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随着化肥、农膜等在农业生产中的过量投入,耕地面源污染的程度随之加重。文章选取塔里木河流域上游和田地区为研究区域,依据P-S-R框架理论,构建和田地区耕地面源污染生态风险评价指标体系,加入土壤理化数据,使用生态风险评价模型对和田地区1980 年及2016 年耕地面源污染状况进行生态风险评价,运用耕地生态风险模型、生态风险转移矩阵、Arcgis分析和田地区耕地面源污染时空分异状况。研究结论如下:和田地区1980 年耕地生态风险等级均为II级或III级,呈“中间高,两侧低”分布;2016 年耕地生态风险等级上升至IV级或V级,呈“倒W型”分布,各县耕地面源污染程度较1980 年均有较大幅度的上升,其中墨玉县和于田县在2016 年耕地生态风险等级达到最高的V级,而民丰县因自身生态环境的强脆弱性,同样需要提高关注。根据面源污染“从源头治理”的原则,应切实推进和田地区耕地生态环境保护与治理,提高政府重视程度,增强技术指导,开展试点工作,改善和田地区耕地面源污染现状。 相似文献
24.
2008年年初的低温、连阴降雪、冰冻天气使和田地区各县(市)的红柳大芸受到不同程度的冻害。通过对和田地区红柳大芸冻害情况进行调查分析,提出科学的接种深度和灌溉管理以及应采取的防护措施。 相似文献
25.
Quantifying preferential flow in soils: A review of different techniques 总被引:19,自引:0,他引:19
Preferential flow (PF) in soil has both environmental and human health implications since it favours contaminant transport to groundwater without interaction with the chemically and biologically reactive upper layer of soil. PF is, however, difficult to measure and quantify. This paper reviews laboratory and field techniques, such as breakthrough curves, dye tracing, and scanning techniques, for evaluating PF in soil at different scales. Advanced technologies, such as scanning techniques, have increased our capability to quantify transport processes within the soil with minimal soil disturbance. Important issues with respect to quantifying PF concern large-scale studies, frozen soil conditions, tracing techniques for particles and gases, a lack of simple mathematical tools for interpreting field data, and the lack of a systematic approach for comparing PF data resulting from different measurement techniques. Also, more research is required to quantify the relative importance of the various PF processes that occur in soil rather than the integrated result of all PF processes in soils. 相似文献
26.
Pebble clusters are reported widely as characteristic of gravel river beds and are known to influence the initial entrainment of bedload. A field assessment suggests that their distribution is not ubiquitous, favouring channel bars, but also reveals a tendency towards a preferred stream wise spacing. A series of laboratory flume experiments shows that flow resistance rises to, and falls from, a peak value as the longitudinal spacing of pebble clusters decreases, in a manner similar to that shown by others for strip roughness, isolated blocks, and simulated ripples and dunes. The experiments also reveal a strong inverse relationship between bedload flux rates and the flow resistance induced by the concentration of pebble clusters. It is concluded that pebble cluster spacing tends towards an equilibrium that is regulated by a feedback process involving sediment transport rates and that the spatial concentration of these microforms will adjust to the point where they induce maximum flow resistance. 相似文献
27.
分析了新疆和田地区1992年4月5日发生的Ms5.9地震和同年9月2日、12月25日发生的Ms4.6级地震的震前地倾斜异常情况。利用迭代法对地震平静年份的资料进行处理,做出正常背景曲线并与异常图象比较,收到了良好效果。另外还各单位介绍了田地区的地质构造背景及历史地震活动,并对常用处理资料方法的预报效能以及异常量大小和震级的关系进行了讨论。 相似文献
28.
Surface water/groundwater interaction in the Piora Aquifer,Switzerland: evidence from dye tracing tests 总被引:5,自引:2,他引:3
Martin?H.?OtzEmail author Heinz?K.?Otz Ines?Otz Donald?I.?Siegel 《Hydrogeology Journal》2003,11(2):228-239
Results of seven dye tracing tests done from 1993–1997 to investigate the extent to which lakes and surface water interact
with the underlying Triassic Piora Aquifer, Switzerland, are reported here. Two of the dye tracing tests showed that groundwater
flows in the Piora Aquifer from the Piora Valley to springs in the adjacent Santa Maria Valley, and even further east to the
di Campo Valley considerably outside of the Piora Valley surface water divide.
Lake Ritom located in the Piora Valley loses water only to the Canaria Valley outside of the lake's surface-water watershed
at the lake's western margin when lake levels are above 1,835 m above sea level. Dye tracing tests show that a major sinkhole
in the Piora Valley, Calderoni Sinkhole, is located precisely on the water divide where subsurface flow in the Piora Valley
and surface water diverge and move in opposite directions. The dye tracing results also showed no hydraulic connection between
surface water in the Piora Valley and the famous Pertusio Spring, located in the upper Santa Maria Valley. Only a small amount
of dye from the two dye tracing tests done in 1993 and 1997 entered an exploratory gallery built to test the viability of
the AlpTransit tunnel, being built in competent rock under the Triassic Piora Aquifer, effectively perched above.
Electronic Publication 相似文献
29.
High-resolution grain-size characterisation of gravel bars using imagery analysis and geo-statistics 总被引:2,自引:0,他引:2
The scarcity of grain-size data from gravel-bed rivers has traditionally hindered hydraulic, sediment transport and river habitat studies. A new remote sensing methodology to estimate grain-size distribution is presented. It combines textural digital images of the riverbed at 1 : 1000 and 1 : 40 scales with grain-size sampling. It was applied to a 12-km reach of the Isábena River (Central Pyrenees NE Spain). First, textural patterns for each grain-size range were obtained, selecting the most closely related texture variables, including the use of semivariograms. Second, multiple linear regression equations were derived from the textural variables to estimate each value of the grain-size distribution. The highest correlation values (r2) were obtained from the central part of the distribution (D50 with a RMS error of 12.7%). Finally, new multiple linear regression equations to estimate the D50 and D84 were obtained from 1 : 1000 images and four textural variables. These were used to derive D50 and D84 maps of the riverbed, re-sampled at a resolution of 1.5 m pixels, with RMS estimation errors of 26% and 32%, respectively. Downstream change in grain-size is also well reproduced by the method. The mean D50 of 72 and 32 mm were estimated in the upper and the lower reaches of the river, respectively. The methodology shows great potential for application, the relation between the spatial resolution of the images and the mean grain-size of the riverbed sediment being the main issue for future development. 相似文献
30.
阿尔金山东段山前砾石钙膜累积速率及其在估算断层活动年代方面的应用 总被引:3,自引:0,他引:3
干旱-半干旱地区冲洪积物顶面土壤中发育的砾石钙膜含有明显的年龄信息,其工及由统计计算得到的累积速率可用来估算所在冲洪积物或土壤的形成年代。 相似文献