effectively save water in the HP region. In this study, crop coefficient and vegetation remote sensing data were used to estimate evapotranspiration ( ET a ) for winter wheat and summer maize on the HP from 2009 to 2013. For early maize, ET a and yield were based on the results from the APSIM (Agricultural Production System Simulator) crop model, which had been calibrated and validated using field experimental data. The effects on groundwater conservation and grain yield were estimated at the regional scale for the conventional winter wheat (WW) and summer maize (SM) double cropping system (Y 1 M 2 ) and three alternative cropping systems: three harvests in two years system (Y 2 M 3 , 1st year: WW-SM; 2nd year: early maize), four harvests in three years system (Y 3 M 4 , 1st year: WW-SM; the next two years: early maize), as well as a continuous early maize monoculture system (Y 1 M 1 ). The results showed that: (1) Relative to Y 1 M 2 , the water savings in each alternative cropping system exceeded 50% of the groundwater overdraft on the HP. The evapotranspirations of Y 2 M 3 , Y 3 M 4 and Y 1 M 1 decreased by 14%, 19% and 29% over that of Y 1 M 2 (740 mm), respectively. The economic water use efficiencies (WUE e ) of the alternative cropping systems were 7% –16% greater than that of Y 1 M 2 . The groundwater drop by Y 1 M 2 (0.59 m year − 1 ) was higher than that by Y 2 M 3 (0.20 m year − 1 ) and Y 3 M 4 (0.07 m year − 1 ), and the drop by Y 1 M 1 was negative, indicating a groundwater rise of 0.20 m. The groundwater overdraft in Y 1 M 2 was 160 mm (3.83 billion m 3 ), and the alternative cropping systems were more sustainable, with groundwater overdrafts that were less than the recharge value of 128 mm on the HP. (2) In comparison with Y 1 M 2 , the total yield was reduced by 2.28, 3.04 and 4.56 billion kg a − 1 (or 7.7%, 10.2% and 15.3%) for Y 2 M 3 , Y 3 M 4 and Y 1 M 1 , respectively, which accounted for 2 M 3 is a preferred alternative cropping system over Y 1 M 2 in the near future because of the advantages of high WUE e , economic return, mitigated groundwater level decline and balance between wheat supply and demand on the HP. Y 1 M 1 , which had the least water use and highest WUE e and economic return, is an option for the most serious groundwater overdraft area despite a contradiction between the traditional dietary habit and complete abandonment of wheat. Y 3 M 4 is recommended as the transitional cropping system between Y 2 M 3 and Y 1 M 1 . The method in this study is applicable to relevant regional research, and the results can be of use to the government when formulating policies on cropping systems and groundwater management.

Excessive use of groundwater in irrigation (mainly for production of winter wheat) in the North China Plain (NCP) has resulted in markedly decreased groundwater levels. Alternative cropping systems may have potential to reduce groundwater use in the region. The APSIM (Agricultural Production System Simulator) farming systems model was used to simulate long-term (1981–2015) water use, net overdraft and crop yield for eight cropping systems. The wheat-maize double cropping system (WW–SM) in the study area resulted in overdrafts of 258 mm yr − 1 , about 100 mm yr − 1 more than estimated groundwater recharge. Although six of eight simulated systems reduced overdrafts below the estimated recharge value of 150 mm yr − 1 , a triple-cropping system consisting of winter wheat/summer maize followed by fallow and early maize (WW–SM/F–EM) in two years appears to be the most viable alternative. Annual grain yield under the triple cropping system was only 13% less than that under the current WW–SM double cropping system. Groundwater overdrafts under triple-cropping system were about equal to lateral recharge from the mountains, water brought in via the South-North Water Transfer (SNWT) project and water from other water-saving measures (e.g. plastic film mulching) in the region.

