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【SCIENCE CHINA Earth Sciences 等】基流硝态氮输出对面源污染的贡献 等
发布时间:2016-09-26  来源:土壤与农业可持续发展国家重点实验室  浏览:560

【中国草原碳储量的时空动态模拟】ZHANG Li, ZHOU GuangSheng, JI YuHe, BAI YongFei. Spatiotemporal dynamic simulation of grassland carbon storage in China. SCIENCE CHINA Earth Sciences 59(10), 1946-1958 (2016)

Based on the Terrestrial Ecosystem Model (TEM 5.0), together with the data of climate (temperature, precipitation and solar radiation) and environment (grassland vegetation types, soil texture, altitude, longitude and latitude, and atmospheric CO2 concentration data), the spatiotemporal variations of carbon storage and density, and their controlling factors were discussed in this paper. The results indicated that: (1) the total carbon storage of China’s grasslands with a total area of 394.93×104 km2 was 59.47 Pg C. Among them, there were 3.15 Pg C in vegetation and 56.32 Pg C in soil carbon. China’s grasslands covering 7.0–11.3% of the total world’s grassland area had 1.3–11.3% of the vegetation carbon and 9.7–22.5% of the soil carbon in the world grasslands. The total carbon storage increased from 59.13 to 60.16 Pg C during 1961–2013 with an increasing rate of 19.4 Tg C yr-1. (2) The grasslands in the Qinghai-Tibetan Plateau contributed most to the total carbon storage during 1961–2013, accounting for 63.2% of the total grassland carbon storage, followed by Xinjiang grasslands (15.8%) and Inner Mongolia grasslands (11.1%). (3) The vegetation carbon storage showed an increasing trend, with the average annual growth rate of 9.62 Tg C yr-1 during 1961–2013, and temperature was the main determinant factor, explaining approximately 85% of its variation. The vegetation carbon storage showed an increasing trend in most grassland regions, however, a decreasing trend in the central grassland in the southern China, the western and central parts of the Inner Mongolian grasslands as well as some parts on the Qinghai-Tibetan Plateau. The soil carbon storage showed a significantly increasing trend with a rate of 7.96 Tg C yr-1, which resulted from the interaction of more precipitation and low temperature in the 1980s and 1990s. Among them, precipitation was the main determinant factor of increasing soil carbon increases of China’s grasslands.


【基流硝态氮输出对面源污染的贡献】HE ShengJia, LU Jun. Contribution of baseflow nitrate export to non-point source pollution. SCIENCE CHINA Earth Sciences 59(10), 1912-1929 (2016)
 
As a common pollutant of nitrogen in groundwater, nitrate contamination has become a major concern worldwide. Baseflow, one of the dominant hydrological pathways for nitrate migration to streamflow, has been confirmed as a leading nitrate source for stream water where groundwater or subsurface flow contaminated heavily by nitrate. That is, sufficient improvements of water quality may not be attained without proper management for baseflow, even if non-point sources (NPS) pollutants discharged through surface runoff are being well managed. This article reviews the primary nitrate sources, the main factors affecting its transport, and the methodologies for baseflow nitrate estimation, to give some recommendations for future works, including: (1) giving sufficient consideration for the effects of climatological, morphological, and geological factors on baseflow recessions to obtain more reliable and accurate baseflow separation; (2) trying to solve calibration and validation problems for baseflow loads determining in storm flow period; (3) developing a simple and convenient algorithm with certain physics that can be used to separate baseflow NPS pollution from the total directly in different regions, for a reliable estimation of baseflow NPS pollution at larger scale (e.g., national scale); (4) improving groundwater quality simulation module of existing NPS pollution models to have a better simulation for biogeochemical processes in shallow aquifers; (5) taking integrated measures of “source control”, “process interception” and “end remediation” to prevent and control NPS nitrate pollution effectively, not just only the strict control of nutrients loss from surface runoff.


Zaigham Shahzad, Matthieu Canut, Colette Tournaire-Roux, Alexandre Martinière, Yann Boursiac, Olivier Loudet, Christophe Maurel. A Potassium-Dependent Oxygen Sensing Pathway Regulates Plant Root Hydraulics. Cell, 2016, Volume 167, Issue 1, p87-98

Aerobic organisms survive low oxygen (O2) through activation of diverse molecular, metabolic, and physiological responses. In most plants, root water permeability (in other words, hydraulic conductivity, Lpr) is downregulated under O2 deficiency. Here, we used a quantitative genetics approach in Arabidopsis to clone Hydraulic Conductivity of Root 1 (HCR1), a Raf-like MAPKKK that negatively controls Lpr. HCR1 accumulates and is functional under combined O2 limitation and potassium (K+) sufficiency. HCR1 regulates Lpr and hypoxia responsive genes, through the control of RAP2.12, a key transcriptional regulator of the core anaerobic response. A substantial variation of HCR1 in regulating Lpr is observed at the Arabidopsis species level. Thus, by combinatorially integrating two soil signals, K+ and O2 availability, HCR1 modulates the resilience of plants to multiple flooding scenarios.


【气候变化对作物的产量影响评估】T.A.M. Pugh, C. Müller, J. Elliott, D. Deryng, C. Folberth, S. Olin, E. Schmid & A. Arneth. Climate analogues suggest limited potential for intensification of production on current croplands under climate change. Nature Communications, 2016, 7: 12608

Climate change could pose a major challenge to efforts towards strongly increase food production over the coming decades. However, model simulations of future climate-impacts on crop yields differ substantially in the magnitude and even direction of the projected change. Combining observations of current maximum-attainable yield with climate analogues, we provide a complementary method of assessing the effect of climate change on crop yields. Strong reductions in attainable yields of major cereal crops are found across a large fraction of current cropland by 2050. These areas are vulnerable to climate change and have greatly reduced opportunity for agricultural intensification. However, the total land area, including regions not currently used for crops, climatically suitable for high attainable yields of maize, wheat and rice is similar by 2050 to the present-day. Large shifts in land-use patterns and crop choice will likely be necessary to sustain production growth rates and keep pace with demand.


【土壤碳吸收】Yujie He, Susan E. Trumbore, Margaret S. Torn, Jennifer W. Harden, Lydia J. S. Vaughn, Steven D. Allison, James T. Randerson. Radiocarbon constraints imply reduced carbon uptake by soils during the 21st century. Science, 2016, Vol. 353, Issue 6306, pp. 1419-1424

Soil is the largest terrestrial carbon reservoir and may influence the sign and magnitude of carbon cycle–climate feedbacks. Many Earth system models (ESMs) estimate a significant soil carbon sink by 2100, yet the underlying carbon dynamics determining this response have not been systematically tested against observations. We used 14C data from 157 globally distributed soil profiles sampled to 1-meter depth to show that ESMs underestimated the mean age of soil carbon by a factor of more than six (430 ± 50 years versus 3100 ± 1800 years). Consequently, ESMs overestimated the carbon sequestration potential of soils by a factor of nearly two (40 ± 27%). These inconsistencies suggest that ESMs must better represent carbon stabilization processes and the turnover time of slow and passive reservoirs when simulating future atmospheric carbon dioxide dynamics.

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