民勤绿洲的环境问题及其治理措施

民勤绿洲目前面临多个严重的环境问题,包括绿洲地下水位急剧下降,荒漠化加剧,土壤次生盐渍化加剧,以及耕地的白色污染等.本文分别从自然因素和人为因素两个方面分析了导致这些环境问题产生的原因,并且针对不同的问题提出相应的治理措施.要解决民勤绿洲的这些环境问题,必须同时采取各项措施,包括严格控制人口增长,发展节水农业,降低对水资源的需求量,同时保护天然植被,恢复盐渍化土地,集中回收地膜减少白色污染等.这样才能逐步减少人与自然的矛盾,避免民勤绿洲成为第二个罗布泊.     

生态重建目标下石羊河流域水资源空间配置优化——基于分布式水资源管理模型

石羊河流域的生态环境退化对于河西走廊乃至西北干旱地区的生态安全形成了严重的威胁。论文构建了基于GBEM模型的分布式水资源管理模型,研究了在生态重建目标下石羊河流域水资源空间配置优化方案和实现途径。分析结果显示,“石羊河流域重点治理规划”的预期目标难以实现,应当在不影响生态重建目标的前提下,以提高流域整体的水资源利用效益为导向,优化水资源利用的空间组织,并通过流域内部的利益补偿,解决水资源空间配置优化带来的区域间收入差异问题。应通过推进水权交易实现水资源空间配置优化及相应的利益补偿,在提高水效益的同时,促进水资源分配的公平。生态退化严重的民勤湖区的农业人口需要逐步转移出来,以减轻当地的生态环境负荷。     

民勤地下水水化学特征和矿化度的时空变化

为了遏制民勤生态环境恶化的趋势,促进石羊河流域经济社会的可持续发展,当地政府2001年和2006年分别开始实施了关井压田节水措施和石羊河下游放水工程.以此为背景,于2008年采集65个民勤地下水水样,对地下水中的主要离子含量进行测试分析,利用传统的统计学分析方法研究了地下水的水化学特征.结果表明,民勤地下水中SO42-、Cl-、HCO3-、CO32-、Na+、Mg2+、Ca2+和K+浓度分别为(921±1 042)(、241±211)(、282±123)、(4.7±11.7)(、468±599)、(156±166)(、142±89)和(17.6±34.5)mg/L,沿地下水水流方向,它们的浓度均呈现增加的趋势.2008年民勤地下水矿化度为(2.2±1.9)g/L;地下水的类型主要属于SO42--Cl--Na+-Mg2+型水.地下水中NO3-的平均浓度为(8.1±9.9)mg/L,有1.54%的水样中硝态氮含量超过了国家一级饮用水标准.结合2002年和2005年同期的矿化度资料,利用地统计学方法,对民勤2002年以来矿化度的时空变异规律进行了研究.矿化度的Kringing插值结果表明,在空间分布上,矿化度呈从南...     

马俊河：为民勤增添一抹绿

“若是不能保证荒漠化地区居民的收入，那么我们所有的治理行动都有可能成为泡影。拯救民勤最大的难点在于如何建立起一种新的治理荒漠化的模式，以解决目前发展生产就等于破坏环境的困境。”     

石羊河流域经济发展与生态环境协调度评价

以石羊河流域117个乡(镇)为基本研究单元,借助流域1986、2000和2011年的Landsat TM解译数据和相关社会经济统计数据构建了ESV模型、EEH模型和AGPI模型,依据ESV指数和EEH指数揭示石羊河流域经济发展与生态环境系统的相关关系和演变特征.研究表明:①1986年以来石羊河流域生态系统服务功能价值呈小幅下降趋势,1986—2000年年均损失0.48%,2000—2011年年均损失0.27%.②1986年以来石羊河流域各乡镇经济发展较快,AGPI增长呈现从上游向下游转移的趋势,流域北部增长率明显高于南部.③石羊河流域经济与生态环境协调度在1986—2000年期间保持了原始和自然发展状态,经济发展与生态环境协调度较差.此后2000—2011年期间二者协调度有所改善,但石羊河流域经济与生态环境关系正处于矛盾多发且此消彼长的不稳定阶段,两极分化现象比较明显.     

