The rapid growth of impervious areas in urban basins worldwide has increased the number of impermeable surfaces in cities,leading to severe flooding and significant economic losses for civilians.This trend highlights ...The rapid growth of impervious areas in urban basins worldwide has increased the number of impermeable surfaces in cities,leading to severe flooding and significant economic losses for civilians.This trend highlights the urgent need for methodologies that assess flood hazards and specifically address the direct impact on pedestrians,which is often overlooked in traditional flood hazard analyses.This study aims to evaluate a methodology for assessing the risk to pedestrians from hydrodynamic forces during urban floods,with a specific focus on Cúcuta,Colombia.The methodology couples research outcomes from other studies on the impact of floodwaters on individuals of different ages and sizes with 1D/2D hydrological modeling.Advanced computational algorithms for image recognition were used to measure water levels at 5-s intervals on November 6,2020,using drones for digital elevation model data collection.In Cúcuta,where flood risk is high and drainage infrastructure is limited,the PCSWMM(Computer-based Urban Stormwater Management Model)was calibrated and validated to simulate extreme flood events.The model incorporated urban infrastructure details and geomorphological parameters of Cúcuta's urban basin.Four return periods(5,10,50,100),with extreme rainfall of 3 h,were used to estimate the variability of the risk map.The output of the model was analyzed,and an integrated and time-varying comparison of the results was done.Results show that the regions of high-water depth and high velocity could vary significantly along the duration of the different extreme events.Also,from 5 to 100 years return period,the percentage of area at risk increased from 9.6%to 16.6%.The pedestrian sensitivity appears much higher than the increase in velocities or water depth individually.This study identified medium to high-risk locations,which are dynamic in time.We can conclude dynamics are spatiotemporal,and the added information layer of pedestrians brings vulnerability information that is also dynamic.Areas of immediate concern in Cúcuta can enhance pedestrian safety during flash flood events.The spatiotemporal variation of patterns requires further studies to map trajectories and sequences that machine learning models could capture.展开更多
This study was undertaken to help highlight the negative impacts of economic activities on wetlands in East Africa with a specific focus on Mara Bay and Masirori wetlands, Tanzania, a region where the local communitie...This study was undertaken to help highlight the negative impacts of economic activities on wetlands in East Africa with a specific focus on Mara Bay and Masirori wetlands, Tanzania, a region where the local communities still harness wetland resources for economic sustenance. Key economic activities and the negative impacts of the income-generating activities on the wetlands are identified, including the main goods harnessed, level of dependency of the locals to the wetlands, and the level of environmental knowledge of the locals on the wetlands’ ecosystem services. Both qualitative and quantitative tools and techniques viz.: questionnaires, semi-structured interviews, market surveys and spreadsheet analysis were used in this study. The proportion of wetland users involved in papyrus harvesting, food crop cultivation and fishing was 30%, 25% and 24%, respectively while charcoal/firewood and grass for livestock accounted for 12% and 7%, respectively. Significant differences in incomes for charcoal (p < 0.05) across the four villages were recorded but farming, fishing, mat making, herding and fish mongering were non-significant. About 6% of those interviewed had some considerable knowledge on wetland ecosystem services, while the rest (94%) lacked information. Issues identified as having detrimental impacts on the wetlands’ ecosystem services included conversion of sections of the wetlands into farmlands, grazing, charcoal burning, unsustainable fishing, overharvesting of papyrus and brick-making. Farming was found to be a major income-generating activity within the two wetlands. Other important economic activities were charcoal burning, fishing, mat making and fish mongering. The findings from the research are useful for devising appropriate strategies for wetland conservation. Such measures may include assigning wetland ecologists to the village governments, valuation of the wetlands, commissioning of a price and resource regulatory board for the wetland goods, creation of wetlands monitoring program, a fining regime system and a roll-out of mass environmental education in the wetlands regions.展开更多
