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[学术文献 ] 灌溉方式对石灰性褐土团聚体分布特征、稳定性及养分含量的影响 进入全文
中国生态农业学报(中英文)
为探明不同灌溉方式对石灰性褐土团聚体分布特征、稳定性及养分含量的影响， 于2016—2021年在山西农业大学小麦研究所韩村实验基地开展大田定位试验。设连续微喷灌（SI）、连续滴灌（DI）、连续漫灌（FI）和第1、2、5年漫灌与第3、4年微喷灌轮换（RI） 4个处理。定位5年后， 测定>0.25 mm团聚体重量百分含量(DR0.25、WR0.25)、平均重量直径（MWD）、几何平均直径（GMD）、破坏率（PAD）、分形维数（D）等土壤团聚体粒径分布、稳定性指标， 以及土壤水稳性团聚体有机碳、有效磷、速效钾含量等养分指标， 并对水稳性团聚体分布特征、稳定性及养分含量进行了相关分析。主要结果: 1)机械稳定性团聚体在0～10 cm土层SI、DI和RI处理均以0.5～1 mm为优势粒径（FI为<0.25 mm）， 在10～20 cm土层DI、FI和RI处理均以>5 mm为优势粒径（SI为0.5～1 mm）， 在20～50 cm土层各灌溉处理的优势粒径则均为>5 mm; 水稳性团聚体在0～50 cm土层4种灌溉处理均以<0.25 mm为优势粒径， 但FI处理的重量百分比最高。2) SI和DI处理在0～50 cm土层有效提高了WR0.25、降低了D， 且MWD、GMD总体上高于FI和RI处理， 并在30～50 cm土层显著降低了PAD， 而FI、RI处理的这些稳定性指标受土层深度影响较大。3)与其他2个处理相比， SI、DI处理在0～50 cm土层提高了土壤水稳性大团聚体（>0.25 mm）有机碳、有效磷、速效钾含量， 尤其在提高0～30 cm土层有效磷含量和30～50 cm土层速效钾含量上效果更为显著。4)相关性分析表明， 土层、WR0.25、MWD、GMD、PAD、D、水稳性大团聚体养分含量（有机碳、有效磷、速效钾）之间的相关性均达到显著（P<0.05）或极显著（P<0.01）水平。综上所述， 微喷灌、滴灌水肥一体化更有利于改善土壤结构和性状， 促进土壤大团聚体形成， 提高水稳性团聚体稳定水平及养分含量， 应值得推广应用。
[学术文献 ] Translating wastewater reuse for irrigation from OECD guideline: Tramadol sorption and desorption in soil-water matrices 进入全文
sciencedirect
Treated and untreated wastewater is often used for agricultural irrigation and, despite the many benefits of this practice, it poses the risk of biologically active chemical pollutants (such as pharmaceuticals, like tramadol) entering the environment. The partitioning of tramadol between soil/water at environmentally relevant concentrations is important to understand its environmental toxicity. Kinetics and isotherm sorption studies based on the Organisation for Economic Cooperation and Development (OECD) 106 Guideline were undertaken, ensuring comparability to previous studies. Studies were undertaken in three soils of different characteristics using aqueous concentrations of tramadol from 500 ng L−1 (environmentally relevant) to 100 μg L−1 (comparable to previous studies). Two of the soils presented a significantly (p < 0.05) higher sorption at a lower initial tramadol concentration (5000 ng L−1), compared to 20,000 ng L−1. Hysteresis was observed in all studied soils, indicating the accumulation of tramadol. Higher sorption to soils correlated with higher clay content, with soil/water partitioning coefficients (Kd) of 5.5 ± 13.3, 2.5 ± 3.8 and 0.9 ± 3.0 L kg1 for soils with clay contents of 41.9%, 24.5% and 7.4%, respectively. Cation exchange was proposed as the main sorption mechanism for tramadol to soils when the pH was below tramadol's pKa values (9.41 and 13.08). A comparative kinetics study between tramadol in soil/calcium chloride buffer and soil/wastewater effluent demonstrated significantly higher (p < 0.05) tramadol sorption to soil from wastewater effluent. This has the environmental implication that clay soils will be able to retain tramadol from irrigation water, despite the organic content of the irrigation water. Therefore, our studies show that tramadol soil sorption is likely to be higher in agricultural environments reusing wastewater than that predicted from experiments using the OECD 106 Guideline calcium chloride buffer.
[学术文献 ] Bias correction of satellite soil moisture through data assimilation 进入全文
sciencedirect
Soil moisture exhibits great spatio-temporal heterogeneity and plays a critical part in land surface energy and water cycles, being identified as a terrestrial essential climate variable. Thus, it is urgently needed in a wide variety of environmental processes such as hydrology, meteorology, agriculture, and ecology. Microwave remote sensing has the potential to provide near real-time soil moisture estimates on large spatial scales according to the distinctive contrast between dielectric properties of water and dry soils. Thus, many space-borne microwave sensors have been launched for retrieving soil moisture. Especially, SMOS and SMAP at L-band frequency (1.4 GHz) supply an unprecedented opportunity for retrieving surface soil moisture due to their deeper penetration than instruments at other bands. However, these satellite soil moisture products need bias correction before application such as data assimilation. Two common correction methods require reliable land surface soil moisture simulations. However, the quality of these simulations relies heavily on model parameters, such as soil porosity and texture, which are almost unavailable in remote regions such as the Tibetan Plateau. In this study, a dual-cycle assimilation algorithm is taken to make on-line bias correction when assimilating SMAP soil moisture products. During the assimilation, a linear bias correction scheme is regarded as the observation operator to link the simulated soil moisture values and the satellite retrievals. In the inner cycle, a sequentially based assimilation algorithm is run with both model parameters and bias correction coefficients, which are provided by the outer cycle. At the same time, both the analyzed soil moisture and the innovation are reserved at each analysis moment. In the outer cycle, the innovation time series kept by the inner cycle are fed into a likelihood function to adjust the values of both model parameters and correction coefficients through an optimization algorithm. A series of numerical experiments are designed and conducted, indicating that the soil moisture estimates by the presented algorithm are superior to those with the existing bias correction schemes.
