不同土壤对阿散酸和洛克沙胂添加剂的吸附研究

采用平衡振荡法,研究了不同利用类型的北方土和南方土对阿散酸和洛克沙胂2种有机胂添加剂的吸附行为.结果表明:有机质和总铁含量高的偏酸性南方土对2种有机胂的吸附强度远远大于有机质和总铁含量低的偏碱性北方土;北方土添加腐殖质后对阿散酸和洛克沙胂吸附量分别增加了3倍和10倍左右,南方土去除有机质后吸附量显著下降;南方树木园土和农场土对洛克沙胂和阿散酸的吸附更符合Langmuir吸附等温线,树木园土对阿散酸和洛克沙胂的饱和吸附量分别为1 111和1 250 mg.kg-1,农场土对阿散酸和洛克沙胂的饱和吸附量分别为66和250 mg.kg-1,初始质量浓度对洛克沙胂的吸附量影响更大.

辽西土石质山区侵蚀坡面不同治理措施减蚀效果研究

为探究辽西土石质山区侵蚀坡面不同治理措施减蚀规律,对朝阳县木头沟小流域侵蚀沟道坡面布设3种不同生态治理措施并对其气象特征、表层土壤含水量、产流产沙情况进行连续监测。结果表明:(1)不同治理措施与对照(裸地)比较均有减少地表径流的效果,其中植草袋措施及植草砖种草措施减流效益达到显著水平,减流效果依次为植草袋(55.75%)>植草砖植草(51.00%)>砾石覆盖(12.51%)。(2)不同治理措施与对照比较产沙量均有减少,其中植草袋措施及植草砖种草措施减沙效益达到显著水平,减沙效果依次为植草袋(58.00%)>植草砖植草(53.71%)>砾石覆盖(7.72%)。(3)产沙量对产流量响应特征均呈极显著正相关(P<0.05,r>0)。

Study on Land Suitability Evaluation in the northern China Crop-pasture Band

Basing on the limiting factor method and Composite Index method,for the northern China crop-pasture band,the authors established the system of evaluation index,and abstracted the dominant factor,then through applying expert grade and weighing way the suitability of grids are evaluated,the results showed that：without the input of a large number of cash,most of the area was not suitable for farming,and more appropriate area for farming was only 8.45% of total area,mainly located in the southeast and southwest of the study area,followed by the study area in the northeast,areas that was not suitable for farming mainly in the middle of the east,large areas of central and western regions.

Effects of Grazing Exclusion on Plant Productivity and Soil Carbon, Nitrogen Storage in Alpine Meadows in Northern Tibet, China

Grazing exclusion is widely adopted in restoring degraded alpine grasslands on the Qinghai-Tibetan Plateau. However, its effectiveness remains poorly understood. In this study, we investigated the effects of grazing exclusion on plant productivity, species diversity and soil organic carbon （SOC） and soil total nitrogen （STN） storage along a transect spanning from east to west of alpine meadows in northern Tibet, China. After six years of grazing exclusion, plant cover, aboveground biomass （AGB）, belowground biomass （BGB）, SOC and STN were increased, but species diversity indices declined. The enhancement of AGB and SOC caused by grazing exclusion was correlated positively with mean annual precipitation （MAP）. Grazing exclusion led to remarkable biomass increase of sedge species, especially Kobresia pygmaea, whereas decrease of biomass in forbs and no obvious change in grass, leguminous and noxious species. Root biomass was concentrated in the near surface layer （10 cm） after grazing exclusion. The effects of grazing exclusion on SOC storage were confined to shallow soil layer in sites with lower MAP. It is indicated that grazing exclusion is an effective measure to increase forage production and enhance soil carbon sequestration in the studied region. The effect is more efficient in sites with higher precipitation. However, the results revealed a tradeoff between vegetation restoration and ecological biodiversity. Therefore, carbon pools recover more quickly than plant biodiversity in the alpine meadows. We suggest that grazing exclusion should be combined with other measures to reconcile grassland restoration and biodiversitv conservation.

