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This mixed-method study, employing inquiry-based science teaching theory, delves into the interaction of English Medium Instruction (EMI) and scientific inquiry by investigating science teachers' understanding and perceptions of conducting inquiry-based science activities in EMI classrooms. Drawing on a questionnaire of 166 EMI science teachers and in-depth individual interviews with five of them, the findings suggest that these EMI science teachers encountered similar challenges to other science teachers teaching science in their first languages through an inquiry-based approach. They were found to hold a -scientific -method-oriented understanding of inquiry-based science teaching and a conflict between Chinese learning culture and -inquiry-based science learning culture. Furthermore, the findings indicate that EMI science teachers faced additional challenges in inquiry-based science classrooms in the EMI context, including (a) the tension between passive English learning and the mutual learning of scientific inquiry and English, and (b) the contradictory stance between -inquiry-based science teaching and EMI policy. This study has implications for policymakers in terms of the teaching and provision of -inquiry-based science in the EMI classroom. [ABSTRACT FROM AUTHOR]

Confidence in model estimates of soil CO2 flux depends on assumptions regarding fundamental mechanisms that control the decomposition of litter and soil organic carbon (SOC). Multiple hypotheses have been proposed to explain the role of lignin, an abundant and complex biopolymer that may limit decomposition. We tested competing mechanisms using data‐model fusion with modified versions of the CN‐SIM model and a 571‐day laboratory incubation dataset where decomposition of litter, lignin, and SOC was measured across 80 soil samples from the National Ecological Observatory Network. We found that lignin decomposition consistently decreased over time in 65 samples, whereas in the other 15 samples, lignin decomposition subsequently increased. These "lagged‐peak" samples can be predicted by low soil pH, high extractable Mn, and fungal community composition as measured by ITS PC2 (the second principal component of an ordination of fungal ITS amplicon sequences). The highest‐performing model incorporated soil biogeochemical factors and daily dynamics of substrate availability (labile bulk litter:lignin) that jointly represented two hypotheses (C substrate limitation and co‐metabolism) previously thought to influence lignin decomposition. In contrast, models representing either hypothesis alone were biased and underestimated cumulative decomposition. Our findings reconcile competing hypotheses of lignin decomposition and suggest the need to precisely represent the role of lignin and consider soil metal and fungal characteristics to accurately estimate decomposition in Earth‐system models. [ABSTRACT FROM AUTHOR]

English as a Medium of Instruction (EMI) is being used to teach academic subjects in international programmes in China to meet the growing number of Chinese students' need to study abroad. Through the lens of inquiry-based science teaching, this study examined how the four EMI science teachers of an international programme at a private high school employed translanguaging in scientific practices such as identifying variables and formulating hypotheses. Based on the data collected from a case study, the analyses demonstrate how these science teachers used multilingual and multimodal resources to facilitate students' engagement in scientific inquiry activities and to promote the construction of scientific knowledge. A total of seven types of translanguaging practices were identified, including opening the inquiry, negotiating directions, teacher encouragement, managing discipline, fun learning environment, definitions, and explanations. The findings imply that pedagogical translanguaging can create a space for the construction of scientific knowledge, as well as a space for the implementation of scientific practices in an inquiry-based EMI classroom environment. [ABSTRACT FROM AUTHOR]

The atmospheric concentration of nitrous oxide (N2O) has increased by 23% since the pre‐industrial era, which substantially destructed the stratospheric ozone layer and changed the global climate. However, it remains uncertain about the reasons behind the increase and the spatiotemporal patterns of soil N2O emissions, a primary biogenic source. Here, we used an integrative land ecosystem model, Dynamic Land Ecosystem Model (DLEM), to quantify direct (i.e., emitted from local soil) and indirect (i.e., emissions related to local practices but occurring elsewhere) N2O emissions in the contiguous United States during 1900–2019. Newly developed geospatial data of land‐use history and crop‐specific agricultural management practices were used to force DLEM at a spatial resolution of 5 arc‐min by 5 arc‐min. The model simulation indicates that the U.S. soil N2O emissions totaled 0.97 ± 0.06 Tg N year−1 during the 2010s, with 94% and 6% from direct and indirect emissions, respectively. Hot spots of soil N2O emission are found in the US Corn Belt and Rice Belt. We find a threefold increase in total soil N2O emission in the United States since 1900, 74% of which is from agricultural soil emissions, increasing by 12 times from 0.04 Tg N year−1 in the 1900s to 0.51 Tg N year−1 in the 2010s. More than 90% of soil N2O emission increase in agricultural soils is attributed to human land‐use change and agricultural management practices, while increases in N deposition and climate warming are the dominant drivers for N2O emission increase from natural soils. Across the cropped acres, corn production stands out with a large amount of fertilizer consumption and high‐emission factors, responsible for nearly two‐thirds of direct agricultural soil N2O emission increase since 1900. Our study suggests a large N2O mitigation potential in cropland and the importance of exploring crop‐specific mitigation strategies and prioritizing management alternatives for targeted crop types. [ABSTRACT FROM AUTHOR]

The pervasive use of digital technologies in different scenarios has led to an increasing number of empirical studies on digital translanguaging. Following the emergence of the global pandemic and its huge impact on the education sector, attention to translanguaging among teachers and students in the digital context has reached a new height. This systematic review provides scholars with a current overview of research on digital translanguaging among teachers and students by analysing research backgrounds, the methodologies used, and the research themes of interest, supported by the software CiteSpace , to visualise the structure of existing research. A search of five databases identified 32 empirical studies on digital translanguaging among teachers and students, published from 2015 to 2022. The findings reveal that research on digital translanguaging for teachers and students is characterised by two distinct directions: one focused on teaching and learning, and the other on social purposes. More specifically, the former direction encompasses three subthemes: digital translanguaging pedagogy, the effects of digital translanguaging practices on English language writing, and translanguaging practices in digital multimodal composing. The implications of these findings for future research directions and pedagogical practice are discussed. [ABSTRACT FROM AUTHOR]

SnO 2 is recognized as an excellent electron transport layer. However, it does not possess the optimal morphology required by perovskite photovoltaic devices, and the conduction band of SnO 2 cannot match well with perovskite conduction bands. In the present study, we introduced graphene quantum dots (GQDs) into SnO 2. The results show that the introduction of graphene quantum dots effectively improved the morphology of the SnO 2 film, reduced the roughness of the surface, and increased the ohmic contact between the SnO 2 and perovskite layer. In addition, the conductivity of the SnO 2 film was improved, thereby facilitating the transfer of electrons. The optimized SnO 2 : GQDs layer reduced the density of defect state, suppressed the pinholes appearance to a certain extent, and facilitated the extraction of electrons, thereby ultimately improving the FF, and increasing the efficiency of the perovskite photovoltaic device. [ABSTRACT FROM AUTHOR]

• We developed a fully distributed water quality model for tile-drained catchments. • In-field management and catchment features control daily flows of water and NO 3 -N. • Subsurface flows, especially tile flow, dominate the water and NO 3 -N loads. • Roles of the model improvements in enhancing prediction accuracy were quantified. It is essential to identify the dominant flow paths, hot spots and hot periods of hydrological nitrate-nitrogen (NO 3 -N) losses for developing nitrogen loads reduction strategies in agricultural watersheds. Coupled biogeochemical transformations and hydrological connectivity regulate the spatiotemporal dynamics of water and NO 3 -N export along surface and subsurface flows. However, modeling performance is usually limited by the oversimplification of natural and human-managed processes and insufficient representation of spatiotemporally varied hydrological and biogeochemical cycles in agricultural watersheds. In this study, we improved a spatially distributed process-based hydro-ecological model (DLEM-catchment) and applied the model to four tile-drained catchments with mixed agricultural management and diverse landscape in Iowa, Midwestern US. The quantitative statistics show that the improved model well reproduced the daily and monthly water discharge, NO 3 -N concentration and loading measured from 2015 to 2019 in all four catchments. The model estimation shows that subsurface flow (tile flow + lateral flow) dominates the discharge (70–75%) and NO 3 -N loading (77–82%) over the years. However, the contributions of tile drainage and lateral flow vary remarkably among catchments due to different tile-drained area percentages and the presence of farmed potholes (former depressional wetlands that have been drained for agricultural production). Furthermore, we found that agricultural management (e.g. tillage and fertilizer management) and catchment characteristics (e.g. soil properties, farmed potholes, and tile drainage) play important roles in predicting the spatial distributions of NO 3 -N leaching and loading. The simulated results reveal that the model improvements in representing water retention capacity (snow processes, soil roughness, and farmed potholes) and tile drainage improved model performance in estimating discharge and NO 3 -N export at a daily time step, while improvement of agricultural management mainly impacts NO 3 -N export prediction. This study underlines the necessity of characterizing catchment properties, agricultural management practices, flow-specific NO 3 -N movement, and spatial heterogeneity of NO 3 -N fluxes for accurately simulating water quality dynamics and predicting the impacts of agricultural conservation nutrient reduction strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon (C) emission and uptake due to land use and land cover change (LULCC) are the most uncertain term in the global carbon budget primarily due to limited LULCC data and inadequate model capability (e.g., underrepresented agricultural managements). We take the commonly used FAOSTAT‐based global Land Use Harmonization data (LUH2) and a new high‐resolution multisource harmonized national LULCC database (YLmap) to drive a land ecosystem model (DLEM) in the conterminous United States. We found that recent cropland abandonment and forest recovery may have been overestimated in the LUH2 data derived from national statistics, causing previously reported C emissions from land use have been underestimated due to the definition of cropland and aggregated LULCC signals at coarse resolution. This overestimation leads to a strong C sink (30.3 ± 2.5 Tg C/year) in model simulations driven by LUH2 in the United States during the 1980–2016 period, while we find a moderate C source (13.6 ± 3.5 Tg C/year) when using YLmap. This divergence implies that previous C budget analyses based on the global LUH2 dataset have underestimated C emission in the United States owing to the delineation of suitable cropland and aggregated land conversion signals at coarse resolution which YLmap overcomes. Thus, to obtain more accurate quantification of LULCC‐induced C emission and better serve global C budget accounting, it is urgently needed to develop fine‐scale country‐specific LULCC data to characterize the details of land conversion. [ABSTRACT FROM AUTHOR]

