Vertical Distribution Characteristics Research Articles

Vertical Distribution Characteristics of PM2.5 Observed by a Mobile Vehicle Lidar in Tianjin, China in 2016

We present mobile vehicle lidar observations in Tianjin, China during the spring, summer, and winter of 2016. Mobile observations were carried out along the city border road of Tianjin to obtain the vertical distribution characteristics of PM2.5. Hygroscopic growth was not considered since relative humidity was less than 60% during the observation experiments. PM2.5 profile was obtained with the linear regression equation between the particle extinction coefficient and PM2.5 mass concentration. In spring, the vertical distribution of PM2.5 exhibited a hierarchical structure. In addition to a layer of particles that gathered near the ground, a portion of particles floated at 0.6–2.5-km height. In summer and winter, the fine particles basically gathered below 1 km near the ground. In spring and summer, the concentration of fine particles in the south was higher than that in the north because of the influence of south wind. In winter, the distribution of fine particles was opposite to that measured during spring and summer. High concentrations of PM2.5 were observed in the rural areas of North Tianjin with a maximum of 350 μg m–3 on 13 December 2016. It is shown that industrial and ship emissions in spring and summer and coal combustion in winter were the major sources of fine particles that polluted Tianjin. The results provide insights into the mechanisms of haze formation and the effects of meteorological conditions during haze–fog pollution episodes in the Tianjin area.

Vertical distribution and release characteristics of phosphorus forms in the sediments from the river inflow area of Dianchi Lake, China

Columnar sediment samples were collected from five representative river inflow areas of Dianchi Lake, China. The vertical distribution of each form of P were tested. Results showed that the concentration of TP in the sediments from areas A, B, C, D and E in the order of D > B > A > C > E, and the average concentration of D, B, A, C and E were 2991, 2064, 1308, 879, and 759 mg•kg−1, respectively. The concentration of Ex-P, Fe/Al-P, Ca-P and Org-P all decreased with increasing depth. The release of Ex-P was significantly related to TP whereas the Fe/Al-P was not significantly related to TP in the samples from areas polluted by domestic sewage. However, the release of Ex-P and Fe/Al-P were both significantly related to TP in the samples from areas polluted by phosphate mining and phosphate fertilizer application. The results of equilibrium P concentration (EPC0) analysis showed that P in the sediments of areas A, D and E were the source of P in Dianchi Lake, and the P in the sediments of areas B and C were in relative equilibrium with the overlying water.

基于CALIPSO卫星的不同天气类型下气溶胶垂直分布特征对比研究

基于CALIPSO卫星的不同天气类型下气溶胶垂直分布特征对比研究

Species diversity and vertical distribution characteristics of Metarhizium in Gaoligong Mountains, southwestern China

Species diversity and vertical distribution characteristics of Metarhizium in Gaoligong Mountains, southwestern China

Environmental significance of phosphorus existing forms in the sediments of Yuqiao Reservoir in Tianjin

研究天津于桥水库沉积物中磷形态的空间分布特征和垂直分布特征对了解水源型水库富营养化现状及其过程具有重要的现实意义.利用抓斗式采泥器及柱状采泥器分别采集表层沉积物样品及柱状沉积物样品，采用Psenner提出的连续提取法对沉积物磷形态进行分级测定，揭示整个水库沉积物各形态磷的空间分布特征以及不同区域垂直方向上的分布规律.结果表明：于桥水库表层沉积物总磷（TP）含量为303.7~997.8 mg/kg，各形态磷含量大小顺序依次为：钙结合态磷（Ca-P） > 铁结合态磷（Fe-P） > 残渣态磷（Res-P） > 铝结合态磷（Al-P） > 有机态磷（Org-P） > 可交换态磷（Ex-P）.表层沉积物中Fe-P、Al-P、Ca-P与TP含量由东至西逐渐递减，主要受到黎河河水夹带的外源性磷输入的影响；Res-P含量由东至西逐渐递增，与活性磷的分布规律相反，表明水库下游比上游的水质更好.垂直分布上，南部区域底层与表层沉积物相差不大，说明从1960s以来磷的沉积量就比较大；西部区域沉积物中Fe-P和Org-P含量较高，随深度的增加有明显降低的趋势；中心区域的各形态磷和TP含量均较低，且随着深度增加逐渐降低，现阶段沉积物中的磷以滞留为主，释放潜力较小.;It is of great significance to study the status of eutrophication and its process in water source reservoirs by analyzing the spatial and vertical distribution characteristics of phosphorus forms in the sediment of Yuqiao Reservoir in Tianjin. The samples of surface sediments and sediment cores were collected by grab-type sampler and column-type sampler, respectively, and the phosphorus forms of sediments were analyzed by continuous extraction method proposed by Psenner, in order to reveal the spatial distribution of various forms of phosphorus in the reservoir, as well as the distribution in the vertical direction of different regions. The results showed:The contents of total phosphorus in the surface sediments of Yuqiao Reservoir were 303.7-997.8 mg/kg, and the order of the mass fraction of phosphorus forms was:Ca-P > Fe-P > Res-P > Al-P > Org-P > Ex-P. The Fe-P, Al-P, Ca-P and TP in the surface sediments gradually decreased from east to west, mainly affected by the input of exogenous phosphorus entrained by the Lihe River. The Res-P is gradually increasing from east to west, contrary to the distribution of active phosphorus, indicating that the water quality in the downstream of the reservoir is better than that in the upstream. For the vertical distribution, there is little difference between the bottom sediments and the surface sediments in the southern region, which indicates that the deposition amount of phosphorus is relatively large since the 1960s; and the Fe-P and Org-P contents in the western sediments are higher, and the trend is significantly reduced as the depth increases. The various forms of phosphorus and TP contents in the central area are almost the lowest, and gradually decrease with the depth, phosphorus in the sediments at this stage is mainly retained with small release potential.

