Comparing global warming potential,energy use and land use of organic,conventional and integrated winter wheat production

To ensure a sustainable food supply for the growing population, the challenge is to find agricultural systems that can meet production requirements within environmental constraints and demands. This study compares the impacts of winter wheat production on energy use, land use and 100 years Global Warming Potential (GWP₁₀₀) under different arable farming systems and farming practices. Life cycle assessment was used to simulate the impacts of organic, conventional and integrated farming (IF) systems along the production chain from input production up to the farm gate. The IF system models were designed to combine the best practices from organic and conventional systems to reduce negative environmental impacts without significant yield reductions. An integrated system that used food waste digestate as a fertiliser, and utilised pesticides and no‐tillage had the lowest energy use and GWP per functional unit of 1000 kg wheat output. When the impacts of some specific practices for reducing energy use and GWP were compared, the highest energy use reductions were achieved by replacing synthetic nitrogen fertilisers with anaerobically treated food waste or nitrogen fixing crops, increasing yields through crop breeding and using no‐tillage instead of ploughing. The highest GWP reductions were achieved by using nitrification inhibitors, replacing synthetic nitrogen fertilisers and increasing yields. The major contributors to the uncertainty range of energy use were associated with machinery fuel use and the assumed crop yields. For GWP results, the main source of uncertainty related to the N₂O emissions. In conclusion, farming systems that combine the best practices from organic and conventional systems have potential to reduce negative environmental impacts while maintaining yield levels.     

The effect of air humidity on nutrient uptake of some greenhouse plants

Young plants of nine different greenhouse species were grown for 24 to 100 days at 55–60, 70–75, and 90–95% relative air humidity (RH) in growth rooms. They were given a complete nutrient solution twice a week. Transpiration rate decreased significantly by increasing RH from the lowest to the highest level inEuphorbia pulcherrima (60%), Begonia × hiemalis (54%), Saintpaulia ionantha (54%), Nephrolepis exaltata (48%), andLycopersicon esculentum (44%). The content of macro nutrient elements in the plant leaves decreased by increasing RH. This decrease was significant only for K and Ca in Lycopersicon and Kjeldahl-N in Nephrolepis. The content of the macro nutrient elements in the growth medium at the end of the experiment was lowest when the plants had been growing at high RH. The elements mainly affected were N and K. Report No. 342     

The good,the bad,and the future: Systematic review identifies best use of biomass to meet air quality and climate policies in California

California has large and diverse biomass resources and provides a pertinent example of how biomass use is changing and needs to change, in the face of climate mitigation policies. As in other areas of the world, California needs to optimize its use of biomass and waste to meet environmental and socioeconomic objectives. We used a systematic review to assess biomass use pathways in California and the associated impacts on climate and air quality. Biomass uses included the production of renewable fuels, electricity, biochar, compost, and other marketable products. For those biomass use pathways recently developed, information is available on the effects—usually beneficial—on greenhouse gas (GHG) emissions, and there is some, but less, published information on the effects on criteria pollutants. Our review identifies 34 biomass use pathways with beneficial impacts on either GHG or pollutant emissions, or both—the “good.” These included combustion of forest biomass for power and conversion of livestock-associated biomass to biogas by anaerobic digestion. The review identified 13 biomass use pathways with adverse impacts on GHG emissions, criteria pollutant emissions, or both—the “bad.” Wildfires are an example of one out of eight pathways which were found to be bad for both climate and air quality, while only two biomass use pathways reduced GHG emissions relative to an identified counterfactual but had adverse air quality impacts. Issues of high interest for the “future” included land management to reduce fire risk, future policies for the dairy industries, and full life-cycle analysis of biomass production and use.     

Managing Global Atmospheric Change: A U.S. Policy Perspective

There are several air pollution issues that concern the international community at the regional and global level, including acid deposition, heavy metals, persistent organic pollutants, stratospheric ozone depletion, and climate change. Governments at the regional and global levels have entered into various agreements in an effort to deal with these problems. This paper deals with two major global atmospheric change issues: stratospheric ozone depletion and climate change. The focus is on the policy responses of the United States to these global issues. The United States has signed and ratified international agreements to deal with both problems. The Vienna Convention and the Montreal Protocol on Substances that Deplete the Ozone Layer have led to an effort in both developed and developing countries to phase out ozone depleting substances. The United Nations Framework Convention on Climate Change (UNFCCC) has been signed and ratified by over 180 countries. The UNFCC contained no binding targets and timetables for emissions reductions. The Kyoto Protocol (1997) to the UNFCCC did contain targets and timetables for reductions of greenhouse gases on the part of developed countries. The United States has signed but not ratified the Kyoto Protocol. The United States has experienced some movement to reduce greenhouse gas emissions on the part of various levels of government as well as the private sector. The policy process is constantly informed by scientific research. In the case of stratospheric ozone depletion and climate change, much of this work is carried out under the auspices of international scientific panels. From a policy perspective, there is a great deal of interest in the use of indicators for assessing the scope and magnitude of these problems, both for fashioning policy responses as well as assessing the impact of adopted programs to reduce ozone depleting substances, and potentially, greenhouse gases. This paper will discuss some of the indicators used for stratospheric ozone depletion and climate change.     