Combined Effects of Water Quality and Furrow Gradient on Runoff and Soil Erosion in North China

Irrigation-induced soil erosion seriously affects the sustainability of irrigated agriculture. The effects of irrigation water quality and furrow gradient on runoff and soil loss were studied under simulated furrow irrigation in laboratory using a soil collected from an experimental station of China Agricultural University, North China. The experimental treatments were different combinations of irrigation water salt concentrations of 5, 10, 20, and 30 mmol c L-1 , sodium adsorption ratios (SAR) of 0.5, 5.0, and 10.0 (mmol c L-1 ) 0.5 , and furrow gradients of 1%, 3%, and 5%, with distilled water for irrigation at 3 furrow gradients as controls. The experimental data indicated that total runoff amount, sediment concentration in runoff, and total soil loss amount generally decreased with increasing salt concentration in irrigation water but increased with its sodicity and furrow gradient. The effects of water quality and furrow gradient on soil loss were greater than those on runoff, and the increase of furrow gradient decreased the influence of water quality on soil loss. When the salt concentration increased from 5 to 30 mmol c L-1 at SAR of 10.0 (mmol c L-1 ) 0.5 , total runoff amount, sediment concentration, and total soil loss amount decreased by 3.89%, 52.1%, and 53.92%, and 10.57%, 38.86%, and 42.03% at the furrow gradients of 1% and 5%, respectively. However, they respectively increased by 3.37%, 45.34%, and 55.36%, and 3.86%, 10.77%, and 13.91% when SAR increased from 0.5 to 10.0 (mmol c L-1 ) 0.5 at the salt concentration of 5 mmol c L-1 . Irrigation water quality and furrow gradient should be comprehensively considered in the planning and management of furrow irrigation practices to decrease soil loss and improve water utilization efficiency.

Study on Relative Soil and Water Conservation Benefits of Ridge Tillage in Different Terrain Conditions in the Black Soil Area of Northeast China

Ridge tillage, which is a very common and important tillage measure in the black soil area of northeast China, has some soil and water conservation bene- fits, but has little attention. It is very important to explore the spatial distribution of the ridge direction of the arable land and its soil and water conservation benefits in different terrain conditions in the black soil area. So Binxian County of Heilongjiang Province was selected as the study area, and 168 field investigation units were ex- tracted by stratified sampling method and investigated. According to equations of slope gradient factor and slope gradient in ridge direction, and based on the soft- ware of Arcmap, SPSS and Excel, the investigation data of soil and water loss in Binxian County were analyzed and counted, The results show that in plain, hilly and mountainous areas, the average ground slope gradients are 1.92°, 6.20° and 8.27° respectively, and the average slope gradients along ridge direction are 1.33°, 4.52°and 6.45° respectively, which account for about 70%, 73% and 78% of the average ground slope gradients in the same terrain condition; the relative quantities of soil erosion in the present ridge tillage condition account for about 55%, 69% and 67% respectively of that in down-slope ridge tillage conditions, so the present ridge tillage has obviously relative soil and water conservation benefits. Based on these results, the reasons of the present ridge tillage status were analyzed, and some reform measures were proposed. The results could not only help to comprehend the spatial distribution and soil and water conservation benefits of ridge tillage in the black soil area of Northeast China, but also provide scientific references for the layout of local soil and water conservation measures.

Evaluation of AMSR-E——Derived Soil Moisture over Northern China

In this study,the authors evaluated two re-motely sensed surface soil moisture datasets derived from the Advanced Microwave Scanning Radiometer of the Earth Observing System (AMSR-E) over northern China.The soil moisture datasets were derived from algorithms developed by the National Snow and Ice Data Center (NSIDC) and jointly developed by the Vrije Universiteit Amsterdam and NASA Goddard Space Flight Center (VUA-NASA).The NSIDC and VUA-NASA products were compared to in situ soil moisture data from nine enhanced coordinated observation stations.The VUA-NASA dataset presented a strong correlation with top layer in situ soil moisture observations,and the correla-tion coefficients ranged from 0.34 to 0.73 (p<0.01).The correlation coefficients decreased as the observed soil layer depth increased.The correlation coefficients be-tween the NSIDC retrievals and the top layer in situ ob-servations were between 0.10 and 0.62 (p<0.01).Fur-thermore,VUA-NASA soil moisture variations agreed well with in situ soil moisture dynamics and responded sensitively to precipitation events.In contrast,the NSIDC dataset failed to capture signals of soil moisture dynamics.The analyses demonstrated that the VUA-NASA product was capable of representing soil moisture conditions over northern China.