Detection of aerosol pollution sources during sandstorms in Northwestern China using remote sensed and model simulated data

The present paper has used a comprehensive approach to study atmosphere pollution sources including the study of vertical distribution characteristics, the epicenters of occurrence and transport of atmospheric aerosol in North-West China under intensive dust storm registered in all cities of the region in April 2014. To achieve this goal, the remote sensing data using Moderate Resolution Imaging Spectroradiometer satellite (MODIS) as well as model-simulated data, were used, which facilitate tracking the sources, routes, and spatial extent of dust storms. The results of the study have shown strong territory pollution with aerosol during sandstorm. According to ground-based air quality monitoring stations data, concentrations of PM10 and PM2.5 exceeded 400 μg/m3 and 150 μg/m3, respectively, the ratio PM2.5/PM10 being within the range of 0.123–0.661. According to MODIS/Terra Collection 6 Level-2 aerosol products data and the Deep Blue algorithm data, the aerosol optical depth (AOD) at 550 nm in the pollution epicenter was within 0.75–1. The vertical distribution of aerosols indicates that the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) 532 nm total attenuates backscatter coefficient ranges from 0.01 to 0.0001 km−1 × sr−1 with the distribution of the main types of aerosols in the troposphere of the region within 0–12.5 km, where the most severe aerosol contamination is observed in the lower troposphere (at 3–6 km). According to satellite sounding and model-simulated data, the sources of pollution are the deserted regions of Northern and Northwestern China.

Evolution Characteristics and Environmental Significance of Heavy Metals in Sediments of Yanma Reservoir

The sediment column samples of Yanma reservoir were collected. The sedimentary age of the column sediments were confirmed based on radioisotope 210Pb dating means to calculate the deposition rate and to draw out the age trend chart of the quality changes of heavy metal elements and to analyse their related factors. According to the above data this study comparatively analysed the vertical distribution characteristics of five heavy metal elements ( Cr, Cu, Zn, As, Pb) and investigated the relationship between the change of heavy metal concentration and the changes of natural environment, human activities as well as explore its referential meaning, provided the basis for the ecological management of Yanma reservoir. The results showed that the main heavy metal pollutants of the Yanma reservoir were Zn and Cr, followed by Cu, Pb and As. The water environment has been polluted gradually since 1958 the Yanma reservoir established. During 1993 -1997, the metal elements were obviously enriched and the water quality of the reservoir deteriorated obviously. During 1994-2010, the water pollution of the reservoir had been weakened, and the water environment had been improved effectively.

Vertical Distribution Characteristics of Fe and Mn in Subtropical Reservoirs During Summer

