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For the management of eutrophic lakes, watershed nitrogen and phosphorus control is oriented to future water quality. Assessing future nutrient dynamics and the risk of lake eutrophication is necessary. However, current assessments often lack integrated consideration of socioeconomic and climatic factors, which reduces the reference value of the results. In this study, a typical large shallow lake Chaohu, which is highly influenced by human activities, was selected as the study area, and the current and future total nitrogen (TN) and total phosphorus (TP) loading in the basin were analysed using the improved MARINA model, and the risk of water bloom were assessed. The results showed that socioeconomic factors alone varied future TN and TP loading by −24% to 32% and −40% to 34%, respectively, under different development patterns. After considering the effect of increased precipitation, the changes of TN and TP loading became −10% to 163% and −29% to 108%, respectively. The effect on loading reduction under the sustainable development pattern was weakened (58% and 28% for TN and TP loading, respectively) and the increase in loading under the brutal development pattern was significantly amplified (409% and 215% for TN and TP loading, respectively). The adoption of active environmental policies remained an effective way of loading control. However, the risk of water bloom in local lake areas might persist due to factors such as urbanization. Timely and comprehensive assessments can provide managers with more information to identify key factors that contribute to the risk of water blooms and to develop diverse water quality improvement measures. The insights from our study are applicable to other watersheds around the world with similar socio-economic background and climatic conditions. • Analysis of the compounding effect of socio-economic and climatic factors on loading. • Complex impact of precipitation on loading under different development scenarios. • Improved MARINA model to enhance model accuracy and applicability. • Assessing the risk of future water bloom from a local perspective in the lake. [ABSTRACT FROM AUTHOR]

Water diverted from rivers for irrigation areas often contains large amounts of nitrogen (N), which is frequently overlooked and its role in contributing to N pollution is unknown. To investigate the influence of water diversion on N in different systems within irrigation areas, we developed and optimized the N footprint model, taking into account the N carried by irrigation water diversion and drainage in irrigated areas. This optimized model can serve as a reference for evaluating N pollution in other irrigated areas. By analyzing 29 years (1991–2019) of statistical data from a diverted irrigation area in Ningxia Hui Autonomous Region (Ningxia), China, the study assessed the contribution of water diversion to N in agriculture, animal husbandry, and human domestic activities. The results demonstrated that water diversion and drainage accounted for 10.3% and 13.8% in whole system, of the total N input and output in Ningxia, highlighting the potential N pollution risks associated with these activities. Additionally, the use of fertilizers in the plant subsystem, feed in the animal subsystem, and sanitary sewage in the human subsystem represented the main sources of N pollution in each subsystem. On a temporal scale, the study found that N loss increased year by year before reaching a stable level, indicating that N loss had reached its peak in Ningxia. The correlation analysis suggested that rainfall could regulate N input and output in irrigated areas by showing a negative correlation with water diversion, agricultural water consumption, and N from irrigated areas. Moreover, the study revealed that the amount of N brought by water diverted from rivers for irrigation should be taken into account when calculating the amount of fertilizer N required in the irrigation area. [Display omitted] • The risk of nitrogen pollution exists from the irrigation water. • Nitrogen in irrigation water should be considered when applying fertilizer. • The nitrogen of feed is the main pollution source in animal subsystem. • Nitrogen introduced from the river is insignificant in animal and human subsystems. [ABSTRACT FROM AUTHOR]

The effect of salinity on the nitrogen removal performance and microbial community of activated sludge was investigated in a sequencing batch reactor. The NH 4 +-N removal efficiency was over 95% at 0–4% salinity, indicating that the nitrification performance of activated sludge was slightly affected by lower salinity. The obvious nitrite accumulation was observed with the increment of the salinity to 5%, followed by a notable decline in the nitrogen removal performance at 6% salinity. The salinity inhibited the microbial activity, and the specific rate of nitrification and denitrification was decreased by the increasing salinity obviously. Additionally, the lower activity of superoxide dismutase and peroxidase and higher reactive oxygen species content in activated sludge might account for the deteriorative nitrogen removal performance at 6% salinity. Metagenomics analysis revealed that the genes encoding the ABC-type quaternary amine transporter in the ABC transporter pathway were abundant in the activated sludge at 2% and 4% salinity, and the higher salinity of 6% led to the loss of the genes encoding the p-type Na+ transporter in the ABC transporter pathway. These results indicated that the salinity could weaken the ABC transporter pathway for the balance of osmotic pressure in activated sludge. The microbial activity and nitrogen removal performance of activated sludge were decreased due to the unbalanced osmotic pressure at higher salinity. [Display omitted] • N removal efficiency was excellent at 0–4% salinity and worsened at 5%–6% salinity. • SOD and POD was the key antioxidase to response oxidative stress arising from salt. • Genes encoding ABC-type quaternary amine favored N removal at 2%–4% salinity. • Loss of genes encoding p-type Na+ transporter worsened N removal at 6% salinity. [ABSTRACT FROM AUTHOR]