It is generally believed that problems surrounding water scarcity led earlier generations to develop and employ a variety of indigenous rainwater harvesting(RWH)techniques.This paper is based on literature review and ...It is generally believed that problems surrounding water scarcity led earlier generations to develop and employ a variety of indigenous rainwater harvesting(RWH)techniques.This paper is based on literature review and aims to discuss the current status and impact of these widely practiced indigenous RWH systems with references to archaeological case studies from different agro-ecological areas.Our review shows that indigenous RWH systems are declining as a result of multiple factors but chiefly groundwater use,rural-urban migration,climate change,and changes in policy.However,our review also reveals that revitalized indigenous RWH systems can play an important role in alleviating water scarcity problems and sustaining livelihoods in both dry and developing regions.While new technologies have negatively affected several indigenous RWH systems when combined with traditional knowledge they can help to modernize indigenous RWH practices to make them more resilient,efficient,and productive.展开更多
In continuous biomass torrefaction plants,the products'yields,composition and homogeneity highly depend on the residence time of particles.A characterization of particle residence time distribution(RTD)was therefo...In continuous biomass torrefaction plants,the products'yields,composition and homogeneity highly depend on the residence time of particles.A characterization of particle residence time distribution(RTD)was therefore carried out in an industrial-scale multiple hearth furnace on poplar wood chips using radio frequency identification tracers.The effects of operating conditions,namely,mass flow rate of biomass,shaft speed of the rabbling system and interdental length on the RTD were studied.The increase of shaft speed and mass flow rate reduces particles’mean residence time.Lowering the length between two successive teeth also increases the bed speed.Uncontrollable biomass accumulation(also called“bulldozing”)was observed during several tests.This phenomenon is favored by a high mass flow rate of resources,a small interdental length between the teeth and a low shaft speed.RTD measurements were compared to the axial dispersion model.For all tests,the Peclet number is ranging between 20 and 62,indicating that the multiple hearth furnace cannot be modelled as an ideal plug flow reactor.展开更多
Anaerobic digestion technology,effective for sustainable waste management and renewable energy,but challenged by slow reaction rates and low biogas yields,could benefit from advancements in magnetic nanomaterials.This...Anaerobic digestion technology,effective for sustainable waste management and renewable energy,but challenged by slow reaction rates and low biogas yields,could benefit from advancements in magnetic nanomaterials.This review explores the potential of magnetic nanomaterials,particularly magnetic biochar nanocomposites,to address these challenges by serving as electron conduits and providing essential iron.This review contributes a thorough overview of the application of magnetic nanoparticles loaded into biochar in anaerobic digestion and engages in a comprehensive discussion regarding the synthesis methods and characterization of various magnetic nanoparticles,elucidating their mechanisms of action in both the absence and presence of magnetic fields.Our review underscores the predominance of co-precipitation(53%)and commercially sourced nanoparticles(29%)as the main synthesis methods,with chemical reduction,pyrolysis,and green synthesis pathways less commonly utilized(8%,5%,and 5%,respectively).Notably,pyrolysis is predominantly employed for synthesizing magnetic biochar nanocomposites,reflecting its prevalence in 100%of cases for this specific application.By offering a critical evaluation of the current state of knowledge and discussing the challenges and future directions for research in this field,this review can help researchers and practitioners better understand the potential of magnetic biochar nanocomposites for enhancing anaerobic digestion performance and ultimately advancing sustainable waste management and renewable energy production.展开更多
Biorefneries contribute to a circular bioeconomy using renewable feedstock to produce commodity and specialty chemicals as an alternative to petroleum chemicals.Using waste streams such as food waste and agricultural ...Biorefneries contribute to a circular bioeconomy using renewable feedstock to produce commodity and specialty chemicals as an alternative to petroleum chemicals.Using waste streams such as food waste and agricultural waste as a feedstock for biorefneries is a promising approach for obtaining value-added products in an economically feasible and sustainable way.The conversion of biomass to chemicals ofers diverse opportunities but poses new technological challenges.This paper aims to review the current state of food and agricultural waste valorisation by giving a brief technical overview,summarizing the current state of the bio-based market,and identifying the current barriers to scaling-up biorefneries.Utilizing lignocellulosic biomass in biorefneries calls for pre-treatment due to its complex structure,in which biomass is broken into monosaccharides,building blocks of value-added products.Diferent state of the art technologies for lignocellulose pre-treatment is introduced in the review followed by a brief explanation of the role of the hydrolysis and fermentation.The economic aspect of chemical production from biomass waste at an industrial scale is also introduced by giving an overview of some recent techno-economic studies.展开更多
