山东省小麦-夏直播花生种植体系碳足迹

明确小麦-夏直播花生(W-P)种植体系的主要碳排放环节,可为采取有效措施实现该体系高产与低碳排放的协同效益提供参考.本文依据全生命周期方法,构建碳足迹模型,并核算了山东省W-P种植体系生命周期碳排放.结果表明:山东省W-P种植体系的净收益较小麦-玉米(W-M)种植体系高71.2%~88.3%;W-P种植体系的单位面积碳排放达6977.9~8018.5 kg·hm^-2,较W-M种植体系高6.2%,但单位净产值的碳排放为每元0.23~0.28kg CO_2-eq,较W-M种植体系低37.4%~44.1%.综合2种种植体系的净收益和单位净产值碳排放发现,W-P种植体系可以实现高产出与低碳排放的协同效益,符合优化供给、提质增效、农民增收的农业供给侧结构性改革目标.     

中国农作物生产碳足迹及其空间分布特征

基于中国1993—2013年的农业统计数据,采用生命周期评价、重心模型以及GIS等方法分析农作物生产碳排放及碳足迹的时序变化、碳足迹重心的移动轨迹、碳排放和碳足迹的空间分布特征以及影响碳排放的主导因素.结果表明: 研究期间,中国农作物生产碳排放量(GHGe)、单位播种面积碳足迹(CFs)和单位耕地面积碳足迹(CFc)均显著增加,而单位产量碳足迹(CFy)和单位产值碳足迹(CFv)显著减少.CFs重心一直分布在河南,且逐渐移向西南;CFc重心位于湖北或河南,并向西北方向移动;CFy重心位于陕西或河南,且整体移向东南;CFv重心始终在河南,并逐渐移向西南.GHGe和碳足迹存在显著的省域差异,GHGe具有南北低、中部高的特点,CFs是东西两翼高、中间低,CFc高值区主要集中在中部及东部沿海省份,CFy在西北-东南方向上表现为“高-低-高”,CFv在西北-东南方向上则是由高走低.农业生产过程中不同投入占农作物碳足迹的比例以化肥最为突出,化肥投入构成中以氮肥和复合肥所占比例较大.通过分析GHGe与各影响因素的关联度,得出化肥尤其是磷肥和氮肥、灌溉以及农田N₂O排放是导致GHGe显著增加的主导因素,并据此提出发展低碳农业的对策建议.     

Optimizing rice yields while minimizing yield‐scaled global warming potential

To meet growing global food demand with limited land and reduced environmental impact, agricultural greenhouse gas (GHG) emissions are increasingly evaluated with respect to crop productivity, i.e., on a yield‐scaled as opposed to area basis. Here, we compiled available field data on CH₄ and N₂O emissions from rice production systems to test the hypothesis that in response to fertilizer nitrogen (N) addition, yield‐scaled global warming potential (GWP) will be minimized at N rates that maximize yields. Within each study, yield N surplus was calculated to estimate deficit or excess N application rates with respect to the optimal N rate (defined as the N rate at which maximum yield was achieved). Relationships between yield N surplus and GHG emissions were assessed using linear and nonlinear mixed‐effects models. Results indicate that yields increased in response to increasing N surplus when moving from deficit to optimal N rates. At N rates contributing to a yield N surplus, N₂O and yield‐scaled N₂O emissions increased exponentially. In contrast, CH₄ emissions were not impacted by N inputs. Accordingly, yield‐scaled CH₄ emissions decreased with N addition. Overall, yield‐scaled GWP was minimized at optimal N rates, decreasing by 21% compared to treatments without N addition. These results are unique compared to aerobic cropping systems in which N₂O emissions are the primary contributor to GWP, meaning yield‐scaled GWP may not necessarily decrease for aerobic crops when yields are optimized by N fertilizer addition. Balancing gains in agricultural productivity with climate change concerns, this work supports the concept that high rice yields can be achieved with minimal yield‐scaled GWP through optimal N application rates. Moreover, additional improvements in N use efficiency may further reduce yield‐scaled GWP, thereby strengthening the economic and environmental sustainability of rice systems.     

