Advanced Materials Research Vols. 726-731

Abstract: In this study, the spatial distribution of soil lead (Pb) concentration in topsoil in Henan, China, was surveyed and analyzed using geostatistics and geography information systems (GIS). The concentrations of Pb in topsoil were investigated based on 603 samples. Pb mean concentration of 28.2 mg/kg in surface soils was found to be higher than those in global soils, which ranged from 16.31376.9 mg/kg.. From spatial analysis results, soil lead concentration anomaly regions were found in Henan Province, central China. The classification of a soil Pb environmental risk in an area was likewise presented based on the different levels of environmental quality of Pb and was done by GIS technology. Accordingly, there is a higher local concentration of Pb in the surrounding areas of Luoyang and Nanyang, which is historic mining area.

Abstract: Dry-land spring maize is a main cultivated crop in North-West China. To explore the mechanism for changes of evapotranspiration and heat consumption in dry-land spring maize, eddy covariance technique was used to monitor the energy-exchange characteristics of the crop in Eastern Loess Plateau field. The results showed that the field-energy-balance ratio of dry-land spring maize is in the 0.75 - 1.0 range during non-rainfall daily noon (12:00 - 14:00). The Bowen ratio exhibited "L-type" trend during the total growth stages, namely, the highest Bowen ratio was at seedling stage with phase average 4.85 ± 1.42. The evaporation fraction showed a single peak trend in August, and the higher evaporation ratio met with more precipitation with average values 0.55 ± 0.06. The Bowen ratio and average evaporation fraction at the entire growth period were 1.78 ± 1.71 and 0.40 ± 0.18, respectively. About 40% of surface energy obtained from drought agro-ecosystem was used for evapotranspiration and heat consumption.

Abstract: Gravel-mulched field is a unique mode of conservation tillage created by the working people with gravel as cover material and dependent on natural rainfall. However, with the growth of the planting years of the gravel-mulched field, the ecological effects gradually reduce. Thus, on the basis of the analysis to summarize the type and the thickness of gravel-mulched field, the insulation effect of gravel-mulched field to farmland, the water retention properties, the suppressing salinity function, anti-wind and water erosion capacity and increase production and income etc., we must attach importance to increase the replenishment fertilization to gravel-mulched field, improve the planting patterns of gravel-mulched field, select new varieties of drought-resistant crops, establish modern water-saving supporting system of the gravel-mulched field and other management measures and recommendations of ecosystem to provide a theoretical basis for sustainable development of gravel-mulched field agriculture.

Abstract: As for some large-scale and arid irrigation district in China, such as Jinghuiqu irrigation district and Shihezi reclamation district, hydro-ecosystem was gradually degenerated and imbalanced due to water shortage and unreasonable exploitation. In order to study hydrological elements, water cycle process and ecological response caused by human activities and other factors, and improve the quality of hydro-ecosystem, scientific connotation of establishing hydro-eco dynamic monitoring system in large-scale and arid irrigation district was defined. Hydro-ecosystem dynamic monitoring indexes including meteorological elements, hydrological elements, ecological elements closely related to hydrological elements and cycle, and socio-economic elements were proposed. Comprehensive monitoring methods based on automatic monitoring net, remote sensing satellite monitoring, field test and investigation were determined, and overall framework of hydro-eco dynamic monitoring was designed, which provided a theoretical basis for establishing hydro-eco dynamic monitoring system in large-scale and arid irrigation district.

Abstract: SWAT (Soil and Water Assessment Tool) model is one of distributed hydrological model, based on spatial data offered by GIS and RS. This article mainly introduces the SWAT model principle, structure, and it is the application of stream flow simulation in China and other countries, then points out the deficiency existing in the process of model research. In order to service in water resources management work better, experts and scholars further research the rate constant and uncertainty of the simplification of the model parameters, and the combination of RS and GIS to use, and hydrological scale problems.