Rainfed agriculture has a high yield potential if rainfall and land resources are effectively used.In this study,conventional(NC)and six in-situ water conservation practices were used to cultivate Soybean in 2011 and ...Rainfed agriculture has a high yield potential if rainfall and land resources are effectively used.In this study,conventional(NC)and six in-situ water conservation practices were used to cultivate Soybean in 2011 and 2012 in Ile-lfe,Nigeria.The conservation practices are:Tied ridge(TR),Soil bund(BD),Mulch(ML),Mulch plus Soil bund(MLBD),Tied ridge plus Mulch(TRML),Tied ridge plus Soil bund(TRBD).The practices were arranged in Randomised Complete Block Design with four replicates.Seasonal rainfall was 539 and 761 mm in 2011 and 2012,respectively.Seasonal soil water storage(SWS)ranged from 485 mm for NC to 517 mm for TRML in the two seasons.ML increased the SWS in the upper 30 cm of the soil by 17% while TR increased the soil water content in the lower 30-60 cm by 22% compared with NC.ML reduced soil temperature in the upper 30 cm between 2.2 and 2.9℃ compared with NC,TR and TRML.Seasonal crop evapotranspiration ranged between 432 mm for NC and 481 mm for BD in the seasons.Grain yield increased by 41.7% and 44.3% for BD and MLBD,respectively compared with NC.Water conservation practices increased water productivity for grain yield by 14.0-41.8% compared with NC.Similarly,it increased average seasonal transpiration efficiency by 15.3-32.5% compared with NC.These findings demonstrate that when there are fluctuations in rainfall,in-situ water conservation practices improve SWS,land,and water productivity and transpiration efficiency of Soybeans.展开更多
Modelling of the effects of water and different levels of nitrogen on evapotranspiration and water productivity of rainfed soybeans is very important in optimising resource use in the production of the crop.The object...Modelling of the effects of water and different levels of nitrogen on evapotranspiration and water productivity of rainfed soybeans is very important in optimising resource use in the production of the crop.The objective of the study was to model evapotranspiration,soil water storage and water productivity of rainfed soybeans under different levels of nitrogen fertilizer by using the FAO AquaCrop model.Field experiments were conducted at the Teaching and Research Farms of Obafemi Awolowo University,Nigeria in the rainy seasons of 2015 and 2016.There were five levels of nitrogen,which are 00,25,50,75 and 100%of the recommended nitrogen applications and two varieties of soybeans,which produced a 2 by 5 factorial experimental design.The data of the wetter year 2015,were used for calibration of the AquaCrop model because AquaCrop is water driven.The 2016 data were used for the validation.The AquaCrop model simulated canopy cover with R2 and EF>0.90,d-in-dex>0.99.The model captured the trend of the soil water storage well,R2 and EF>0.70.The AquaCrop model simulated soil water storage below wilting point for seasonal rainfall less than 600 mm,and it did not overestimate it.The model predicted evapotranspirationwith R and EF>0.89,d-index=1.00.Above ground biomass was overestimated even though R2>0.98.Although,nitrogen stress reduced seed yield and water productivity,there was no under or over estimation of the seed yields.They were predicted with low error under the different levels of nitrogen fertilizer,R>0.99,EF and d-index>0.99.The AquaCrop model is suitable for simulating canopy cover,soil water storage,evapotranspiration,and seed yieldof rainfed soybeans with different levels of nitrogen fertilizer under temporal distribution of seasonal rainfall.Therefore,it can serve as a useful tool for smallholder farmers in predicting productivity of soybeans and optimising resource allocation,land and water use in the tropical farming systems.We recommend simulation of the effects of pest on biomass,seed yield and water produc-tivity by subsequent versions of the AquaCrop model.In addition,incorporating an eco-nomic sub-unit in the model will enable users to make financial decisions.展开更多