Soil ^(35)S Transformation and Availability to Plants

Sulfur transformation in 3 soils maintained in a closed incubation system and its availability to plants were investigated using carrier-free35S-SO42- and 35S-labeled ryegrass straw. For carrier-free Na235SO4 treatment, 78%, 70% and 64% of 35S applied were found in Ca (H2PO4)2-extractble S fraction 14%, 5% and 7% in slowly soluble inorganic S, 11%, 15% and 18% in C-O-S, 5%, 7% and 6% in C-bonded S, and 5%,7% and 6% in unidentified organic S 120 days after incubation in black soil, cinnamon soil and chestnut soil, respectively. Most of 35S uptake by plants came from extractable 35S42-, and little from C-O-35S and C-bonded 355. In the treatment with 35S-labeled straw, 51%, 46% and 36% of 355 incorporated were found in C a (H2PO4)2 -extractable S fraction) 7%, 6% and 7% in slowly solub ie inorganic S, 13%, 15% and 18% in C-O-S, 8%, 8% and 6% in C-bonded S, and 18%, 25% and 35% in unidentified organic S at the end of incubation in above-mentioned three soils, respectively. Higher availability of C-O-35S, C-bonded 35S and unidentified organic 35S from 35S-labeled straw was observed in 35S-labeled straw treatment compared to carrier-free Na235SO4 treatment.

Composition of Sulphur Pool in Selected Upland Soils inNorth China

Soil sulfur fractions, including monocalcium phosphate-extractable S, slowly soluble inorganic S, C- O-S ,C-bonded S and unidentified organic S, were analyzed for 48 soils, as representatives of 6 major groups ofupland soils, fiuvisol, cinnamon soil, loessial soil, chestnut soil, black soil and brown soil, in North China.The contemns of total S and monocalcium phosphate-extractable S in the above 48 soils ranged from 234 to860 and 5.1 to 220.3 mg kg--1 , respectively, and each of 6 soil groups contained the samples with a low level ofphosph ate-extractable S. Great differences in the average contents of each fraction of S were observed amongthe above 6 soil groups. Expressed as average percentage of the total S in soils, fiuvisols, cinnamon soils,loessial soils, chestnut soils, black soils and brown soils contained 6.1%, 9.5%, 5.7%, 13.2%, 3.5% and 6.8%monocalcium phosphate-extractable S, 5. 7%, 3. 0%, 9. 3%, 1 0. 4%, 3. 2% and 3. 1 % slowly soluble inorganic S ,51.6%, 26.7%, 17.4%, 31.2%, 28.9% and 22.7% C-O-S, 11.0%, 9.1%, 6.6%, 6.8%, 9.7% and 9.4% in C-bondedS, and 25.6%, 51.7%, 60.8%, 38.4%, 54.7% and 53.0% unidentified organic S, respectively. For the above 6groups of soils, the mean C/N ratios were remarkably similar, ranging from 9.7 to 10.7, while the mean N/Sratios ranged from 1.16 to 3.12. The highest ratios of C/N, C/C-O-S and C/C-bonded S were found in blacksoils, averaging 30.4, 104.9 and 314.7, respectively, while the lowest ratios arose in chestnut soil, averaging12.4, 39.7 and 183.3, respectively.