Appropriate nitrogen (N) application increases crop yield, while its unreasonable application results in environmental problem. Determining the appropriate N application rate is the key to sustainable development. Here, the denitrification-decomposition (DNDC) model was used to analyze the effects of N fertilizer on maize yields, economic benefits, nitrate leaching, and nitrous oxide emissions in China. The N application rate for the trade-off between economy and environment at the county scale was further determined. The geodetector model was used to identify the main driving factors and their interactions of the recommended N rate in each agricultural zone. The results showed that the recommended N rate was generally high in the northwest but low in the south, consistent with the spatial patterns of yield potential. However, clay soils with clay ratios greater than 34% in southern China and sandy soils with bulk densities greater than 1.5 g cm−3 on the Huanghuaihai Plain experienced high N levels and low yields, and thus soils need to be improved. Potential grain yield was the main driving factor in most zones, yet its effects gradually weakened from north to south. The influence of soil characteristics increased from north to south. It was found that the current average N application rate of farmers in China was 249 kg N/ha, and 86.55% of counties had excessive N applications. Compared to the regional optimal N rate at a regional scale, a differentiated N application strategy at the county scale determined in this study increased maize yield and economic benefit by 10.51% and 10.85%, respectively, and reduced N 2 O emissions and NO 3 − leaching by 28.72% and 33.60%, respectively. The current research provides a scientific basis for China to formulate a win-win N management strategy for economy and environment and provides a method reference for other countries. [Display omitted] • N application rates that balanced economy and environment in China were determined. • Differentiated fertilization strategies can achieve a high yield and low pollution. • Environmental factors' impacts on the recommended rate were quantitatively analyzed. • From north to south China, PGY's effect weakened, while soil's effect increased. • Soils with clay ratio >34% or BD > 1.5 g cm−3 need to be improved. [ABSTRACT FROM AUTHOR]

Cattle-slurry (liquid manure) application to soil is a common practice to provide nutrients and organic matter for crop growth but it also strongly impacts the environment. The objective of the present study was to assess the efficiency of cattle-slurry treatment by solid–liquid separation and/or acidification on nitrogen dynamics and global warming potential (GWP) following application to an acidic soil. An aerobic laboratory incubation was performed over 92 days with a Dystric Cambisol amended with raw cattle-slurry or separated liquid fraction (LF) treated or not by acidification to pH 5.5 by addition of sulphuric acid. Soil mineral N contents and NH 3 , N 2 O, CH 4 and CO 2 emissions were measured. Results obtained suggest that the acidification of raw cattle-slurry reduced significantly NH 3 emissions (−88%) but also the GWP (−28%) while increased the N availability relative to raw cattle-slurry (15% of organic N applied mineralised against negative mineralisation in raw slurry). However, similar NH 3 emissions and GWP were observed in acidified LF and non-acidified LF treatments. On the other hand, soil application of acidified cattle-slurry rather than non-acidified LF should be preferred attending the lower costs associated to acidification compared to solid–liquid separation. It can then be concluded that cattle-slurry acidification is a solution to minimise NH 3 emissions from amended soil and an efficient strategy to decrease the GWP associated with slurry application to soil. Furthermore, the more intense N mineralisation observed with acidified slurry should lead to a higher amount of plant available N and consequently to higher crop yields. [ABSTRACT FROM AUTHOR]