Actual evapotranspiration(ET)is a major component of the water balance.While several international flux measurement programs have been executed in the tropical rain forest of the Amazon,those measurements represent th...Actual evapotranspiration(ET)is a major component of the water balance.While several international flux measurement programs have been executed in the tropical rain forest of the Amazon,those measurements represent the evaporative process at a few selected sites only.The aim of this study is to obtain the spatial distribution of ET,using remote sensing techniques,across the entire Amazon River Basin.Results from six global ET products based on remote sensing techniques(GLEAM,SEBS,ALEXI,CMRSET,MOD16,and SSEBop)were merged to obtain an ensemble prediction of the ET rates for the complex and in-accessible environment of the Amazon at a spatial resolution of 250 m.The study shows that the basinwide average ET is 1316 mm/year with a standard deviation of 192 mm/year.This new ET-Amazon product was validated against seven different historic flux tower measurements.The energy balance closure of the in situ measurements varied between 86 and 116%.Only months with more than 70%completeness of in situ measurements were considered for validation.Different procedures for closure correction were included in the analyses.The correlation between measured and remotely sensed ET is good(R2>0.97 for consecutive periods of 2 to 12months),and the bias correction is negligible for the energy balance residual method,which seemed most favorable.Monthly ET values have more uncertainty.The monthly RMSE values vary between 7.4 and 27.8 mm/month(the average RMSE is 22.2mm/month),and the coefficient of determination(R2)varies between 0.48 and 0.87(the average R2 is 0.53).The ET from the water balance is 1380 mm/year,being−64 mm/year difference and 4.6%less than ET derived from the water balance.The evaporation from the Amazon basin inside Brazil is 5063 km3/year,followed by Peru with 1165 km3/year.ET-Amazon shows more spatial details and accuracy than alternative global ET products such as LandFlux-EVAL,Model Tree Ensemble(MTE),and WACMOS-ET.This justifies the development of new regional ET products.展开更多
Wastewaters from various process industries,namely food and agricultural,sugar mill,brewery,milk,vegetable and fruit,and meat and fsheries processing industries and their wastewater efuents contain nutrients,organic m...Wastewaters from various process industries,namely food and agricultural,sugar mill,brewery,milk,vegetable and fruit,and meat and fsheries processing industries and their wastewater efuents contain nutrients,organic matter,inorganic,heavy metals,suspended solids,and pathogens.The discharges of non-treated wastewater enter the nearby aquatic ecosystem(e.g.,lakes,rivers)and are a signifcant concern due to the presence of diferent nutrients,competing ions and C containing pollutants.It causes excessive growth of algae,loss of habitat/species,and other negative impacts on human health/environment.In the present review,diferent treatment approaches have been discussed in utilizing these nutrients to synthesize value-added products such as biopolymer,biofuel,pigment,organic acid,or enzymes.These biopolymers can be used to prepare various food products/packaging materials.Dextran,chitosan,carrageenan,alginate,and pectin are good examples of non-food biopolymers.Besides these products,poly-β-hydroxybutyrate(PHB)synthesis from wastewater nutrients is reported as a new source of bio-nanocomposite materials/biopolymer-based coatings.In this review,the diferent treatment approaches are discussed,which are being used worldwide for the removal/recovery of nutrients,toxic pollutants,and the potential resource recovery of value-added products from wastewater.展开更多
In this study,a highly porous chemically activated granular activated carbon(GAC)was prepared from coconut husk and tested as an adsorbent to remove nitrate from contaminated groundwater.The prepared GAC was character...In this study,a highly porous chemically activated granular activated carbon(GAC)was prepared from coconut husk and tested as an adsorbent to remove nitrate from contaminated groundwater.The prepared GAC was characterized by Fouriertransform infrared spectroscopy(FTIR),thermogravimetric and differential thermal analysis(TGA/DTA),scanning electron microscopy(SEM)and the Brunauer-Emmett-Teller(BET)surface area(SBET)analysis.The effects of various process parameters such as initial nitrate concentration,contact time and adsorbent dose on nitrate removal efficiency(response)by the modified GAC were investigated using the statistically significant response surface methodology and Box-Behnken design of experiments.The experimental data were fitted to well-known adsorption isotherms and kinetic models to ascertain the mechanism of the adsorption process.Analysis of variance(ANOVA)was performed to determine the significance of the individual and the interactive effects of process variables on the response.The BET surface area(SBET)and micropore volume of the prepared GAC from coconut husk was 1120 m^(2)/g and 0.392 cm^(3)/g,respectively.The experimental results showed that physisorption was the main adsorption mechanism governing the process,while the rate of adsorption was limited at initial nitrate concentrations>10 mg/L.The Langmuir mono-layer adsorption isotherm best fitted the experimental data with a maximum adsorption capacity of 6.0±1.3 mg/g(~92.5%)with an adsorbent dose of 0.1 g/50 mL,an equilibrium time of 6 h at 28±2℃,and at pH 7.6(±0.2).Among the tested process variables,the adsorbent dose and initial nitrate concentration showed significant effects on the nitrate removal efficiency.展开更多
