[Effects of exogenous attapulgite addition on water conservation function of reclaimed soils in a semi-arid mining area]. / å¤–æºå‡¹å‡¸æ£’åœŸæ·»åŠ å¯¹åŠå¹²æ—±çŸ¿åŒºå¤åž¦åœŸå£¤æ°´åˆ†æ¶µå »åŠŸèƒ½çš„å½±å“.

Large-scale mining has greatly damaged vegetation and caused ecological degradation in the semi-arid area in China. It is urgent to restore the vegetation to solve the deteriorating ecological and environmental problems in mining area. How to reclaim soils for effectively storing and utilizing precipitation is the primary issue for vegetation restoration in the area. In this study, we proposed to take the mixture of attapulgite clay and local sandy soils as covering materials to improve the weak water conservation function of soils in mining areas, and studied the effects of the addition of attapulgite clay on soil infiltration, drainage and water storage sampled from the Shenmu mining area. The results showed that, with increasing application rates of attapulgite clay, the cumulated infiltration volumes decreased by 4.8%-37.4%, the infiltration rates dropped by 6.4%-46.3%, the wetting front advance rates decreased by 9.8%-116.9%, the saturated hydraulic conductivities decreased by 14.3%-59.5%, the drained water volumes reduced by 0.3%-4.3% for 24 hours and by 0.3%-2.5% for 72 hours, and the maximum soil water storages increased by 1.6%-22.4%. The maximum effect of attapulgite clay peaked at the application rate of 150 t·hm-2. Considering the economic cost, the optimum application rate should be 30-150 t·hm-2. The results syste-matically revealed the mechanism of reclaiming mining soils with attapulgite clay to restore the function of water conservation, and demonstrated that attapulgite clay is an effective material for soil reclamation in the semi-arid mining area, which can provide references for soil reclamation and ecological restoration in the semi-arid mining area.

[Spatial variability of soil organic carbon sequestration rate and its influencing factors in Fengqiu County, Henan, China.] / æ²³å—å°ä¸˜åŽ¿åŸŸå†œç”°åœŸå£¤å›ºç¢³é€ŸçŽ‡ç©ºé—´å˜å¼‚ç‰¹å¾åŠå ¶å½±å“å› ç´ .

Carbon sequestration rate in cropland soil is an important index to evaluate the effect and potential capacity of soil carbon sequestration. Accurate estimation of soil organic carbon sequestration rate is very important for studying cropland soil fertility and environmental effect. In this research, a typical fluvor-aquic soil area, Fengqiu County of Henan Province, located in Yellow Ri-ver basin of Huang-Huai-Hai Plain of China, was chosen as the study area. A total of 70 soil samples were collected according to combined unit grid method of soil utilization with soil type in 2011. The soil organic carbon content, soil mechanical composition, soil bulk density and pH were mea-sured, respectively. The spatial variability of the soil organic carbon sequestration rate of Fengqiu County in recent 30 years was also investigated by using geostatistics method and geography information system (GIS) technique, based on the comparative analysis of soil organic carbon content from samples surveyed in 2011 and the results surveyed by the 2nd state soil survey of China in 1981. In addition, the influencing factors of the soil carbon sequestration rate were quantitatively analyzed by statistical methods, such as significance testing, regression analysis and variance analysis. The results revealed that the soil organic carbon sequestration rate of recent 30 years was about 0.33 t C·hm-2·a-1 with a coefficient variance of 74%, which belonged to a medium variation. The spatial variability characteristics of soil organic carbon sequestration rate was of sheet distribution, which was higher in the west and lower in the east, and decreased from the central region to the south and north. The primary influencing factors of soil organic carbon sequestration rate were structural factors, such as soil type, mechanical composition, soil bulk density and pH, which could explain 59.5% of the spatial variability in the study area. The secondary factors were random factors, such as straw application and fertilizing amount, which could explain 40.5% of the spatial variability.

[Diversity of soil fauna in corn fields in Huang-Huai-Hai Plain of China under effects of conservation tillage].

An investigation was made on the abundance and diversity of soil fauna in the corn fields under conventional and conservation tillage in Huang-Huai-Hai Plain of China. The abundance and diversity of soil fauna were higher at corn maturing (September) than at its jointing stage (July), and higher at jointing stage under conservation tillage than under conventional tillage. Soil fauna mainly distributed in surface soil layer (0-10 cm), but still had a larger number in 10-20 cm layer under conservation tillage. The individuals of acari, diptera, diplura, and microdrile oligochaetes, especially those of acari, were higher under conservation tillage than under conventional tillage. At maturing stage, an obvious effect of straw-returning under conservation tillage was observed, i. e., the more the straw returned, the higher the abundance of soil fauna, among which, the individuals of collembola, acari, coleopteran, and psocoptera, especially those of collembolan, increased significantly. The abundance of collembola at both jointing and maturing stages was significantly positively correlated with the quantity of straw returned, suggesting that collembola played an important role in straw decomposition and nutrient cycling.

[Numerical simulation of isothermal equilibrium adsorption of virus onto typical soils in China].

An isothermal batch experiment was conducted in the laboratory to compare adsorption of bacteriophages MS2 and phiX174 onto 6 different soils (red loam soil, red clay soil, wushan soil, huangni soil, sandy fluvo-aquic soil and loamy fluvo-aquic soil) in China. Soils with sterilized or non-sterilized treatment were used. Relative coefficients of each numerical simulation of the isotherms using three models were evaluated. The results show that the properties of the soil and virus, and presence/absence of the soil autochthonous microorganisms have pronounced effect on the virus adsorption. Both MS2 and phiX174 are almost completely adsorbed by the red clay soil, but minimal adsorption is observed in the two fluvo-aquic soils. Adsorption of phiX174 to all the non-sterilized soils is generally much greater than that of MS2, while sterilization leads to opposite results. Freundlich and Langmuir isotherms are found to have better coefficients to simulate the apparent steady-state virus concentrations. Freundlich isotherm is capable of demonstrating the effect of virus concentration on adsorption behavior. Langmuir isotherms can be used to compare relative adsorption among treatments, while the present study suggests that maximum adsorption can not be calculated when using the Langmuir isotherms.

[Virus adsorption from batch experiments as influenced by air-water interface].

The presence of air-water interface in batch sorption experiments may result in inaccurate estimation of virus adsorption onto various soils. A batch sorption experiment was conducted to compare the adsorption results of MS2 in different soils under presence/absence of air-water interface. Soils with sterilization/nonterilization treatment were used. Virus recovery efficiency in a blank experiment (no soil) was also evaluated as affected by different amount of air-water interface. The presence of air-water interface altered the results of virus adsorption in different soils with different extent, with Sandy fluvo-aquic soil being the most considerably affected, followed by Red loam soil, and the least being Red clay soil, probably because of different soil properties associated with virus adsorption/inactivation. Soil sterilization resulted in more significant difference of virus adsorption onto the Sandy fluvo-aquic soil between the presence and absence of air-water interface, while a reduced difference was observed in the Red loam soil. The presence of air-water interface significantly decreased virus recovery efficiency, with the values being decreased with increase in the amount of air-water interface. Soil particles likely prohibit viruses from reaching the air-water interface or alter the forces at the solid-water-air interface so that the results from the blank experiment did not truly represent results from control blank, which probably resulted in adsorption difference between presence and absence of the air-water interface.