The leaching of nitrogen in farmland could lead to groundwater nitrogen pollution, while precipitation is the driving factor. Nevertheless, the influences of extreme precipitation on soil organic nitrogen leaching, such as urea, is not clear. In this study, we used soil column experimental data to construct a nitrogen migration and transformation model. The constructed model was applied to unsaturated zones in farmlands in the Dagu River Basin of China. Three rainfall scenarios, namely rainstorms, heavy rainstorms, and extreme rainstorms, were simulated to analyze the variation in urea nitrogen leaching to groundwater. As the rainfall intensity increased, the quantity of urea nitrogen leaching increased from 0.04% to 18.09%. The cumulative urea nitrogen leaching flux is related to the initial soil moisture content. The time interval between fertilization inversely influenced the urea nitrogen leaching flux. Applying urea-based fertilizers shortly before high-intensity rainfall significantly increases the soil-crop system urea leaching loss and decreases crop nitrogen utilization. These findings imply that urea leaching under extreme rainstorms should not be ignored, and based on weather forecasting, fertilizer application in farmland should be avoided before high-intensity rainfall. • Numerical model is a useful tool for evaluating accumulated nitrogen leaching flux and nitrogen balance in the unsaturated zone. • The urea nitrogen leaching flux increase with the rainfall intensity increase, and the nitrogen use efficiencydecrease. • Under extreme rainstorms, 18.5% of urea nitrogen can leach to groundwater without hydrolysis. • The urea leaching flux was affected by the initial soil moisture and the time interval between fertilization and rainfall. [ABSTRACT FROM AUTHOR]

Comprehensive assessment tools are needed that reliably describe environmental impacts of different agricultural systems in order to develop sustainable high yielding agricultural production systems with minimal impacts on the environment. Today, Life Cycle Assessment (LCA) is increasingly used to assess and compare the environmental sustainability of agricultural products from conventional and organic agriculture. However, LCA studies comparing agricultural products from conventional and organic farming systems report a wide variation in the resource efficiency of products from these systems. The studies show that impacts per area farmed land are usually less in organic systems, but related to the quantity produced impacts are often higher. We reviewed 34 comparative LCA studies of organic and conventional agricultural products to analyze whether this result is solely due to the usually lower yields in organic systems or also due to inaccurate modeling within LCA. Comparative LCAs on agricultural products from organic and conventional farming systems often do not adequately differentiate the specific characteristics of the respective farming system in the goal and scope definition and in the inventory analysis. Further, often only a limited number of impact categories are assessed within the impact assessment not allowing for a comprehensive environmental assessment. The most critical points we identified relate to the nitrogen (N) fluxes influencing acidification, eutrophication, and global warming potential, and biodiversity. Usually, N-emissions in LCA inventories of agricultural products are based on model calculations. Modeled N-emissions often do not correspond with the actual amount of N left in the system that may result in potential emissions. Reasons for this may be that N-models are not well adapted to the mode of action of organic fertilizers and that N-emission models often are built on assumptions from conventional agriculture leading to even greater deviances for organic systems between the amount of N calculated by emission models and the actual amount of N available for emissions. Improvements are needed regarding a more precise differentiation between farming systems and regarding the development of N emission models that better represent actual N-fluxes within different systems. We recommend adjusting N- and C-emissions during farmyard manure management and farmyard manure fertilization in plant production to the feed ration provided in the animal production of the respective farming system leading to different N- and C-compositions within the excrement. In the future, more representative background data on organic farming systems (e.g. N content of farmyard manure) should be generated and compiled so as to be available for use within LCA inventories. Finally, we recommend conducting consequential LCA – if possible – when using LCA for policy-making or strategic environmental planning to account for different functions of the analyzed farming systems. [ABSTRACT FROM AUTHOR]

Mitigating the environmental impact of nitrogen (N) derived from agricultural production is a significant issue in our progression towards a sustainable society. This study aims to estimate the N stock (i.e., as the accumulation of N input into farmland that is neither taken up by the crops nor discharged into the environment, but rather remains in the soil) related to rice production in Japan and to identify the relationship between the economic behaviour of rice farmers and N stock. The results indicate a persistent reduction in N stock since the early 1990s, caused mainly by the change in N input by a change in government policy away from production subsidies to more extensive use of market mechanisms. It seems clear that production subsidy policies provide little incentive for farmers to reduce their N input; however, even if the introduction of market mechanisms, farmers may not properly evaluate the contribution of N stock to agricultural production. Consequently, it may be difficult to achieve the optimal level of N stock from an environmental impact perspective. To achieve the optimal N stock, the relationship between farmer behaviour and N stock needs to be better understood. • Nitrogen stock contributes to agricultural production while causing environmental impact. • Analysis of nitrogen stock and farmer's behaviour is lacking. • The results show reduction in N stock since the early 1990s, caused mainly by a change in rice policy of government. [ABSTRACT FROM AUTHOR]

