无序的矿山开采作业会破坏矿山区域土壤结构,造成水土流失,使植被生长、水资源、大气环境和人类生命活动受到严重的威胁.因此,矿山废弃地的生态保护和修复管理极为重要.通过查阅文献,分析了矿山废弃地的各类生态问题,以土壤和植被为主要生态要素归纳了物理性、化学性和生物性三大类矿山生态修复核心技术,并针对目前已有矿山生态修复技术体系的不足,从降低灾害发生风险、矿山生态修复技术选择和景观生态重建 3个方面入手,构建出一套适用于我国实际的生态修复技术体系,主要包括风险预警技术、土地重建防固技术、土壤基质改良技术、水资源重建技术、植被生态恢复技术和景观生态养护技术 6个方面,旨在为生态修复技术的筛选和优化提供更多的科学参考,为提高矿山生态修复效率和解决矿山区域水土流失等问题提供更有力的技术支撑.

采用盆栽法研究了15 mg·kg-1Cd胁迫条件下0.05～0.30 mmol·L-1硝普钠(SNP)与0.50和1.50 mmol·L-1[s,s]-乙二胺二琥珀酸(EDDS)单一或复合处理对紫苜蓿(Medicago sativa Linn.)幼苗生长、生理和Cd积累的影响,并分析了生长和Cd积累指标间及其与SNP和EDDS浓度的相关性.结果显示:在土壤Cd胁迫条件下,与对照(不施用SNP和EDDS)相比,不同浓度SNP单一处理总体上可提高紫苜蓿幼苗的株高、主根长、地上部的鲜质量和干质量、地下部的鲜质量和干质量、根系活力及光合色素含量,也可提高地上部和地下部的Cd含量、Cd转运系数、地上部和地下部的Cd富集系数、Cd修复效率、地上部各亚细胞组分的Cd含量及地下部细胞器和可溶部分的Cd含量;经不同浓度EDDS单一处理后,上述多数指标显著升高,仅部分指标显著降低;而经不同浓度SNP与EDDS复合处理后,部分生长、生理和Cd积累指标高于对照或同浓度SNP单一处理,其中,经不同浓度SNP与0.50 mmol·L-1EDDS复合处理后,部分指标还高于同浓度SNP与1.50 mmol·L-1 EDDS复合处理.总体上看,0.10～0.20 mmol·L-1 SNP与0.50 mmol·L-1 EDDS复合处理对紫苜蓿幼苗的生长、生理和Cd积累的促进作用更明显;地下部的Cd含量和Cd富集系数大幅度高于地上部,地上部和地下部的细胞壁和可溶部分的Cd含量大幅度高于细胞器和线粒体.在SNP单一处理下,紫苜蓿幼苗地上部的Cd含量和Cd富集系数以及地下部的鲜质量、干质量、Cd含量和Cd富集系数与SNP浓度显著正相关;在不同浓度SNP与1.50 mmol·L-1 EDDS复合处理下,地上部Cd含量和Cd富集系数与SNP浓度显著负相关;而在其他处理条件下,生长和Cd积累指标与SNP和EDDS浓度无显著相关性.综合分析结果表明:在土壤Cd胁迫条件下,施用适宜浓度的SNP和EDDS有利于紫苜蓿幼苗的生长及对Cd的吸收积累,有助于细胞壁中Cd向可溶部分转移及降低细胞器和线粒体中Cd含量.综合考虑认为,0.10～0.20 mmol·L-1 SNP与0.50 mmol·L-1 EDDS联用可强化紫苜蓿对Cd污染土壤的修复效应.

Recently, the water quality of the second longest River in China (the Yellow river) is deteriorating severely. To investigate the heavy metals contaminated degrees, potential risks and pollution sources of heavy metals in the river, we measured the concentrations of 8 heavy metals (Fe, Mn, Cu, Ni, Zn, Cr, Pb and Cd) from 122 surface sediment samples collected along the upstream Yellow River. According to the results of enrichment factor (EF) analysis and the geoaccumulation index (Igeo) evaluation, we found Cd accumulated significantly for moderately contaminated level and the other heavy metals existed at uncontaminated levels. We conducted risk assessment by using calculation of the sediment quality guidelines (TEC-PEC SQGs) and potential ecological risk index (RI), and the results implied that the concentrations of Ni, Cr and Cd had potential harm for aquatic organisms and the upstream Yellow River had integral no toxic. Moreover, the results of multivariate analysis (principle component analysis, hierarchical cluster analysis and correlation analysis) indicated that Fe, Mn, Cu, Zn, Cr and Cd in the river primarily originated from natural sources, while Ni and Pb mainly derived from different human activities. In addition, partial Cu and Cd come from anthropogenic sources of Ni discharge.

