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【SCIENCE CHINA Earth Sciences 等】土壤水分蒸发的影响因素和变化特征
发布时间:2016-11-08  来源:土壤与农业可持续发展国家重点实验室  浏览:374

【半干旱地区土壤水分蒸发的影响因素和变化特征】Zhang Q, Wang S, Wang SS, Zhao YD, Wen XM. Influence factors and variation characteristics of water vapor absorption by soil in semi-arid region. SCIENCE CHINA Earth Sciences 59(11), 2240-2251(2016);  10.1007/s11430-015-5531-5

Abstract

The adsorption of water vapor by soil is one of the crucial contributors to non-rainfall water on land surface, particularly over semi-arid regions where its contribution can be equivalent to precipitation and can have a major impact on dry agriculture and the ecological environment in these regions. However, due to difficulties in the observation of the adsorption of water vapor, research in this area is limited. This study focused on establishing a method for estimating the quantitative observation of soil water vapor adsorption (WVA), and exploring the effects of meteorological elements (e.g., wind, temperature, and humidity) and soil environmental elements (e.g., soil temperature, soil moisture, and the available energy of soil) on WVA by soil over the semi-arid region, Dingxi, by combining use of the L-G large-scale weighing lysimeter and meteorological observation. In addition, this study also analyzed the diurnal and annual variations of WVA amount, frequency, and intensity by soil, how they changed with weather conditions, and the contribution of WVA by soil to the land surface water budget. Results showed that WVA by soil was co-affected by various meteorological and soil environmental elements, which were more likely to occur under conditions of relative humidity of 6−50% and the diurnal variation of relative humidity was large, inversion humidity, wind velocity of 3−4 m/s, lower soil water content, low surface temperature and slightly unstable atmospheric conditions. There was a negative feedback loop between soil moisture and the adsorption of water vapor, and, moreover, the diurnal and annual variations of WVA amount and frequency were evident—WVA by soil mainly occurred in the afternoon, and the annual peak appeared in December and the valley in June, with obvious regional characteristics. Furthermore, the contribution of WVA by soil to the land surface water budget obviously exceeded that of precipitation in the dry season.


【植物及生态系统对干旱的响应】Megan K. Bartletta,1,2, Tamir Kleinb, Steven Jansenc, Brendan Choatd, and Lawren Sacka. The correlations and sequence of plant stomatal, hydraulic, and wilting responses to drought. PNAS, doi: 10.1073/pnas.1604088113

Abstract

Climate change is expected to exacerbate drought for many plants, making drought tolerance a key driver of species and ecosystem responses. Plant drought tolerance is determined by multiple traits, but the relationships among traits, either within individual plants or across species, have not been evaluated for general patterns across plant diversity. We synthesized the published data for stomatal closure, wilting, declines in hydraulic conductivity in the leaves, stems, and roots, and plant mortality for 262 woody angiosperm and 48 gymnosperm species. We evaluated the correlations among the drought tolerance traits across species, and the general sequence of water potential thresholds for these traits within individual plants. The trait correlations across species provide a framework for predicting plant responses to a wide range of water stress from one or two sampled traits, increasing the ability to rapidly characterize drought tolerance across diverse species. Analyzing these correlations also identified correlations among the leaf and stem hydraulic traits and the wilting point, or turgor loss point, beyond those expected from shared ancestry or independent associations with water stress alone. Further, on average, the angiosperm species generally exhibited a sequence of drought tolerance traits that is expected to limit severe tissue damage during drought, such as wilting and substantial stem embolism. This synthesis of the relationships among the drought tolerance traits provides crucial, empirically supported insight into representing variation in multiple traits in models of plant and ecosystem responses to drought.


【空间监测与全球碳预算】John A. Gamona,b,c,1, K. Fred Huemmrichd, Christopher Y. S. Wonge,f, Ingo Ensmingere,f,g, Steven Garrityh, David Y. Hollingeri, Asko Noormetsj, and Josep Peñuelask,l. A remotely sensed pigment index reveals photosynthetic phenology in evergreen conifers. PNAS, doi: 10.1073/pnas.1606162113

Abstract

In evergreen conifers, where the foliage amount changes little with season, accurate detection of the underlying “photosynthetic phenology” from satellite remote sensing has been difficult, presenting challenges for global models of ecosystem carbon uptake. Here, we report a close correspondence between seasonally changing foliar pigment levels, expressed as chlorophyll/carotenoid ratios, and evergreen photosynthetic activity, leading to a “chlorophyll/carotenoid index” (CCI) that tracks evergreen photosynthesis at multiple spatial scales. When calculated from NASA’s Moderate Resolution Imaging Spectroradiometer satellite sensor, the CCI closely follows the seasonal patterns of daily gross primary productivity of evergreen conifer stands measured by eddy covariance. This discovery provides a way of monitoring evergreen photosynthetic activity from optical remote sensing, and indicates an important regulatory role for carotenoid pigments in evergreen photosynthesis. Improved methods of monitoring photosynthesis from space can improve our understanding of the global carbon budget in a warming world of changing vegetation phenology.


