Aeolian Sandy Soil Research Articles

Regional Variability of Agriculturally-Derived Nitrate-Nitrogen in Shallow Groundwater in China, 2004–2014

Increasing diffuse nitrate loading of groundwater has long been a major environmental and health concern in China, but little is known about the spatial and temporal variability of nitrate concentrations in groundwater at regional scales. The aim of this study was to assess the spatial distribution and variation of nitrate-nitrogen (NO3−-N) concentrations in groundwater. We used groundwater quality monitoring data and soil physical characteristics from 21 agro-ecosystems in China for years 2004 to 2014. The results indicated that NO3−-N concentrations were highly variable in shallow groundwater across the landscape. Over the study period, most of the NO3−-N concentrations were below the World Health Organization permissible limit for drinking water (<10 mg N·L). NO3−-N concentrations in groundwater neither significantly increased nor decreased in most agro-ecosystems, but fluctuated with seasons. In addition, groundwater NO3−-N under purple soil (6.81 mg·L−1) and Aeolian sandy soil (6.02 mg·L−1) were significantly higher (p < 0.05) than that under other soil types, and it was medium-high (4.49 mg·L−1) under aquic cinnamon soil. Elevated nitrate concentrations occurred mainly in oasis agricultural areas of northwestern China, where farmlands with coarse-textured soils use flood irrigation. Therefore, arid and semi-arid areas are expected to sustain high NO3−-N concentrations in groundwater. Mitigation strategies can prevent this problem, and include control of N fertilizer input, balanced fertilization, proper rotation system, adoption of improved irrigation methods, and establishment of environmental policies.

Phytoextraction of rhenium by lucerne (Medicago sativa) and erect milkvetch (Astragalus adsurgens) from alkaline soils amended with coal fly ash

Coal fly ash (CFA) is an industrial waste generated in huge amounts worldwide, and the management of CFA has become an environmental concern. Recovery of valuable metals from CFA is one of the beneficial reuse options of CFA. Rhenium (Re) is one of the rarest metals in the Earth's crust and one of the most expensive metals of strategic significance in the world market. A CFA at the Jungar Thermal Power Plant, Inner Mongolia, China, contains more Re than two alkaline soils in the surrounding region. Pot experiments were undertaken to grow lucerne (Medicago sativa) and erect milkvetch (Astragalus adsurgens) in a loessial soil and an aeolian sandy soil amended with different rates (5%, 10%, 20%, and 40%) of CFA. The results show that plant growth was considerably enhanced and Re concentration in plants was significantly increased when CFA was applied to the alkaline soils at rates of ≤20%; while in some cases plant growth was also markedly enhanced by the 40% CFA treatment, which increased plant Re concentration the most of all treatments. Both lucerne and erect milkvetch showed potential for phytoextracting Re from CFA-amended alkaline soils. Using CFA for soil amendment not only offers a potential solution for the waste disposal problem of CFA, but the phytoextraction of Re by both lucerne and erect milkvetch may also bring an economic profit in the future.

Analyzing the Sand-fixing Effect of Feldspathic Sandstone from the Texture Characteristics

The purpose of this research was aimed to study the sand fixing effect of feldspathic sandstone in Mu Us Sandy Land, to provide a scienticic basis for desertification control, soil and water conservation and development of farming there. Methods of mixing feldspathic sandstone and aeolian sandy soil according to 1: 0, 1: 1, 1: 2, 1: 5, and 0: 1 mass ratioes, the graded composition and characteristics were studied with laser particle size analyzer. The result showed that these features of sand-based, loosely structured, easy to wind erosion of aeolian sandy soil were changed before feldspathic sandstone and aeolian sandy soil compounding. The <0.05 mm particle mass increased with feldspathic sandstone mass increasing. The texture presented this kind of change from sand to sandy loam to loam to silt loam. The small particle size distribution, good homogeneity and other features of aeolian sandy soil were improved to a certain degree, and the particle size distribution became broad before feldspathic sandstone and aeolian sandy soil compounding. The particle grading was continuous, and the grading characteristic was good when m(F): m(S) was 1: 5(Cu was 54.71 and Cc was 2.54) or when m(F): m(S) was 1: 2(Cu was 76.21, Cc was 1.12). The conclusion is that feldspathic sandstone has sand-fixing effect in texture characteristics, which heightens with feldspathic sandstone mass increasing, and when the mass ratio of feldspathic sandstone: aeolian sandy soil is 1: 2 or 1: 5 which compound better.