黄河流域荒漠化协同防治与上、中、下游绿色发展

黄河流域在国家发展中具有重要的战略地位,但其生态系统脆弱,荒漠化问题突出,面临经济发展与生态环境建设双重挑战。本文从国家战略全局和全流域视角入手,分析黄河流域荒漠化现状及荒漠化治理存在的问题,提出了黄河流域荒漠化协同防治与全流域绿色发展的五大策略,即上中下游协同攻坚,打好黄河流域荒漠化防治与生态保护总体战;创新突破,建立黄河上游重要水源补给生态特区;积极布局推广荒漠化治理重大先进技术工程模式,多途径破解荒漠化治理难题;建立黄河流域绿色生态经济体系,实现人地关系协调、绿色循环高质量发展;多渠道融资,构建荒漠化治理资金保障长效机制。本文旨在为黄河流域上中下游统筹协调防治荒漠化,实现全流域绿色发展提供新思路。     

中国将斥巨资治理生态恶化严重的石羊河流域

《石羊河流域重点治理规划》近日正式出台,中国将投资47.49亿元治理这一生态恶化严重的流域。石羊河是中国西北省份甘肃境内的一条内陆河,位于古丝绸之路河西走廊的东端,发源于祁连雪山,最终流入巴丹吉林沙漠和腾格里沙漠之间的青土湖。因为是河西走廊的门户,又是阻隔两大沙漠合拢的天然屏障,石羊河流域生态区位十分重要。作为甘肃省重要的商     

石羊河流域水资源问题的制度原因及对策

文章从制度角度分析了石羊河流域的水资源问题并提出了对策。在分析石羊河流域水资源及其开发利用和现行管理体制的基础上认为:水资源问题的制度原因是传统的发展模式导致部门间水资源供需矛盾紧张;区域管理体制导致上下游地区间水资源冲突频繁;忽视和挤占环境用水导致生态环境严重恶化;不透明的补贴方式扭曲价格信号和影响水资源需求;区域内分散的管理体制加剧了流域水资源问题。因此,从制度上解决石羊河流域的水资源问题,需要推行流域水、土地、森林资源统一管理,制定《石羊河流域管理条例》,改革现行资源管理体制,建立透明的补贴机制和合理的价格机制。     

民勤盆地沙漠化、贫困化与水资源开发利用

以3S技术与PR A工具,通过对民勤盆地水资源状况的变化与沙漠化、贫困化发生发展规律对比研究,表明自然条件恶劣、基础设施弱是沙漠化、贫困化产生的内在因素,而人类活动则是强大的驱动力。石羊河流域武威盆地不合理的水资源利用造成进入民勤盆地水量日益减少,从20世纪50-70年代的4×108～6×108m 3下降到目前的0.5×108m 3,民勤盆地内大规模开采地下水导致水位下降达30m,同时造成地下水水质恶化、植被退化与沙漠化。沙漠化导致了贫困,贫困反过来加剧沙漠化,两者不断恶性循环。为此,要加强流域内水资源管理,严禁超采地下水;以“退耕还林,种草养畜”为出发点促进流域产业结构调整和节水;加大资金投入和科技扶贫,实现可持续发展。     

石羊河流域多水体酸根离子特征及影响因素

2014年7月~2015年6月在石羊河流域采集降水、地表水及地下水样品,使用离子色谱仪分析获取样品主要酸根离子含量,研究石羊河流域不同水体酸根离子特征、季节分异及其影响因素.结果显示：石羊河流域不同水体均呈弱碱性,酸根离子组成以SO₄^2-和HCO₃^-为优势离子,分别占酸根离子总量的38.68%和33.49%;不同季节水体酸根离子浓度差别较大,春季水体中酸根离子浓度最高,夏季最低,地下水季节变异小于地表水;地表水和地下水的酸根离子浓度都呈现出从上游到下游递增的规律,地表水酸根离子浓度大大低于地下水.碳酸盐的风化及蒸发岩溶解是酸根离子的主要来源,人类活动对石羊河流域水体已造成轻度污染.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.