This work reports on the potential application of UiO-66 in gas sweetening and its structural stability against water, air, dimethylformamide (DMF), and chloroform. The UiO-66 nanoparticles were solvothermally synthesized at different scales and activated via solvent exchange technique using chloroform, methanol, and ethanol. Thus prepared and aged MOFs were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and nitrogen adsorption-desorption analysis. The chloroform-activated MOF showed the largest surface area among all activation solvents, and presented high uptakes of 8.8 and 4.3 mmol/g for CO 2 and CH 4 , respectively, at 298 K and 30 bar. This might be due to removing all unreacted organic ligands and DMF molecules from the pores of the framework. The UiO-66 nanoparticles are stable at the experimental conditions with no significant loss in crystalline structure and gas adsorption ability even after aging under different conditions for one year. The UiO-66 could be easily regenerated at 373 K with no observed significant reduction in gas uptakes even after five consecutive adsorption-desorption cycles. The present findings suggest the excellent potential of the UiO-66-derived MOFs as the promising materials for CO 2 /CH 4 separation at low pressures and results can be applied in practical natural gas sweetening. Image 1 • High ideal CO 2 /CH 4 selectivity obtained using UiO-66 aged in DMF for one year. • Uptake of CO 2 by UiO-66 depends on BET surface area, pore diameter, and defects. • CO 2 /CH 4 selectivity at low pressure depends on pore dia and number of defects on UiO-66 framework. • Crystalline and porous structures of UiO-66 were highly stable in harsh conditions. • Scale of used materials, activation solvents, and aged conditions determine gas adsorption onto UiO-66. [ABSTRACT FROM AUTHOR]

Stable supply of nitrite is often a major obstacle for achieving mainstream anammox due to washout failure of nitrite oxidizers (NOB) at low influent ammonia of municipal wastewater. In this study, an integrated nitrification, partial denitrification and anammox (INPDA) as a one-stage mainstream nitrogen removal alternative was established in a low-oxygen sequencing batch biofilm reactor treating synthetic sewage. The overall nitrogen removal and nitrous oxide (N 2 O) emission were mainly investigated at 50 mg/L NH 4 +-N influent with a low carbon/nitrogen (C/N) of 2.5. Continuous operation demonstrated that as high as 98.8% NH 4 +-N and 94.1% TN were removed in SBBR system. Cyclic experiment verified sequential completion of nitrification, partial denitrification and anammox were responsible for high-rate TN removal. During one typical cycle, the trend of N 2 O emission was characterized by firstly rapid rise, then fluctuant decrease followed by rapid decrease and finally slow disappearance. The maximum N 2 O emission rate reached up to 6.7 μg/(L·min) occurred at 75 min. High-throughput sequencing revealed the co-existence of nitrifying, denitrifying and anammox species and large detection of key functional genes (Hzs , Hdh , Hao , Nor) in an oxygen-limited SBBR, thereby highly correlating nitrogen removal and N 2 O emission characteristics. Nitrogen metabolic pathways analysis further suggest denitratation(NO 3 −-N to NO 2 −-N)-based anammox is a main route for mainstream nitrogen removal. Moreover, N 2 O might be generated by both hydroxylamine oxidation step in nitrification and also heterotrophic denitrification pathway. The research findings provide more deep understandings of enhanced nitrogen removal and mitigated N 2 O footprint from a single mainstream anammox-based system. Image 1 • A novel one-stage mainstream anammox-based process was developed. • 94.1% TN removal from a low C/N synthetic sewage was achieved. • N 2 O emission behaviour in one SBBR cycle was explored. • Maximum N 2 O emission rate of 6.7 μg/(L·min) occurred at 75 min. • Metagenome analysis revealed nitrogen removal and N 2 O formation pathways. [ABSTRACT FROM AUTHOR]