Paleoclimate records identified a severe drought lasting approximately a decade on the Mongolian Plateau during the 2000s, the severity of which was only exceeded by a single drought during the last two millennia. Under high‐emission scenarios, arid and semiarid areas are projected to continue to experience a drying trend over the coming decades; therefore, understanding how ecosystems respond to long‐lasting drought has global implications. Here we used a process‐based ecosystem model to examine the interannual and intra‐annual variations in net ecosystem productivity in response to climate extremes across the Mongolian Plateau. We find that the recent‐decade drought caused Mongolian terrestrial ecosystems to shift from a carbon (C) sink to a C source, canceling 40% of climate‐induced C accumulation over the entire twentieth century. Our study details a shortened C sequestering season, increased summer C source, and accelerated C depletion during the 2000s drought. Plain Language Summary: Multiple lines of evidence have shown detrimental effects of drought events on ecosystem production and carbon dynamics, but it remains uncertain how arid and semiarid ecosystems respond to long‐lasting drought. Here we reveal that a severe drought during the first decade of the 2000s on the Mongolian Plateau considerably weakened C sequestration capacity and accelerated C depletion. This work has broad implications for understanding impacts of persistent droughts on terrestrial C dynamics as a drying trend, in many arid and semiarid areas, is projected to continue over the coming decades. Key Points: The recent decade (2000–2009) has been identified as one of the driest periods on the Mongolian Plateau over the most recent ~2,000 yearsThis long‐duration drought shortened the C sequestration season, increased the summer C source, and led to a net annual C releaseThe NEP amplitude in this dry decade increased due to reduced C uptake and increased C emissions, implying an accelerated C depletion [ABSTRACT FROM AUTHOR]

To meet the increasing food and biofuel demand, the Midwestern United States has become one of the most intensively human-disturbed hotspots, characterized by widespread cropland expansion and various management practices. However, the role of human activities in the carbon (C) cycling across managed landscape remains far from certain. In this study, based on state- and national census, field experiments, and model simulation, we comprehensively examined long-term carbon storage change in response to land use and cover change (LUCC) and agricultural management in the Midwest from 1850 to 2015. We also quantified estimation uncertainties related to key parameter values. Model estimation showed LUCC led to a reduction of 1.35 Pg (with a range of 1.3-1.4 Pg) in vegetation C pool of the Midwest, yet agricultural management barely affected vegetation C change. In comparison, LUCC reduced SOC by 4.5 Pg (3.1 to 6.2 Pg), while agricultural management practices increased SOC stock by 0.9 Pg. Moreover, we found 45% of the study area was characterized by continuously decreasing SOC caused by LUCC, and SOC in 13% and 31% of the area was fully and partially recovered, respectively, since 1850. Agricultural management was estimated to increase the area of full recovery and partial recovery by 8.5% and 1.1%. Our results imply that LUCC plays an essential role in regional C balance, and more importantly, sustainable land management can be beneficial for strengthening C sequestration of the agroecosystems in the Midwestern US, which may serve as an important contributor to C sinks in the US. [ABSTRACT FROM AUTHOR]

Recent earlier greening trends are believed to enhance terrestrial ecosystem productivity. However, advanced onset of growing season may also deplete soil water in early spring, leading to summer water stress for plant growth. In this study, we linked soil moisture with start of growing season (SGS, represented by day of year) to examine the responses of ecosystem productivity to water stress during 1982–2011 on the Mongolian Plateau. Results showed that, though not significant, earlier SGS has tendency to enhance spring productivity at north part of the study area. Nonetheless, we observed that suppressed summer photosynthesis due to phenology-induced water stress dramatically reduced annual carbon assimilation. Thus, phenology-associated changes in soil moisture have profound potential in regulating seasonal and annual productivity in arid and semi-arid ecosystems. The relationship between SGS and GPP was not observed in more mesic forest ecosystems (R 2 = 0.04, p > 0.10) nor in the agricultural area (R 2 = 0.03, p > 0.10) where practices like irrigation aim to alleviate summer water stress. Therefore, at the scale of the entire study area, earlier growing season did not translate to higher productivity (R 2 = 0.006). On the contrary, advanced SGS aggravated growing-season water stress, which in turn, supressed annual carbon assimilation in water limited area. This mechanism implies the advanced greening trends may not necessarily lead to more carbon uptake in terrestrial ecosystems but rather a carbon loss, especially in the arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

Abstract: Aim: Land use and land cover changes (LCLUC) are among the most important driving forces that alter terrestrial ecosystem functions and their feedbacks to climate systems, but reliable, spatially explicit datasets over century‐long periods are still lacking for fine‐scale earth system modeling. We aimed to combine multiple data sources and reconstruct long‐term land use history in the continental U.S., examining cropland expansion and abandonment since 1850. Location: Conterminous U.S. Time period: 1850 to 2016. Major taxa studied: Cropland. Methods: Cropland density maps, displaying the distribution and percentage of cultivated land each year (excluding summer idle/fallow, cropland pasture), were reconstructed by harmonizing multiple sources of inventory data and high‐resolution satellite images. The cropland data are freely available to the public. Results: In total, national cropland expansion was 104 million hectares (Mha) from 1850 to 2016 and peaked at about 127 Mha in 1920. Forests and shrublands were the dominant land cover types that croplands were converted from during 1850 to 1880, which may be primarily attributed to agriculture development in the northeast U.S. Croplands began to expand into grasslands from 1870 onwards and the encroached area dramatically increased, mainly due to cultivation development in the Great Plain and midwestern areas. In comparison, the area of abandoned cropland in the U.S. was 65 Mha during the study period. We found cropland abandonment mostly occurred in the central and southeast U.S., while cropland expansion was centered upon the midwestern states, central California, and the Mississippi Alluvial Plain. Main conclusions: Nationally, cultivated lands shifted from the eastern to midwestern U.S. during the study period, contributing to the increasingly important role of the Midwest in the rise of food and biofuel production, enhanced greenhouse gas (GHG) emissions, and high nitrogen loads into the Gulf of Mexico. Our cropland database is essential for modeling assessments of LCLUC impacts, crop production estimation and socioeconomic analysis. [ABSTRACT FROM AUTHOR]

A wide variety of studies have revealed a substantial increase in nitrogen (N) deposition in China, but the lack of spatially-explicit time-series N deposition data set has long hindered us from assessing the impacts of atmospheric N input on ecosystem services. In this study, we combined site-level monitoring, gridded precipitation data and atmospheric transport modeling results to generate annual N bulk deposition data in China with a spatial resolution of 10 km × 10 km and a time span from 1961 to 2008. It shows that national average N deposition rate had large interannual variation, and it increased by 59%, from 12.64 kg N ha −1 yr −1 in the 1960s to 20.07 kg N ha −1 yr −1 in the recent decade, with the most rapid increase centered in the southeastern China that is already N-enriched. Large spatial variation as well as dry deposition input has to be taken into account when estimating the amount of N deposited onto land surface of China. The spatial and temporal information on N deposition derived from this study could be used by ecosystem, hydrological, and climate modeling as well as by policy makers for assessing the impacts of nitrogen enrichment on regional climate, water resources, and biogeochemical cycles. [ABSTRACT FROM AUTHOR]