Iron (Fe) and manganese (Mn) are redox-sensitive elements that are both important chemical indicators of water quality. To study their vertical distribution characteristics in south-subtropical reservoirs during summer, Fe and Mn concentrations in the water column, as well as the physical and chemical conditions of the water, were investigated in the lacustrine zones of nine reservoirs in the eastern of Guangdong Province, in July 2016. These results showed that Fe and Mn exhibited a strong concentration gradient in deep reservoirs due to thermal stratification. The total Fe (TFe), total Mn (TMn), dissolved Fe (DFe), and dissolved Mn (DMn) concentrations in the surface water are significantly lower than in these in bottom zones (TFe, F=6.708, P=0.032; TMn, F=9.720, P=0.014; DFe, F=8.129, P=0.029; DMn, F=11.125, P=0.016). The average concentrations of TFe and TMn are 0.399 mg·L-1 and 0.422 mg·L-1, respectively at the bottom five of the deep reservoirs, and the dissolved ions accounted for more than 70% of this concentration. In shallow reservoirs without thermal stratification, TFe, TMn, DFe and DMn concentrations in surface water are lower than those measured at bottom of the reservoir, no significant difference was detected (TFe, F=0.135, P=0.726; TMn, F=0, P=1; DFe, F=0.006, P=0.943; DMn, F=0.007, P=0.936). The average concentrations of TFe and TMn are 0.110 mg·L-1 and 0.089 mg·L-1, respectively at the bottom of the four shallow reservoirs, and they were present predominantly in particulate form. The concentrations of TFe and DFe correlated significantly (P<0.05) with the dissolved oxygen (DO) concentration, pH and depth, but did not significantly correlate with TN or TP concentration in the deep reservoirs. The gradient distributions of DO and pH levels is critical to the gradient distribution of Fe and Mn in deep reservoirs because of water stratification. Low DO concentrations and acidic conditions in these areas contributed to the release of Fe and Mn from sediment and result in high dissociation of these elements in the bottom of deep reservoirs. Simultaneously, high concentrations of Fe and Mn at the bottom of reservoirs may also attribute to the characteristic red soil of this region. The results from this study imply that the high concentrations of Fe and Mn common in the bottom of deep reservoirs is associated with the stable stratification of these reservoirs in the summer. The concentrations of Fe and Mn may be exceed water standards when deep water is taken for public water provision. The problem may be avoided with surface water supplying.

Stratum development characteristics and sedimentary evolution model of the second member of Shuangyang formation in Moliqing area, Yitong Fault Basin

During the Second Member of Shuangyang Formation of Moliqing fault in the Yitong Basin, northeast of China, the intermittent transportation and rapid accumulation of nearshore gravity flows make the facies belts of fan apron narrow and changefully. Lacking stable contrastive maker layers, while the several tectonic events such as strike slip, transtension and compression occurring in the later period make the stratigraphic distribution of this area more complex. For these reasons, the research on stratigraphic correlation and the distribution of sedimentary facies are extremely difficult. To solve the above problems, this paper proposes the following solutions: (1) This paper assists to achieve the stratigraphic cycle analysis through logging data entropy spectrum analysis, on which basis and combining with the core data, seismic interfaces and geological markers to achieve the division and correlation of small layers of single sand body; (2) By analyzing the coarse clastic sedimentary system, we research the coarse clastic glutenite sediments of Shuangyang Formation in Moliqing fault from the fluid properties and fluid type conversion so as to clearly understand the vertical sequences and horizontal distribution characteristics analysis of core facies as well as deduce the fluid type of supply source and the characteristics of sediments. The results show that: (1) The sequence development is dominated by tectonic movements, and the strata can be divided into 5 middle-term cycles and 25 short-term cycles adopting T-R mode; (2) studies suggest that because the fluid property of supply source occurs cyclical changes under the condition of multiple sources, and the fluid shows alternation and conversion between gravity flow and traction flow under the control of particular ancient landform, therefore, the sediments of researched area form a mixed sedimentary system of gravity flow and traction flow. On the basis of source characteristics and sedimentary characteristics analysis, this paper proposed the sedimentary type of continental facies slope apron, which is divided into three sub-facies: proximal, middle and distal sub-facies. Among them, proximal sub-facies mainly develop the slop channel sedimentation dominated by mud debris flow deposits, central sub-facies develop the superposition channel microfacies dominated by mix depositions of gravity flow and traction flow and the leading edge microfacies of fan dominated by traction flow, while the distal sub-facies is mainly based on the thin sheet sand body and gravity flow slump depositions.

Impact and Suggestion of Column-to-Surface Vertical Correction Scheme on the Relationship between Satellite AOD and Ground-Level PM2.5 in China

