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1.
早在4000年前的原社社会,塔里木河(以下简称塔河)下游绿色走廊已经形成。在近百年的历史中,前20年是绿色走廊的兴盛时期,自20世纪20年代中期以后,绿色走廊开始近代历史上的衰败过程,特别是近50年来塔里木河上中游的水土开发活动,使得下游地区的来水量骤减并中断有近30年的历史,从而引发了下游绿色走廊的逐步走向衰败、土地荒漠化趋势加剧等生态环境恶化问题。为了改善塔河下游地区的生态与环境、抑制土地退化的加剧、挽救濒临灭绝的下游天然植被,截止2005年11月共向该地区输水7次,断流30年的塔里木河下游完成了第四次应急输水后,大体达到维系下游生态的必须水量,输水使河道两侧植被生长状况发生明显改善,生物呈多样化变化。笔者在1998年5月,2002年10月和2004年5月三次对塔河中、下游地区进行实地考察获得了第一手资料,本文在前人研究的成果基础上和实地考察资料相结合,对塔里木河下游生态输水前后生态与环境的动态变化进行探讨。 相似文献
2.
【目的】研究新疆盐碱环境中耐盐植物白刺的根际土壤和叶片内生微生物群落的结构丰富度和多样性。【方法】运用Novaseq测序平台对白刺根际土壤和叶片进行16SrDNA-V4区和ITS1区测序。经FLASH进行拼接,经过Qiim过滤叶绿体和线粒体序列,得到的序列在97%的序列相似性水平上聚类成为操作分类单元(OTUs)。对序列数据进行生物信息学分析,评价物种的Chao1指数、shannon指数以及Alpha多样性。【结果】白刺根际土壤细菌优势菌群为放线菌门(Actinobacteria)、变形菌门(Proteobacteria)、芽单胞菌门(Gemmatimonadetes);真菌优势菌群为子囊菌门(Ascomycota)。叶片内生细菌优势菌群为蓝细菌门(Cyanobacteria)和放线菌门(Actinobacteria);真菌优势菌群为子囊菌门(Ascomycota),白刺不同部位的微生物菌群数量和多样性有显著差异(P<0.05),白刺各样地之间微生物群落构成差异明显。【结论】白刺不同部位微生物群落的丰富度和多样性分布。 相似文献
3.
Zainal Abidin Cik Mohd Rizuan Mohd Noor Hafidzi Hamid Noor Hisham Ravindran Shakinah Puan Chong Leong Kasim Azhar Salim Hasber 《Journal of pest science》2022,95(2):1009-1022
Journal of Pest Science - In Peninsular Malaysia, barn owls (Tyto javanica javanica) have been utilized as biological control of rats since the 1960s. In this study, the impact of introduced barn... 相似文献
4.
The upper incipient lethal temperatures of the freshwater mullet, Rhinomugil corsula, acclimated to 15, 20, 25, 30 and 35°C in fresh water, were 32.4, 34.1, 36.0, 36.2 and 36.5°C respectively, and the corresponding lower lethal temperatures were 10.5, 11.5, 13.2, 15.8 and 19.5°C. The mullet has a total tolerance (area of thermal polygon) of 569°C with an upper and lower thermal tolerance of 253 and 316°C2. Likewise, the total resistance of the mullet was 391°C2, with upper and lower resistance zones of 181 and 210°C respectively. The upper critical temperatures of swimming inhibition of R. corsula (17.2 cm; acclimation 30°C), determined in a swimming tunnel, were 35.2, 34.6 and 34.2 for water current velocities of 38, 62 and 77 cm s?1 respectively. The corresponding lower critical temperatures were 26.2, 27.5 and 28.1°C. These results indicated the stenothermal nature of the mullet by comparison with other fishes, e.g. Tilapia mossambica.In tests on the influence of ambient salinity on thermal resistance, R. corsula survived longest at 7‰ (iso-osmotic salinity). At salinities above and below this point, survival times were shorter at any lethal temperature. In a tentative scheme for quantification of stress due to temperature and salinity at death (after acclimation to 30°C and tested at 37°C), the hypo-osmotic and hyper-osmotic stress were estimated to be 50 and 31% of the thermal stress (100%) respectively. 相似文献
5.
David Schwartzman Margaret Kasim Lorin Stieff James H. Johnson Jr. 《Water, air, and soil pollution》1987,32(3-4):363-378
The potential use of lichens as quantitative monitors of airborne heavy metal pollution has been demonstrated by measurements of Po210, Pb, Cd, Zn, and V levels in sequential growth of the foliose lichen Pseudoparmelia baltimorensis from three localities in the greater Washington, D.C. area. Samples were dated using the growth rate measured by Lawrey and Hale (1977). Po210, Pb, and V increase with age in a given colony. Higher levels of Pb, V, Cd, and Zn are present in samples from the two more polluted sites. The retention of heavy metals is consistent with trapping by an ion exchange mechanism. Since Po210 is the daughter product of in situ decay of Pb210, accumulated from atmospheric fallout of known rate, its levels can be used to calculate trapping efficiencies of Pb and retrospective fallout rates. These rates are similar to published data from rural and urban areas. 相似文献
6.