Emerging studies have reported that long non-coding RNAs (lncRNAs) were crucial regulators in the progression of colorectal cancer (CRC). LncRNA susceptibility 9 (CASC9) was involved in several cancers; however, its role in CRC remains unknown.RT-PCR was done to probe the expression of CASC9 and miR-193a-5p in CRC samples. CRC cell lines (HCT116 and SW480) were used as cell models. The biological influence of CASC9 on cancer cells was studied using CCK-8 assay, Transwell assay and TUNEL assay in vitro, and subcutaneous xenotransplanted tumor model in vivo. Interaction between CASC9 and miR-193a-5p was investigated by bioinformatics analysis, RT-PCR, and luciferase reporter assay. The expression level of the downstream gene of miR-193a-5p, erb-b2 receptor tyrosine kinase 2 (ERBB2), was tested by Western blot.CASC9 was significantly up-regulated in CRC samples, while miR-193a-5p was markedly down-regulated. Overexpression of CASC9 promoted viability, migration and invasion of CRC cells, while overexpression of miR-193a-5p had the opposite effect. CASC9 could down-regulate miR-193a-5p via sponging it, and there was a negative relevancy between CASC9 and miR-193a-5p in CRC samples. CASC9 also enhanced the expression levels of ERBB2, while this effect could be reversed by co-transfection with miR-193a-5p.CASC9, an oncogenic lncRNA, was abnormally up-regulated in CRC tissues, and it could indirectly modulate the expression of ERBB2 via reducing the expression level of miR-193a-5p.

Groundwater plays a major role in agro-hydrological processes in the North China Plain (NCP). The NCP is facing a water deficit, due to a rapid decline in the water table because of the double cropping system. A two crop (maize and wheat) rotation is required to balance the food supply and demand, which leads to an imbalance between evapotranspiration (ET) and precipitation. Thus, there has been a decline of about 1.35 m yr&minus, 1 of groundwater (Luancheng Agroecosystem Experimental Station (LAES), NCP) during the last 10 years. Lysimeter experiments were conducted under different irrigation treatments (flood, surface drip, and subsurface drip) to account for ET in the selection of a suitable irrigation method. Subsurface drip irrigation reduced ET by 26% compared to flood irrigation, and 15% compared to surface drip irrigation, with significant grain yield and biomass formation due to decreased evaporation losses. Grain yield, yield components, and above ground biomass were similar in subsurface drip and flood irrigation. However, these biomass parameters were lower with surface drip irrigation. Furthermore, subsurface drip irrigation increased the crop water productivity (24.95%) and irrigation water productivity (19.59%) compared to flood irrigation. The subsurface irrigated plants showed an increase in net photosynthesis (~10%), higher intrinsic water use efficiency (~36%), lower transpiration rate (~22%), and saved 80 mm of water compared to flood irrigation. Our findings indicate that subsurface drip irrigation can be adopted in the NCP to increase water use efficiency, optimize grain yield, and minimize water loss in order to address scarcity.

Daily continuous evapotranspiration (ET) estimates of 1 km spatial resolution can benefit agricultural water resources management at regional scales. Thermal infrared remote sensing-derived land surface temperature (LST) is a critical variable for ET estimation using energy balance-based models. However, missing LST information under cloudy conditions remains a long-standing barrier for spatiotemporally continuous monitoring of daily ET at regional scales. In this study, LST data of 1 km spatial resolution at 11:00 local solar time under all-weather conditions across the North China Plain (NCP) were first generated using a data fusion approach developed previously. Second, combined with the generated LST data, MODIS products, and meteorological forcing from the China Land Data Assimilation System, the Two-Source Energy Balance model (TSEB) and a temporal upscaling method were jointly used to estimate daily ET at 1 km spatial resolution across the NCP for a decade from 2008 to 2017. In particular, to better incorporate the impact of crop phenology on ET and improve the ET estimation, the fraction of greenness in TSEB was determined in terms of a leaf area index threshold during the crop growth period. Compared with observed instantaneous latent heat flux (LE) corrected for energy balance closure, the estimated LE reasonably captures inter- and intra-annual variations in LE measured at the Huailai, Daxing, Weishan, and Guantao flux towers, with R2 of 0.63–0.79. Estimated daily ET against in situ ET measurements with energy balance closure at the Huailai, Daxing, and Guantao sites showed good performance in terms of R2 greater than 0.70 and RMSE below 0.91 mm/d. These accuracies are comparable with published results, with our ET data set validated by many more observations than previous studies and featuring spatiotemporal continuity and high spatial resolution across the entire NCP for a decade. Furthermore, seasonal ET variations reflected by our product outperform two widely used global products in capturing water consumption characteristics in the winter wheat-summer maize rotation system. In terms of temporal trends, annual ET estimates across the NCP show a decreasing and then increasing trend over the past decade, which is attributed to the increased cropping intensity over the recent years reflected by an increase in leaf area index.

