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Duckweed Landoltia punctata purifies micro-polluted surface water and produces starch
No full text根据地表水环境质量标准研究少根紫萍(Landoltia punctata)对微污染地表水的净化效果,同时,对其淀粉积累能力进行评价.结果显示,少根紫萍对微污染地表水体可以实现深度处理,经处理的Ⅴ类、劣Ⅴ类水体中氨氮(NH_4~+-N)和总磷(TP)均在1 d内提升一个水质级别,在3 d内达到地表Ⅱ类水标准(NH_4~+-N < 0.15 mg/L,TP < 0.09 mg/L),且氮、磷去除率均达到98.5%和82.9%以上.此外,少根紫萍在快速修复水体的同时能大量积累淀粉.处理3 d, Ⅴ类和劣Ⅴ类水处理中浮萍干重的淀粉含量分别为28.38%、21.57%,15 d后达到52.15%、49.58%.另外研究发现,额外添加二氧化碳(CO_2)对淀粉积累有进一步促进作用.处理3 d淀粉含量相比未添加CO_2提升了55.7%,平均淀粉积累速率提高了2.72倍.因此,少根紫萍不仅能够快速净化微污染水体,同时也能积累大量的淀粉干物质,结果可为实际污水处理及后期少根紫萍资源化应用提供参考
Preparation of Immobilized Thrombin and Its Application in Screening and Analyzing Bioactive Compounds from Flos Sophorae Immaturus
No full text槐米是药食两用植物,有清肝明目和凉血止血之功效;其主要化学成分为黄酮类物质,具有抗氧化、抗凝血、降血压等多种生物活性。本文将凝血酶(THR)固定于氨基修饰的磁珠表面,以其为亲和固相萃取吸附剂,开发出一种快速筛选中药中凝血酶抑制剂的方法。首先合成了表面修饰氨基的磁珠,然后以戊二醛作为交联剂将凝血酶共价固定于磁珠表面得到磁珠固定化的凝血酶(MNP@THR)。利用TEM,VSM,FT-IR等对合成的固定化酶进行了表征,同时获得了优化的合成条件为: THR浓度200 mug/mg, pH值7.0,时间60 min,温度37 ℃为最佳合成条件,此时酶的固定化量为65 mug/mg。利用MNP@THR从槐米提取物中特异性地吸附得到两个活性化合物,并通过磁分离进行前处理后,由HPLC-ESI-MS鉴定其分别为槲皮素和芦丁。通过体外酶活抑制实验测出,槲皮素具有较好的抑制活性,其半数抑制浓度IC_(50)为16.6 0.68 muM;芦丁的凝血酶抑制活性较弱,IC_(50)值为1.5 0.14 mM
Analysis of Free Amino Acids During Fermentation of Iturin A by High Performance Liquid Chromatography
No full text建立一种快速、高效测定游离氨基酸含量的异硫氰酸苯酯(PITC)柱前衍生高效液相色谱法,并利用此方法分析检测iturin A发酵过程中游离氨基酸的动态变化。以异硫氰酸苯酯(PITC)为衍生化试剂,采用Venusil-AA(4.6 mm * 250 mm,5 mum)氨基酸分析专用柱,并优化HPLC检测色谱条件。结果表明:梯度洗脱程序、流动相pH值、色谱柱温对分析时间、色谱峰分离及峰型具有重要影响。当最优色谱条件为:流动相A为0.1 mol/L无水乙酸钠缓冲溶液(pH6.40.1)-乙腈(66∶5),流动相B为乙腈-水(4∶1),流速1.0 mL/min,检测波长254 nm,色谱柱温40℃,梯度程序洗脱,35 min内可完全分离16种氨基酸,且各氨基酸在一定浓度范围内线性关系良好(R2均大于0.9986),加标回收率在83.84%-108.02%之间,RSD值均小于2.77%。该方法耗时短、操作简便、准确可靠,具有良好的精密度和稳定性。通过此方法研究分析伊枯草菌素A发酵过程中各游离氨基酸含量变化规律,发现其氨基酸浓度变化规律大致分为三类
Effects of grazing intensity on soil organic matter and microorganisms in the Zoige alpine meadow
No full text若尔盖高寒草甸处于生态脆弱带,人类活动会对若尔盖草甸的结构和功能产生影响。本研究以若尔盖高寒草甸为对象,以植被盖度作为放牧干扰强度的划分依据,将其分为:D_1,盖度0%~20%;D_2,20%~40%;D_3, 40%~60%;D_4,60%~80%;D_5,80%~100%,分析探讨了不同放牧强度对土壤有机质、微生物群落结构及数量的影响。实验结果表明:随着放牧强度的增加,土壤有机质含量逐渐降低。同时,随着放牧强度增加,细菌、真菌、放线菌含量、革兰氏阳性菌(G~+)及革兰氏阴性菌(G~-)整体呈现先降低后增加的趋势,土壤G~+/G~-在D_3处最大,D_4处最小。以磷脂脂肪酸生物标记作为数量测度,引入生态学多样性指数的计算方法得到的微生物多样性指数表现为:D_5>D_4>D_1>D_2>D_3,且不同放牧强度之间差异不显著(P>0.05)。土壤微生物含量与土壤有机质含量存在显著的正相关关系。放牧强度不仅与高寒草甸植被生产力密切相关,还与土壤有机质及微生物群落紧密相关;因此,控制放牧强度是高寒草地恢复、维持其生产力和改善土壤质量的重要途径
川西山地生态旅游景观资源及灌丛景观资源调查研究
No full text生态旅游是一种回归自然、保护自然的高层次旅游活动,近年来在国内外获得广泛关注。四川省是我国生态旅游大省,具有得天独厚的地势条件和自然景观资源。其中,川西山地地广人稀、地势起伏大,较之四川省东部地区更有利于开展生态旅游活动。因此,本文利用统计资料和前人研究成果,对川西山地地区生态旅游景观资源的整体情况加以阐述,主要内容涵盖地质地貌景观资源、水文景观资源、生物景观资源和气象气候景观资源。并重点对资料统计过程中发现空缺的灌丛景观资源部分,以野外调查的方法予以补充分析,以期为进一步研究该区域生态旅游资源的开发与利用提供支撑
A Gender Analysis of Changing Livelihood Activities in the Rural Areas of Central Nepal