Environmental footprinting of hospitals: Organizational life cycle assessment of a Canadian hospital

Healthcare is a critical and complex service sector with direct and indirect greenhouse gas (GHG) emissions amounting to 5%–10% of the national total in developed economies like Canada and the United States. Along with a growing, albeit sporadic, set of life cycle assessment (LCA) (and “carbon footprinting”) studies of specific medical products and procedures, there is growing interest in “environmental footprinting” of hospitals. In this article, we advance this rapidly evolving area through a comprehensive organizational LCA of a 40-bed hospital in British Columbia, Canada, in its 2019 fiscal year. Our results indicate that the total environmental footprint of the hospital includes, among other things, global warming potential of 3500–5000 t CO₂ eq. (with 95% confidence). “Hotspots” in this footprint are attributable to energy and water use (and wastewater released), releases of anesthetic gases (which are potent GHGs), and the upstream production of the thousands of materials, chemicals, pharmaceuticals, and other products used in the hospital. The generalizability and comparability of these results are limited by inconsistencies across the few environmental footprinting studies of hospitals conducted to date. Nonetheless, our novel methodological approach, in which we compiled new LCA data for 200 goods and services used in healthcare—strategically selected to statistically represent the 2927 unique products in the hospital's “supply-chains”—has broad applicability in healthcare and beyond.     

森林伐后碳减排核算方法演进与展望

森林生态系统的碳汇功能对我国完成“双碳目标”具有独特意义，其中森林伐后碳减排，包括木质林产品全生命周期内的碳储和替代减排，是增强林业中长期碳减排能力的重要路径。当前我国森林伐后碳减排研究尚落后于欧美等发达国家，不利于我国林业国家碳库模型的构建以及更好地指导固碳增汇的森林管理策略。系统回顾了近30余年国内外学术界关于森林伐后碳减排方法学的演进动态，总结了碳循环和碳减排模型的核心参数，为推进我国森林伐后碳减排研究提供理论基础。学术界近30余年涉及方法模型的主要成果如下：(1)建立并完善了立足于木材采伐国的生产法和简单分解法，以及立足于终端木质林产品消费国的储量变化法和大气流动法两类方法框架；(2)形成了体系化的碳储计算模型，并在包括发达国家和主要发展中国家取得了大量实测数据和参数积累；(3)初步完成了替代减排分析模型和基于情景设定的分析框架，并在以欧美国家为主体的部分地区进行了应用。在梳理历史文献的基础上，本研究认为当前存在的方法缺陷包括：第一，既有依靠实测调研获取数据的成本过高，限制了研究国家的深度和广度，尤其导致广大发展中国家研究较为薄弱；第二，当前方法框架在追踪木质林产品贸易流方面较...     

多年冻土退化地区湿地土壤温室气体排放及其影响因子

采用野外原位实验静态箱-气相色谱法,研究了兴安岭多年冻土不同程度退化地区生长季湿地土壤温室气体CH4、CO2和N2O的排放通量特征,同时分析了环境因子对土壤温室气体排放的影响。结果表明:1)3种类型冻土区(季节性冻土区、岛状多年冻土区、连续多年冻土区,分别用D1、D2、D3表示)土壤在生长季时期表现为CO2和N2O的源;D1和D3为CH4的源,D2为CH4的汇。D1、D2、D3土壤在生长季中平均CH4排放通量分别为(0.127±0.021)、(-0.020±0.006)、(0.082±0.019)mg·m^-2·h^-1;CO2排放通量分别为(371.50±66.73)、(318.43±55.67)、(213.19±37.05)mg·m^-2·h^-1;N2O排放通量分别为(24.05±2.62)、(8.07±2.42)、(2.17±0.25)μg·m-2·h-1。土壤CO2和N2O排放通量随多年冻土退化程度的加剧呈现出升高的趋势。2)细根生物量、凋落物生物量、全碳、全氮、可溶性有机碳、总可溶性氮、土壤容重、土壤温度、土壤含水量等均影响温室气体排放,3种不同类型冻土区土壤CH4、CO2和N2O的排放差异是诸多影响因子综合作用的结果。     