We conducted a four-year in situ experiment using chamber, eddy covariance, and mass spectrometry methods to partition nocturnal respiratory components (Fr, ecosystem respiration; Frs, soil respiration; Frsh, heterotrophic respiration; Fraa and Frab, above and below ground autotrophic respirations) and their respective carbon isotopic signatures (δr, δrs, δrsh, δraa, and δrab) in a wheat–maize rotation in the North China Plain. The annual patterns in Fr, Frs, Fraa, and Frab showed a bimodal curve in response to plant development, nitrogen fertilization, irrigation and precipitation events. Frs, Frsh, Fraa and Frab accounted for 43.4, 13.5, 56.6 and 29.9 % of Fr in the wheat season and 34.0, 15.2, 66.0 and 18.8 % of Fr in the maize season, respectively. The annual values of Fr, Frs, Frsh, Fraa, and Frab in the maize season were 2.18, 1.71, 2.45, 2.54, and 1.37 times those in the wheat season, respectively. In comparison, the annual values of δr, δrs, δrsh, δraa, and δrab in the wheat season were 5.84, 10.4, 9.84, 9.63, and 11.6 % more depleted than those in the maize season, respectively. The δraa and δrab means in the wheat (C3) season significantly depleted than those in the maize (C4) season due to the different photosynthetic carbon metabolisms in the two systems. Hysteretic response (2-3 hours) where soil temperature leads soil respiration was found, suggesting a causal role of temperature in the relationship. Higher soil temperature and water filled pore space (≥ 50 %) depleted δ13CO2 signatures. Overall, this study revealed the carbon balance of nocturnal respiratory components and their respective δ13CO2 signatures in a wheat-maize rotation.

Water resources are critical in semiarid Xinjiang, northwestern China, a mountainous region that heavily relies on meltwater, making it sensitive to climate change. A better understanding of climatic and hydrological changes is therefore highly required for water resources management. In this review, spatio-temporal climate change, climate extremes, snow and glacier fluctuations and variability in semiarid Xinjiang are summarized. In general terms, the available historical data demonstrate a rising mean temperature, likely increased precipitation (subject to greater uncertainty), declining snow cover and glacier extent, and increased streamflow in most rivers. Although the changes of projected future climate differ with different climate resembles, average temperature is expected to increase and seasonal precipitation will experience a slightly increase tendency. Additionally, climate extremes are predicted to become more frequent. Projected future streamflow is expected to increase although initial increase may be followed by a long-term decrease. Water demand is predicted to increase due to irrigation, population growth and economic development. We thereby conclude that water variability in semiarid Xinjiang is and will further be affected by future climate change and their hydrological impacts. However, climatic and hydrological changes differ in different basins, and the impacts of climate change on hydrological changes cannot be generalized. Historical and future climatic and hydrological changes have possible implications for vegetation and can intensify regional hydrological cycle and enhance pressure on seasonal water availability. Future research on climatic and hydrological changes in this region should reveal the mechanisms behind the change phenomenon, quantify the implications on water resources management and expand observational networks, in particular focus on snow and glacier melt processes, as meltwater is a crucial water source in this region. This research may provide suggestions for water resources management in semiarid Xinjiang and endorheic basins where totally depending on water from the surrounding mountains in central Asia or elsewhere.