Conventional intensive logging promotes loss of organic carbon from the mineral soil

There are few data, but diametrically opposed opinions, about the impacts of forest logging on soil organic carbon (SOC). Reviews and research articles conclude either that there is no effect, or show contradictory effects. Given that SOC is a substantial store of potential greenhouse gasses and forest logging and harvesting is routine, resolution is important. We review forest logging SOC studies and provide an overarching conceptual explanation for their findings. The literature can be separated into short‐term empirical studies, longer‐term empirical studies and long‐term modelling. All modelling that includes major aboveground and belowground biomass pools shows a long‐term (i.e. ≥300 years) decrease in SOC when a primary forest is logged and then subjected to harvesting cycles. The empirical longer‐term studies indicate likewise. With successive harvests the net emission accumulates but is only statistically perceptible after centuries. Short‐term SOC flux varies around zero. The long‐term drop in SOC in the mineral soil is driven by the biomass drop from the primary forest level but takes time to adjust to the new temporal average biomass. We show agreement between secondary forest SOC stocks derived purely from biomass information and stocks derived from complex forest harvest modelling. Thus, conclusions that conventional harvests do not deplete SOC in the mineral soil have been a function of their short time frames. Forest managers, climate change modellers and environmental policymakers need to assume a long‐term net transfer of SOC from the mineral soil to the atmosphere when primary forests are logged and then undergo harvest cycles. However, from a greenhouse accounting perspective, forest SOC is not the entire story. Forest wood products that ultimately reach landfill, and some portion of which produces some soil‐like material there rather than in the forest, could possibly help attenuate the forest SOC emission by adding to a carbon pool in landfill.     

居住-就业距离对交通碳排放的影响

城市扩张过程使交通需求量增加,导致来自交通部门的碳排放量增加。紧凑型城市发展有助于减少交通需求从而降低交通部门的碳排放量。本研究基于一个问卷调查利用情景分析的方法定量探讨居住-就业距离变化对通勤碳排放量的影响,为科学规划城市格局提供理论依据。研究结果表明在居住-就业距离不超过15 km（适宜公共交通出行距离）的情景中居住-就业距离缩短21.3%,交通碳排放量减小28.2%,费用节省21.2%;在居住-就业距离不超过5 km（适宜非机动车出行距离）的情景中居住-就业距离缩短56.3%,碳排放量减小53.1%,费用节省34.6%。两种情景下不同出行方式中,公交系统对行驶里程缩短的影响最大,私家车对碳排放量减小和花费降低的影响最大。在城市扩张过程中应该力求实现功能多元化的扩张格局,城市交通体系建设应为低碳出行提供最大便利。     

Low-frequency distortion product otoacoustic emissions in two species of kangaroo rats: implications for auditory sensitivity

Low-frequency distortion-product otoacoustic emissions were measured in two species of kangaroo rats to test the prediction that a large footdrumming species (e.g., Dipodomys spectabilis) would have greater distortion-product otoacoustic emission amplitude than a small non-footdrumming species (e.g., Dipodomys merriami), indicating better hearing sensitivity at low frequencies. Equal-level (65 dB SPL) stimulus tones (f ₁, f ₂), presented over a (f ₁) range of 200–1000 Hz, were used to evoke the 2f ₁–f ₂ distortion-product otoacoustic emission. Mean 2f ₁–f ₂ levels for D. merriami showed good correspondence to previously published audiograms for that species. Mean 2f ₁–f ₂ levels and 95% confidence intervals indicated species differences below 400 Hz, supporting the theory that low-frequency hearing sensitivity is better in large kangaroo rat species. These results suggest that the size-related divergence in footdrumming behavior may be related to differential auditory sensitivity.Abbreviations DPOAE distortion-product otoacoustic emission - OAE otoacoustic emission - PVC polyvinyl chloride     

Temporal variation in nitrous oxide (N2O) fluxes from an oil palm plantation in Indonesia: An ecosystem-scale analysis

The rapidly growing areal extent of oil palm (Elaeis guineensis Jacq.) plantations and their high fertilizer input raises concerns about their role as substantial N₂O sources. In this study, we present the first eddy covariance (EC) measurements of ecosystem-scale N₂O fluxes in an oil palm plantation and combine them with vented soil chamber measurements of point-scale soil N₂O fluxes. Based on EC measurements during the period August 2017 to April 2019, the studied oil palm plantation in the tropical lowlands of Jambi Province (Sumatra, Indonesia) is a high source of N₂O, with average emission of 0.32 ± 0.003 g N₂O-N m⁻² year⁻¹ (149.85 ± 1.40 g CO₂-equivalent m⁻² year⁻¹). Compared to the EC-based N₂O flux, average chamber-based soil N₂O fluxes (0.16 ± 0.047 g N₂O-N m⁻² year⁻¹, 74.93 ± 23.41 g CO₂-equivalent m⁻² year⁻¹) are significantly (~49%, p < 0.05) lower, suggesting that important N₂O pathways are not covered by the chamber measurements. Conventional chamber-based N₂O emission estimates from oil palm up-scaled to ecosystem level might therefore be substantially underestimated. We show that the dynamic gas exchange of the oil palm canopy with the atmosphere and the oil palms' response to meteorological and soil conditions may play an important but yet widely unexplored role in the N₂O budget of oil palm plantations. Diel pattern of N₂O fluxes showed strong causal relationships with photosynthesis-related variables, i.e. latent heat flux, incoming photosynthetically active radiation and gross primary productivity during day time, and ecosystem respiration and soil temperature during night time. At longer time scales (>2 days), soil temperature and water-filled pore space gained importance on N₂O flux variation. These results suggest a plant-mediated N₂O transport, providing important input for modelling approaches and strategies to mitigate the negative impact of N₂O emissions from oil palm cultivation through appropriate site selection and management.     