No full textGender mainstreaming is a key for achieving inclusive economic growth, poverty reduction and equitable development. A gender disaggregated analysis of changing livelihood activities is, therefore, crucial for devising gender-sensitive policies and programs. This paper presents a gender disaggregated analysis to assess trend and influencing factors of switching livelihood to higher returning activities at the intra-household level in three villages in rural areas of central Nepal. The result showed that both men and women have changed their livelihood activities from subsistence to cash-earning activities in the last decade. However, the livelihood activities of men have changed considerably compared to women. Men are primarily attracted to out-migration and non-farm wage-based jobs whereas women to market-oriented commercial farming and rural enterprises. Individual as well as location-specific characteristics influence behavior switching to higher returning activities irrespective of gender, while the ethnicity of a household influences only women. Building human and financial capital through education and training along with strengthening access to credit and increasing connectivity through rural road and market centers would be pivotal for encouraging rural men and women to change traditional subsistence activities to higher returning undertakings, leading to equitable livelihood improvement in rural Nepal
Giant panda distributional and habitat-use shifts in a changing landscape
No full textLong-term data on populations, threats, and habitat-use changes are fundamentally important for conservation policy and management decisions affecting species, but these data are often in short supply. Here, we analyze survey data from 57,087 plots collected in approximately three-fourths of the giant panda's (Ailuropoda melanoleuca) distributional range during China's national surveys conducted in 1999-2003 and 2011-2014. Pandas associated preferentially with several ecological factors and avoided areas impacted by human activities, such as roads, livestock, mining, and tourism. Promise is shown by dramatic declines in logging rates, but is counterbalanced with recently emerging threats. Pandas have increasingly utilized secondary forest as these forests recovered under protective measures. Pandas have undergone a distributional shift to higher elevations, despite the elevational stability of their bamboo food source, perhaps in response to a similar upward shift in the distribution of livestock. Our findings showcase robust on-the-ground data from one of the largest-scale survey efforts worldwide for an endangered species and highlight how science and policy have contributed to this remarkable success story, and help frame future management strategies
Impacts of oxalic acid and glucose additions on N transformation in microcosms via artificial roots