基金University of PamplonaColombian School of Engineering Julio Garavito。
文摘The rapid growth of impervious areas in urban basins worldwide has increased the number of impermeable surfaces in cities,leading to severe flooding and significant economic losses for civilians.This trend highlights the urgent need for methodologies that assess flood hazards and specifically address the direct impact on pedestrians,which is often overlooked in traditional flood hazard analyses.This study aims to evaluate a methodology for assessing the risk to pedestrians from hydrodynamic forces during urban floods,with a specific focus on Cúcuta,Colombia.The methodology couples research outcomes from other studies on the impact of floodwaters on individuals of different ages and sizes with 1D/2D hydrological modeling.Advanced computational algorithms for image recognition were used to measure water levels at 5-s intervals on November 6,2020,using drones for digital elevation model data collection.In Cúcuta,where flood risk is high and drainage infrastructure is limited,the PCSWMM(Computer-based Urban Stormwater Management Model)was calibrated and validated to simulate extreme flood events.The model incorporated urban infrastructure details and geomorphological parameters of Cúcuta's urban basin.Four return periods(5,10,50,100),with extreme rainfall of 3 h,were used to estimate the variability of the risk map.The output of the model was analyzed,and an integrated and time-varying comparison of the results was done.Results show that the regions of high-water depth and high velocity could vary significantly along the duration of the different extreme events.Also,from 5 to 100 years return period,the percentage of area at risk increased from 9.6%to 16.6%.The pedestrian sensitivity appears much higher than the increase in velocities or water depth individually.This study identified medium to high-risk locations,which are dynamic in time.We can conclude dynamics are spatiotemporal,and the added information layer of pedestrians brings vulnerability information that is also dynamic.Areas of immediate concern in Cúcuta can enhance pedestrian safety during flash flood events.The spatiotemporal variation of patterns requires further studies to map trajectories and sequences that machine learning models could capture.
文摘This study was undertaken to help highlight the negative impacts of economic activities on wetlands in East Africa with a specific focus on Mara Bay and Masirori wetlands, Tanzania, a region where the local communities still harness wetland resources for economic sustenance. Key economic activities and the negative impacts of the income-generating activities on the wetlands are identified, including the main goods harnessed, level of dependency of the locals to the wetlands, and the level of environmental knowledge of the locals on the wetlands’ ecosystem services. Both qualitative and quantitative tools and techniques viz.: questionnaires, semi-structured interviews, market surveys and spreadsheet analysis were used in this study. The proportion of wetland users involved in papyrus harvesting, food crop cultivation and fishing was 30%, 25% and 24%, respectively while charcoal/firewood and grass for livestock accounted for 12% and 7%, respectively. Significant differences in incomes for charcoal (p < 0.05) across the four villages were recorded but farming, fishing, mat making, herding and fish mongering were non-significant. About 6% of those interviewed had some considerable knowledge on wetland ecosystem services, while the rest (94%) lacked information. Issues identified as having detrimental impacts on the wetlands’ ecosystem services included conversion of sections of the wetlands into farmlands, grazing, charcoal burning, unsustainable fishing, overharvesting of papyrus and brick-making. Farming was found to be a major income-generating activity within the two wetlands. Other important economic activities were charcoal burning, fishing, mat making and fish mongering. The findings from the research are useful for devising appropriate strategies for wetland conservation. Such measures may include assigning wetland ecologists to the village governments, valuation of the wetlands, commissioning of a price and resource regulatory board for the wetland goods, creation of wetlands monitoring program, a fining regime system and a roll-out of mass environmental education in the wetlands regions.
