The great majority of prior phytoscreening applications have been conducted in humid and temperate environments wherein groundwater is relatively shallow (similar to 1-6m deep). The objective of this research is to evaluate its use in semi-arid environments for sites with deeper groundwater (>10 m). To that end, phytoscreening is applied to three chlorinated-solvent hazardous-waste sites in Arizona. Contaminant concentrations were quantifiable in tree-tissue samples collected from two of the sites (Nogales, Park-Euclid). Contaminant concentrations were detectable, but not quantifiable, for the third site. Tree-tissue concentrations of tetrachloroethene (PCE) ranged from approximately 400-5000 ug/kg wet weight for burrobrush, cottonwood, palo verde, and velvet mesquite at the Nogales site. In addition to standard trunk-core samples, leaf samples were collected to test the effectiveness of a less invasive sampling method. Leaf-sample concentrations were quantifiable, but several times lower than the corresponding core-sample concentrations. Comparison of results obtained for the test sites to those reported in the literature suggest that tree species is a major factor mediating observed results. One constraint faced for the Arizona sites was the relative scarcity of mature trees available for sampling, particularly in areas adjacent to industrial zones. The results of this study illustrate that phytoscreening can be used effectively to characterize the presence of groundwater contamination for semi-arid sites with deeper groundwater. (C) 2017 Elsevier B.V. All rights reserved.
2017-12-31 Web of ScienceSoil erosion control (SEC), carbon sequestration (CAS), and soilmoisture (SMO) strongly interact in the semi-arid Loess Plateau. Since SMO has supportive effects on SEC and CAS, it can be considered as ecosystem service (ES), and there is an immediate need to coordinate the relationships among these ecosystem services (ESs) to promote the sustainability of vegetation recovery. In this study, we quantified the ESs, ES trade-offs, and the environmental factors in 151 sample plots in the Ansai watershed, and we used a redundancy analysis (RDA) to clarify the effects of environmental factors on these ESs and their trade-offs. The results were as follows: (1) the general trend in the SEC of vegetation types was Robinia pseudoacacia (CH) > native grass (NG) > small arbor (ST) > Hippophae rhamnoides (SJ) > artificial grass (AG) > Caragana korshinskii (NT) > apple orchard (GY) > crop (CP); the CAS trend was CH > SJ > NT > AG > CP > ST > GY > NG; and the SMO trend was CP > NG > GY > AG > SJ > ST > CH > NT. (2) For SEC-SMO trade-offs, the influence of vegetation type, altitude, silt and sand composition was dominant. The arrangement of NG, AG, and SJ could decrease the extent of the trade-offs. (3) For CAS-SMO trade-offs, vegetation coverage and types were the dominant factors, but the effects were not complex. The extent of these trade-offs was lowest for NT, and that for SJ was the second lowest. (4) Considering the relationships among the three ESs, SJ was the most appropriate afforestation plant. Combing the vegetation types, slope position, slope gradient, and soil properties could regulate these ES relationships. The dominant factors influencing ES trade-offs varied among the different soil layers, so we must consider the corresponding influencing factors to regulate ESs. Moreover, manual management measures were also important for coordinating the ES relationships. Our research provides a better understanding of the mechanisms influencing the relationships among ESs. (C) 2017 Elsevier B.V. All rights reserved.