Effects of biochar addition on evaporation in the five typical Loess Plateau soils

Soil evaporation is the main route of soil moisture loss and often exceeds precipitation in the arid and semi-arid regions of the Loess Plateau. This study was conducted to determine whether biochar addition could reduce soil evaporation in drylands. We measured the evaporative loss in five typical topsoils (0–20cm) from the Loess Plateau, Shaanxi, China, that differed in texture (Eum-Orthic Anthrosol, Isohumisol, Loess, Sandy loess, and Aeolian sand) with five different biochar addition amounts (0, 10, 50, 100, and 150g-biochar/kg soil) and three biochar particle sizes (2–1mm, 1–0.25mm, and <0.25mm). The results showed that biochar addition generally increased the soil average water content (by 35.6% in biochar treatments and 33.5% in control treatments) and effectively reduced soil cumulative evaporation (by 322.64g in biochar treatments and 326.68g in control treatments). In addition, the inhibition of evaporation was enhanced with increases in biochar particle size and addition amount. Biochar addition had contrasting effects in the two evaporation stages: Biochar decreased evaporation through capillary flow during the first stage of evaporation but increased evaporation during the second, diffusion-limited vapour transport stage, particularly in the Aeolian sandy soil. When expressed on a mass basis, the effect of biochar addition amount on the cumulative evaporation (CE) was dependent on biochar particle size. In the larger sized (2–1mm and 1–0.25mm) biochar treatments, the final CE decreased as the addition amount increased, but for <0.25mm particles, increasing the biochar addition amount increased the final CE due to the creation of micropores. However, biochar addition decreased the ratio of evaporative loss in all soils proportional to the biochar addition amount. Soil texture and biochar particle size were the main factors affecting soil evaporation. Biochar application has the potential to improve soil water availability in semi-arid lands, but the results will depend on the biochar particle size and addition amount.

Spatial Distribution of Soil Particles and Heavy Metals Under Different Psammophilic Shrubs in the Ulan Buh Desert

Aeolian sandy soil was collected at depths of 0 to 100 cm at intervals of 0-10, > 10-20, > 20-30, > 30-40, > 40-60, > 60-80, and > 80-100 cm from under the cover of psammophilous shrubs Ammopiptanthus mongolicus, Hedysarum scoparium, Oxytropis aciphylla, Nitraria tangutorum and Haloxylon ammodendron and from a mobile dune in the Ulan Buh Desert. Multi-fractal theory was used to determine the soil particle size distribution (PSD), which measured the fractions of ω(Mn), ω(Zn), ω(Cr), ω(Cu), ω(Pb), ω(Ni), ω(As), and ω(Cd), as well as their distribution status in the laboratory and analyzed correlations between the PSD and heavy metal content to identify the relationship between soil structure and heavy metal pollution. This result shows that a range of different types of shrubs can increase the distribution of fine soil particles, and specifically Ammopiptanthus mongolicus and Hedysarum scoparium can increase range, heterogeneity and degree of dispersion of the PSD. The heavy metal content in the soil under the different shrubs is ranked as ω(Mn) > ω(Zn) > ω(Cr) > ω(Cu) > ω(Pb) > ω(Ni) > ω(As) > ω(Cd). In the first 10 cm of the soil under the shrubs, the concentration of all heavy metals are higher than samples from the mobile dune except for Cr and Cu. Average value of ω(Mn) and ω(Cd) is 354.899 and 1.429 mg·kg-1 under Ammopiptanthus mongolicus and Hedysarum scoparium respectively. Concentrations of Mn and Cd under Ammopiptanthus mongolicus and Hedysarum scoparium shrubs are significantly higher than those of mobile dune (P<0.05), and the concentration of both is significantly various between each soil layers (P<0.05). The highest value for ω(Mn) is in soil layer between 30 and 40 cm below the surface and the highest for ω(Cd) appears between 10 and 20 cm below the surface. The average ω(Pb) under Hedysarum scoparium is 13.556 mg·kg-1 which is the highest among all the shrubs, exceeding 3.24% under Ammopiptanthus mongolicus and higher than samples from mobile dune. However, average ω(As) under Hedysarum scoparium is exceeded 0.37% under Ammopiptanthus mongolicus but still higher than samples from mobile dune. The grain size of φ(silt) and φ(medium coarse sand) are determining factors for heavy metal concentrations in fine and coarse particles of aeolian sandy soil. Heavy metal measurements all positively correlate with φ(silt) and φ(clay), however, they negatively correlate with φ(medium coarse sand), except for ω(Cr). The correlation coefficients between heavy metal contents and the multifractal parameters are similar for φ(clay), φ(silt), and φ(medium coarse sand). Therefore, multifractal parameters can describe the correlation between heavy metals and their determinant soil grain size. This study shows that, Ammopiptanthus mongolicus and Hedysarum scoparium can entrap and deposit fine particles from the sand flow to surface soil layers around shrubs and improve the condition of PSDs for different soil layers with respect to heavy metals. Hence, in aeolian sandy soil these concentrations are higher than for mobile dunes after planting Ammopiptanthus mongolicus and Hedysarum scoparium. Therefore both should be used to promote good soil structure of particular areas to entrap and in-situ control heavy metals to decrease heavy metal pollution in downwind cities.