As an essential part of terrestrial ecosystems, farmland plays a critical role in the carbon cycle. The spatial and temporal characterization of farmland biomass and carbon sequestration capacity is important to understand the carbon cycle of a farmland system. The study area is located in mid-south Hebei Province (MSHP), which is a food production region in North China. Based on land-use data (1980, 1990, 2000 and 2008) and food production data (1984–2008), agricultural biological productivity and carbon capture capacity were estimated. In addition, the spatial-temporal characteristics and related influencing factors were analyzed. Regionwide, aboveground biomass increased from 600 g C·m−2·a−1 (1985) to 1200 g C·m−2·a−1 (2008) with an increase-decrease-increase pattern during the same period. Spatially, it increased in the piedmont plains and declined in the western mountains and piedmont plains. The carbon capture capacity of cropland in the piedmont area increased from 700 g C·m−2·a−1 to 1000 g C·m−2·a−1, and it declined in the low plain area. Mountainous and coastal areas had the lowest capability of agricultural carbon capture. Although farmland is a dynamic carbon pool overall, its carbon sequestration capacity is likely to be enhanced with proper farming practices.

With population growth and social and economic development, water shortage is becoming a serious issue worldwide. As a key alternative water resource, wastewater can be used in agriculture to compensate for water shortages. Wastewater irrigation has a long development history and has undergone different phases in developing and developed countries. Untreated wastewater irrigation can come with numerous environmental problems. Strong management practices, such as the application of suitable treated and irrigated technologies, can be used to reap substantial benefits while minimizing risks. We discussed the major challenges associated with wastewater irrigation and its future use to help improve wastewater irrigation practices around the world. For further resources related to this article, please visit the WIREs website.

Accurate evapotranspiration (ET) estimation is important for understanding hydrological cycle and water resources management in the cropland. Based on eight flux sites within the North China Plain (NCP) and the surrounding area, which were integrated together for the first time, we applied support vector regression method to develop ET dataset for the cropland in NCP from 1982 to 2015 with 1/12° spatial resolution and eight-day temporal interval. The mean annual ET over cropland within NCP was 575 mm yr−1 with a non-significant increasing trend. In wheat season, the seasonal ET increased significantly at the rate of 1.28 mmyr−2 with a mean value of 238 mmyr−1; in maize season, the mean value of seasonal ET was 221 mmyr−1 with a decreasing trend of −0.95 mmyr−2. The comparatively high mean annual ET values occurred primarily in the well irrigated area near the Taihang Mountains, irrigation districts along the Yellow River and the humid region. The attribution analysis which combined multiple regression with the first difference method revealed that human activities dominated ET trend at annual scale as well as in wheat season, with relative contributions of 52% and 56%, respectively. While in maize season, ET trend was mostly controlled by climate change with relative contribution of 77%. Among the climate factors, in wheat season, the significantly increasing air temperature was the principal climatic cause of ET increase which was partly offset by the significantly decreasing wind speed; while in maize season, the significant ET decline was primarily resulted from the significantly decreasing net radiation and wind speed. Compared with our ET dataset, the four widely used global or national ET datasets significantly underestimated ET in wheat season, especially in the extensively irrigated areas, suggesting that local observations are crucial for regional studies.

Although irrigation has markedly increased agricultural productivity in the North China Plain, it hasreduced groundwater levels by up to 0.8 m yr m 1and dried up the Yellow River for extended times sincethe 1970s. The objective of this study was to compare water, energy, and carbon fluxes in regions irrigatedwith groundwater and surface water (Yellow River) using almost four years of eddy covariance data fromagricultural stations in Luancheng (water table depth: s 42 m ) and Weishan (near Yellow River, watertable depth: 1n3 m). Irrigation is mostly restricted to winter wheat as summer maize grows during therainy season. Mean annual ET was 693 mm yr m 1for Luancheng site, which is higher than Weishan site(648 mm, ignore partial years). About s 390n480 mm of ET occurred during the wheat season (from earlyOctober to next early June, about 247 days), 230n300 mm in the maize season (from early June to lateSeptember, about 107 days). Annual crop yields were s 6864 kg /ha in the two regions. Annual wateruse efficiencies ranged from 4 to 6 g CO2kg m 1H2O. Water use efficiencies were higher for maize than forwheat. Annual cropland carbon budget (CCB) was 230n280 g C m m 2yr m 1at the two sites and suggesteda weak carbon sink. Irrigation compensated for seasonal and inter-annual variability in precipitation.Shifting the cropping pattern from wheatnmaize double crops to a single crop of maize could significantlyreduce water withdrawal and lead to a more sustainable use of water resource in this region.