The land of the conterminous United States (CONUS) has been transformed dramatically by humans over the last four centuries through land clearing, agricultural expansion and intensification, and urban sprawl. High-resolution geospatial data on long-term historical changes in land use and land cover (LULC) across the CONUS are essential for predictive understanding of natural–human interactions and land-based climate solutions for the United States. A few efforts have reconstructed historical changes in cropland and urban extent in the United States since the mid-19th century. However, the long-term trajectories of multiple LULC types with high spatial and temporal resolutions since the colonial era (early 17th century) in the United States are not available yet. By integrating multi-source data, such as high-resolution remote sensing image-based LULC data, model-based LULC products, and historical census data, we reconstructed the history of land use and land cover for the conterminous United States (HISLAND-US) at an annual timescale and 1 km × 1 km spatial resolution in the past 390 years (1630–2020). The results show widespread expansion of cropland and urban land associated with rapid loss of natural vegetation. Croplands are mainly converted from forest, shrub, and grassland, especially in the Great Plains and North Central regions. Forest planting and regeneration accelerated the forest recovery in the Northeast and Southeast since the 1920s. The geospatial and long-term historical LULC data from this study provide critical information for assessing the LULC impacts on regional climate, hydrology, and biogeochemical cycles as well as achieving sustainable use of land in the nation. The datasets are available at 10.5281/zenodo.7055086 (Li et al., 2022). [ABSTRACT FROM AUTHOR]

• We synthesized county-level crop N budget and climate stress data during 1981-2016. • The U.S. corn N surplus dynamics are strongly regulated by climatic stresses. • A 51% increase in U.S. corn N surplus was associated with extremely hot conditions. • N surplus increases of 47% (dry) and 20% (wet) were related to extreme water stress. • The Midwest and the Northern Great Plains are hotspots of climate-driven N surplus. Increasing extreme climate conditions present significant threats to crop nitrogen (N) management and environmental conservation in the United States. Previous studies have examined the impacts of extreme climate on crop production but often overlooked its impacts on N loss from agricultural areas to the environment. Here we examined the relationship between county-level N surplus (the part of N that is not recovered by crops) and extreme climate conditions for corn in the U.S. during 1981–2016. We adopted multi-source long-term datasets of corn N budget and growing season (defined from May to August) maximum temperature and precipitation for each corn-planting county. Compared with the long-term N surplus trend, we found an increase of 51% and 47% in corn N surplus associated with extremely high temperature and extremely low precipitations, respectively. A moderate N surplus increase (20%) was associated with extremely high precipitations, while an N surplus decrease of 14% was shown to be related to extremely low temperatures. Across the U.S., the Midwest and the Northern Great Plains were identified as N surplus hotspots when extreme climate conditions occur. As the major corn-planting region, the Midwest accounted for 35% of the national extreme county-year samples but yielded 68% of the national total N surplus associated with extreme climate conditions. Our results highlighted the urgency of understanding the impacts of extreme climate conditions on crop nutrient losses and identifying the effective intervention practices to adapt to more frequent climate extremes in the future. [ABSTRACT FROM AUTHOR]

Increasing reactive nitrogen (N) input has been recognized as one of the important factors influencing climate system through affecting the uptake and emission of greenhouse gases ( GHG). However, the magnitude and spatiotemporal variations of N-induced GHG fluxes at regional and global scales remain far from certain. Here we selected China as an example, and used a coupled biogeochemical model in conjunction with spatially explicit data sets (including climate, atmospheric CO2, O3, N deposition, land use, and land cover changes, and N fertilizer application) to simulate the concurrent impacts of increasing atmospheric and fertilized N inputs on balance of three major GHGs ( CO2, CH4, and N2O). Our simulations showed that these two N enrichment sources in China decreased global warming potential ( GWP) through stimulating CO2 sink and suppressing CH4 emission. However, direct N2O emission was estimated to offset 39% of N-induced carbon (C) benefit, with a net GWP of three GHGs averaging −376.3 ± 146.4 Tg CO2 eq yr−1 (the standard deviation is interannual variability of GWP) during 2000-2008. The chemical N fertilizer uses were estimated to increase GWP by 45.6 ± 34.3 Tg CO2 eq yr−1 in the same period, and C sink was offset by 136%. The largest C sink offset ratio due to increasing N input was found in Southeast and Central mainland of China, where rapid industrial development and intensively managed crop system are located. Although exposed to the rapidly increasing N deposition, most of the natural vegetation covers were still showing decreasing GWP. However, due to extensive overuse of N fertilizer, China's cropland was found to show the least negative GWP, or even positive GWP in recent decade. From both scientific and policy perspectives, it is essential to incorporate multiple GHGs into a coupled biogeochemical framework for fully assessing N impacts on climate changes. [ABSTRACT FROM AUTHOR]

Understanding and assessing the spatiotemporal patterns in crop-specific phosphorus (P) fertilizer management is crucial for promoting crop yield and mitigating environmental problems. The existing P fertilizer dataset, derived from sales data, depicts an average application rate on total cropland at the county level but overlooks cross-crop variations. Conversely, the survey-based dataset offers crop-specific application details at the state level yet lacks inter-state variability. By reconciling these two datasets, we developed long-term gridded maps to characterize crop-specific P fertilizer application rates, timing, and methods across the contiguous US at a resolution of 4 km × 4 km from 1850 to 2022. We found that P fertilizer application rate on fertilized area in the US increased from 0.9 g P m-2 yr-1 in 1940 to 1.9 g P m-2 yr-1 in 2022, with substantial variations among crops. However, approximately 40 % of cropland nationwide has remained unfertilized in the recent decade. The hotspots for P fertilizer use have shifted from the southeastern and eastern US to the Midwest and the Great Plains over the past century, reflecting changes in cropland area, crop choices, and P fertilizer use across different crops. Pre-planting (fall and spring) and broadcast application are prevalent among corn, soybean, and cotton in the Midwest and the Southeast, indicating a high P loss risk in these regions. In contrast, wheat and barley in the Great Plains receive the most intensive P fertilizer at planting and via non-broadcast application. The P fertilizer management dataset developed in this study can advance our comprehension in agricultural P budget and facilitate the refinement in P fertilizer best management practices to optimize crop yield and reduce P loss. Datasets are available at https://doi.org/10.5281/zenodo.10700822 (Cao et al., 2024). [ABSTRACT FROM AUTHOR]

Agricultural soils play a dual role in regulating the Earth's climate by releasing or sequestering carbon dioxide (CO2) in soil organic carbon (SOC) and emitting non‐CO2 greenhouse gases (GHGs) such as nitrous oxide (N2O) and methane (CH4). To understand how agricultural soils can play a role in climate solutions requires a comprehensive assessment of net soil GHG balance (i.e., sum of SOC‐sequestered CO2 and non‐CO2 GHG emissions) and the underlying controls. Herein, we used a model‐data integration approach to understand and quantify how natural and anthropogenic factors have affected the magnitude and spatiotemporal variations of the net soil GHG balance in U.S. croplands during 1960–2018. Specifically, we used the dynamic land ecosystem model for regional simulations and used field observations of SOC sequestration rates and N2O and CH4 emissions to calibrate, validate, and corroborate model simulations. Results show that U.S. agricultural soils sequestered 13.2±1.16$$ 13.2\pm 1.16 $$ Tg CO2‐C year−1 in SOC (at a depth of 3.5 m) during 1960–2018 and emitted 0.39±0.02$$ 0.39\pm 0.02 $$ Tg N2O‐N year−1 and 0.21±0.01$$ 0.21\pm 0.01 $$ Tg CH4‐C year−1, respectively. Based on the GWP100 metric (global warming potential on a 100‐year time horizon), the estimated national net GHG emission rate from agricultural soils was 122.3±11.46$$ 122.3\pm 11.46 $$ Tg CO2‐eq year−1, with the largest contribution from N2O emissions. The sequestered SOC offset ~28% of the climate‐warming effects resulting from non‐CO2 GHG emissions, and this offsetting effect increased over time. Increased nitrogen fertilizer use was the dominant factor contributing to the increase in net GHG emissions during 1960–2018, explaining ~47% of total changes. In contrast, reduced cropland area, the adoption of agricultural conservation practices (e.g., reduced tillage), and rising atmospheric CO2 levels attenuated net GHG emissions from U.S. croplands. Improving management practices to mitigate N2O emissions represents the biggest opportunity for achieving net‐zero emissions in U.S. croplands. Our study highlights the importance of concurrently quantifying SOC‐sequestered CO2 and non‐CO2 GHG emissions for developing effective agricultural climate change mitigation measures. [ABSTRACT FROM AUTHOR]