Applicability of five models to simulate water infiltration into soil with added biochar

As a soil amendment, biochar can reduce soil bulk density, increase soil porosity, and alter soil aggregates and thus affect the infiltration. Researchers have proposed and revised several theoretical models to describe the process of soil infiltration. Although these models have been successfully used to evaluate the soil infiltration in different scenarios in agricultural fields, little effort has been devoted to assess their performances in arid and semi-arid soils after the addition of biochar. A laboratory experiment was performed to study the infiltration characteristics of two typical Loess Plateau soils at three particle sizes (2–1, 1–0.25, and <0.25 mm) and five biochar application amounts (0, 10, 50, 100, and 150 g/kg). The performance of five models (i.e., the Philip model, Kostiakov model, Mezencev model, USDA-NRCS model, and Horton model) in simulating the infiltration process was then evaluated based on the adjusted coefficient of determination and a reduced Chi-Square test. Results indicated that the Horton model best simulated the water-infiltration process in an aeolian sandy soil with added biochar. However, the Mezencev model best simulated the infiltration process in a loamy clay soil (Eum-Orthic Anthrosol). The three-parameter model, i.e., Mezencev and Horton models can better describe the relationship between cumulative infiltration and infiltration time. In conclusion, biochar reduced the soil infiltration capacity of the aeolian sandy soil and increased that of the Eum-Orthic Anthrosol.

Analyses of the Strength Characteristics of Solidified Desert Aeolian Sandy Soil

The strength characteristics of solidified desert aeolian sandy soil are investigated to expand its scope of application in road engineering. Its suitability as sub-base of pavement structure is analyzed in terms of its strength. The unconfined compressive strengths of the solidified desert aeolian sandy soil specimens with different contents of curing agent are measured using a pavement material strength meter. The microstructures of aeolian sand and the solidified aeolian sandy soil to which the curing agent PX is added are analyzed by scanning electron microscopy(SEM). The strength characteristics and strength formation mechanism of the solidified Aeolian sandy soil are revealed by the analyses. The results point to the following conclusions: (1) the solidified aeolian sandy soil with 10% PX and cured for 7 d achieves an unconfined compressive strength that meets the strength requirement of the pavement sub-base. (2) the strength of the solidified soil is associated with the content of PX, and the optimal dosage is10%. (3) the SEM image shows that intergranular filling consisting of gel and cumularspharolith is formed after adding the curing agent PX. This formation changed the adhesive strength between the soil particles, accounting for the chief cause of the increase in overall strength.

Transport of natural soil nanoparticles in saturated porous media: effects of pH and ionic strength

To understand the effects of ionic strength and pH on the transport of natural soil nanoparticles (NS) in saturated porous media, aeolian sandy soil nanoparticles (AS), cultivated loessial soil nano particles (CS), manural loessial soil nanoparticles (MS) and red soil nanoparticles (RS) were leached with solutions of varying pH and ionic strength. The recovery rate of soil nanoparticles decreased in the order AS > RS > MS > CS. Transport of soil nanoparticles was enhanced with increasing pH and decreasing ionic strength and was attributable to changes in the Zeta potential of NS. Deposition of NS was also affected by the composition of soil nanoparticles and the surface charge. Column experiments showed that the interaction between soil nanoparticles and saturated quartz sand was mainly due to the physical and chemical properties of soil nanoparticles. The Derjaguin–Landau–Verwey–Overbeek interaction energies between NS and sand were affected by pHs and ionic strengths. Soil nanoparticles transport through saturated porous media could be accurately simulated by the one-dimensional advection-dispersion-reaction equation.