Plain (NCP) where water shortage is a serious problem. The objectives of this research were to explore the characteristics of water balance, energy transfer and carbon exchange of irrigated pear orchards by a combination of multiple measurement methods (eddy covariance system, sap flow method, and the other equipment). Experiments from 08/01/2011 to 10/31/2012 were conducted in a pear orchard located in the NCP. Annual net radiation (Rn) was 2490 MJ m m 2 of which latent heat flux accounted for 74.5%, a little higher than the agro-ecosystem with wheat n maize rotation (70%). Annual mean water use efficient ( WUE ) was 1.98 g CO 2 /kg H 2 O which was lower than the agro-ecosystem in the same area. Annual evapotranspiration ( ET ) was 759 mm and daily transpiration ( T ) ranged from 0.5 to 4.3 mm during May to October while daily T / ET varied from 0.6 to 0.9. Variation of ET can be explained well by the change of LAI. As annual drainage was 86 mm, it will take a long time for the shallow soil water (0 n 140 cm ) to replenish deep groundwater. Optimal values of daily downward short wave radiation (Rs) (20 MJ m m 2 d m 1 ) and ET ( s 4.8 mm d m 1 ) were probably important thresholds for the plant growth. Changing irrigation method and crops planting structure adjusting according to the water balance and trees growth characteristics, were probably useful for keeping high yield with less water depletion while further research should be done in future.

Yucui Zhang, Yanjun Shen,* Yaning Chen and Yun Wang 1 Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China 2 Gaduate University of Chinese Academy of Sciences, Beijing 100049, China 3 State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, 830011, China

summary Groundwater overdraft threatens the future of irrigated agriculture in the North China Plain. Because irrigated winter wheat is the dominant user of extracted groundwater, improved understanding of water cycling through the soil–plant–atmosphere continuum during wheat cultivation in the North China Plain is necessary for improving the sustainable utilization of limited water resources and promoting food security. In this paper, a combination of micrometeorological and stable isotope techniques was used to investigate evapotranspiration and soil water dynamics in a typical winter wheat agro-ecosystem (Luancheng Agro-ecosystem Experiment Station, Hebei Province). Stable isotope mixing models were used with eddy covariance evapotranspiration estimates and micro-lysimeter evaporation measurements to partition evapotranspiration and determine temporal variability of root water uptake depths. Results suggest that evaporation during the winter wheat irrigation season can reach up to 30% of the total water consumption (almost two typical irrigations). The main depths of root water uptake were 0–40 cm. Therefore, it is suggested that the planned irrigation wetting depth can be reduced at least to 40 cm, rather than the traditional 100 cm, as a means of water conservation. Widespread implementation of these practices could amount to a significant water savings for the North China Plain.

The North China Plain, which is critical for food production in China, is encountering serious water shortage due to heavy agricultural water requirement. The accurate modelling of carbon dioxide flux and evapotranspiration (ET) in croplands is thus essential for yield prediction and water resources management. The land surface model is powerful in simulating energy and carbon dioxide fluxes between land and atmosphere. Some key processes in the Simple Biosphere Model (Version 2, SiB2) were parameterized based on the observations. The simulated fluxes were tested against the eddy covariance flux measurements over two typical winter wheat/maize double cropping fields. A simple diagnostic parameterisation of soil respiration, not included in SiB2, was added and calibrated using the observations to model the carbon budget. The Ball-Berry stomatal conductance model was calibrated using observed leaf gas exchange rate, showing that the original SiB2 could significantly underpredict the ET in the wheat field. SiB2 significantly underpredicted soil resistance at the Weishan site, leading to overpredict the ET. Overall, there was a close agreement between the simulated and observed latent heat fluxes and net CO2 exchange using the re-parameterized SiB2. These findings are important when the model is used for the regional simulation in the North China Plain. Copyright © 2011 John Wiley & Sons, Ltd.