We address the reachable set bounding problem of linear systems subject to both time-varying delay and polytopic uncertainties. A novel criterion is established to give a more accurate description of the set which bounds the states starting from the origin by inputs with peak values. By combining the maximal Lyapunov functional and the reciprocally convex approach, we obtain a tighter reachable set estimation with lower computational complexity. The corresponding reachable set condition for the common Lyapunov functional can be obtained naturally as a special case of the above result. Finally, two examples illustrate the advantages of our proposed method.

The problem of bounding the reachable set for a class of neural networks in the presence of both polytopic uncertainties and time-varying delay is addressed in this paper. The maximal Lyapunov functional, combined with the Razumikhin methodology, is utilized to give a non-ellipsoidal description of the reachable set. An optimization algorithm is proposed in order to make the description as accurate as possible. This method shows great advantages compared to the existing ones. Finally, two examples are given to show the merits of our proposed method. (C) 2013 Elsevier B.V. All rights reserved.

The problem of reachable set estimation for linear delayed systems subject to polytopic uncertainties is revisited in this paper. The maximal Lyapunov–Krasovskii functional, combined with the free-weighting matrix technique, is utilized to derive a refined condition for a non-ellipsoidal reachable set bound. One of our discoveries is that the number of Lyapunov matrices can be chosen to be greater than the number of vertices for the uncertain polytope. Moreover, the choice of appropriate Lyapunov–Krasovskii functional candidate and the introduction of Leibniz–Newton formula lead to decoupling of the system matrices and the Lyapunov matrices. The useful term which was ignored in our previous result is retained. These treatments bring much tighter bound of the reachable set than the existing ones. Finally, the negligence in our previous paper is pointed out.

In this paper, the reachable set estimation problem is studied for a class of dynamic neural networks subject to polytopic uncertainties. The problem addressed here is to find a set as small as possible to bound the states starting from the origin by inputs with peak values. The maximal Lyapunov functional is proposed to derive a sufficient condition for the existence of a non-ellipsoidal bound to estimate the states of neural networks. It is theoretically shown that this method is superior to the traditional one based on the common Lyapunov function. Finally, two examples illustrate the advantages of our proposed result.

The problem of reachable set estimation for linear systems subject to both time delay and polytopic uncertainties is considered in this paper. Our aim is to find a set as small as possible to bound the states starting from the origin by inputs with peak values. The Lyapunov-Krasovskii functional together with free-weighting matrix technique are proposed to derive some sufficient conditions for the existence of an ellipsoidal bound to estimate the states. This method eliminates the conservatism generated by Jensen's inequality and obtains a much tighter reachable set bound. In addition, the number of variables to be determined is smaller than the previous result based on the maximal Lyapunov functional. Finally, an example illustrates the merits of our proposed results.

The daily and seasonal variations of soil respiration and its environmental factors were measured in different habitats(fixed,semi-fixed and moving sand dune) in Horqin sandy land.Results showed that:(1) Soil respiration rate has a significantly positive relationship with plant biomass,soil organic carbon,total nitrogen and silt+clay content.The mean soil respiration rate in fixed sand dune during the study period is 1.18 and 2.02 times of that in semi-fixed and moving sand dune,respectively.(2) Soil temperature and surface air temperature show an increment from fixed,semi-fixed to moving sand dune,while soil water contents show a decrement.(3)The relationships between soil respiration rate and temperature for the different sandy habitats can be described by exponential equations significantly.The temperature sensibility of soil respiration decreases as follows: surface air temperature 5cm soil temperature air temperature 10 cm soil temperature 15 cm soil temperature.Both temperature and water content control seasonal variation of CO2 efflux,but the function of temperature is greater than water content.

The pollutant of nitrate-N(NO-3-N) plays an important role in water pollution nowadays.Analyzing the data of NO-3-N contents of rural drinking water from 98 plots around Lanzhou,we evaluated the water quality in comparison with the National Standard(GB 5749—2006),and investigated the correlation between NO-3 content and the EC.The results showed:①The mean NO-3-N content of drinking water was(5.42±6.63)mg·L-1 and the Rate of Qualification(RQ) was 86.73% in Lanzhou rural area.②The NO-3-N contents were not beyond the limit of the National Standard in Gaolan County,Xigu and Anning District;whereas overproof samples were observed in Yuzhong County,Qilihe,Yongdeng and Honggu District,in which the RQ was 77.27%,77.78%,80.00% and 83.33% respectively.③Significant differences of NO-3-N contents were detected on different types of water.The RQ was 100% in tap water,river water,and pool water,whereas the RQ was 92.00%,91.66%,and 55.56% in cellar water,deep well(more than 30 m) water,and spring water,respectively.The highest content of NO-3-N was detected in shallow well,which was(22.27±10.54) mg·L-1,and the RQ was 25.00%.④There was significantly positive correlation between EC value and NO-3-N content except for the pool and shallow well waters.⑤The significantly negative correlation was detected between pH value and NO-3-N content in shallow well water.⑥The nitrogen input in farmlands was significantly positively correlated with NO-3-N content in shallow well and spring waters.