[Display omitted] • A high-sensitivity and stable β-GICNT/rGO sensor was fabricated. • PEI was used to be an ideal modifier for the composite of rGO and c-CNTs. • PEI-CNTs and rGO form a three-dimensional stacking structure. • β-GICNT/rGO achieves highly sensitive detection of capsaicinoids. Rapid quantification of the content of capsaicinoids helps in classifying the degree of spiciness, standardized production, and quality control of leisure meat products. To rapidly quantify the content of capsaicinoids in soy sauce and pot-roast meat products, we developed an electrochemical sensor based on reduced graphene oxide (rGO)/polyethylene imine (PEI) - carbon nanotubes (CNTs)/β-cyclodextrin (β-CD) to detect the content of capsaicinoids in leisure meat products. Our findings showed that the electrochemical sensor presented highly sensitive performance toward capsaicinoids with a relatively wide linear range (0.01–100 µmol/L), a lower limit of detection (0.01 µmol/L), and an acceptable recovery rate (94.80–112.20%). The sensor performed well and was effective mainly because of the three-dimensional stacking structure and synergistic catalysis of rGO with cCNTs and also due to the improved dispersion of the composite material by β-CD. The sensor detected trace contents of capsaicinoids in leisure meat products, and thus, it might be considered for practical applications. [ABSTRACT FROM AUTHOR]

Human‐induced nitrogen–phosphorus (N, P) imbalance in terrestrial ecosystems can lead to disproportionate N and P loading to aquatic ecosystems, subsequently shifting the elemental ratio in estuaries and coastal oceans and impacting both the structure and functioning of aquatic ecosystems. The N:P ratio of nutrient loading to the Gulf of Mexico from the Mississippi River Basin increased before the late 1980s driven by the enhanced usage of N fertilizer over P fertilizer, whereafter the N:P loading ratio started to decrease although the N:P ratio of fertilizer application did not exhibit a similar trend. Here, we hypothesize that different release rates of soil legacy nutrients might contribute to the decreasing N:P loading ratio. Our study used a data‐model integration framework to evaluate N and P dynamics and the potential for long‐term accumulation or release of internal soil nutrient legacy stores to alter the ratio of N and P transported down the rivers. We show that the longer residence time of P in terrestrial ecosystems results in a much slower release of P to coastal oceans than N. If contemporary nutrient sources were reduced or suspended, P loading sustained by soil legacy P would decrease much slower than that of N, causing a decrease in the N and P loading ratio. The longer residence time of P in terrestrial ecosystems and the increasingly important role of soil legacy nutrients as a loading source may explain the decreasing N:P loading ratio in the Mississippi River Basin. Our study underscores a promising prospect for N loading control and the urgency to integrate soil P legacy into sustainable nutrient management strategies for aquatic ecosystem health and water security. [ABSTRACT FROM AUTHOR]

The introduction of nanostructures is an effective method to boost the photovoltaic performance of hybridized organic-inorganic halide perovskite-film solar cells. Taking into account their excellent light-scattering in the ultraviolet–visible range and their chemical inertness, silicon (Si) nanorods can be incorporated into the perovskite-film solar cells to enhance the light harvesting of the devices. By depositing Si nanorods between the prepared film and the substrate, the light scattering induced by the Si nanorods significantly promoted light absorption of the films. Moreover, resulting from the incorporation of Si nanorods, the enlarged grain size and compact structure of the films prolonged the lifetime of the carriers, which promoted the photoelectric properties of the perovskite films. By the appropriate incorporation of Si nanorods, the photovoltaic conversion efficiency of the CH 3 NH 3 Pb(Br 0.25 I 0.75) 3 -film-based solar cell was increased from 12.6% to 14.9% and the relative stability of the devices under dark humidity was improved. This strategy of employing low-cost and easily prepared Si nanorods to enhance the light harvesting of perovskite photovoltaic devices could be applied to photovoltaic devices based on perovskite films with other compositions. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) is an important greenhouse gas and also an ozone-depleting substance that has both natural and anthropogenic sources. Large estimation uncertainty remains on the magnitude and spatiotemporal patterns of N2O fluxes and the key drivers of N2O production in the terrestrial biosphere. Some terrestrial biosphere models have been evolved to account for nitrogen processes and to show the capability to simulate N2O emissions from land ecosystems at the global scale, but large discrepancies exist among their estimates primarily because of inconsistent input datasets, simulation protocol, and model structure and parameterization schemes. Based on the consistent model input data and simulation protocol, the global N2O Model Intercomparison Project (NMIP) was initialized with 10 state-of-the-art terrestrial biosphere models that include nitrogen (N) cycling. Specific objectives of NMIP are to 1) unravel the major N cycling processes controlling N2O fluxes in each model and identify the uncertainty sources from model structure, input data, and parameters; 2) quantify the magnitude and spatial and temporal patterns of global and regional N2O fluxes from the preindustrial period (1860) to present and attribute the relative contributions of multiple environmental factors to N2O dynamics; and 3) provide a benchmarking estimate of N2O fluxes through synthesizing the multimodel simulation results and existing estimates from ground-based observations, inventories, and statistical and empirical extrapolations. This study provides detailed descriptions for the NMIP protocol, input data, model structure, and key parameters, along with preliminary simulation results. The global and regional N2O estimation derived from the NMIP is a key component of the global N2O budget synthesis activity jointly led by the Global Carbon Project and the International Nitrogen Initiative. [ABSTRACT FROM AUTHOR]

In this paper, the two-step sequential deposition method was used to prepare the CH 3 NH 3 PbBr X I 3-X films by introducing CH 3 NH 3 Br in the precursors. The surface morphology of the PbI 2 films was controlled by anti-solvent extraction ( ASE ) to improve the microstructure and photo-physical properties of the perovskite films. It was noteworthy that, compared to the compact PbI 2 films, the porous PbI 2 films facilitated the growth of crystals and bromine incorporation in films, and the prepared perovskite films exhibited enlarged grain size, increased light absorption, enhanced Br incorporation and prolonged carrier lifetime, which resulted in excellent photo-electrical properties of the CH 3 NH 3 PbBr X I 3-X films. With porous PbI 2 templates, the inverted planar perovskite solar cells based on films with appropriate Br incorporation (CH 3 NH 3 Br/CH 3 NH 3 I mole ratio = 3/7) showed a photovoltaic conversion efficiency ( PCE ) of 14.9%, and the stability of the devices in air was elevated. Consequently, the high-quality CH 3 NH 3 PbBr X I 3-X films can be obtained with porous PbI 2 templates for improving the performance of the perovskite solar cells. [ABSTRACT FROM AUTHOR]

Abstract: Mammalian herbivores are an essential component of grassland and savanna ecosystems, and with feedbacks to the climate system. To date, the response and feedbacks of mammalian herbivores to changes in both abiotic and biotic factors are poorly quantified and not adequately represented in the current global land surface modeling framework. In this study, we coupled herbivore population dynamics in a global land model (the Dynamic Land Ecosystem Model, DLEM 3.0) to simulate populations of horses, cattle, sheep, and goats, and their responses to changes in multiple environmental factors at the site level across different continents during 1980–2010. Simulated results show that the model is capable of reproducing observed herbivore population dynamics across all sites for these animal groups. Our simulation results also indicate that during this period, climate extremes led to a maximum mortality of 27% of the total herbivores in Mongolia. Across all sites, herbivores reduced aboveground net primary productivity (ANPP) and heterotrophic respiration (Rh) by 14% and 15%, respectively (p < 0.05). With adequate parameterization, the model can be used for historical assessment and future prediction of mammalian herbivore populations and their relevant impacts on biogeochemical cycles. Our simulation results demonstrate a strong coupling between primary producers and consumers, indicating that inclusion of herbivores into the global land modeling framework is essential to better understand the potentially large effect of herbivores on carbon cycles in grassland and savanna ecosystems. [ABSTRACT FROM AUTHOR]