Influence of Climate on Soil Organic Carbon in Chinese Paddy Soils

Soil organic carbon(SOC) is a major component of the global carbon cycle and has a potentially large impact on the greenhouse effect. Paddy soils are important agricultural soils worldwide, especially in Asia. Thus, a better understanding of the relationship between SOC of paddy soils and climate variables is crucial to a robust understanding of the potential effect of climate change on the global carbon cycle. A soil profile data set(n = 1490) from the Second National Soil Survey of China conducted from 1979 to 1994 was used to explore the relationships of SOC density with mean annual temperature(MAT) and mean annual precipitation(MAP) in six soil regions and eight paddy soil subgroups. Results showed that SOC density of paddy soils was negatively correlated with MAT and positively correlated with MAP(P < 0.01). The relationships of SOC density with MAT and MAP were weak and varied among the six soil regions and eight paddy soil subgroups. A preliminary assessment of the response of SOC in Chinese paddy soils to climate indicated that climate could lead to a 13% SOC loss from paddy soils. Compared to other soil regions, paddy soils in Northern China will potentially more sensitive to climate change over the next several decades. Paddy soils in Middle and Lower Yangtze River Basin could be a potential carbon sink. Reducing the climate impact on paddy soil SOC will mitigate the positive feedback loop between SOC release and global climate change.

Indices of Sulfur-Supplying Capacities of Upland Soils in North China

Fifteen upland soils collected from the major arable areas in North China were used to assess the availability of soil sulfur (S) to plants in a pot experiment. Soils were extracted with various reagents and the extractable S was determined using turbidimetric method or inductively coupled plasma atomic emission spectrometry (ICP-AES), respectively. In addition, mineralizable organic S, organic S, N/S ratio, sulfur availability index (SAI) and available sulfur correction value (ASC) in soils were also determined. The S amount extracted by 1.5 g L-1 CaCl2 was nearly equivalent to that by 0.25 mol L-1 KCl (40 ℃), and both of them were slightly smaller than that by 0.01 mol L-1 Ca(H2PO4)2 solution, as measured by turbidimetric method or ICP-AES. The extractable S measured by turbidimetric method was consistently smaller than that by ICP-AES. All methods tested except that for organic S and N/S ratio produced satisfactory results in the regression analyses of the relationships between the amounts of S extracted and plant dry matter weight and S uptake in the pot experiment. In general, 0.01 mol L-1 Ca (H2PO4) 2-extracted S determined by ICP-AES or turbidimetric method and 0.25 mol L-1 KCl(40℃)-extracted S determined by ICP-AES appeared to be the best indicators for evaluation of soil available S.

Effects of Tillage Management on Infiltration and Preferential Flow in a Black Soil, Northeast China

The impacts of no-tillage （NT） and moldboard plough （MP） managements on infiltration rate and preferential flow were characterized using a combined technique of double-ring device and dye tracer on a black soil （Mollisols） in Northeast China. The ob- jective of this study is to evaluate how tillage practices enhance soil water infiltration and preferential flow in favor of soil erosion con- trol in the study area. The steady infiltration rates under NT management are 1.6 and 2.1 times as high as those under MP management in the 6th and 8th years of the tillage management in place, while the infiltrated water amounts under NT management are 1.4 and 2.0 times as high as those under MP management, respectively. The depth of methylene blue penetrated into NT soil increases from 43 cm in the 6th year to 57 cm in the 8th year, which are 16 cm and 19 em deeper than those in MP soil, respectively. The results of morphol- ogic image show that more biological macro-pores occur in NT soil than in MP soil. These macro-pores play a key role in enhancing preferential flow in NT soil, which in turn promotes water infiltration through preferential pathways in NT soil. The results are helpful to policy-making in popularizing NT and have the implications for tillage management in regard to soil erosion control in black soil region of China.

Invasion and Morphological Variation of the Non- Indigenous Barnacle Chthamalus challengeri(Hoek, 1883) in Yangshan Port and its Surrounding Areas

Invasive species generally possess unique characteristics that allow them to survive the invasion process in order to es- tablish and spread in new habitats. Successful invaders must resist both physical and physiological stresses associated with the changing environment. A common littoral barnacle, Chthamalus challengeri Hoek, 1883 （Crustacea, Cirripedia）, which is native to Japan, South Korea and northern China, has become established in the high-littoral zone adjacent to Yangshan Port, Shanghai, China. A comparison of the morphology of Chthamlus species from Zhoushan archipelago with previous description indicates the occur- rence of C. challengeri. The new immigrant becomes a dominant species in certain high-intertidal habitats of the adjacent area to of Yangshan Port. C. challengeri was found in part of sampling sites in Zhoushan in 2010; however, it dispersed to all the eleven sam- piing sites in 2012. Densities of C.challengeri had increased over 10 times in the last 2 years, with the highest mean value reaching 39533 ± 6243 ind. m-2 in the new habitat. The specific ratios of both operculum area （Sa） to base area （SA） and average height of pa- rietal plates （H） to length of base （L） revealed that C. challengeri displays morphological changes to resist stronger currents in the new habitats for invasion.