The biogeochemistry of sulfur at Hubbard Brook

A synthesis of the biogeochemistry of S was done during 34 yr(1964–1965 to 1997–1998) in reference and human-manipulated forestecosystems of the Hubbard Brook Experimental Forest (HBEF), NH. There have beensignificant declines in concentration (–0.44µmol/liter-yr) and input (–5.44mol/ha-yr)of SO₄ ^2– in atmospheric bulk wet deposition, and inconcentration(–0.64 µmol/liter-yr) an d output (–3.74mol/ha-yr) of SO₄ ^2– in stream water ofthe HBEF since 1964. These changes arestrongly correlated with concurrent decreases in emissions of SO₂from the source area for the HBEF. The concentration and input ofSO₄ ^2– in bulk deposition ranged from a low of 13.1µmol/liter (1983–1984) and 211 mol/ha-yr(1997–1998) to a high of 34.7 µmol/liter(1965–1966) and 479 mol/ha-yr (1967–1968), with along-term mean of 23.9 µmol/liter and 336mol/ha-yr during 1964–1965 to 1997–1998. Despiterecentdeclines in concentrations, SO₄ ^2– is the dominantanion in both bulk deposition and streamwater at HBEF. Dry deposition is difficult to measure, especially inmountainousterrain, but was estimated at 21% of bulk deposition. Thus, average totalatmospheric deposition was 491 and 323 mol/ha-yr during1964–1969 and 1993–1998, respectively. Based on the long-term³⁴S pattern associated with anthropogenic emissions,SO₄ ^2– deposition at HBEF is influenced by numerousSO₂sources, but biogenic sources appear to be small. Annual throughfall plusstemflow in 1993–1994 was estimated at 346 molSO₄ ^2–/ha. Aboveground litterfall, for thewatershed-ecosystemaveraged about 180 mol S/ha-yr, with highest inputs (190 molS/ha-yr) in the lower elevation, more deciduous forest zone. Weatheringrelease was calculated at a maximum of 50 mol S/ha-yr. Theconcentration and output of SO₄ ^2– in stream waterranged from a low of 42.3µmol/liter (1996–1997) and 309 mol/ha-yr(1964–1965), to a high of 66.1 µmol/liter(1970–1971) and 849 mol/ha-yr (1973–1974), with along-term mean of 55.5 µmol/liter and 496mol/ha-yr during the 34 yrs of study. Gross outputs ofSO₄ ^2– in stream water consistently exceeded inputsin bulkdeposition and were positively and significantly related to annualprecipitationand streamflow. The relation between gross SO₄ ^2–output and annual streamflow changed with time asatmospheric inputs declined. In contrast to the pattern for bulk depositionconcentration, there was no seasonal pattern for streamSO₄ ^2– concentration. Nevertheless, stream outputs ofSO₄ ^2– were highly seasonal, peaking during springsnowmelt, andproducing a monthly cross-over pattern where net hydrologic flux (NHF) ispositive during summer and negative during the remainder of the year. Nosignificant elevational pattern in streamwaterSO₄ ^2– concentration was observed. Mean annual,volume-weightedsoil water SO₄ ^2– concentrations were relativelyuniform by soil horizon andacross landscape position. Based upon isotopic evidence, much of theSO₄ ^2– entering HBEF in atmospheric depositioncycles throughvegetation and microbial biomass before being released to the soil solution andstream water. Gaseous emissions of S from watershed-ecosystems at HBEF areunquantified, but estimated to be very small. Organic S (carbon bonded andestersulfates) represents some 89% of the total S in soil at HBEF. Some 6% exists asphosphate extractable SO₄ ^2– (PSO₄).About 73% of the total S in the soilprofile at HBEF occurs in the Bs2 horizon, and some 9% occurs in the forestfloor. The residence time for S in the soil was calculated to be 9 yr, butonly a small portion of the total organic soil pool turns over relativelyquickly. The S content of above- and belowground biomass is about 2885mol/ha, of which some 3–5% is in standing dead trees. Yellowbirch, American beech and sugar maple accounted for 89% of the S in trees, with31% in branches, 27% in roots and 25% in the lightwood of boles. The pool of Sin living biomass increased from 1965 to 1982 due to biomass accretion, andremained relatively constant thereafter. Of current inputs to the availablenutrient compartment of the forest ecosystem, 50% is from atmospheric bulkdeposition, 24% from net soil release, 11% from dry deposition, 11% from rootexudates and 4% is from canopy leaching. Comparing ecosystem processes for Sfrom 1964–1969 to 1993–1998, atmospheric bulk deposition decreasedby 34%, stream output decreased by 10%, net annual biomass storage decreased by92%, and net soil release increased by 184% compared to the 1964–1969values. These changes are correlated with decreased emissions of SO₂from the source area for the HBEF. Average, annual bulk deposition inputsexceeded streamwater outputs by 160.0 ± 75.3 SD molS/ha-yr,but average annual net ecosystem fluxes (NEF) were much smaller, mostlynegativeand highly variable during the 34 yr period (–54.3 ± 72.9 SDmol S/ha-yr; NEF range, +86.8 to –229.5). While severalmechanisms may explain this small discrepancy, the most likely are netdesorption of S and net mineralization of organic S largely associated with theforest floor. Our best estimates indicate that additional S from dry depositionand weathering release is probably small and that desorption accounts for about37% of the NEF imbalance and net mineralization probably accounts for theremainder (60%). Additional inputs from dry deposition would result fromunmeasured inputs of gaseous and particulate deposition directly to the forestfloor. The source of any unmeasured S input has important implications for therecovery of soils and streams in response to decreases in inputs of acidicdeposition. Sulfate is a dominant contributor to acid deposition at HBEF,seriously degrading aquatic and terrestrial ecosystems. Because of the strongrelation between SO₂ emissions and concentrations ofSO₄ ^2– in both atmospheric deposition and streamwater at HBEF,further reductions in SO₂ emissions will be required to allowsignificant ecosystem recovery from the effects of acidic deposition. Thedestruction or removal of vegetation on experimental watershed-ecosystems atHBEF resulted in increased rates of organic matter decomposition andnitrification, a lowering of soil and streamwater pH, enhancedSO₄ ^2– adsorption on mineral soil and smallerconcentrations andlosses of SO₄ ^2– in stream water. With vegetationregrowth, this adsorbedSO₄ ^2– is released from the soil, increasingconcentrations andfluxes of SO₄ ^2– in drainage water. Streamwaterconcentration ofSO₄ ^2– and gross annual output ofSO₄ ^2–/ha are essentially the same throughout theHubbard BrookValley in watersheds varying in size by about 4 orders of magnitude, from 3 to3000 ha.     