A wide range of estimates on global wetland methane (CH 4 ) fluxes has been reported during the recent two decades. This gives rise to urgent needs to clarify and identify the uncertainty sources, and conclude a reconciled estimate for global CH 4 fluxes from wetlands. Most estimates by using bottom-up approach rely on wetland data sets, but these data sets show largely inconsistent in terms of both wetland extent and spatiotemporal distribution. A quantitative assessment of uncertainties associated with these discrepancies among wetland data sets has not been well investigated yet. By comparing the five widely used global wetland data sets (GISS, GLWD, Kaplan, GIEMS and SWAMPS-GLWD), it this study, we found large differences in the wetland extent, ranging from 5.3 to 10.2 million km 2 , as well as their spatial and temporal distributions among the five data sets. These discrepancies in wetland data sets resulted in large bias in model-estimated global wetland CH 4 emissions as simulated by using the Dynamic Land Ecosystem Model (DLEM). The model simulations indicated that the mean global wetland CH 4 emissions during 2000–2007 were 177.2 ± 49.7 Tg CH 4 yr −1 , based on the five different data sets. The tropical regions contributed the largest portion of estimated CH 4 emissions from global wetlands, but also had the largest discrepancy. Among six continents, the largest uncertainty was found in South America. Thus, the improved estimates of wetland extent and CH 4 emissions in the tropical regions and South America would be a critical step toward an accurate estimate of global CH 4 emissions. This uncertainty analysis also reveals an important need for our scientific community to generate a global scale wetland data set with higher spatial resolution and shorter time interval, by integrating multiple sources of field and satellite data with modeling approaches, for cross-scale extrapolation. [ABSTRACT FROM AUTHOR]

Excessive anthropogenic nitrogen (N) inputs to the biosphere have disrupted the global nitrogen cycle. To better quantify the spatial and temporal patterns of anthropogenic N inputs, assess their impacts on the biogeochemical cycles of the planet and the living organisms, and improve nitrogen use efficiency (NUE) for sustainable development, we have developed a comprehensive and synthetic dataset for reconstructing the History of anthropogenic Nitrogen inputs (HaNi) to the terrestrial biosphere. The HaNi dataset takes advantage of different data sources in a spatiotemporally consistent way to generate a set of high-resolution gridded N input products from the preindustrial period to the present (1860–2019). The HaNi dataset includes annual rates of synthetic N fertilizer, manure application/deposition, and atmospheric N deposition on cropland, pasture, and rangeland at a spatial resolution of 5 arcmin × 5 arcmin. Specifically, the N inputs are categorized, according to the N forms and land uses, into 10 types: (1) NH4+ -N fertilizer applied to cropland, (2) NO 3- -N fertilizer applied to cropland, (3) NH4+ -N fertilizer applied to pasture, (4) NO 3- -N fertilizer applied to pasture, (5) manure N application on cropland, (6) manure N application on pasture, (7) manure N deposition on pasture, (8) manure N deposition on rangeland, (9) NH x -N deposition, and (10) NO y -N deposition. The total anthropogenic N (TN) inputs to global terrestrial ecosystems increased from 29.05 Tg N yr -1 in the 1860s to 267.23 Tg N yr -1 in the 2010s, with the dominant N source changing from atmospheric N deposition (before the 1900s) to manure N (in the 1910s–2000s) and then to synthetic fertilizer in the 2010s. The proportion of synthetic NH4+ -N in fertilizer input increased from 64 % in the 1960s to 90 % in the 2010s, while synthetic NO 3- -N fertilizer decreased from 36 % in the 1960s to 10 % in the 2010s. Hotspots of TN inputs shifted from Europe and North America to East and South Asia during the 1960s–2010s. Such spatial and temporal dynamics captured by the HaNi dataset are expected to facilitate a comprehensive assessment of the coupled human–Earth system and address a variety of social welfare issues, such as the climate–biosphere feedback, air pollution, water quality, and biodiversity. The data are available at 10.1594/PANGAEA.942069 (Tian et al., 2022). [ABSTRACT FROM AUTHOR]

The terrestrial ecosystems of North America have been identified as a sink of atmospheric CO though there is no consensus on the magnitude. However, the emissions of non-CO greenhouse gases (CH and NO) may offset or even overturn the climate cooling effect induced by the CO sink. Using a coupled biogeochemical model, in this study, we have estimated the combined global warming potentials (GWP) of CO, CH and NO fluxes in North American terrestrial ecosystems and quantified the relative contributions of environmental factors to the GWP changes during 1979-2010. The uncertainty range for contemporary global warming potential has been quantified by synthesizing the existing estimates from inventory, forward modeling, and inverse modeling approaches. Our 'best estimate' of net GWP for CO, CH and NO fluxes was −0.50 ± 0.27 Pg CO eq/year (1 Pg = 10 g) in North American terrestrial ecosystems during 2001-2010. The emissions of CH and NO from terrestrial ecosystems had offset about two thirds (73 %±14 %) of the land CO sink in the North American continent, showing large differences across the three countries, with offset ratios of 57 % ± 8 % in US, 83 % ± 17 % in Canada and 329 % ± 119 % in Mexico. Climate change and elevated tropospheric ozone concentration have contributed the most to GWP increase, while elevated atmospheric CO concentration have contributed the most to GWP reduction. Extreme drought events over certain periods could result in a positive GWP. By integrating the existing estimates, we have found a wide range of uncertainty for the combined GWP. From both climate change science and policy perspectives, it is necessary to integrate ground and satellite observations with models for a more accurate accounting of these three greenhouse gases in North America. [ABSTRACT FROM AUTHOR]

In rice cultivation, there are controversial reports on net impacts of nitrogen (N) fertilizers on methane ( CH4) emissions. Nitrogen fertilizers increase crop growth as well as alter CH4 producing (Methanogens) and consuming (Methanotrophs) microbes, and thereby produce complex effects on CH4 emissions. Objectives of this study were to determine net impact of N fertilizers on CH4 emissions and to identify their underlying mechanisms in the rice soils. Database was obtained from 33 published papers that contained CH4 emissions observations from N fertilizer (28-406 kg N ha−1) treatment and its control. Results have indicated that N fertilizers increased CH4 emissions in 98 of 155 data pairs in rice soils. Response of CH4 emissions per kg N fertilizer was significantly ( P < 0.05) greater at < 140 kg N ha−1 than > 140 kg N ha−1 indicating that substrate switch from CH4 to ammonia by Methanotrophs may not be a dominant mechanism for increased CH4 emissions. On the contrary, decreased CH4 emission in intermittent drainage by N fertilizers has suggested the stimulation of Methanotrophs in rice soils. Effects of N fertilizer stimulated Methanotrophs in reducing CH4 emissions were modified by the continuous flood irrigation due to limitation of oxygen to Methanotrophs. Greater response of CH4 emissions per kg N fertilizer in urea than ammonia sulfate probably indicated the interference of sulfate in the CH4 production process. Overall, response of CH4 emissions to N fertilizers was correlated with N-induced crop yield ( r = +0.39; P < 0.01), probably due to increased carbon substrates for Methanogens. Using CH4 emission observations, this meta-analysis has identified dominant microbial processes that control net effects of N fertilizers on CH4 emissions in rice soils. Finally, we have provided a conceptual model that included microbial processes and controlling factors to predict effects of N fertilizers on CH4 emissions in rice soils. [ABSTRACT FROM AUTHOR]

Summary: Little is known about how the terrestrial hydrological cycle responds to multiple environmental changes at large spatial scale and over long time period. Here, we applied a well calibrated and verified ecosystem model (the Dynamic Land Ecosystem Model, DLEM), in conjunction with newly developed data sets of multiple environmental factors including land use change, climate variability, elevated atmospheric carbon dioxide (CO2), nitrogen deposition, ozone pollution, and nitrogen fertilizer application, to characterize the spatial and temporal patterns of evapotranspiration (ET) and runoff in eastern China during 1961–2005 and further quantified the relative contributions of multiple environmental factors to these patterns at both basin and regional scales. The simulation results indicated that annual ET in the study area had a significantly increasing trend from 1961 to 2005. Yet there were no significant changing trends for estimated runoff and net water balance (precipitation minus ET). Substantial spatial heterogeneities in ET and runoff were observed. Annual ET increased in all basins except Yellow River Basin. Runoff increased in the southern part of the study area (including Pearl River and the Southeast basin), but decreased in northern part of the study area, particularly in Haihe and Huaihe river basins. Factorial analysis showed that climate change was the dominant factor responsible for the interannual variations in ET and runoff in the past 45years. Land use change (including land conversions and land management practices) yielded minor effects on the interannual variations in ET and runoff but caused relatively large effects over long-term period. For the accumulated change in ET at basin scale, climate change was the dominant factor in the basins of Song-Liao, Pearl River, while land use change contributed the most in the basin of Haihe, Huaihe, and Yellow River. Climate change was the dominant factor controlling runoff change in all basins except Huaihe and Yangtze River basins. Our simulated results imply that it is important to quantify relative roles of natural and anthropogenic disturbances on water fluxes for maintaining water sustainability in a changing climate. [Copyright &y& Elsevier]