【长江流域人类活动净氮输入的时空变化】Wang A, Tang LH, Yang DW, Lei HM. Spatio-temporal variation of net anthropogenic nitrogen inputs in the upper Yangtze River basin from 1990 to 2012. SCIENCE CHINA Earth Sciences 59(11), 2189-2201(2016);  10.1007/s11430-016-0014-6

Abstract

The net anthropogenic nitrogen input (NANI) is an important nutrient source that causes eutrophication in water bodies. Understanding the spatio-temporal variation of NANI is important for regional environment assessment and management. This paper calculated NANI in the upper Yangtze River basin (YRB), upstream of the Three Gorges Dam (TGD), from 1990 to 2012, and analyzed its spatio-temporal characteristics. Over the past 23 years of the study, the average annual NANI increased from 3200 kg N km-2 to 4931 kg N km-2. The major components were fertilizer N application, atmospheric N deposition, and net food and feed N import. In the northwest high mountainous region with a sparse population, the main component was atmospheric N deposition. Fertilizer N application and net food and feed N import were concentrated in the Chengdu Plain because of the high population density and large areas of farmland. This research found that NANI increased with rapid urbanization and increasing population. The Pearson correlation results illustrated that the spatial distributions of NANI and its major components were affected by land cover/use, agricultural GDP and total population. Increasing NANI has been the major cause of the degrading stream water quality over the past 20 years and is becoming a major threat to the water quality of the TGD reservoir.


【CO2观测综述】Yue TX, Zhang LL, Zhao MW, Wang YF, John Wilson. Space- and ground-based CO2 measurements: A review. SCIENCE CHINA Earth Sciences 59(11), 2089-2097(2016);  10.1007/s11430-015-0239-7

Abstract

The climate warming is mainly due to the increase in concentrations of anthropogenic greenhouse gases, of which CO2 is the most important one responsible for radiative forcing of the climate. In order to reduce the great estimation uncertainty of atmospheric CO2 concentrations, several CO2-related satellites have been successfully launched and many future greenhouse gas monitoring missions are planned. In this paper, we review the development of CO2 retrieval algorithms, spatial interpolation methods and ground observations. The main findings include: 1) current CO2 retrieval algorithms only partially account for atmospheric scattering effects; 2) the accurate estimation of the vertical profile of greenhouse gas concentrations is a long-term challenge for remote sensing techniques; 3) ground-based observations are too sparse to accurately infer CO2 concentrations on regional scales; and 4) accuracy is the primary challenge of satellite estimation of CO2 concentrations. These findings, taken as a whole, point to the need to develop a high accuracy method for simulation of carbon sources and sinks on the basis of the fundamental theorem of Earth’s surface modelling, which is able to efficiently fuse space- and ground-based measurements on the one hand and work with atmospheric transport models on the other hand.


Wang Jinnan, Hu Qing, Wang Xiahui, Li Xiaoliang, Yang Xiao Jin. Protecting China's soil by law. Science  04 Nov 2016: Vol. 354, Issue 6312, pp. 562 DOI: 10.1126/science.aal1847

 

After severe problems with air and water pollution, China is getting serious about its soil (1, 2). On 31 May, China's State Council released an action plan for soil pollution prevention and remediation, aiming to make 90% of polluted, arable land safe for human use by 2020 and increase this to 95% by 2030 (3). This ambitious action plan calls for the support of strong environmental laws to monitor, prevent, and remediate serious levels of soil contamination. However, national legislation protecting soil quality has lagged behind that of air and water for more than a decade, while Chinese lawmakers debate the focus and purpose of a soil protection law.

On 3 September, China released a draft of its first environmental tax law, which designates four taxable types of pollution: airborne and water pollutants, solid waste, and noise (4). Soil is conspicuously absent. A soil protection law could close the current environmental legislation system's loopholes, make China's new environmental tax system more comprehensive, and protect China's soil.

To make a pragmatic soil protection law, the central government must clearly identify local government's liability and responsibility for soil pollution, as ambiguous responsibility has been one of the major problems in soil management in the past. The law must stipulate the division of duties between government agencies, establish a surveying and monitoring system, and introduce funding mechanisms. Remediation of contaminated soil is extremely costly, and China needs to create a national soil fund by allocating an adequate percentage of its land revenues and environmental tax revenues. Some members of the soil pollution plan panel initially suggested that 10% of land revenues be designated to the fund (5). Because China lacks comprehensive risk assessment systems for contaminated land management (6), the law should stipulate risk management and control approaches for contaminated sites.

China's soil pollution has become a critical issue that affects public health and creates social unrest and instability (1, 7, 8). China should not repeat its past mistakes of focusing on economic growth at the expense of the environment.

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