As China is suffering from severe fine particle pollution from dense industrialization and urbanization, satellite-derived aerosol optical depth (AOD) has been widely used for estimating particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5). However, the correlation between satellite AOD and ground-level PM2.5 could be influenced by aerosol vertical distribution, as satellite AOD represents the entire column, rather than just ground-level concentration. Here, a new column-to-surface vertical correction scheme is proposed to improve separation of the near-surface and elevated aerosol layers, based on the ratio of the integrated extinction coefficient within 200–500 m above ground level (AGL), using the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP)) aerosol profile products. There are distinct differences in climate, meteorology, terrain, and aerosol transmission throughout China, so comparisons between vertical correction via CALIOP ratio and planetary boundary layer height (PBLH) were conducted in different regions from 2014 to 2015, combined with the original Pearson coefficient between satellite AOD and ground-level PM2.5 for reference. Furthermore, the best vertical correction scheme was suggested for different regions to achieve optimal correlation with PM2.5, based on the analysis and discussion of regional and seasonal characteristics of aerosol vertical distribution. According to our results and discussions, vertical correction via PBLH is recommended in northwestern China, where the PBLH varies dramatically, stretching or compressing the surface aerosol layer; vertical correction via the CALIOP ratio is recommended in northeastern China, southwestern China, Central China (excluding summer), North China Plain (excluding Beijing), and the spring in the southeast coast, areas that are susceptible to exogenous aerosols and exhibit the elevated aerosol layer; and original AOD without vertical correction is recommended in Beijing and the southeast coast (excluding spring), where the elevated aerosol layer rarely occurs and a large proportion of aerosol is aggregated in near-surface. Moreover, validation experiments in 2016 agreed well with our discussions and conclusions drawn from the experiments of the first two years. Furthermore, suggested vertical correction scheme was applied into linear mixed effect (LME) model, and high cross validation (CV) R2 (~85%) and relatively low root mean square errors (RMSE, ~20 μg/m3) were achieved, which demonstrated that the PM2.5 estimation agreed well with the measurements. When compared to the original situation, CV R2 values and RMSE after vertical correction both presented improvement to a certain extent, proving that the suggested vertical correction schemes could further improve the estimation accuracy of PM2.5 based on sophisticated model in China. Estimating PM2.5 with better accuracy could contribute to a more precise research of ecology and epidemiology, and provide a reliable reference for environmental policy making by governments.

Study on Aerosol Properties Based on CALIPSO in Representative Regions over China

To assess the aerosol direct and indirect radiative forcing, this paper analyzed the seasonal aerosol optical properties and vertical distribution characteristics in eight representative regions over China by using CALIPSO Level 2 products. The seasonal aerosol optical properties were validated by the AERONET data. The results show that the Taklamakan Desert (TD) and Tibet Plateau (TP) have the greatest depolarization and color ratios (PDR and CR) while the Northeast Plain (NP), Sichuan Basin (SB), North China Plain (NCP) and Yangtze River Delta (YRD) have the smallest PDR and CR, the Loess Plateau (LP) has intermediate PDR and CR, and that the Pearl River Delta (PRD) has the same PDR and greater CR compared with the polluted regions. The dust is transported to the middle and upper troposphere in spring, the strong vertical convection activities in summer transport massive aerosols from the atmospheric boundary layer to the free troposphere, and the stable meteorological conditions in autumn and winter trap massive aerosols within the boundary layer. The ratio of the AOD within 1.5 km above the ground to the total AOD and the extinction lapse rate in winter are greater than those in other seasons and 48.25% and 0.13km-2, respectively. The extinction lapse rates in the planetary boundary layer for the heavier polluted regions are greater than those in the polluted regions.

The vertical distribution characteristics of integral turbulence statistics in the atmospheric boundary layer over an urban area in Beijing

Turbulence data (2008–2012) from a 325 m meteorological tower in Beijing, which consisted of three layers (47, 140, and 280 m), was used to analyze the vertical distribution characteristics of turbulent transfer over Beijing city according to similarity theory. The conclusions were as follows. (1) Normalized standard deviations of wind speeds σ i / u * were plotted as a function only of a local stability parameter. The values under near-neutral conditions were 2.15, 1.61, and 1.19 at 47 m, 2.39, 1.75, and 1.21 at 140 m, and 2.51, 1.77, and 1.30 at 280 m, showing a clear increase with height. The normalized standard deviation of wind components fitted the 1/3 law under unstable stratification conditions and decreased with height under both stable and unstable conditions. (2) The normalized standard deviation of temperature fitted the ‒1/3 law in the free convection limit, but was quite scattered with different characteristics under near-neutral conditions. The normalized standard deviations of humidity and the CO2 concentration fitted the ‒1/3 law under unstable conditions, and remained constant under near-neutral and stable stratification. The normalized standard deviation of scalars, i.e., temperature, humidity, and CO2 concentration, all increased with height. (3) Compared with momentum, and the water vapor and CO2 concentrations, the turbulence correlation coefficient for heat was smaller under near-neutral conditions, but larger under both stable and unstable conditions. A dissimilarity between heat, and the water vapor and CO2 concentrations was observed in urban areas. The relative correlation coefficients between heat and each of momentum, humidity, and CO2 concentration (| r wT / r uw |, | r wT / r wc | and | r wT / r uq |) in the lower layers were always larger than in higher layers, except for the relative correlation coefficient between heat and humidity in an unstable stratification. Therefore, the ratio between heat and each of momentum, humidity, and CO2 concentration decreased with height.