基金funded by the Netherlands Organization for Internationalization in Education(NUFFIC)through the Netherlands Initiative for Capacity Development in Higher Education(NICHE 27).
文摘It is generally believed that problems surrounding water scarcity led earlier generations to develop and employ a variety of indigenous rainwater harvesting(RWH)techniques.This paper is based on literature review and aims to discuss the current status and impact of these widely practiced indigenous RWH systems with references to archaeological case studies from different agro-ecological areas.Our review shows that indigenous RWH systems are declining as a result of multiple factors but chiefly groundwater use,rural-urban migration,climate change,and changes in policy.However,our review also reveals that revitalized indigenous RWH systems can play an important role in alleviating water scarcity problems and sustaining livelihoods in both dry and developing regions.While new technologies have negatively affected several indigenous RWH systems when combined with traditional knowledge they can help to modernize indigenous RWH practices to make them more resilient,efficient,and productive.
文摘In continuous biomass torrefaction plants,the products'yields,composition and homogeneity highly depend on the residence time of particles.A characterization of particle residence time distribution(RTD)was therefore carried out in an industrial-scale multiple hearth furnace on poplar wood chips using radio frequency identification tracers.The effects of operating conditions,namely,mass flow rate of biomass,shaft speed of the rabbling system and interdental length on the RTD were studied.The increase of shaft speed and mass flow rate reduces particles’mean residence time.Lowering the length between two successive teeth also increases the bed speed.Uncontrollable biomass accumulation(also called“bulldozing”)was observed during several tests.This phenomenon is favored by a high mass flow rate of resources,a small interdental length between the teeth and a low shaft speed.RTD measurements were compared to the axial dispersion model.For all tests,the Peclet number is ranging between 20 and 62,indicating that the multiple hearth furnace cannot be modelled as an ideal plug flow reactor.
基金support from the earmarked fund for CARS(CARS-06-14.5-A31)Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences.Yadong Yang would like to acknowledge the financial support from National Natural Science Foundation of China(42271401)special funds for basic scientific research business of central public welfare research institutes(1610132023015,GJ2023-18-1).
文摘Anaerobic digestion technology,effective for sustainable waste management and renewable energy,but challenged by slow reaction rates and low biogas yields,could benefit from advancements in magnetic nanomaterials.This review explores the potential of magnetic nanomaterials,particularly magnetic biochar nanocomposites,to address these challenges by serving as electron conduits and providing essential iron.This review contributes a thorough overview of the application of magnetic nanoparticles loaded into biochar in anaerobic digestion and engages in a comprehensive discussion regarding the synthesis methods and characterization of various magnetic nanoparticles,elucidating their mechanisms of action in both the absence and presence of magnetic fields.Our review underscores the predominance of co-precipitation(53%)and commercially sourced nanoparticles(29%)as the main synthesis methods,with chemical reduction,pyrolysis,and green synthesis pathways less commonly utilized(8%,5%,and 5%,respectively).Notably,pyrolysis is predominantly employed for synthesizing magnetic biochar nanocomposites,reflecting its prevalence in 100%of cases for this specific application.By offering a critical evaluation of the current state of knowledge and discussing the challenges and future directions for research in this field,this review can help researchers and practitioners better understand the potential of magnetic biochar nanocomposites for enhancing anaerobic digestion performance and ultimately advancing sustainable waste management and renewable energy production.
基金The research was funded by ERASMUS+International Master of Science in Environmental Technology and Engineering(IMETE)to pursue the MSc programme(2017–1957/001–001-EMJMD).
文摘Biorefneries contribute to a circular bioeconomy using renewable feedstock to produce commodity and specialty chemicals as an alternative to petroleum chemicals.Using waste streams such as food waste and agricultural waste as a feedstock for biorefneries is a promising approach for obtaining value-added products in an economically feasible and sustainable way.The conversion of biomass to chemicals ofers diverse opportunities but poses new technological challenges.This paper aims to review the current state of food and agricultural waste valorisation by giving a brief technical overview,summarizing the current state of the bio-based market,and identifying the current barriers to scaling-up biorefneries.Utilizing lignocellulosic biomass in biorefneries calls for pre-treatment due to its complex structure,in which biomass is broken into monosaccharides,building blocks of value-added products.Diferent state of the art technologies for lignocellulose pre-treatment is introduced in the review followed by a brief explanation of the role of the hydrolysis and fermentation.The economic aspect of chemical production from biomass waste at an industrial scale is also introduced by giving an overview of some recent techno-economic studies.