Sorption of vanadium (V) onto natural soil colloids under various solution pH and ionic strength conditions

Batch sorption kinetics and isothermal characteristics of V(V) were investigated on three natural soil colloids (manual loessial soil colloid (MSC), aeolian sandy soil colloid (ASC), and cultivated loessial soil colloid (CSC)) under various solution pH and ionic strength (IS) conditions. Colloids were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). AFM micrographs showed CSC with an aggregated shape with larger particle diameter as compared with ASC and MSC. XRD spectra revealed the presence of different minerals in natural soil colloids including biotite, kaolinite, calcite and quartz, which might contribute to sorption process. The sorption ability decreased with increase of colloidal particle size. The sorption was mainly attributed to complexation by active carboxylate and alcohol groups of colloidal components. Sorption kinetics and isotherms of V(V) onto natural soil colloids were best fitted with Pseudo-second-order and Freundlich models. Langmuir model indicated that sorption capacity of MSC and ASC was comparable (285.7 and 238.1 mg g−1); however, CSC exhibited the lowest sorption capacity (41.5 mg g−1) due to its larger particle diameter and aggregated shape. The maximum V(V) sorption capacity reached plateau values at a solution pH ranged between 5.0 and 9.0 for MSC and ASC, and 6.0–8.0 for CSC. Sorption capacity of V(V) onto natural soil colloids decreased with increasing IS. Based on result of this study we can conclude that sorption of V(V) onto natural soil colloids is pH- and IS-dependent. These findings provide insights on the remediation of vanadium-contaminated soils.

Biological soil crust formation under artificial vegetation effect and its properties in the Mugetan sandy land, northeastern Qinghai-Tibet Plateau

Mugetan sandy land is an inland desertification area of about 2,065 km2 in the northeastern Qinghai-Tibet Plateau. In the ecological restoration region of the Mugetan sandy land, different crusts have formed under the action of vegetation in three types of sandy soil (i.e. semi-fixed sand dune, fixed sand dune and ancient fixed aeolian sandy soil). The surface sand particle distribution, mineral component and vegetation composition of moving sand dunes and three types of sandy soil were studied in 2010-2014 to analyze the biological crust formation properties in the Mugetan sandy land and the effects of artificial vegetation. Results from this study revealed that artificial vegetation increases the clay content and encourages the development of biological curst. The fine particles (i.e. clay and humus) of the surface layer of the sand dunes increased more than 15% ten years after the artificial vegetation planting, and further increased up to 20% after one hundred years. The interaction of clay, humus, and other fine particles formed the soil aggregate structure. Meanwhile, under the vegetation effect from the microbes, algae, and moss, the sand particles stuck together and a biological crust formed. The interconnection of the partial crusts caused the sand dunes to gradually be fixed as a whole. Maintaining the integrity of the biological crust plays a vital role in fixing the sand under the crust. The precipitation and temperature conditions in the Mugetan sandy land could satisfy the demand of biological crust formation and development. If rational vegetation measures are adopted in the region with moving sand dunes, the lichen-moss-algae biological curst will form after ten years, but it still takes more time for the sand dunes to reach the nutrient enrichment state. If the biological curst is partly broken due to human activities, reasonable closure and restoration measures can shorten the restoration time of the biological crust.

Effects of Modified Excess Sludge on the Growth of Artemisia ordosica and Transformation of Heavy Metals

A greenhouse experiment was accomplished to investigate the feasibility of excess sludge modified by coal fly ash pretreatment and γ-ray irradiation in soil application for cultivation of Artemisia ordosica. The results showed that modified excess sludge provided a positive effect on the growth of Artemisia ordosica. The modified excess sludge and aeolian sandy soil at the volume ratio of 1:2 was optimal, and nutrient concentrations of Artemisia ordosica reached the highest. In the aeolian sandy soil, the bio-concentration factor values of most heavy metals were less than 1.0 except for Cu, Zn, and Ni. The average bio-concentration factor values of heavy metals in Artemisia ordosica increased in a sequence of Mo < Cd < Fe < V < Cr < Co < Mn < Pb < Cu < Zn < Ni for all samples. Artemisia ordosica could be used to decrease the bioavailability and eco-toxicity of Ni, V, and Mo in all cultivation experiments of artificial soil, and Artemisia ordosica could also reduce the bioavailability and eco-toxicity of Cu, Cd, Cr, and Mn in the artificial soil of modified excess sludge and aeolian sandy soil at the volume ratio of 1:2.