Our understanding and quantification of global soil nitrous oxide (N2O) emissions and the underlying processes remain largely uncertain. Here, we assessed the effects of multiple anthropogenic and natural factors, including nitrogen fertilizer (N) application, atmospheric N deposition, manure N application, land cover change, climate change, and rising atmospheric CO2 concentration, on global soil N2O emissions for the period 1861–2016 using a standard simulation protocol with seven process‐based terrestrial biosphere models. Results suggest global soil N2O emissions have increased from 6.3 ± 1.1 Tg N2O‐N/year in the preindustrial period (the 1860s) to 10.0 ± 2.0 Tg N2O‐N/year in the recent decade (2007–2016). Cropland soil emissions increased from 0.3 Tg N2O‐N/year to 3.3 Tg N2O‐N/year over the same period, accounting for 82% of the total increase. Regionally, China, South Asia, and Southeast Asia underwent rapid increases in cropland N2O emissions since the 1970s. However, US cropland N2O emissions had been relatively flat in magnitude since the 1980s, and EU cropland N2O emissions appear to have decreased by 14%. Soil N2O emissions from predominantly natural ecosystems accounted for 67% of the global soil emissions in the recent decade but showed only a relatively small increase of 0.7 ± 0.5 Tg N2O‐N/year (11%) since the 1860s. In the recent decade, N fertilizer application, N deposition, manure N application, and climate change contributed 54%, 26%, 15%, and 24%, respectively, to the total increase. Rising atmospheric CO2 concentration reduced soil N2O emissions by 10% through the enhanced plant N uptake, while land cover change played a minor role. Our estimation here does not account for indirect emissions from soils and the directed emissions from excreta of grazing livestock. To address uncertainties in estimating regional and global soil N2O emissions, this study recommends several critical strategies for improving the process‐based simulations. The ensemble of terrestrial biosphere models indicates that global soil N2O emissions have increased from 6.3 ± 1.1 Tg N2O‐N/year in the preindustrial period (the 1860s) to 10.0 ± 2.0 Tg N2O‐N/year in the recent decade (2007–2016). Cropland soil emissions increased from 0.3 Tg N2O‐N/year to 3.3 Tg N2O‐N/year over the same period, accounting for 82% of the total increase, among which 54% attributes to nitrogen fertilizer application. Regionally, China, South Asia, and Southeast Asia underwent rapid increases in cropland N2O emissions since the 1970s. However, European cropland N2O emissions appear to have decreased by 14%. [ABSTRACT FROM AUTHOR]

In this study, pentabasic CuIn x Ga y Al 1-x-y Se 2 (CIGAS) powder was prepared by heating in ethylene diamine at 290 °C for 20 h, using a solvent thermal reaction technique. The microstructures and electrical properties of the CIGAS targets doped with different aluminum content were investigated by XRD, SEM, XPS and Hall Effect techniques. The results indicate that Al doping had an important effect on the electrical properties and microstructure of the CIGAS targets, especially at the (112) crystal orientation. It was found that the peak of (112) clearly shifted to higher 2θ values with the increase of aluminum incorporation, while the peak intensity weakened gradually, thus indicating that the crystallinity of the CIGAS targets decreased. The SEM results revealed that the sizes of the CIGAS grains could be adjusted by varying the stoichiometric ratio of In, Ga and Al, and that the Al incorporation could enhance the density of the CIGAS targets. The XRD and XPS analysis showed that some In and Ga atoms in the crystal lattice of chalcopyrite structure could be replaced with Al atoms in the CIGAS materials. Finally, the electrical properties of the targets were analyzed based on the Hall Effect measurements. The results showed that the conductivity, mobility and carrier concentration of the targets changed significantly along with the increase of the Al incorporation content, and that the mobility reducing may have been a result of Al incorporation, which prevents the grain from growing, followed by high-density target forming. [ABSTRACT FROM AUTHOR]

In this paper, the CH 3 NH 3 PbBr X I 3-X films were prepared by introducing CH 3 NH 3 Br into CH 3 NH 3 I precursor solution, after which the microstructure and photoelectric properties of the films were thoroughly investigated. Due to Br incorporation in the perovskite films, the band gap increased and the light absorption was slightly reduced while the charge carrier lifetime was prolonged due to the enhanced crystallinity. For the films with higher bromine content, the red shift of the photoluminescence peaks indicated that the phase segregation appeared in the films under illumination, which led to the formation of the iodine-rich domains in this process and the reduced carrier lifetime. On the contrary, for films with lower bromine content, the red shift of the photoluminescence peaks was negligible, which revealed that instability of the perovskite films under illumination can be suppressed by adjusting the bromine content of the films. Consequently, by moderate Br incorporation (CH 3 NH 3 Br/CH 3 NH 3 I mole ratio = 3:7), the CH 3 NH 3 PbBr X I 3-X films with optimal photoelectric properties and photo-stability were achieved, and the stable photoelectric conversion efficiency of corresponding device under illumination can reach 13.8%. [ABSTRACT FROM AUTHOR]

Human demand for livestock products has increased rapidly during the past few decades largely due to dietary transition and population growth, with significant impact on climate and the environment. The contribution of ruminant livestock to greenhouse gas ( GHG) emissions has been investigated extensively at various scales from regional to global, but the long-term trend, regional variation and drivers of methane ( CH4) emission remain unclear. In this study, we use Intergovernmental Panel on Climate Change ( IPCC) Tier II guidelines to quantify the evolution of CH4 emissions from ruminant livestock during 1890-2014. We estimate that total CH4 emissions in 2014 was 97.1 million tonnes (MT) CH4 or 2.72 Gigatonnes (Gt) CO2-eq (1 MT = 1012 g, 1 Gt = 1015 g) from ruminant livestock, which accounted for 47%-54% of all non- CO2 GHG emissions from the agricultural sector. Our estimate shows that CH4 emissions from the ruminant livestock had increased by 332% (73.6 MT CH4 or 2.06 Gt CO2-eq) since the 1890s. Our results further indicate that livestock sector in drylands had 36% higher emission intensity ( CH4 emissions/km2) compared to that in nondrylands in 2014, due to the combined effect of higher rate of increase in livestock population and low feed quality. We also find that the contribution of developing regions (Africa, Asia and Latin America) to the total CH4 emissions had increased from 51.7% in the 1890s to 72.5% in the 2010s. These changes were driven by increases in livestock numbers ( LU units) by up to 121% in developing regions, but decreases in livestock numbers and emission intensity (emission/km2) by up to 47% and 32%, respectively, in developed regions. Our results indicate that future increases in livestock production would likely contribute to higher CH4 emissions, unless effective strategies to mitigate GHG emissions in livestock system are implemented. [ABSTRACT FROM AUTHOR]

• A unified agricultural modeling framework is implemented in DLEM v4.0. • Simulated results agree well with site-scale LAI, biomass and yield measurements. • Regional simulations can well reproduce spatial-temporal patterns of crop production. • DLEM v4.0 can be used to support agricultural climate adaptation and mitigation. Agricultural decision-making by different interest groups (e.g., farmers, development agents and policy makers) usually takes place on different scales (e.g., plot, landscape and country). Currently, tools to assist decision-making are either dedicated to small-scale management guidance or large-scale assessment, which ignore the cross-scale linkages and interactions and thus may not provide robust and consistent guidance and assessment. Here, we developed an advanced agricultural modeling framework by integrating the strengths of conventional crop models in representing crop growth processes and management practices into a terrestrial biosphere model (TBM), the Dynamic Land Ecosystem Model (DLEM), to meet the cross-scale application needs (e.g., adaptation and mitigation). Specifically, dynamic crop growth processes, including crop-specific phenological development, carbon allocation, yield formation, biological nitrogen fixation processes, and management practices such as tillage, cover cropping and genetic improvements, were explicitly represented in DLEM. The new model was evaluated against site-scale observations and the results showed that the model performed generally well, with an average normalized root mean square error of 19.91% for leaf area index and 17.46% for aboveground biomass at the seasonal scale and 14.42% for annual yield. Then the model was applied to simulate corn, soybean, and winter wheat productions in the conterminous United States from 1960 to 2018. The spatial patterns of simulated crop productions were consistent with ground survey data. Our model also captured both the long-term trends and interannual variations of the total national productions of the three crops. This study demonstrates the significance of fusing conventional crop modeling techniques into TBMs to establish a unified modeling framework, which holds the potential to address climate impacts, adaptation and mitigation across varied spatiotemporal scales. [ABSTRACT FROM AUTHOR]