文摘Rainfed agriculture has a high yield potential if rainfall and land resources are effectively used.In this study,conventional(NC)and six in-situ water conservation practices were used to cultivate Soybean in 2011 and 2012 in Ile-lfe,Nigeria.The conservation practices are:Tied ridge(TR),Soil bund(BD),Mulch(ML),Mulch plus Soil bund(MLBD),Tied ridge plus Mulch(TRML),Tied ridge plus Soil bund(TRBD).The practices were arranged in Randomised Complete Block Design with four replicates.Seasonal rainfall was 539 and 761 mm in 2011 and 2012,respectively.Seasonal soil water storage(SWS)ranged from 485 mm for NC to 517 mm for TRML in the two seasons.ML increased the SWS in the upper 30 cm of the soil by 17% while TR increased the soil water content in the lower 30-60 cm by 22% compared with NC.ML reduced soil temperature in the upper 30 cm between 2.2 and 2.9℃ compared with NC,TR and TRML.Seasonal crop evapotranspiration ranged between 432 mm for NC and 481 mm for BD in the seasons.Grain yield increased by 41.7% and 44.3% for BD and MLBD,respectively compared with NC.Water conservation practices increased water productivity for grain yield by 14.0-41.8% compared with NC.Similarly,it increased average seasonal transpiration efficiency by 15.3-32.5% compared with NC.These findings demonstrate that when there are fluctuations in rainfall,in-situ water conservation practices improve SWS,land,and water productivity and transpiration efficiency of Soybeans.
文摘Modelling of the effects of water and different levels of nitrogen on evapotranspiration and water productivity of rainfed soybeans is very important in optimising resource use in the production of the crop.The objective of the study was to model evapotranspiration,soil water storage and water productivity of rainfed soybeans under different levels of nitrogen fertilizer by using the FAO AquaCrop model.Field experiments were conducted at the Teaching and Research Farms of Obafemi Awolowo University,Nigeria in the rainy seasons of 2015 and 2016.There were five levels of nitrogen,which are 00,25,50,75 and 100%of the recommended nitrogen applications and two varieties of soybeans,which produced a 2 by 5 factorial experimental design.The data of the wetter year 2015,were used for calibration of the AquaCrop model because AquaCrop is water driven.The 2016 data were used for the validation.The AquaCrop model simulated canopy cover with R2 and EF>0.90,d-in-dex>0.99.The model captured the trend of the soil water storage well,R2 and EF>0.70.The AquaCrop model simulated soil water storage below wilting point for seasonal rainfall less than 600 mm,and it did not overestimate it.The model predicted evapotranspirationwith R and EF>0.89,d-index=1.00.Above ground biomass was overestimated even though R2>0.98.Although,nitrogen stress reduced seed yield and water productivity,there was no under or over estimation of the seed yields.They were predicted with low error under the different levels of nitrogen fertilizer,R>0.99,EF and d-index>0.99.The AquaCrop model is suitable for simulating canopy cover,soil water storage,evapotranspiration,and seed yieldof rainfed soybeans with different levels of nitrogen fertilizer under temporal distribution of seasonal rainfall.Therefore,it can serve as a useful tool for smallholder farmers in predicting productivity of soybeans and optimising resource allocation,land and water use in the tropical farming systems.We recommend simulation of the effects of pest on biomass,seed yield and water produc-tivity by subsequent versions of the AquaCrop model.In addition,incorporating an eco-nomic sub-unit in the model will enable users to make financial decisions.