Modeling Soil Type Effects to Improve Rainfed Corn Yields in Northeast China

Understanding how soil type in the Corn Belt of Northeast China affects both the potential yield of a rainfed crop [Yp(r)] and the yield gap [YG(r)] between Yp(r) and the water non‐limiting potential yield (Yp) is essential for enhancing corn (Zea mays L.) production and identifying critical irrigation windows for different soil types. The Root Zone Water Quality Model 2 (RZWQM2) was calibrated and validated based on 2 yr of experimental data and then used to estimate Yp and Yp(r) along with YG(r) in aeolian sandy soil vs. black soil using the same weather data from 1980 to 2012. The values for Yp were the same for both soil types, and the mean Yp was 11.299 Mg ha−1 (CV of 15.6%) during the 33‐yr simulation period. The mean Yp(r) was lower in the aeolian sandy soil (7.628 Mg ha−1, CV of 39.8%) than in the black soil (8.893 Mg ha−1, CV of 34.5%). The mean YG(r) was 3.672 Mg ha−1 in the aeolian sandy soil and 2.406 Mg ha−1 in the black soil. Values for Yp(r) were positively correlated with precipitation in June and July in the aeolian sandy soil and in July in the black soil. The YG(r) was negatively correlated with precipitation in June and July in both soils. Therefore, soil type affected Yp(r) and YG(r) through the soil water condition under the same weather conditions. The critical irrigation window to decrease YG(r) is in June and July for aeolian sandy soils and in July for black soils.

Optimized single irrigation can achieve high corn yield and water use efficiency in the Corn Belt of Northeast China

Abstract Decreasing the corn ( Zea mays L.) gap between the potential yield and farm yield and reducing the risk of grain yield of drought are very important for corn production in the Corn Belt of Northeast China (CBNC). To achieve a high and stable corn yield, the effects of supplementary irrigation on yield, water use efficiency (WUE) and irrigation water use efficiency (IWUE) were studied using a modelling approach. The Root Zone Water Quality Model 2 was parameterized and evaluated using two years of experimental data in aeolian sandy soil and black soil. The evaluated model was then used to investigate responses to various irrigation strategies (rainfed, full irrigation and 12 single irrigation scenarios) using long-term weather data from 1980 to 2012. Full irrigation guarantees a high and stable corn grain yield (12.92 Mg ha −1 and has a coefficient of variation (CV) of 14.8% in aeolian sandy soil; 12.30 kg Ma −1 and CV of 11.1% in black soil), but has a low water use efficiency (19.92 and 21.81 kg ha −1 mm −1 ) and a low irrigation water use efficiency (10.01 and 11.03 kg ha −1 mm −1 ). A single irrigation can increase corn yields by 3–35% for aeolian sandy soil and 5–35% for black soil over different irrigation dates compared with no irrigation. The most suitable single irrigation date was during late June to early July for aeolian sandy soil (yield = 10.73 Mg ha −1 and WUE = 27.94 kg ha −1 mm −1 ) and early to mid-July for black soil (yield = 11.20 Mg ha −1 and WUE = 27.70 kg ha −1 mm −1 ). The lowest yield risk of falling short of the yield goal of 8, 9, and 10 Mg ha −1 were 9.1%, 18.2%, and 33.33% in aeolian sandy soil and 3.0%, 15.25, and 21.2% in black soil when an optimized single irrigation was applied in late June or early July, respectively. Therefore, an optimized single irrigation should be applied in late June to early July with the irrigation amount to refill soil water storage of root zone to field capacity in CBNC.

Depth-dependent heterogeneity of water flow in sandy soil under grass

AbstractThe non-equilibrium water flow was studied on an aeolian sandy soil under grass using the dye tracer infiltration experiments. Two experiments simulating infiltration of 20 mm and 70 mm of rain water were conducted. The improved digital image analysis technique for estimating the effective cross section (ECS) and degree of preferential flow (DPF) from stained soil profiles was used to analyze the depth dependency and variation of the ECS and DPF parameters. It was found that the heterogeneity of water flow in sandy soil under grass increased with depth. Extremes of heterogeneity parameters (minimum value of the ECS and maximum value of the DPF) were almost the same for the two cumulative infiltrations, and the depth, in which the extremes of heterogeneity parameters occurred, increased with an increase in cumulative infiltration. Moreover, considerable variation of infiltration patterns was indentified in consecutive vertical sections.