The seasonal-cycle amplitude (SCA) of the atmosphere-ecosystem carbon dioxide (CO2) exchange rate is a useful metric of the responsiveness of the terrestrial biosphere to environmental variations. It is unclear, however, what underlying mechanisms are responsible for the observed increasing trend of SCA in atmospheric CO2 concentration. Using output data from the Multi-scale Terrestrial Model Intercomparison Project (MsTMIP), we investigated how well the SCA of atmosphere-ecosystem CO2 exchange was simulated with 15 contemporary terrestrial ecosystem models during the period 1901-2010. Also, we made attempt to evaluate the contributions of potential mechanisms such as atmospheric CO2, climate, land-use, and nitrogen deposition, through factorial experiments using different combinations of forcing data. Under contemporary conditions, the simulated global-scale SCA of the cumulative net ecosystem carbon flux of most models was comparable in magnitude with the SCA of atmospheric CO2 concentrations. Results from factorial simulation experiments showed that elevated atmospheric CO2 exerted a strong influence on the seasonality amplification. When the model considered not only climate change but also land-use and atmospheric CO2 changes, the majority of the models showed amplification trends of the SCAs of photosynthesis, respiration, and net ecosystem production (+0.19 % to +0.50 % yr-1). In the case of land-use change, it was difficult to separate the contribution of agricultural management to SCA because of inadequacies in both the data and models. The simulated amplification of SCA was approximately consistent with the observational evidence of the SCA in atmospheric CO2 concentrations. Large inter-model differences remained, however, in the simulated global tendencies and spatial patterns of CO2 exchanges. Further studies are required to identify a consistent explanation for the simulated and observed amplification trends, including their underlying mechanisms. Nevertheless, this study implied that monitoring of ecosystem seasonality would provide useful insights concerning ecosystem dynamics. [ABSTRACT FROM AUTHOR]

It is highly uncertain on how human and natural environmental factors have altered methane (CH 4 ) emissions from terrestrial ecosystems in India. Using a process-based, Dynamic Land Ecosystem Model (DLEM) driven by climate, land cover and land use change (LCLUC), atmospheric nitrogen deposition (NDEP), atmospheric carbon dioxide (CO 2 ) concentration, and tropospheric ozone (O 3 ) pollution, we examined CH 4 flux from terrestrial in India during 1901–2010. The DLEM simulations have shown that total CH 4 flux over the country ranged from 2.9 Tg C year −1 to 6.5 Tg C year −1 with significant inter-annual variations driven by climate during 1901–2010. Contemporary CH 4 emissions have primarily occurred from rice fields (3.9 ± 0.9 Tg C year −1 ) while wetlands contributed to 2.1 ± 0.6 Tg C year −1 in the 2000s. During 1901–2010, total CH 4 emission from the terrestrial biosphere has increased by ∼2.1 Tg C year −1 . LCLUC has increased CH 4 emissions by 2.3 Tg C year −1 primarily due to increase in the rice-based cropping systems as well as irrigation expansion during the study period. Elevated CO 2 concentration stimulated plant biomass production in both rice fields and wetlands that increased CH 4 emissions by 0.7 Tg C year −1 . On the contrary, climate change decreased net CH 4 emissions by ∼1.2 Tg C year −1 due to negative effects of extreme high temperature as well as occurrences of extreme drought events on plant growth. Our study suggests that LCLUC and elevated CO 2 concentration have significantly increased CH 4 emissions from terrestrial ecosystems in India. [ABSTRACT FROM AUTHOR]

Quantitative information on the response of global terrestrial net primary production (NPP) to climate change and increasing atmospheric CO2 is essential for climate change adaptation and mitigation in the 21st century. Using a process-based ecosystem model (the Dynamic Land Ecosystem Model, DLEM), we quantified the magnitude and spatiotemporal variations of contemporary (2000s) global NPP, and projected its potential responses to climate and CO2 changes in the 21st century under the Special Report on Emission Scenarios (SRES) A2 and B1 of Intergovernmental Panel on Climate Change (IPCC). We estimated a global terrestrial NPP of 54.6 (52.8–56.4) PgC yr−1 as a result of multiple factors during 2000–2009. Climate change would either reduce global NPP (4.6%) under the A2 scenario or slightly enhance NPP (2.2%) under the B1 scenario during 2010–2099. In response to climate change, global NPP would first increase until surface air temperature increases by 1.5°C (until the 2030s) and then level-off or decline after it increases by more than 1.5°C (after the 2030s). This result supports the Copenhagen Accord Acknowledgement, which states that staying below 2°C may not be sufficient and the need to potentially aim for staying below 1.5°C. The CO2 fertilization effect would result in a 12%–13.9% increase in global NPP during the 21st century. The relative CO2 fertilization effect, i.e. change in NPP on per CO2 (ppm) bases, is projected to first increase quickly then level off in the 2070s and even decline by the end of the 2080s, possibly due to CO2 saturation and nutrient limitation. Terrestrial NPP responses to climate change and elevated atmospheric CO2 largely varied among biomes, with the largest increases in the tundra and boreal needleleaf deciduous forest. Compared to the low emission scenario (B1), the high emission scenario (A2) would lead to larger spatiotemporal variations in NPP, and more dramatic and counteracting impacts from climate and increasing atmospheric CO2. [ABSTRACT FROM AUTHOR]

The Loess Plateau of China has the highest soil erosion rate in the world where billion tons of soil is annually washed into Yellow River. In recent decades this region has experienced significant climate change and policy-driven land conversion. However, it has not yet been well investigated how these changes in climate and land use have affected soil organic carbon (SOC) storage on the Loess Plateau. By using the Dynamic Land Ecosystem Model (DLEM), we quantified the effects of climate and land use on SOC storage on the Loess Plateau in the context of multiple environmental factors during the period of 1961–2005. Our results show that SOC storage increased by 0.27 Pg C on the Loess Plateau as a result of multiple environmental factors during the study period. About 55% (0.14 Pg C) of the SOC increase was caused by land conversion from cropland to grassland/forest owing to the government efforts to reduce soil erosion and improve the ecological conditions in the region. Historical climate change reduced SOC by 0.05 Pg C (approximately 19% of the total change) primarily due to a significant climate warming and a slight reduction in precipitation. Our results imply that the implementation of “Grain for Green” policy may effectively enhance regional soil carbon storage and hence starve off further soil erosion on the Loess Plateau. [ABSTRACT FROM AUTHOR]

Organic polymer solar materials are shown to exhibit better solubility in mixed solvents than in pure ones, which affects the performance of their solar cells. In this article, poly[ N-9-hepta-decanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2,1,3-benzothiadiazole) (PCDTBT) and [6,6]-phenyl-C71-butyric acid methyl ester (PCBM) are used as active layer materials in solar cells. To optimize the performance of these active materials, the ratio of chloroform (CF) to chlorobenzene used as solvents to dissolve PCDTBT, and PCBM is varied, which is shown to affect power conversion efficiency (PCE). The solar cell that shows the best performance with a PCE as high as 6.82 % is produced using a volume ratio of CF to chlorobenzene of 1:1. [ABSTRACT FROM AUTHOR]

Abstract: Tropical Asia has experienced dramatic cropland expansion and agricultural intensification to meet the increasing food demand and is likely to undergo further rapid development in the near future. Much concern has been raised about how cropland expansion and associated management practices (nitrogen fertilizer use, irrigation, etc.) have affected the terrestrial carbon cycle in this region. In this study, we used a process-based ecosystem model, the Dynamic Land Ecosystem Model (DLEM), to assess the magnitude, spatial and temporal patterns of terrestrial carbon fluxes and pools in Tropical Asia as resulted from cropland expansion and land management practices during 1901–2005. The results indicated that cropland expansion had resulted in a release of 19.12±3.06PgC (0.18±0.029PgC/yr) into the atmosphere in Tropical Asia over the study period. Of this amount, approximately 22% (4.18±0.66PgC) was released from South Asia and 78% (14.94±2.40PgC) from Southeast Asia. Larger land area was converted to cropland while less carbon was emitted from South Asia than from Southeast Asia, where forest biomass and soil carbon were significantly higher. Changes in vegetation, soil organic matter, and litter pools caused emissions of 15.58, 2.25, and 1.71PgC, respectively, from the entire region. Significant decreases in vegetation carbon occurred across most regions of Southeast Asia due to continuous cropland expansion and shrink of natural forests. When considering land management practices, however, less carbon was released into the atmosphere, especially in South Asia where land management practices contributed to an approximately 10% reduction in carbon emission. This implies that optimizing land management practices could greatly reduce the carbon emissions caused by cropland expansion and might be one of important climate mitigation options in Tropical Asia. [Copyright &y& Elsevier]