文摘Actual evapotranspiration(ET)is a major component of the water balance.While several international flux measurement programs have been executed in the tropical rain forest of the Amazon,those measurements represent the evaporative process at a few selected sites only.The aim of this study is to obtain the spatial distribution of ET,using remote sensing techniques,across the entire Amazon River Basin.Results from six global ET products based on remote sensing techniques(GLEAM,SEBS,ALEXI,CMRSET,MOD16,and SSEBop)were merged to obtain an ensemble prediction of the ET rates for the complex and in-accessible environment of the Amazon at a spatial resolution of 250 m.The study shows that the basinwide average ET is 1316 mm/year with a standard deviation of 192 mm/year.This new ET-Amazon product was validated against seven different historic flux tower measurements.The energy balance closure of the in situ measurements varied between 86 and 116%.Only months with more than 70%completeness of in situ measurements were considered for validation.Different procedures for closure correction were included in the analyses.The correlation between measured and remotely sensed ET is good(R2>0.97 for consecutive periods of 2 to 12months),and the bias correction is negligible for the energy balance residual method,which seemed most favorable.Monthly ET values have more uncertainty.The monthly RMSE values vary between 7.4 and 27.8 mm/month(the average RMSE is 22.2mm/month),and the coefficient of determination(R2)varies between 0.48 and 0.87(the average R2 is 0.53).The ET from the water balance is 1380 mm/year,being−64 mm/year difference and 4.6%less than ET derived from the water balance.The evaporation from the Amazon basin inside Brazil is 5063 km3/year,followed by Peru with 1165 km3/year.ET-Amazon shows more spatial details and accuracy than alternative global ET products such as LandFlux-EVAL,Model Tree Ensemble(MTE),and WACMOS-ET.This justifies the development of new regional ET products.
文摘Wastewaters from various process industries,namely food and agricultural,sugar mill,brewery,milk,vegetable and fruit,and meat and fsheries processing industries and their wastewater efuents contain nutrients,organic matter,inorganic,heavy metals,suspended solids,and pathogens.The discharges of non-treated wastewater enter the nearby aquatic ecosystem(e.g.,lakes,rivers)and are a signifcant concern due to the presence of diferent nutrients,competing ions and C containing pollutants.It causes excessive growth of algae,loss of habitat/species,and other negative impacts on human health/environment.In the present review,diferent treatment approaches have been discussed in utilizing these nutrients to synthesize value-added products such as biopolymer,biofuel,pigment,organic acid,or enzymes.These biopolymers can be used to prepare various food products/packaging materials.Dextran,chitosan,carrageenan,alginate,and pectin are good examples of non-food biopolymers.Besides these products,poly-β-hydroxybutyrate(PHB)synthesis from wastewater nutrients is reported as a new source of bio-nanocomposite materials/biopolymer-based coatings.In this review,the diferent treatment approaches are discussed,which are being used worldwide for the removal/recovery of nutrients,toxic pollutants,and the potential resource recovery of value-added products from wastewater.
文摘In this study,a highly porous chemically activated granular activated carbon(GAC)was prepared from coconut husk and tested as an adsorbent to remove nitrate from contaminated groundwater.The prepared GAC was characterized by Fouriertransform infrared spectroscopy(FTIR),thermogravimetric and differential thermal analysis(TGA/DTA),scanning electron microscopy(SEM)and the Brunauer-Emmett-Teller(BET)surface area(SBET)analysis.The effects of various process parameters such as initial nitrate concentration,contact time and adsorbent dose on nitrate removal efficiency(response)by the modified GAC were investigated using the statistically significant response surface methodology and Box-Behnken design of experiments.The experimental data were fitted to well-known adsorption isotherms and kinetic models to ascertain the mechanism of the adsorption process.Analysis of variance(ANOVA)was performed to determine the significance of the individual and the interactive effects of process variables on the response.The BET surface area(SBET)and micropore volume of the prepared GAC from coconut husk was 1120 m^(2)/g and 0.392 cm^(3)/g,respectively.The experimental results showed that physisorption was the main adsorption mechanism governing the process,while the rate of adsorption was limited at initial nitrate concentrations>10 mg/L.The Langmuir mono-layer adsorption isotherm best fitted the experimental data with a maximum adsorption capacity of 6.0±1.3 mg/g(~92.5%)with an adsorbent dose of 0.1 g/50 mL,an equilibrium time of 6 h at 28±2℃,and at pH 7.6(±0.2).Among the tested process variables,the adsorbent dose and initial nitrate concentration showed significant effects on the nitrate removal efficiency.