Abstract: This paper selected various types of slope soil under different restoration modes of Xiangjiaba hydropower construction to study the fractionation of inorganic phosphorus. The results showed that the content of inorganic phosphorus was lower.In seven different types of slop soil,the content of total inorganic phosphorus was between 254.43 mg·kg^-1 and 992.98 mg·kg^-1,and accounted for between 22.60% and 47.12%.The content of soil total inorganic phosphorus and the raito of Water-soluble phosphorus,Al-P to total phosphorus increased as the content of soil total P increase,but the ratio of soil O-P,Ca-P to total phosphorus decreased.The Water-soluble phosphorus and Al-P in Vegetation-growing concrete gunning were the highest,the O-P in Natural secondary forests were the highest and Ca-P in External-soil spray seeding were the highest among all the types of slope soil.

Abstract: In order to revel aboveground biomass of R. soongorica shrub effect on soil moisture and nutrients spatial distribution, and explore mechanism of the changes of soil moisture and nutrients, soil moisture content, pH, soil organic carbon (SOC) and total nitrogen (TN) at three soil layers (0-10cm,10-20cm, and 20-40cm) along five plant biomass gradients of R. soongorica were investigated. The results showed that soil moisture content increased with depth under the same plant biomass, and increased with plant biomass. Soil nutrient properties were evidently influenced with plant biomass, while decreased with depth. SOC and TN were highest in the top soil layer (0-10 cm), but TN of 10-20cm layer has no significant differences (P < 0.05). Moreover, soil nutrient contents were accumulated very slowly. These suggests that the requirement to soil organic matter is not so high and could be adapted well to the desert and barren soil, and the desert plant R. soongorica could be acted as an important species to restore vegetation and ameliorate the eco-environment.

Abstract: Soil erosion has been the most prominent issue in Chinas ecological environment. The rocky mountain area of Northern China is an important typical area of soil erosion and one of the most dangerous regions of potential erosion in China characterized by more stones in thinner soils and the land surface is easily reduced to sand gravel or rocky desertification. Concentrated rainfall with frequent rainstorms, broken topography with steep slope and highly dense gully are important natural factors resulting in soil erosion. However, unreasonable land utilization especially slope farmland aggravates soil erosion. Soil erosion results in land degradation, threatens regional water resources security, intensifies regional poverty and restricts socio-economic development. Sloping cultivated land transformation will be the necessary choice for soil and water conservation and ecological construction in this region.

Abstract: The analysis of the slope stability is important in soil conservation. To analyze the slope stability, optimization methods were coded and compared with the traditional experience-based methods. Furthermore, the results were visualized in the program, so that the user can easily check the results and can designate an area, in which the program seeks the center and radius of the most hazardous slide arc. Moreover, the graphic interaction function was implemented in the program. In addition, the Standard Model One, recommended by ACAD (The Association for Computer Aided Design), was calculated by the program, of which the results (safety factor Ks=0.95~0.96) were smaller than the official recommend value (Ks=1). It is because that the traditional slice method, which neglects the normal stress and shear stress between the slices, was applied for calculation of Ks.

Abstract: We simulated P leaching on active dune (AD), semi-stabilized dune (SSD) and stabilized dune (SD) under 140, 700 and 1400 mm of rainfall in Horqin Sandy Land Inner Mongolia, China. The results showed that the available phosphorus (AP) pool decreased by 5–50% in topsoil (0–10 cm), and increased by -5–220% in subsoil (10–20 cm) in AD, SSD, and SD soil. The total P (TP) pool in topsoil (0–10 cm) decreased by 1.8–5.0%, and increased by -5–4.6% in subsoil (10–20 cm) in AD, SSD, and SD soil. The P loss in the soils (0-20 cm) was 0.5–4.5% in AD, SSD, and SD soil. These data indicated that significant downward movement of P occurred during soil leaching. And, the movement of soil P by leaching can cause P loss and changes in vertical distribution of P. Moreover, the difference in P concentration, drawn up by plant roots, between topsoil and subsoil can buffer the P loss at the start of leaching. Therefore, vegetation restoration is essential to reduce P loss in sandy lands.