2017-12-31 Web of ScienceClimate variability and recurrent droughts have a strong negative impact on agricultural production and hydrology in the highlands northern Ethiopia. Since the 1980s, numerous mitigation and land rehabilitation measures have been implemented by local and national authorities to reduce these impacts, are often poorly effective. As underlying reason may be that controlling relationships between climate and ecohydrology at medium-sized catchments (10-10,000 km(2)) of semi-arid highlands are not well known. We investigated trends and relationships in precipitation, temperature, streamflow, and net primary productivity (NPP). The results were mixed, with both significant increasing and decreasing trends for temperature and streamflow. Precipitation time series did not show a significant trend for the majority of stations, both over the years and over each season, except for a few stations. A time series indicated a significant abrupt increase of NPP in annual, seasonal and monthly timescale. Cross-correlation and regression analysis indicate precipitation and maximum temperature were the dominant climatic variables in the Geba catchment for streamflow and NPP. In view of these results, also land use and land cover change over the past three decades was analysed as a possible factor of importance, as human intervention, may affect streamflow and NPP. Factors that mainly correlate with streamflow and NPP are precipitation and maximum temperature. Important interventions that appear beneficial for these responses are construction of micro-dams, soil and water conservation and ecological restoration measures. The awareness that interactions can be quite different in semi-arid and semi-humid regions, as well as in upstream and downstream areas, should be reflected in management aimed at sustainable water and land resources use. (C) 2017 Elsevier B.V. All rights reserved.
2017-12-31 Web of ScienceThe long-term and large-scale soil moisture (SM) record is important for understanding land atmosphere interactions and their impacts on the weather, climate, and regional ecosystem. SM products are one of the parameters used in some Earth system models, but these records require evaluation before use. The water resources on the Qinghai-Tibet Plateau (QTP) are important to the water security of billions of people in Asia. Therefore, it is necessary to know the SM conditions on the QTP. In this study, the evaluation metrics of multilayer (0-10, 10-40, and 40-100cm) SM in different reanalysis datasets of the European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-Interim [ERA]), National Centers for Environmental Prediction Climate Forecast System and the Climate Forecast System version 2 (CFSv2), and China Meteorological Administration Land Data Assimilation System (CLDAS) are compared with in situ observations at 5 observation sites, which represent alpine meadow, alpine swamp meadow, alpine grassy meadow, alpine desert steppe, and alpine steppe environments during the thawing season from January 1, 2011, to December 31, 2013, on the QTP. The ERA SM remains constant at approximately 0.2m(3)m(-3) at all observation sites during the entire thawing season. The CLDAS and CFSv2 SM products show similar patterns with those of the in situ SM observations during the thawing season. The CLDAS SM product performs better than the CFSv2 and ERA for all vegetation types except the alpine swamp meadow. The results indicate that the soil texture and land cover types play a more important role than the precipitation to increase the biases of the CLDAS SM product on the QTP.
2017-12-30 Web of Science本发明属于一种植物纤维阻沙固沙网表面抗老化处理剂及其制备方法。处理剂分为溶剂型处理剂和水基型处理剂。该处理剂是一种由成膜材料丁腈橡胶、丁腈胶乳或氯丁胶乳以及乙丙胶乳中的一种或几种,混合溶剂或水、抗老化剂、防水剂、耐寒性增韧剂等助剂组成的液体,是将丁腈橡胶溶于混合溶剂中,再加入适量的其他助剂制备而成。本发明在保留植物纤维阻沙固沙网可降解、风阻小等技术优势的同时,赋予了抗老化、耐高低温、耐水、抗撕裂等性能。有效解决植物纤维阻沙固沙网不耐老化、力学性能差等缺陷和使用寿命短的不足,有效降低该产品的综合成本,为大面积推广提供了技术支撑。
2017-12-29本发明公开了一种基于站点的冻土指数确定方法及电子设备,涉及信息处理技术领域,包括:获取目标监测站点的历史监测数据,所述历史监测数据包括:预设时间段内所述目标监测站点采集的每日平均气温和每日平均地温以及土壤属性;将所述每日平均气温、每日平均地温及土壤属性输入到预设的冻土指数模型中,得到所述目标监测站点所对应的多个温度相关的冻土指数及多个深度相关的冻土指数,所述预设的温度模型包括多个用于计算温度相关的冻土指数的函数关系式和多个用于计算深度相关的冻土指数的函数关系式。本发明提供了一种基于站点的冻土指数确定方法,具有准确性高,运算方式简单等优点,为计算冻土指数提供一种便捷手段。