Lithium-ion battery cell production in Europe: Scenarios for reducing energy consumption and greenhouse gas emissions until 2030

The market for electric vehicles is growing rapidly, and there is a large demand for lithium-ion batteries (LIB). Studies have predicted a growth of 600% in LIB demand by 2030. However, the production of LIBs is energy intensive, thus contradicting the goal set by Europe to reduce greenhouse gas (GHG) emissions and become GHG emission free by 2040. Therefore, in this study, it was analyzed how the energy consumption and corresponding GHG emissions from LIB cell production may develop until 2030. Economic, technological, and political measures were considered and applied to market forecasts and to a model of a state-of-the art LIB cell factory. Notably, different scenarios with trend assumptions and above/below-trend assumptions were considered. It could be deduced that, if no measures are taken and if the status quo is extrapolated to the future, by 2030, ∼5.86 Mt CO₂-eq will be emitted due to energy consumption from European LIB cell production. However, by applying a combination of economic, technological, and political measures, energy consumption and GHG emissions could be decreased by 46% and 56% by 2030, respectively. Furthermore, it was found that political measures, such as improving the electricity mix, are important but less dominant than improving the production technology and infrastructure. In this study, it could be deduced that, by 2030, through industrialization and application of novel production technologies, the energy consumption and GHG emissions from LIB cell production in Europe can be reduced by 24%.