Land Use Change Effects on Discharge and Sediment Yield of Song Cau Catchment in Northern Vietnam

The purpose of this paper is to implement ＂Soil and Water Assessment Tool （SWAT）＂ model to examine the effects of land use change scenarios; associated with crop rotations and special cultivation techniques most susceptible to erosion; exert on runoff discharge and sediment yield from Song Cau catchment in Northern Viet Nam. All scenarios＇ simulations resulted in a decrease of soil losses and sediment yield comparing to the current land use status. SWAT successfully predicted soil losses from different HRUs that caused significant sediment yield, and it predicted explicitly the consequences of non-structural mitigation measures against erosion.

Evapotranspiration and ratio of soil evaporation to evapotranspiration of winter wheat and maize in north China

Evapotranspiration （ETc） is an important quantity for hydrological cycle. This study shows evapotranspiration, the ratio of evaporation to evapotranspiration （E/ETc） of winter wheat and maize in north China. Several relationships, namely, E/ET0 and soil surface moisture, E/ET0 and leaf area index （LAI）, are also analyzed. The average seasonal ETc values for winter wheat, maize （2008） and maize （2009） are 431.21,456.3 and 341.4mm. The value of E/ET0 varied from 1 at initial growth stage to 0.295 at the later growth for winter wheat, and from 1 to 0.492, from 1 to 0.566 for maize （2008） and maize （2009）. The relationship between E/ET0 and surface soil water content, and E/ET0 and LAI are fitted to a quadratic parabola equation with significant correlation coefficients, respectively, for wheat and maize. These results should help the precise planning and efficient management of irrigation for these crops in this region.

Modeling the impacts of drying trend scenarios on land systems in northern China using an integrated SD and CA model

Climate-induced drought has exerted obvious impacts on land systems in northern China.Although recent reports by the Intergovernmental Panel on Climate Change(IPCC) have suggested a high possibility of climate-induced drought in northern China,the potential impacts of such drying trends on land systems are still unclear.Land use models are powerful tools for assessing the impacts of future climate change.In this study,we first developed a land use scenario dynamic model(iLUSD) by integrating system dynamics and cellular automata.Then,we designed three drying trend scenarios(reversed drying trend,gradual drying trend,and acceleration of drying trend) for the next 25 years based on the IPCC emission scenarios and considering regional climatic predictions in northern China.Finally,the impacts of drying trend scenarios on the land system were simulated and compared.An accuracy assessment with historic data covering 2000 to 2005 indicated that the developed model is competent and reliable for understanding complex changes in the land use system.The results showed that water resources varied from 441.64 to 330.71 billion m3 among different drying trend scenarios,suggesting that future drying trends will have a significant influence on water resource and socioeconomic development.Under the pressures of climate change,water scarcity,and socioeconomic development,the ecotone(i.e.,transition zone between cropping area and nomadic area) in northern China will become increasingly vulnerable and hotspots for land-use change.Urban land and grassland would have the most prominent response to the drying trends.Urban land will expand around major metropolitan areas and the conflict between urban and cultivated land will become more severe.The results also show that previous ecological control measures adopted by the government in these areas will play an important role in rehabilitating the environment.In order to achieve a sustainable development in northern China,issues need to be addressed such as how to arrange land use structure and patterns rationally,and how to adapt to the pressures of climate change and socioeconomic development together.