Spatial–temporal characteristics of haze and vertical distribution of aerosols over the Yangtze River Delta of China

Variation of haze events occurred in the Yangtze River Delta (YRD) of China, the characteristics of meteorological elements and the vertical distribution of aerosols during haze episodes were analyzed by utilizing data of ground observation, radiosonde and CALIPSO. The results illustrate that the frequency of haze events between 1981 and 2010 peaked in winter but bottomed out in summer and decreased from north to south in the YRD region, reaching at the lowest point in “low frequency center” — Shanghai. When haze happened, the most seriously affected area was 2–4km above the ground and the concentrated range of total backscattering coefficient (TBC) that decreased with altitude was 0.8×10−3–2.5×10−3km−1·sr−1. Particulate depolarization ratio (PDR) was less than 40% in a large part and 93% aerosols over the YRD area were regular particles, while the irregular ones concentrated on 2km above the surface and the irregularity rose up but the diversity diminished when altitude increased. Color ratio (CR) was lower than 1.2 mostly at all altitudes and distributed asymmetrically above the ground. Nearly 80% aerosols under 10km were fine particles (CR<1.0) and 22.54% coarse particles (CR>1.0) clustered at 2–4km. Large particles (CR>1.2) aggregated in lower troposphere massively yet relatively smaller ones gathered in middle and upper troposphere. In the YRD region, aerosols with more powerful capabilities were wider and less regular than the ones of Northwestern China.

Spatial pattern and heterogeneity of soil moisture along a transect in a small catchment on the Loess Plateau

Spatial pattern and heterogeneity of soil moisture is important for the hydrological process on the Loess Plateau. This study combined the classical and geospatial statistical techniques to examine the spatial pattern and heterogeneity of soil moisture along a transect scale (e.g. land use types and topographical attributes) on the Loess Plateau. The average values of soil moisture were on the order of farmland>orchard>grassland>abandoned land>shrubland>forestland. Vertical distribution characteristics of soil moisture (0–500cm) were similar among land use types. Highly significant (p<0.01) negative correlations were found between soil moisture and elevation (h) except for shrubland (p>0.05), whereas no significant correlations were found between soil moisture and plan curvature (Kh), stream power index (SPI), compound topographic index (CTI) (p>0.05), indicating that topographical attributes (mainly h) have a negative effect on the soil moisture spatial heterogeneity. Besides, soil moisture spatial heterogeneity decreased from forestland to grassland and farmland, accompanied by a decline from 15° to 1° alongside upper to lower slope position. This study highlights the importance of land use types and topographical attributes on the soil moisture spatial heterogeneity from a combined analysis of the structural equation model (SEM) and generalized additive models (GAMs), and the relative contribution of land use types to the soil moisture spatial heterogeneity was higher than that of topographical attributes, which provides insights for researches focusing on soil moisture varitions on the Loess Plateau.

Vertical Stratification Characteristics of Dissolved Oxygen and Phytoplankton in Thousand-Island Lake and Their Influencing Factors

According to the data collected from the five monitoring sites in front of the dam in Thousand-island Lake in September 2015, the vertical distribution characteristics of dissolved oxygen (DO), water temperature, pH, turbidity, conductivity and phytoplankton were analyzed. The influencing factors of special stratification of DO and vertical distribution of phytoplankton were also discussed. The results showed that:① The vertical distribution of DO presented "the surface is higher than the underlying" mode. DO ranged from 1.95 mg·L-1 to 8.25 mg·L-1 and the average concentration was 5.10 mg·L-1. Low-oxygen zones appeared between 12 m and 20 m and the minimum concentration was 1.95 mg·L-1 at 17 m. The concentration of DO maintained at a high level between 0 m and 12 m and the vertical variance was small. Sudden drop of DO occurred between 12 m and 20 m and there was an anoxic zone (<4.0 mg·L-1). The concentration of DO returned to normal level between 20 m and 38 m. Then it reduced under 38m as the water depth increased. The vertical distribution of pH showed the same trend with that of DO and their sudden change regions appeared in the same zone. ② Vertical phytoplankton biomass displayed significant difference. The phytoplankton biomass of S1, S2 and S3 presented:mid-layer > surface > bottom. But S4, S5 presented:bottom > surface > mid-layer. In addition, the depth between 20 m and 30 m was the best for the growth of phytoplankton. ③ The correlation analysis showed that DO and water temperature in the thermocline were significantly correlative. The range and degree of low-oxygen zones in Thousand-island Lake was determined by physical processes like thermal stratification of water and direct or indirect effects of the plankton. Phytoplankton and DO, pH showed significant negative correlation. The phytoplankton was mainly influenced by turbulent mixing and DO stratification in the surface layer while it was mainly influenced by light intensity at the bottom.

