Closing nutrient loops in terrestrial and aquatic ecosystems is integral to achieve resource security in the food-energy-water (FEW) nexus. We performed multiyear (2005–2008), monthly sampling of instream dissolved inorganic nutrient concentrations (NH₄–N, NO₃–N, soluble reactive phosphorus-SRP) along a ∼ 300-km arid-land river (Rio Grande, NM) and generated nutrient budgets to investigate how the net source/sink behavior of wastewater and irrigated agriculture can be holistically managed to improve water quality and close nutrient loops. Treated wastewater on average contributed over 90% of the instream dissolved inorganic nutrients (101 kg/day NH₄–N, 1097 kg/day NO₃–N, 656 kg/day SRP). During growing seasons, the irrigation network downstream of wastewater outfalls retained on average 37% of NO₃–N and 45% of SRP inputs, with maximum retention exceeding 60% and 80% of NO₃–N and SRP inputs, respectively. Accurate quantification of NH₄–N retention was hindered by low loading and high variability. Nutrient retention in the irrigation network and instream processes together limited downstream export during growing seasons, with total retention of 33–99% of NO₃–N inputs and 45–99% of SRP inputs. From our synoptic analysis, we identify trade-offs associated with wastewater reuse for agriculture within the scope of the FEW nexus and propose strategies for closing nutrient loops in arid-land rivers.

The study analysed water use productivity among smallholder homestead food gardening and irrigation crop farmers in the North West province, South Africa. Home gardening and irrigation constitute the most important rural development investment strategies that can have direct impact on poverty and food security. Using a large sample size technique of n>30, 160 gardeners were selected for the study. Data was collected using a structured questionnaire and subjected to analysis using SPSS. Frequency counts and percentages were used to describe demographics. Multiple regressions were also used to identify determinants. The independent variables were significantly related with an F value of 3.074, P < .05. Also, an R value of 0.506 showed that there is a strong correlation between socio-economic characteristics and water use productivity. The results further predicted R Square 26% of the variation in water use productivity. Five out of sixteen were significant, with three variables being significant at 5% (type of crop, social participation and market outlet) while two variables were significant at 10% (home food security and attitude). Significant determinants of water use productivity were type of cropping (t =-2.443, P =.016), social participation (t =2.599, P = .010), marketing outlets (t = 2.810, P = .006), home food security (t=-1.777, P = .078) and attitude (t = -1.727, P = .086). The results imply that the higher attitude, marketing, home food security, social participation and type of crop, the higher the use of water productivity among farmers. However, insignificant determinants of water use productivity were farming experience (t = 0.571, p=0.569), education (t = -1.048, p = 0.296), land ownership (t = -1.416, p = 0.159) and age (t = -0.782, p = 0.436). The results imply that the lower the farming experience, education skill, land ownership and age, the lower the water productivity use among farmers.

Unheated and heat-aggregated β-lactoglobulin (β-lg) solutions were used to stabilize clove oil-in-water emulsion and limonene-in-water emulsion prepared by microchannel (MC) emulsification. The size of the MC array plate was 15 × 15 mm2 consisting of 100 parallel MCs fabricated on each side of the plate. The channels were 4 μm depth, 71 μm length, and 8.2 μm width, with the terrace length of 29.1 μm. Unheated and heat-aggregated β-lg effectively stabilized clove oil-in-water and limonene-in-water emulsions during production using MC emulsification. The emulsion droplets were steadily produced by the channels. The average diameter of clove oil droplets was around 17 μm, with both unheated and heat-aggregated β-lg, regardless of the concentration of β-lg. The average diameter of the limonene droplets was 18–26 μm depending on the conditions (unheated or heat-aggregated) and the concentration of β-lg. The coefficient of variation for all average droplet diameters was ≤8%, which was an indication of monodisperse droplets. Clove oil-in-water emulsion droplets became polydisperse within 2 h observation, whilst limonene-in-water emulsion droplets remained monodisperse over time. The stability of the oil droplets over time related to the solubility of the oil phases rather than the effects of β-lg as the surfactant. In addition, the droplet sizes at different surfactant concentrations seemed to relate to the viscosity ratio between the dispersed phase and the continuous phase rather than the effects of the surfactant.

Systems of producing, consuming, and distributing water, energy, and food involve trade-offs that are rarely explicitly considered by firms and policymakers. The idea of the water-energy-food “nexus” represents an attempt to formalize these trade-offs into decision-making processes. Multinational food and beverage firms operating in arid regions were early promoters of nexus approaches, followed by aid donors, consultancies, and international institutions seeking a new paradigm for resource management and development planning. The first generation of nexus research focused on quantitative input-output modeling to empirically demonstrate interdependencies and options for optimizing resource management. This chapter employs a different approach, analyzing institutional “problemsheds” that shape the implementation of nexus initiatives in arid regions of the United States, the Persian/Arabian Gulf, and China. Our analysis reveals how nexus approaches are conditioned by property rights regimes, economic growth strategies based on resource extraction, and the ability to externalize environmental costs to other regions and states.