Current Soil Nutrient Status of Intensively Managed Greenhouses

Nine districts covering the main greenhouse vegetable areas in Tianjin Municipality of the North China Plain were selected for the soil investigation in 2010 to survey the current soil nutrient status (soil available N, P and K), acidification and salinization due to excessive input of fertilizers in greenhouses in Tianjin. The study showed that, in particular, soil available P content increased with the age of greenhouses. In contrast, our results did not reveal higher K accumulation and lowered pH in the greenhouse soils compared with cultivation in open fields. Over-fertilization, causing high NO 3 accumulation, most likely resulted in salinity problems in the greenhouses. Ninety percent of the investigated greenhouse soils had electrical conductivity values of saturated paste extracts of 2-10 d S m-1 , which might affect the yields of vegetable crops like green bean, pepper, cabbage, carrot, eggplant, lettuce, spinach, celery, cucumber and tomato. The findings of our survey of the current fertility and salinity problems in greenhouse soils suggest that there is an urgent need to improve the farmers' practices and strategies in fertilization management in greenhouses of China. Because education and the agricultural technical extension services may play a more important role in avoiding overuse of fertilizers, we suggest that current nutrient management practices should be improved in the near future through training of local farmers in farmers' schools and through strengthening the agricultural extension services with practical techniques.

Compound-specific hydrogen isotopes of long-chain n-alkanes extracted from topsoil under a grassland ecosystem in northern China

To investigate characteristics of H isotope variation in long-chain n-alkanes （δDn-alkanes） from higher plants in surface soils under a single ecosystem, 12 samples from a basalt regolith were randomly collected from Damaping in Wanquan County of Zhangjiakou in North China. Molecular distribution and C （δ^13Cn-alkanes） and H isotopes of long-chain n-alkanes, as well as C isotopes of TOC （δ^13CTOC）, were analyzed. Both δ^13CTOC and δ^13Cn-alkanes values from four representative dominant long-chain n-alkanes （n-C27, n-C29, n-C31, n-C33） derived from terrestrial higher plants show minor variations among the 12 samples, indicating the major contributor is from local grasses with a uniform C3 photosynthetic pathway. In contrast, variations in δ^13Cn-alkanes values of the four long-chain n-alkanes are relatively large, with the more abundant homologs generally showing more negative δDn-alkanes values and less variation. However, variation of 〈30‰ among weighted averaged δDn-alkanes values of the four long-chain n-alkanes is not only less than that among δDn-alkanes values for different modern terrestrial C3 grasses from the specific locations, but also less than the literature values of δDn-alkanes of long-chain n-alkanes for single species over different seasons. Thus, because the sources of long-chain n-alkanes in surface soils and sediments are similarly from multiple individual plants, our results are significant in confirming that paleoclimatic, paleoenvironmental and paleohydrological information can be interpreted more accurately from δDn-alkanes values of long-chain n-alkanes from sediments, particularly terrestrial sediments with organic matter derived from in-situ plants.

Fertilization and Catch Crop Strategies for Improving Tomato Production in North China

Overuse of fertilizers and the resultant pollution and eutrophication of surface and groundwater is a growing issue in China. Consequently, improved management strategies are needed to optimize crop production with reduced nutrient inputs. Conventional fertilization （CF）, reduced fertilization （RF）, and reduced fertilization with maize （Zea mays L.） as a summer catch crop （RF＋C） treatments were evaluated in 2008 and 2009 by quantifying tomato （Lycopersieon esculentum） fruit yield and soil nutrient balance in a greenhouse tomato double-cropping system. Fertilizer nitrogen （N） application was reduced by 37% in the RF and RF＋C treatments compared to the CF treatment with no significant reduction in fruit yield. Mean soil mineral N （Nmin） content to a depth of 180 cm following tomato and maize harvest was lower in the RF and RF＋C treatments than in the CF treatment. Residual soil Nmin content was reduced by 21% and 55% in the RF and RF＋C treatments, respectively, compared to the CF treatment. Surplus phosphorus （P） and potassium （K） contents in the RFWC treatment were significantly lower than those in the RF treatment, mainly due to additional P and K uptake by the catch crop. We concluded that for intensive greenhouse production systems, the RF and RF＋C treatments could maintain tomato fruit yield, reduce the potential for nitrate （NO3^--N） leaching, and with a catch crop, provide additional benefits through increased biomass production.