How to Build New Interpretation Concept using Dynamic Data: A case Study in Carbonate of Upper Cibulakan, North West Java Basin, Indonesia

Bravo Structure is one of the Pertamina EP gas producing field in North West Java Basin region. This structure located at Subang about 10 km southeast from City Subang. The objective of this structure is a vertical compartment of carbonate due to diagenetic effect and transgression. This evident cause shale deposited and divide multi-layer carbonate reservoir. The carbonate lies at Cibulakan Formation and has three reservoirs: Z-14, Z-15, and Z-16 limestone. Since each reservoir has different pressure data and CO2 contain, so it becomes challenges to make new interpretation and to know those compartments between reservoirs. To look up geometry distribution detailed, this structure is reinterpreted using 3D seismic (2014) and new concept depositional environment based on wells correlation and core analysis. Generating seismic interpretation using seismic inversion and attribute. Amplitude envelope and instantaneous frequency are calculated to obtain sweetness. Both of them are built by 3D volume seismic. High magnitude from amplitude envelope is used to characterize geometry distribution of carbonate while instantaneous frequency determines low frequency because of gas distribution. The result of this study suggests vertical and lateral carbonate distribution characteristics Meanwhile sweetness attribute can determine gas contain in each layer Z-14 and Z-15. Vertical distribution of Z-14 layer about 140 m (porosity 7-11%) and Z-15 about 70 m (porosity 8-13%). Finally, interpreting carbonate both Z-14 and Z-15 as shelf margin that new concept gives a chances to develop this structure and optimize reservoir management.

Vertical distribution characteristics and temporal stability of soil water in deep profile on the Loess Tableland, Northwest China.

Study of impacts of land uses on spatiotemporal dynamics of soil water content (SWC) is of great significance for understanding the performance characteristics of regional water cycling under changing environment. Based on long-term located field observations, this paper explored the temporal dynamics of soil water in 0-15 m soil profile under four land use types on the Loess Tableland from September 2012 to December 2015. Results showed that the annually averaged SWCs over the 0-15 m soil profile for alfalfa field, fallow field, fertilized cropland and unfertilized cropland were 15.1%, 22.0%, 19.6% and 21.1%, respectively. Soil water contents along the shallow soil profile exhibited seasonal and annual wetting and drying cycle from March to June and July to October, and the profile depths were 0-2, 0-4.6, 0-3 and 0-4.2 m, respectively. Soil water contents along the deep soil profiles had better temporal stability and were influenced by land-use types. Du-ring the observation years, the yield and water consumption in alfalfa field increased, which caused the increase of deep soil desiccation, the 2-10 m soil profile had become stable dry layer, blocking the way of precipitation recharge.As for the soil water balance in other three land use types, it was negative in cropland and fallow field during winter wheat growing season, however, during spring maize growing season, it was negative in fertilized cropland but positive in unfertilized cropland and fallow field. During the fallow period, it was positive in the three land use types. The crop water use efficiency in the fertilized cropland was increased by more than 3 times than the unfertilized cropland.