Metabolic characteristics of microbial communities of Aeolian sandy soils induced by saline water drip irrigation in shelter forests

SummaryThe microbial metabolic activities of soils sampled at eight depths (0–5, 5–15, 15–30, 30–50, 50–70, 70–100, 100–150 and 150–200 cm) in shelter forests (comprising the tree species, Haloxylon sp.) along the Tarim Desert Highway under drip irrigation with different saline waters were investigated by using Biolog technology. Variance analysis and principal component analysis were conducted. The average well colour development (AWCD) values for single carbon source use by microorganisms increased with the incubation time. The microorganisms reached a lag phase within 24 hours of incubation and entered exponential and stationary phases after 48 and 216 hours of incubation, respectively; however, the death phase was not obvious. As the salinity of drip irrigation water increased, the AWCD values significantly decreased; the AWCD value in the land drip‐irrigated with lowest saline water (S8) was roughly 20% larger than that of the land drip‐irrigated with highest saline water (S1), which was mainly caused by the differences in the use of carboxylic acids, amino acids and phenolic compounds by soil microorganisms. The vertical differences in carbon source utilization by soil microbial communities were obvious: these may be caused by the vertical differences in soil organism abundance associated with distribution of roots in the shelter forest. The largest and smallest AWCD values were noted in the 70–100‐cm soil layer and 0–5‐cm topsoil layer, respectively. The correlation coefficients between the AWCD values and soil organic matter, total nitrogen, total phosphorus, total potassium, available potassium, available phosphorus, pH, cation exchange capacity and bulk density were &gt; 0.85. Thus, the differences in carbon source metabolism activities of soil microorganisms were caused mainly by the soil chemical properties, with total nutrients being the main driving factor. Furthermore, the amounts of carboxylic acids, amino acids and polymers provided sensitive markers for distinguishing the ability of soil microorganisms to use carbon sources under drip irrigation with different saline waters. Saline water irrigation affected the soil microbial community in shelter forest and produced obvious differences among the shelter forests irrigated with different saline waters.

黑河下游湿地土壤有机氮组分剖面的分布特征

PDF HTML阅读 XML下载 导出引用 引用提醒 黑河下游湿地土壤有机氮组分剖面的分布特征 DOI: 10.5846/stxb201305191113 作者: 作者单位: 1.四川省土壤环境保护重点实验室2. 四川农业大学资源环境学院,1. 四川省土壤环境保护重点实验室2. 四川农业大学资源环境学院,1. 四川省土壤环境保护重点实验室2. 四川农业大学资源环境学院,1. 四川省土壤环境保护重点实验室2. 四川农业大学资源环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家科技支撑计划(2012BAD14B18,NC2010RE0057) Profile distribution characteristics of soil organic nitrogen fractions in the lower reaches of the Heihe River wetland Author: Affiliation: 1 Key Laboratory of Soil Environment Protection of Sichuan Province2 College of Resources and Environment, Sichuan Agricultural University,1 Key Laboratory of Soil Environment Protection of Sichuan Province2 College of Resources and Environment, Sichuan Agricultural University,1 Key Laboratory of Soil Environment Protection of Sichuan Province2 College of Resources and Environment, Sichuan Agricultural University,1 Key Laboratory of Soil Environment Protection of Sichuan Province2 College of Resources and Environment, Sichuan Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:结合野外调查,用Bremner法研究了黑河下游湿地不同土壤类型的有机氮组分,结果表明:在0-50 cm土层,5种土壤有机氮均以酸解性氮为主,占全氮的71.04%-81.79%。泥炭土、沼泽土、草甸土、亚高山草甸土所含的酸解氮、非酸解氮和酸解氮组分氨态氮、氨基酸态氮、氨基糖态氮含量的剖面分布总体上均随土层深度的增加而呈降低趋势,而风沙土却相反,上述有机氮组分呈升高趋势。5种土壤酸解氮及其组分氨态氮、氨基酸态氮、氨基糖态氮占全氮比例的剖面分布总体上均随土层深度的增加而呈降低趋势,而非酸解氮却呈升高趋势。5种土壤酸解未知态氮含量及占全氮比例均在剖面分布上无明显特征。在0-30 cm各相同土层内,5种土壤酸解氮各组分含量及占全氮比例的大小顺序均为氨基酸态氮 > 氨态氮 > 未知态氮 > 氨基糖态氮;而在30-50 cm土层,5种土壤酸解氮各组分含量及占全氮比例的大小顺序均无明显特征。此外,黑河下游湿地土壤干化、沙化过程中,表层0-10 cm土壤有机氮组分含量变化明显,其中土壤氨态氮对生态环境变化最为敏感。 Abstract:Nitrogen (N) is one of the most important element in plant growth and an important part of the global ecosystem substances circulation. Organic N is both the main form of soil N and pool of mineral N. Soil organic N plays an important role in soil fertility, N cycling and environmental protection. Usually, the concentration and distribution of soil organic N mainly affected by soil types, soil level, rhizospheric environment, fertility and farming conditions, etc, and the chemical forms and status of soil organic N is the important factor affecting the availability of soil N. Currently, researchers have focused more on effect of different land use systems on changes of soil organic N fractions, dissolved organic N, particulate organic N and microbial biomass N, as well as effect of different fertilization and irrigation approaches on concentrations and composition of organic N fractions by using the Bremner's method to separate soil organic N fractions. Combined with filed investigation, five types of soil samples in the lower reaches of Heihe river wetland were collected, and the organic N fractions were studied using the Bremner's method, the results showed that acidolysable N was the dominant fraction of organic N in all the soil samples (0-50 cm soil layer), and the proportion of acidolysable N to total N was from 71.04% to 81.79%. The concentrations of acidolysable N, non-acidolysable N and acidolysable N fractions (ammonia N, amino acid N, amino sugar N) of Peat soil, Boggy soil, Meadow soil, Subalpine meadow soil decreased, but increased in the Aeolian sandy soil generally with soil depth in the profile. Furthermore, the proportions of acidolysable N and acidolysable N fractions (ammonia N, amino acid N, amino sugar N) to total N of all the soil samples generally decreased with soil depth in the profile distribution, while the proportion of non-acidolysable N to total N generally increased with soil depth in the profile distribution. The concentration of acidolysable unknown N and the proportion to total N of all the soil samples did not show any specific characteristics. In addition, in the same soil layer (0-30 cm), the concentrations of acidolysable N fractions and the proportions to total N varied as the followings: amino acid N > ammonia N > unknown N > amino sugar N; However, in 30-50 cm soil layer, the concentrations of acidolysable N fractions and the proportions to total N of the soil did not show any typic characteristics. Besides, the soil organic N fractions in the surface soil (0-10 cm) changed obviously along with the soil desiccation and desertification in the lower reaches of the Heihe River wetland, and the soil ammonia N of soil was the most sensitive one to the ecological environment factors. 参考文献 相似文献 引证文献