During the past three decades, the Pisque watershed in Ecuador's Northern Andes has become the country's principal export-roses producing area. Recently, a new boom of local smallholders have established small rose greenhouses and joined the flower-export business. This has intensified water scarcity and material/discursive conflicts over water use priorities: water to defend local-national food sovereignty or production for export. This paper examines how including peasant flower farms in the capitalist dream – driven by a ‘mimetic desire’ and copying large-scale capitalist flower-farm practices and technologies – generates new intra-community conflicts over collective water rights, extending traditional class-based water conflicts. New allocation principles in Ecuador's progressive 2008 Constitution and 2014 Water Law prioritising food production over flowers' industrial water use are unlikely to benefit smallholder communities. Instead, decision-making power for peasant communities and their water users' associations on water use priority would enable water user prioritization according to smallholders' own preferences.

A turn-on fluorescent chemosensor (H-1) for cyanide anions based on dihydroxy phenazine was designed and synthesised. The sensor H-1 exhibits high sensitivity and good selectivity for cyanide in pure water. The CN− response mechanism involves a hydrogen bonding and deprotonation process in the sensor, which induced prominent fluorescence enhancement. The detection limit of the sensor toward CN− is 5.65×10−7M, and other anions had nearly no influence on the probing behavior. In addition, test strips based on the sensor were fabricated, which also exhibit a good selectivity to CN− in water. Notably, this sensor was successfully applied to detect CN− in food samples, which proves a very simple and selective platform for on-site monitoring of CN− in agriculture samples.

Much of our current knowledge about non-limiting dietary carbon supply for herbivorous zooplankton is based on experimental evidence and typically conducted at ~1 mg C L–¹ and ~20°C. Here we ask how low supply of dietary carbon affects somatic growth, reproduction, and survival of Daphnia magna and test effects of higher water temperature (+3°C relative to ambient) and brownification (3X higher than natural water color; both predicted effects of climate change) during fall cooling. We predicted that even at very low carbon supply (~5µg C L–¹), higher water temperature and brownification will allow D. magna to increase its fitness. Neonates (<24 h old) were incubated with lake seston for 4 weeks (October-November 2013) in experimental bottles submerged in outdoor mesocosms to explore effects of warmer and darker water. Higher temperature and brownification did not significantly affect food quality, as assessed by its fatty acid composition. Daphnia exposed to both increased temperature and brownification had highest somatic growth and were the only that reproduced, and higher temperature caused the highest Daphnia survival success. These results suggest that even under low temperature and thus lower physiological activity, low food quantity is more important than its quality for D. magna fitness.

The “nexus” is a potentially very appropriate approach to enhance resource efficiency and good governance in transboundary basins. Until now, however, evidence has been confined to isolated case studies and the nexus approach remains largely undefined. The methodology presented in this paper, developed for preparing a series of nexus assessments of selected river basins under the Water Convention of the United Nations Economic Commission for Europe (UNECE), is a timely contribution to this ongoing debate. The nexus assessment of a transboundary basin has the objective of identifying trade-offs and impacts across sectors and countries and to propose possible policy measures and technical actions at national and transboundary levels to reduce intersectoral tensions. This is done jointly with policy makers and local experts. Compared to an Integrated Water Resource Management approach, the water energy food ecosystems nexus approach concurrently considers multiple sectors and their evolution. This offers the opportunity to better involve key economic sectors—energy and agriculture in particular—in the dialogue over transboundary water resource uses, protection and management.

Advance knowledge of conflicting trajectories of water–energy–food (WEF) nexus is highly relevant for water policy and planning, especially for basins that cross national boundaries. The Brahmaputra River Basin in South Asia, home for 130 million people, is such a basin. Development of new hydropower projects, upstream water diversions and possible climate changes introduce concerns among riparian countries about future water supply for energy and food production in the basin. This study presents a new hydro-economic water system model of the basin coupled with ex post scenario analysis under the “nexus thinking” concept to identify and illustrate where development paths are in conflict. Results indicate that the ability of future development to remain free of conflict hinges mostly on the amount of precipitation falling in the basin in the future. Uncertain future precipitation along with uncertain future temperature and the unknown amount of upstream water diversion combine to strongly influence future water, energy and food production in the basin. Specifically, decreases in precipitation coupled with large upstream diversions (e.g., diversion in the territory of China) would leave one or more riparian countries unable to secure enough water to produce their desired energy and food. Future climate projected by General Circulation Models suggest a warmer and wetter climate condition in the region, which is associated with an increase in streamflow and easing of conflicts at the WEF nexus in the basin. The methodology presented here is expected to be generally useful for diagnosing the conditions that may cause water resources development goals to not be achieved due to either changes in climate or water use among competing users.