紫色土坡耕地土壤属性差异对耕层土壤质量的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 紫色土坡耕地土壤属性差异对耕层土壤质量的影响 DOI: 10.5846/stxb201607181460 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 公益性行业（农业）科研专项（201503119-01-01）；重庆市水利局项目（2016）。 Effect of different soil properties on plow-layer soil quality of sloping farmland in purple hilly areas Author: Affiliation: 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:坡耕地是一个区域最易发生水土流失的土地利用类型，其严重的水土流失、面源污染和耕层退化现象直接威胁着坡耕地持续利用以及当地粮食安全、生态安全；耕层土壤质量对自然因素和人为耕作活动的影响较为敏感。以南方3个地点紫色土坡耕地耕层土壤质量为研究对象，从土壤属性角度，对比分析了重庆合川、江西兴国、云南楚雄不同耕层垂直深度土壤养分特征、土壤物理性质、土壤水库特征、耕作性能差异性及其形成原因。结果表明：（1）坡耕地耕层土壤有机质表现为云南楚雄（28.80 g/kg）>江西兴国（9.03 g/kg）>重庆合川（8.80 g/kg）；除全钾含量外，土壤全量养分和速效养分的含量表现为云南楚雄 > 江西兴国 > 重庆合川；坡耕地耕层速效养分垂直分布变化规律基本一致，主要表现为土壤速效养分主要在0-20 cm土层富集，而20-40 cm和40-60 cm土层无显著差异。（2）不同地点紫色土坡耕地耕层土壤物理性质差异明显，以重庆合川坡耕地土壤物理质量最差，表现为土壤砂粒含量 > 60 %、土壤容重最大（1.43 g/cm3）、土壤总孔隙度（45.97%）和毛管孔隙度（34.36%）最小；从坡耕地耕层土壤物理性质垂直变化特征看，耕作层（0-20 cm）优于心土层（20-40 cm）和底土层（40-60 cm）。（3）紫色土坡耕地耕层土壤初始入渗率以江西兴国坡耕地耕层最大（0.32 mm/min），而以重庆合川坡耕地耕层最小（0.19 mm/min）；土壤稳定入渗率和平均入渗率均表现为云南楚雄 > 重庆合川 > 江西兴国；坡耕地耕层土壤最大有效库容以云南楚雄最好（873.311 t/hm2），说明云南楚雄紫色土坡耕地耕层土壤具有较好的抵御季节性干旱能力；不同地点坡耕地耕层土壤总库容、死库容、兴利库容、滞洪库容、最大有效库容在垂直方向变化表现为耕作层（0-20 cm）大于心土层（20-40 cm）和底土层（40-60 cm）。（4）不同地点紫色土坡耕地耕层土壤抗剪强度和贯入阻力均呈现出相同变化规律，土壤抗剪强度表现为重庆合川（15.39 kg/cm2）>云南楚雄（14.74 kg/cm2）> 江西兴国（10.66 kg/cm2），而土壤贯入阻力值为重庆合川（424.83 kPa）> 云南楚雄（252.50 kPa）> 江西兴国（188.87 kPa），这种土壤力学性能的变化说明重庆合川紫色土坡耕地耕层土壤具有较好抵抗剪切破坏的能力和较大耕作阻力。上述研究结果可为不同地点紫色土坡耕地耕层土壤质量诊断、坡耕地合理耕层评价提供理论依据和数据支持。 Abstract:As the most easily eroded land-use type, severe soil degradation of the plow layer (as a shallow soil layer), deterioration of soil properties, and gravel process, could restrict the sustainable utilization of slope farmland, which also directly threatens local food security and ecological security. Plow-layer soil quality is highly sensitive to both natural factors and artificial farming tillage. Taking the plow-layer soil quality of three slope farmlands in the southern purple hilly area (Hechuan-Chongqing, Xingguo-jiangxi, and Chuxiong-Yunnan) as examples, this study mainly analyzed the differences in soil physical properties, soil reservoir characteristics, and soil nutrient characteristics of slope farmlands, and their vertical distribution characteristics, from the perspective of soil properties, so did the forming causes at the same time. The results indicated the following. (1) The soil organic matter of the plow-layer in the three locations in decreasing order was as follows: Chuxiong-Yunnan (28.80 g/kg) > Xingguo-jiangxi (9.03 g/kg) > Hechuan-Chongqing (8.80 g/kg). With the exception of total soil potassium content, other contents such as total soil nutrients and available soil nutrients, could be arranged in the following order: Chuxiong-Yunnan > Hechuan-Chongqing > Xingguo-jiangxi. The vertical characteristics of available soil nutrients in the plow-layer of slope farmland showed the same distribution, being mainly concentrated in the 0-20-cm soil layer. However, there were no significant differences between the 20-40-cm soil layer and the 40-60-cm soil layer. (2) The soil physical properties of the plow-layer of slope farmlands among the three purple hilly locations showed significant differences. The soil physical quality of the plow-layer in Hechuan-Chongqing was the worst, with the characteristic of soil sand content > 60%, maximum soil bulk density of 1.43 g/cm3, minimum soil total porosity of 45.97%, and capillary porosity of 34.36%. From the viewpoint of the plow-layer vertical characteristics of slope farmland, the soil physical properties of the tillage layer (0-20 cm) were better than those of the subsoil (20-40 cm) and bottom layer (40-60 cm). (3) The initial soil infiltration rate of the plow-layer in the Xingguo-jiangxi slope farmland was the largest (0.32 mm/min), and the initial soil infiltration rate in Hechuan-Chongqing plow-layer was the lowest (0.19 mm/min). The soil infiltration rate and the average soil infiltration rate both showed the same order of Chuxiong-Yunnan > Xingguo-jiangxi > Hechuan-Chongqing. The soil maximum effective capacity of the plow-layer in Chuxiong-Yunnan slope farmland was the best (873.311 t/hm2), which indicated that such plow-layers of slope farmland have better resistance to seasonal drought. Plow-layer vertical characteristics, such as the total storage capacity, dead storage capacity, active storage capacity, flood detention storage capacity, and maximum effective capacity, all showed the same order: tillage layer (0-20 cm) > subsoil layer (20-40 cm) > bottom layer (40-60 cm). (4) The soil shear strength and the soil penetration resistance of the plow-layer among the three slope farmland locations showed the same regular changes. The soil shear strengths of the plow-layer were Hechuan-Chongqing (15.39 kg/cm2) > Chuxiong-Yunnan (14.74 kg/cm2) > Xingguo-jiangxi (10.66 kg/cm2), whereas the soil penetration resistances of the plow-layer were Hechuan-Chongqing (424.83 kPa) > Chuxiong-Yunnan (252.50 kPa) > Xingguo-jiangxi (188.87 kPa), which indicated that the plow-layer soil of slope farmland in the Hechuan-Chongqing purple hilly area has better resistance to shear stress and greater resistance to farming tillage. These results could provide a theoretical basis and supporting data not only for soil quality diagnosis but also for rational plow-layer evaluation for slope farmlands in different purple hilly areas. 参考文献 相似文献 引证文献