结合国家饮用水卫生标准(GB5749-2006),对兰州市不同类型农村生活用水(水窖水,井水、泉水、河水、水库水及自来水等)的主要阴阳离子,矿化度、总硬度、pH、电导率等指标进行了测定和分析.结果表明:各类水体矿化度为0.14～2.72 g·L-1,平均矿化度为0.76±0.63 g·L-1,不同水体存在显著差异性,其大小顺序为:井水>泉水>水库水>自来水>河水>水窖水;各类水体平均总硬度为397.06±307.13 mg·L-1,除水库水外,其余水体均有不同程度超标现象,其大小顺序为:井水>河水>自来水>泉水>水窖水>水库水;除钾离子外,其余阴阳离子在不同类型水体中的含量均存在显著差异性,井水中各离子含量高于其他类型水体;水体硝态氮、硫酸盐及氯化物含量在部分井水水样中有超标现象,但平均含量均低于国家标准限额;各类水体pH与电导率在0.05水平上存在显著差异性;水窖水、河流水及自来水水体的水化学类型以HCO3-Ca-Mg型为主,井水以HCO3-Cl-Ca-Mg型为主,泉水以HCO3-Cl-Ca型为主,水库水以HCO3-Cl-SO4-Ca-Na型为主.

Allocation of soil organic carbon in physical fractions was measured in mobile sand dune,and stabilized sand dune using Pinus sylvestris var.Mongolica(22 year forest land) and Caragana microphylla(24 year shrub land) in Horqin sandy land.Results show that(1) the contents of coarse sand,very fine sand and clay+silt,and electric conductivity increased while fine sand content and soil bulk density decreased in woodland,compared with mobile sand dune,(2) the whole SOC storage increased by 729% with an increment of 357 g/m2 in forest land,and by 1 050% with an increment 514 g/m2 in shrub land,(3) dry organic matters in light fractions account for 0.08%,1.24% and 1.14% of the total soil weights,while carbon storages in light fractions are 9.7,182.5 and 185.9 g/m2,accounting for 20%,45% and 33% of whole SOCs in the mobile sand dune,forest land,and shrub land,respectively,(4) the allocations of SOC in particle-size fractions were in orders as fine sandcoarse sandvery fine sandclay+silt for the mobile sand dune,coarse sandfine sandvery fine sandclay+silt for the forest land,and coarse sandvery fine sandfine sandclay+silt for the shrub land,and(5) the variations of light fraction carbon were more sensitive than the whole SOC after sand dune stabilization.Also,the increase of unprotected organic matter within coarse sand fraction played an important role in the change of whole SOC.

The heavy metals(As,Pb,Cu and Zn) contaminations were evaluated in farmland soil of Lanzhou City according to background values and national standard(GB15618-1995),applying the single factor pollution index and Nemerow integrated index.Based on the national standard.The results showed that,the general integrated pollution index was 0.81,which demonstrated a warning level of contamination,and the single factor index was taking the order of AsPbCuZn in the whole study area;the single factor index was in order of AsPbCuZn in Xigu and Honggu District,and Gaolan County;while the single factor index was in order of AsCuPbZn in urban district,Yongdeng and Yuzhong County;there was a light pollution of As in urban and Xigu District;the integrated pollution index was Xigu Districturban districtGaolan CountyYongdeng CountyHonggu DistrictYuzhong County,and the pollution ranking was light in Xigu District and urban district,warning in Gaolan County,and safety in others.Referred to the Lanzhou background values,the results showed that the general integrated pollution index was 2.20 with a moderate level of contamination,and the single factor index was CuPbAsZn in the whole study area;the order of the single factor index in different counties or districts was the same with the results evaluated by national standard;the integrated pollution index in different counties or districts was Xigu Districturban districtGaolan CountyYongdeng CountyHonggu DistrictYuzhong County.Heavy level of contamination was found in Xigu District,the urban district and Gaolan County were moderate pollution,while others light pollution;in general,the ranking of contamination was safety in farming area,whereas light in non-farming area.