黄土高原不同生态类型区果园地土壤肥力特征综合评价及其区域差异特征研究 总被引：1，自引：1，他引：0
以黄土高原典型苹果园地为研究区域,采用野外调查与试验分析相结合的方法,选取6个土壤养分指标:有机质、全氮、速效磷、全磷、速效钾和全钾,应用多元统计分析方法,分析了黄土高原典型苹果园地3个区段(陕西凤翔、陕西长武、陕西延安)0—300cm土壤剖面层土壤养分含量的分布特征及差异性。结果表明:不同苹果产区土壤养分含量差别明显,3个试点各类果园0—300cm土层土壤全氮含量平均值,全磷含量平均值、速效磷含量平均值、全钾含量平均值、速效钾含量平均值由大到小依次为凤翔长武延安;长武凤翔延安;长武凤翔延安;凤翔长武延安;长武凤翔延安。不同苹果产区果园0—300cm土层土壤氮磷钾全量和速效量剖面分布特征类似,除全钾和速效氮外其余养分全量和速效量剖面分布具有明显"表层积聚效应。长武和延安的0—300cm土层土壤有机质含量的剖面分布特征类似,没有明显的垂直分层现象而凤翔0—100cm土层速效钾含量随土层加深而迅速降低,100—200cm土层内有机质含量的剖面含量没有明显的变化。陕西长武地区土壤养分指数为0.24比陕西凤翔地区(0.23)的高;陕西凤翔地区养分指数(0.23)比陕西延安地区的(0.22)高。针对不同区域果园土壤养分含量差异,提出果园施肥建议:凤翔果园应该增施有机肥和氮肥,增施钾肥。长武果园增施有机肥,氮磷钾肥配合施用。延安地区土壤养分状况最差,应加大施肥力度,增施有机肥,氮磷钾肥配合施用,实行平衡施肥。 相似文献
7.
A Boer goat breeding farm with 800 heads of breeder females, 50 breeder males, and 400 growing goats of various ages in Sabah,
Malaysia was selected to study the effect of implementing herd health program. This included vaccination program against pneumonic
mannheimiosis; fecal monitoring for helminthiasis, coccidiosis, and colibacillosis; and introduction of modified feeding regime
comprised of day-time grazing and feeding of cut grass and supplemented feed. The herd health program was implemented in September
2007 and the impact was observed on body weight gains, body scoring, and annual mortality among adults and kids. It was found
that implementation of herd health program significantly (p < 0.05) increased the average body weight gains in both adults and kids from 1.8 g per kid and 0.6 g per adult in 2006 to
3.7 g per kid and 2.2 g per adult in 2008. The percentage of adults with body scoring of <3 was significantly (p < 0.05) reduced from 82.3% in 2006 to 77.6% in 2007 and 4% in 2008. Similarly, the annual mortality rate was significantly
(p < 0.05) reduced from 6.5% among kids and 58.2% among adults in 2006 to 12.1% among kids and 10.4% among adults in 2007, and
to 9.1% among kids and 1.1% among adults in 2008. Therefore, it was concluded that implementation of herd health program significantly
improved the survival and performance of goats. 相似文献
8.
Mochamad Asrofi Hairul Abral Anwar Kasim Adjar Pratoto Melbi Mahardika Ji-Won Park Hyun-Joong Kim 《Fibers and Polymers》2018,19(8):1618-1625
The successful isolation and characterization of water hyacinth fiber (Eichornia crassipes) (WHF) nanocellulose is presented in this study. The novelty was in exploring a wider range of properties of highly purified samples of WHF after each stage of production in more depth. The isolation was accomplished by pulping in a digester and sonication. Morphological changes before and after treatment were demonstrated by scanning electron microscopy (SEM). The lignin and hemicellulose content decreased during chemical treatment. Transmission electron microscopy (TEM) and particle size analyzer (PSA) were used to determine the morphology of WHF after sonication for 1 h. TEM shows that the diameter and length of nanocellulose WHF were 15.61 and 147.4 nm, respectively. The crystallinity index and crystalline domain area significantly increased after chemical treatment. The highest crystallinity index was 84.87 % after an acid hydrolysis process. The increase in crystallinity leads to good thermal stability. Moisture absorption tests of WHF were carried out before and after treatment. The lowest moisture absorption was in the cellulose fiber after sonication (nanocellulose). 相似文献
9.
根据1999 ～2012年若羌县人口、耕地和社会经济发展统计数据,运用数理统计和主成分分析方法,研究了若羌绿洲耕地变化情况及驱动力.结果表明:若羌县耕地变化显著,耕地面积经历了减少—迅速增长—慢速减少的变化过程;各地耕地相对变化率分布的空间格局不一,若羌镇、吾塔木乡耕地的相对变化率为小于1,铁干里克乡、瓦石峡乡耕地的相对变化率为大于1,瓦石峡乡的最高,为2.77;从时段上看,2002～2008年驱动力综合得分增长较为缓慢,2009 ～2012年驱动力综合得分增加迅速,表明影响若羌县耕地变化的综合因子的驱动力在逐渐加强. 相似文献
10.
根据塔里木河流域近50 a来的水文、经济资料,运用数理统计方法分析了自然驱动因子和人文驱动因子对塔里木河流域水域环境影响的贡献率。结果显示:塔里木河四源流在过去50 a出山口径流量没有减少,但汇入塔里木河干流的水量从20世纪50年代的50.27亿m3减少到2000年以后的46.05亿m3,并且出现干流断流长度增加、地下水位下降、水质矿化度升高等一系列问题。而导致这种恶化的直接原因是人类活动的干扰,如:耕地面积扩大,不合理的灌溉、垦殖、放牧等。因此,今后塔里木河流域在水资源利用和综合治理中,应特别关注人类活动的影响。 相似文献