Vertical distribution and release characteristics of nitrogen fractions in sediments in the estuaries of Dianchi Lake, China

Columnar sediment samples were collected from five representative estuaries of Dianchi Lake, China. And the vertical distribution of each fraction of nitrogen (IEF-N, CF-N, IMOF-N, OSF-N) were tested. The results showed that the TN content in sediments from areas A, B, C, D and E gradually decreased with depth between 0 and 15 cm, then sharply decreased with depth between 15 and 30 cm and stabilized at depth below 30 cm, indicating the exogenous input of N in these areas has not been controlled effectively. The proportion of TN occupied by various N fractions in the sediments ranked as follows: OSF-N > IMOF > CF-N > IEF-N. Correlation analysis results showed both IEF-N and IMOF-N were significantly correlated with the content of TFe2O3 + MnO + Al2O3 in deeper sediments, while no correlation in superficial sediments. The areas A and B have extremely high release risks for N in superficial sediments. However, the N in the sediments of areas C, D and E were in relative equilibrium with the overlying water, indicating release potential risk was relatively low.

沙坡头地区生物结皮覆盖区土壤种子库组成及垂直分布特征

PDF HTML阅读 XML下载 导出引用 引用提醒 沙坡头地区生物结皮覆盖区土壤种子库组成及垂直分布特征 DOI: 10.5846/stxb201609121847 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31500370，41530746，41171042） The composition and vertical distribution characteristics of soil seed banks in soil coverage with biocrusts in the Shapotou Region Author: Affiliation: 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:采用野外随机取样和室内萌发试验相结合的方法，对沙坡头人工植被区的藓类结皮、地衣结皮和裸沙覆盖区土壤种子库的组成及垂直分布特征进行了研究。结果表明：1）人工植被区土壤种子库的物种组成简单，以1年生草本为主，相较于裸沙，两种生物结皮的存在显著增加了土壤种子库的密度（P < 0.01），但降低了土壤种子库的物种多样性及其与地上植被的相似性；2）两种生物结皮覆盖区土壤种子库的总密度虽无显著差异，但在0-2 cm土层中，地衣结皮土壤种子库的密度显著高于藓类结皮（P < 0.05），而在2-5 cm和5-10 cm土层中，藓类结皮土壤种子库的密度高于地衣结皮，但差异不显著；3）不同生物结皮覆盖区土壤种子库的垂直分布特征存在差异，藓类结皮覆盖土壤中有活力的种子主要分布在0-5 cm土层中，而地衣结皮和裸沙覆盖土壤中有活力的种子主要分布在0-2 cm土层中，且随着深度的增加，土壤中有活力的种子急剧减少。该研究表明，相较于裸沙，生物结皮的存在不仅增加了土壤种子库的大小，还改变了土壤种子库的垂直分布格局。生物结皮层下仍有相当比例有活力的小种子，这些种子欠缺萌发条件，对地上植被的贡献作用较小，但它们的存在对荒漠生态系统健康及可持续发展具有重要意义。 Abstract:Using random sampling in the field and observing the emergence of seedlings, we studied the structure, the density and vertical distribution of soil seed banks in moss crusts, lichen crusts, and bare sands in the artificially re-vegetated region of Shapotou. We found that the soil seed banks of this region were mainly composed of annual herbs and had a simple species composition and a significantly higher seed density in soil covered by biocrusts than in bare sands (P < 0.01). However, the existence of biocrusts decreased the species diversity of soil seed banks and the similarity of soil seed banks with corresponding ground vegetation. Furthermore, although the total density of soil seed was not significantly different between the two types of crusts, there were differences in the distribution within the different soil layers. Specifically, the soil seed density in the 0-2 cm soil layer of lichen crusts was significantly higher than in the corresponding layer in moss crusts (P < 0.05), while that of moss crusts was higher in the 2-5 cm and 5-10 cm soil layers. Finally, the effects of biocrusts on vertical distribution of soil seed banks varied with biocrust types. For example, germinative seeds were primarily distributed in the 0-5 cm soil layer for moss crusts and in the 0-2 cm soil layer for lichen crusts and bare sands, and their abundance decreased with soil depths. These results suggest that biocrusts increase the soil seed bank density, but also change the vertical distribution pattern of soil seed banks in artificially re-vegetated regions. A substantial proportion of small seeds are present in soil covered by biocrusts, and these seeds lack germination potential and contribute little to the above-ground vegetation. However, they play a significant role in ecosystem stability and the sustainable development of deserts. 参考文献 相似文献 引证文献