Geotechnical hazards assessment on wind-eroded desert embankment in Inner Mongolia Autonomous Region, North China

Inner Mongolia Autonomous Region is one of the severest desertification areas from wind erosion in North China, and it poses as a potential hazard factor for the slope stability of embankments. As the most common and abundant filler in embankment construction in the desert, Aeolian sandy soil is vulnerable to wind erosion. The embankment is susceptible to suffer from damage and lower slope stability due to wind erosion before placement of surface pavement and erosion resistance materials. The purpose of this paper is to evaluate the influence of wind erosion on the slope stability of embankment through a quantitative analysis of shear strength of Aeolian sandy soil within embankments. Field investigation was conducted to measure the wind field around embankment and the shear strength of Aeolian sandy soil within embankment. The shear strength variation was measured and proposed for a characterization of wind erosion resistance. Then, a model for calculating the progressive wind erosion process was suggested for evaluating the slope stability of wind-eroded embankment through the strength reduction theoretical simulation. The results show that wind erosion resistance of Aeolian sandy soil within embankment tends to increase gradually from slope surface to the core and from the shoulder to the toe. When the embankment suffers from wind erosion along prevailing wind direction, its slope has a much weaker resistance on the windward side. The maximum lateral wind erosion depth is about 0.2 times height of embankment. And factors of safety decrease gradually as wind erosion increases, it has affected the local stability of slope, but the slope global stability is not affected under this given wind erosion condition in this study. If wind erosion increases and wind erosion area expands further, the global stability of slope will be on the hazardous level. The speculative study is discussed between slope stability and geometric size of wind-eroded embankment. When the height of embankment increases and its slope becomes steep, its factor of safety decreases, and its slope stability reduces. The results indicate that embankments in Inner Mongolia Autonomous Region should be designed to be lower and gentler in consideration of wind erosion and also recommend scientific and effective protective measures to prevent further development of wind erosion based on proposed maximum lateral wind erosion depth from this study.