[学术文献 ] Historical and future Palmer Drought Severity Index with improved hydrological modeling 进入全文
sciencedirect
With the ongoing climate warming, changes in drought and the adverse effects on water resources, food production and ecosystem functioning have been key research topics of ever-increasing interest. The Palmer Drought Severity Index (PDSI) is among the most widely used indicators for drought monitoring and research. However, the two-layer bucket water balance model embedded in the original PDSI model has been criticized for being over-simplified to accurately quantify the surface water balance and therefore raising uncertainties in the subsequent PDSI estimates (PDSIoriginal). Here we improve the water balance calculations in the PDSI model by using direct hydrological outputs from physically-based, more sophisticated global hydrological models (GHMs) participated in the Inter-Sectoral Impact Model Inter-Comparison Project (ISIMIP). Validation results show that the estimated runoff (Q) and evapotranspiration (ET) from ISIMIP GHMs perform much better than those from the original PDSI two-layer bucket model in capturing the long-term trend and monthly variabilities of Q and ET, especially in cold regions and relatively dry areas, using observed Q (at 2191 catchments) and an independent satellite-based ET product (the Global Land Evaporation Amsterdam Model, GLEAM; over the entire terrestrial environment) as the reference. In addition, the new PDSI estimates with improved hydrological modeling (PDSIISIMIP) exhibit a significantly stronger correlation with observed Q than PDSIoriginal in nearly all studied catchments, suggesting that PDSIISIMIP is superior to PDSIoriginal in capturing hydrological droughts. We further compare the long-term PDSI trends and changes in drought using PDSIoriginal and PDSIISIMIP under both historical climate (1900-2005) and future climate change scenarios (2006-2099). We find that PDSIoriginal and the PDSIoriginal-identified land areas under drought generally show a larger trend than those based on PDSIISIMIP. For future climate change scenarios, the PDSIoriginal-projected increasing trend of land proportion under drought is about two times larger than that assessed with PDSIISIMIP, implying that PDSIoriginal may largely overestimate future drought increases, as commonly done in existing studies. In this light, our approach of directly using hydrological outputs from physically-based, more sophisticated GHMs provide an effective, yet relatively simple approach to reduce uncertainties in PDSI estimates thereby achieving a better prediction of drought changes under warming.
[学术文献 ] 基于广义可加模型的广东省森林土壤有机质影响因子 进入全文
中国无机分析化学
有效钼是土壤质量评价不可缺少的指标，为准确高效测定土壤中的有效钼，样品采用Tamm溶液进行浸提，浸提液用硝酸（5%）稀释10倍，确定了分析元素钼的同位素95Mo,103Rh为内标，校正基体干扰和信号漂移，优化了仪器分析参数，利用电感耦合等离子体质谱仪（ICP-MS）碰撞模式（KED模式）下进行有效钼的测定，建立的标准曲线相关系数为1.00，方法的检出限（3σ）为0.002μg/L，对3个国家一级标准物质样品进行土壤中有效钼含量的平行测定，相对误差小于2%，相对标准偏差（RSD）小于5%，对200余件实际样品进行不同方法外检比对，合格率为98%。方法具有操作简单、方便快捷，经济适用等特点，适合于各生产实验室各种类型土壤样品有效钼的大批量分析。
[学术文献 ] 南疆无膜棉不同灌溉条件下土壤水分时空变化特征 进入全文
西北农业学报
旨在研究南疆不同灌溉条件下无膜棉田土壤水分时空变化特征,以‘中棉619’为供试品种,南疆常规膜下滴灌模式为对照（CK）,无膜棉田设置6次（wmm1）、8次（wmm2）、10次（wmm3）3个不同的灌水处理,开花前每个处理灌水量均为45mm,开花后灌水量均为69mm,wmm3最后一次灌水量为52.2mm。结果表明:灌水次数较少的处理wmm1、wmm2,土壤水分的垂直分布特征为随着土层深度的增加先增加后减少,wmm3及CK土壤水分垂直分布特征为先增加后减少再增加,CK与无膜处理相对湿润区域存在差异。初花期地膜覆盖保水效果明显,但是随着生育进程的推进以及灌水次数的增加,wmm3处理10～50cm土层土壤含水量与CK持平,50～90cm土层土壤含水量明显高于其他处理,wmm1处理除50～70cm土层外,含水量下降速度最快、含量最低。盛花期前后各处理的耗水量差异显著,最大耗水量出现的日期差异显著,wmm3自开花后耗水量显著高于其他处理。因此,可通过优化灌水量及次数提高水分利用率。