Domestic water versus imported virtual blue water for agricultural production: A comparison based on energy consumption and related greenhouse gas emissions

The supply of water, food, and energy in our global economy is highly interlinked. Virtual blue water embedded into internationally traded food crops has therefore been extensively researched in recent years. This study focuses on the often neglected energy needed to supply this blue irrigation water. It provides a globally applicable and spatially explicit approach to the watershed level for water source specific quantification of energy consumption and related greenhouse gas (GHG) emissions of irrigation water supply. The approach is applied to Israel's total domestic and imported food crop supply of 105 crops by additionally including import-related transportation energy and emissions. Total energy use and related emissions of domestic crop production were much lower (551 GWh/422 kt CO₂-equivalents [CO₂e]) than those embedded into crop imports (1639 GWh/649 kt CO₂e). Domestic energy and emissions were mainly attributable to the irrigation water supply with artificial water sources (treated domestic wastewater and desalinated water, 84%). Transport accounted for 79% and 66% of virtually imported energy and emissions, respectively. Despite transport, specific GHG emissions (CO₂e per ton of crop) were significantly lower for several crops (e.g., olives, almonds, chickpeas) compared to domestic production. This could be attributed to the high share of energy-intensive artificial water supply in combination with higher irrigation water demands in Israel. In the course of an increasing demand for artificial water supply in arid and semi-arid regions, our findings point to the importance of including “energy for water” into comparative environmental assessment of crop supply to support decision-making related to the water–energy–food nexus.     

Enhanced CO2 uptake is marginally offset by altered fluxes of non-CO2 greenhouse gases in global forests and grasslands under N deposition

Despite the increasing impact of atmospheric nitrogen (N) deposition on terrestrial greenhouse gas (GHG) budget, through driving both the net atmospheric CO₂ exchange and the emission or uptake of non-CO₂ GHGs (CH₄ and N₂O), few studies have assessed the climatic impact of forests and grasslands under N deposition globally based on different bottom-up approaches. Here, we quantify the effects of N deposition on biomass C increment, soil organic C (SOC), CH₄ and N₂O fluxes and, ultimately, the net ecosystem GHG balance of forests and grasslands using a global comprehensive dataset. We showed that N addition significantly increased plant C uptake (net primary production) in forests and grasslands, to a larger extent for the aboveground C (aboveground net primary production), whereas it only caused a small or insignificant enhancement of SOC pool in both upland systems. Nitrogen addition had no significant effect on soil heterotrophic respiration (R_H) in both forests and grasslands, while a significant N-induced increase in soil CO₂ fluxes (R_S, soil respiration) was observed in grasslands. Nitrogen addition significantly stimulated soil N₂O fluxes in forests (76%), to a larger extent in grasslands (87%), but showed a consistent trend to decrease soil uptake of CH₄, suggesting a declined sink capacity of forests and grasslands for atmospheric CH₄ under N enrichment. Overall, the net GHG balance estimated by the net ecosystem production-based method (forest, 1.28 Pg CO₂-eq year⁻¹ vs. grassland, 0.58 Pg CO₂-eq year⁻¹) was greater than those estimated using the SOC-based method (forest, 0.32 Pg CO₂-eq year⁻¹ vs. grassland, 0.18 Pg CO₂-eq year⁻¹) caused by N addition. Our findings revealed that the enhanced soil C sequestration by N addition in global forests and grasslands could be only marginally offset (1.5%–4.8%) by the combined effects of its stimulation of N₂O emissions together with the reduced soil uptake of CH₄.     

Second harvest–Is there sufficient stubble for biofuel production in Australia?

Identifying the location and amount of grain crop residues (stubble) in Australia is necessary for determining the viability of potential biofuel plant locations. We combined 22 years of crop statistics with harvest indices and land use to arrive at spatially explicit stubble productivity figures. Stubble quantities using different focal radii and from different seasons provide an insight into the feasibility of its use for bioenergy. We focus on areas where the stubble concentrations within a 50 km radius were at least 500 kt per year; the amount suggested for a viable lignocellolosic bioethanol facility. The outcome of this study has been to show, for the first time, where there are large amounts of stubble in Australia. Whether the supply of stubble is sufficiently constant over time and indeed available at a price that is economic for a biofuel plant must be subject to future work.