Effects of Rainfall Harvesting and Mulching on Corn Yield and Water Use in the Corn Belt of Northeast China

The Corn Belt of Northeast China is the most important corn production area in China, accounting for 30% of the total corn production. However, seasonal drought conditions limit local corn production. Field experiments were conducted in 2011 and 2012 in Lishu county (Jilin Province, China) to study the effects of ridge and furrow rainfall harvesting and mulching on corn yields, evapotranspiration (ET), and water use efficiency (WUE) in black and aeolian sandy soils. The treatments included flat planting bed (FB), plastic‐mulched ridges with bare furrows (RFB), and plastic‐mulched ridges with straw‐mulched furrows (RFM). For both soil types, the RFB and RFM treatments improved soil water conditions in the root zone. However, adding straw mulch did not consistently improve soil water content. In the black soil, the RFB treatment did not affect crop yield but increased WUE by 13% relative to the FB treatment in 2011. Furthermore, yield and WUE decreased by 30 and 24%, respectively, in 2012. In the aeolian sandy soil, the RFB treatment increased yield and WUE by 26 and 25%, respectively, relative to the FB treatment in 2011. However, the RFB treatment had no effect on yield or WUE in 2012. For both soil types, the RFM treatment did not significantly affect yield or WUE relative to the RFB treatment during 2011 or 2012. Therefore, the RFB treatment should only be used in aeolian sandy soils to achieve higher corn yields and WUEs and not be recommended for black soils when the soil water is sufficient.

Determination of 137Cs reference inventories in a large-scale region: A case study in the central-eastern Inner Mongolia Plateau

In isotope 137Cs tracing studies, it is a premise to determine suitable 137Cs reference inventory (CRI) plots and the CRI values. Owing to the heterogeneous spatial distribution of 137Cs deposition in the ground and diverse, or even irregular, operations in sampling and testing procedures, CRI determination is usually faced with many difficulties and uncertainties. In addition, more difficulties occur in an investigation of a large-scale region because of time constraints and measurement cost limitations. In this study, traditional CRI acquiring methods were summarized first, and then a new complex scheme was established, involving seven core steps and coupling the model estimate and sample measurement. The above CRI determination methodology was implemented in the central-eastern Inner Mongolia Plateau. The case study results showed that the CRI in the dark chestnut soil sub-region, located in the east and south of Xing’an City, exhibited 2447 Bq·m−2; the CRI in the aeolian sandy soil sub-region, positioned in the south central Tongliao City and central Chifeng City, showed 2430 Bq·m−2; the CRI in the sandy chernozem soil sub-region, situated in the northwestern Chifeng City, presented 2384 Bq·m−2; and the CRI in the chestnut soil sub-region, in the southern Xilin Gol City, was 2368 Bq·m−2. The newly proposed CRI determination scheme was proved effective, and the determined CRI plots and CRI values were convincing. The methodology offered a framework for 137Cs tracing studies in large-scale regions or long-distance transects.

Soil Detachment Capacity by Overland Flow for Soils of the Beijing Region

Soil type may influence soil detachment process by overland flow, but few studies have quantified the effect fully and systematically. This study was undertaken to quantify the effects of soil type on soil detachment capacity using undisturbed soil samples collected from 11 soil types from the Beijing Region. The soil samples were placed in a 5.0-m long and 0.38-m wide hydraulic flume and eroded by overland flow under three slope gradients (17.4%–34.2%) and three unit discharges (1.32–5.26 × 10−3 m2 sec−1). The results showed that soil detachment capacities were significantly affected by soil types. Aeolian Sandy Soil was the most easily detached, whereas Wet Meadow Soil was the hardest. Soil detachment capacity was significantly affected by soil properties. For soil texture, loamy sand had the largest detachment capacity, followed by sandy loam, loam, and silt loam. Furthermore, detachment capacity was negatively correlated to clay and silt content and positively related to sand content and median diameter of soil particles. Both shear strength and organic matter content were negatively correlated to detachment capacity. Detachment capacity could be predicted reasonably well by stream power, clay content, and organic matter content (r2 = 0.743) with a coefficient of Nash-Sutcliffe efficiency of 0.644. An equation was developed to estimate detachment capacity based on stream power and soil properties (r2 = 0.704; Nash-Sutcliffe efficiency, 0.702). Rill erodibility ranged from 0.73 to 85.22 × 10−3 sec m−1, and the critical shear stress changed from 0.683 to 7.978 Pa. The results are helpful to understand the mechanism of soil detachment process under different soil types and to develop the process-based erosion models.