Abstract: Natural wetland ecosystem plays an important role in global climate change due to its large amounts of stored carbon and nitrogen. The Sanjiang Plain, Northeast China, encompasses large area of natural freshwater marshy wetlands. However, the magnitude and temporal patterns of major greenhouse gases (GHGs: CO2, CH4 and N2O) in this region remain far from certain. Here we used a process-based ecosystem model to examine GHGs fluxes and their underlying mechanisms in the marshland across the Sanjiang Plain over the period 1949–2008. Simulation results indicated that during the past 60 years, the Sanjiang Plain''s marshland acted as a net CO2 sink of 4.20 ± 0.44 Tg C yr−1, while approximately 0.46 ± 0.02 Tg C yr−1 for CH4 and 0.02 ± 0.00 Tg N yr−1 for N2O were released to the atmosphere. Land cover and land use change (LCLUC) was the primary driver for GHGs changes. Climate change and tropospheric ozone (O3) pollution decreased CO2 uptakes, yet elevated CO2 concentration and nitrogen deposition increased CO2 uptake. Tropospheric O3 pollution and nitrogen deposition decreased CH4 emission by 7.94 Gg C and 0.41 Gg C, respectively, while elevated CO2 concentration increased the CH4 emission by 133.81 Gg C. Accumulatively, tropospheric O3 pollution and climate change contributed approximately 5.37% and 4.89% to the increased N2O emission, respectively, while elevated CO2 concentration reduced 2.81% of the N2O emission. The global warming potential (GWP) ranged from −1.81 Tg CO2eq yr−1 in the 1970s to 29.15 Tg CO2eq yr−1 in the 2000s. The decadal GWP by CO2 fluxes shifted from negative values between the 1950s and the 1990s to positive values in the 2000s, while CH4 and N2O emissions enhanced GWP from the 1950s to the 2000s. The total GWP decreased from the 1950s to the 1970s, but increased from the 1980s to the 2000s. This suggested that the reduced GWP by decreased CH4 emissions was gradually offset by the increased GWP by increased N2O emissions and decreased CO2 sink from the 1980s to the 2000s, implying that a full accounting of the greenhouse gas balance is essential in assessing global change impacts. [Copyright &y& Elsevier]

Terrestrial ecosystems in the southern United States (SUS) have experienced a complex set of changes in climate, atmospheric CO concentration, tropospheric ozone (O), nitrogen (N) deposition, and land-use and land-cover change (LULCC) during the past century. Although each of these factors has received attention for its alterations on ecosystem carbon (C) dynamics, their combined effects and relative contributions are still not well understood. By using the Dynamic Land Ecosystem Model (DLEM) in combination with spatially explicit, long -term historical data series on multiple environmental factors, we examined the century-scale responses of ecosystem C storage and flux to multiple environmental changes in the SUS. The results indicated that multiple environmental changes shifted SUS ecosystems from a C source of 1.20 ± 0.56 Pg (1 Pg = 10 g) during the period 1895 to 1950, to a C sink of 2.00 ± 0.94 Pg during the period 1951 to 2007. Over the entire period spanning 1895-2007, SUS ecosystems were a net C sink of 0.80 ± 0.38 Pg. The C sink was primarily due to an increase in the vegetation C pool, whereas the soil C pool decreased during the study period. The spatiotemporal changes of C storage were caused by changes in multiple environmental factors. Among the five factors examined (climate, LULCC, N deposition, atmospheric CO, and tropospheric O), elevated atmospheric CO concentration was the largest contributor to C sequestration, followed by N deposition. LULCC, climate, and tropospheric O concentration contributed to C losses during the study period. The SUS ecosystem C sink was largely the result of interactive effects among multiple environmental factors, particularly atmospheric N input and atmospheric CO [ABSTRACT FROM AUTHOR]

We investigated how ozone pollution and climate change/variability have interactively affected net primary productivity (NPP) and net carbon exchange (NCE) across China's forest ecosystem in the past half century. Continental China. Using the dynamic land ecosystem model (DLEM) in conjunction with 10-km-resolution gridded historical data sets (tropospheric O concentrations, climate variability/change, and other environmental factors such as land-cover/land-use change (LCLUC), increasing CO and nitrogen deposition), we conducted nine simulation experiments to: (1) investigate the temporo-spatial patterns of NPP and NCE in China's forest ecosystems from 1961-2005; and (2) quantify the effects of tropospheric O pollution alone or in combination with climate variability and other environmental stresses on forests' NPP and NCE. China's forests acted as a carbon sink during 1961-2005 as a result of the combined effects of O, climate, CO, nitrogen deposition and LCLUC. However, simulated results indicated that elevated O caused a 7.7% decrease in national carbon storage, with O-induced reductions in NCE (Pg C year) ranging from 0.4-43.1% among different forest types. Sensitivity experiments showed that climate change was the dominant factor in controlling changes in temporo-spatial patterns of annual NPP. The combined negative effects of O pollution and climate change on NPP and NCE could be largely offset by the positive fertilization effects of nitrogen deposition and CO. In the future, tropospheric O should be taken into account in order to fully understand the variations of carbon sequestration capacity of forests and assess the vulnerability of forest ecosystems to climate change and air pollution. Reducing air pollution in China is likely to increase the resilience of forests to climate change. This paper offers the first estimate of how prevention of air pollution can help to increase forest productivity and carbon sequestration in China's forested ecosystems. [ABSTRACT FROM AUTHOR]

The spatial and temporal patterns of CO and CH fluxes in China's croplands were investigated and attributed to multifactor environmental changes using the agricultural module of the Dynamic Land Ecosystem Model (DLEM), a highly integrated process-based ecosystem model. During 1980-2005 modelled results indicated that China's croplands acted as a carbon sink with an average carbon sequestration rate of 33.4 TgC yr (1 Tg = 10 g). Both the highest net CO uptake rate and the largest CH emission rate were found in southeast region of China's croplands. Of primary influences were land-cover and land-use change, atmospheric CO and nitrogen deposition, which accounted for 76%, 42% and 17% of the total carbon sequestration in China's croplands during the study period, respectively. The total carbon losses due to elevated ozone and climate variability/change were equivalent to 27% and 9% of the total carbon sequestration, respectively. Our further analysis indicated that nitrogen fertilizer application accounted for 60% of total national carbon uptake in cropland, whereas changes in paddy field areas mainly determined the variability of CH emissions. Our results suggest that improving air quality by means such as reducing ozone concentration and optimizing agronomic practices can enhance carbon sequestration capacity of China's croplands. [ABSTRACT FROM AUTHOR]

The fabrication process for perovskite films is critical for their microstructure and photo-electrical properties. In this study, a pre-preparation step for perovskite crystal particles with a conventional two step spin-coating method was introduced for improving the quality of the prepared perovskite films. By adding CH 3 NH 3 I into the PbI 2 precursor solution and performing anti-solvent extraction during the preparation process, a small amount of perovskite crystal particles was produced in the PbI 2 layers. We demonstrated that the pre-preparation of perovskite crystal particles enhanced the grain size and coverage of the perovskite films due to modification of the surface morphology and crystallisation of the PbI 2 layers. Furthermore, after optimisation, the crystal size in the perovskite films reached almost 3 μm, which tremendously enhanced the generation and transportation of photo-generated carriers in photo-voltaic devices. Under illumination, the fill factor (FF) and short circuit current density (J sc) of the corresponding devices increased, and the photoelectric conversion efficiency (PCE) was enhanced from 11.7% to 17.5%. Further, the stability of the devices in dark humid air was improved. Our results demonstrate that pre-preparing the perovskite crystal particles is useful for the fabrication of high-quality perovskite films. This approach can also be applied to devices based on perovskite films with other compositions. • Sequential deposition method has been improved for the preparation of perovskite films. • The high quality perovskite films were prepared by the pre-crystallisation. • The crystal size in the perovskite films reached almost 3 μm. • The PCE of perovskite solar cells have been greatly improved. [ABSTRACT FROM AUTHOR]