2017-12-29The hydrological effects of the Grain for Green project (GFGP) on the Loess Plateau have been extensively debated due to the complexity of the water system and its multiple driving factors. The aim of this study was to investigate the response of the hydrological cycle to the GFGP measures based in a case study of the Yanhe Basin, a typical hilly-gully area on the Loess Plateau of China. First, we analyzed the land use and land cover (LULC) changes from 1990 to 2010. Then, we evaluated the effects of LULC changes and sloping land conversion on the main hydrological components in the basin using the Soil and Water Assessment Tool (SWAT). The results indicated that cropland exhibited a decreasing trend, declining from 40.2% of the basin area in 1990 to 17.6% in 2010, and that the woodland and grassland areas correspondingly increased. With the land use changes from 1990 to 2010, the water yield showed a decreasing trend which was mainly due to decrease in surface runoff. In contrast, evapotranspiration (ET) showed an increasing trend over the same period, resulting in a persistent decrease in soil water. The conversion of sloping cropland to grassland or woodland exerted negative effects on water yield and soil water. Compared with the land use condition in 2010, the negative effects were most evident where cropland with a slope >= 15 degrees was converted to woodland, with decreases in surface runoff and soil water of 17.1 and 6.4 %, respectively. These results suggest that the expansive reforestation on sloping land in the loess hilly-gully region decreased water yield and increased ET, resulting in reduced soil water. The results of this study can be used to support sustainable land use planning and water resource management on the Loess Plateau in China.
2017-12-20 Web of Science本发明公开了一种干旱区重金属污染场地的生态修复方法。本发明所述的方法是通过在干旱区重金属污染场地种植吸收植物,同时设置雨水收集系统,浇灌污染区,提高吸收植物的生长能力,进而提高吸收植物对重金属的吸收能力,通过收割吸收植物,实现去除重金属污染区土壤中重金属的目的。本发明的雨水收集系统包括集水沟和集水池,集水池埋设于地表地下,集水沟内充填中粗砂。本发明的吸收植物采用对重金属吸收明显的植物,可处理污染场地的Cd、Pb、Zn、Cu和As等重金属。能够有效的修复干旱区重金属污染场地,所用材料来源广泛,成本低,技术简单有效,可操作性强。
2017-12-19Widespread application of water-saving measures, especially advanced drip irrigation technologies, may significantly impact on the land use, and further potentially alter regional ecological environments in an arid area. In this study, the remote sensing and geographic information system technology were used to analyze the LANDSAT images (1976-2015) and the MOD16 evapotranspiration data (2000-2015) in the Manas River Basin (MRB), China where the water-saving technologies have experienced the past 40 years. Our results show that the area of the cultivated land was approximately doubled from 1976 to 2015 with a dynamic degree of cultivated land ranging from 1.7% to 4%. The reclamation rates were estimated at 9.5% in 1976 and 21.8% in 2015 and the comprehensive index of land use degree shows an increasing trend in the MRB. The evapotranspiration in the MRB suggests that the cultivated land is becoming more humid while the other regions are becoming more arid. Long-term change in the land use is mainly promoted due to the multiple years' efforts on development of the water-saving technologies. This study greatly improves our understanding of the interactions between change in ecological environments and human activities and may provide policy makers guidance of sustainable development at an arid area.
2017-12-19 Web of ScienceIrrigation can influence weather and climate, but the magnitude, timing, and spatial extent of irrigation are poorly represented in models, as are the resulting impacts of irrigation on the coupled land-atmosphere system. One way to improve irrigation representation in models is to assimilate soil moisture observations that reflect an irrigation signal to improve model states. Satellite remote sensing is a promising avenue for obtaining these needed observations on a routine basis, but to date, irrigation detection in passive microwave satellites has proven difficult. In this study, results show that the new enhanced soil moisture product from the Soil Moisture Active Passive satellite is able to capture irrigation signals over three semiarid regions in the western United States. This marks an advancement in Earth-observing satellite skill and the ability to monitor human impacts on the water cycle.
2017-12-16 Web of Science