No full textRoot exudates can accelerate nitrogen (N) cycling by stimulating the decomposition of soil organic matter (SOM); however, it remains unclear how inputs of individual exudate components affect the biotic and abiotic processes that drive the transformation and release of inorganic N. In a well-controlled rhizosphere system, we added two exudate chemicals (i.e., glucose and oxalic acid) through artificial roots to soils collected from two forests (an similar to 70-year-old spruce plantation and an similar to 200-year-old spruce-fir forest) over a period of 50 days. The results showed that oxalic acid significantly accelerated both N mineralization and availability, which are mechanisms involved in abiotic process that disrupt previously protected mineral-organic associations (e.g., metal organic complexes (MOCs) and short-range order phases (SROs)) and biotic process that accelerate microbial processes. Glucose also enhanced N decomposition, but this enhancement was significantly smaller than that obtained with oxalic acid, presumably because glucose addition increased the formation of mineral-organic associations of MOCs and SROs, thereby limiting microbial access. In addition, the preferential utilization of glucose by microbes can also lead to lower N decomposition. Our results also showed that the component induced changes in N mineralization were lower in the established spruce plantation (e.g., from 45% to 89%) than in the spruce-fir forest (e.g., from 105% to 150%), potentially due to the decresed biotic processes observed after exudate additions in the spruce plantation compared with the spruce-fir forest. The decreased changes in N mineralization in the spruce plantation were also related to component-induced abiotic processes. These observations suggested that oxalic acid and glucose differentially impact rhizosphere N transformation in forest soils, but the impacts are mediated by soil type
Responses of soil invertase and urease activities to warming and plant removal during the growing season in an alpine scrub ecosystem
No full text对青藏高原东缘窄叶鲜卑花土壤转化酶与脲酶活性对增温(0.6~ 1.3 ℃)和植物去除的响应进行研究,以了解气候变暖和植被干扰对高寒灌丛生长季不同时期土壤生态过程的影响.结果表明:增温在整个生长季节使去除/不去除植物处理土壤转化酶活性显著增加了3.7%~13.3%.增温除在生长季末期对不去除植物处理土壤脲酶活性影响不显著以外,在其他时期使去除/不去除植物处理土壤脲酶活性显著增加10.8%~ 56.3%.去除植物处理对土壤转化酶与脲酶活性的影响因增温与生长季节而存在显著差异.去除植物显著降低了不增温样方生长季初期和末期与增温样方整个生长季节土壤转化酶活性,而没有显著影响生长季中期不增温样方土壤转化酶活性.去除植物仅在生长季末期使不增温样方土壤脲酶活性显著降低了10.5%;而在增温样方,去除植物仅在生长季初期和中期使土壤脲酶活性显著降低16.0%~ 18.7%.以上结果有利于全面认识高寒灌丛生态系统土壤碳氮循环过程
Responses of soil inorganic nitrogen to increased temperature and plant removal during the growing season in a Sibiraea angustata scrub ecosystem of eastern Qinghai-Xizang Plateau
No full text为了揭示气候变暖背景下高寒灌丛土壤氮转化过程,该文研究了青藏高原东缘窄叶鲜卑花(Sibiraea angustata)灌丛生长季节土壤硝态氮和铵态氮含量对增温和去除植物的响应。结果表明:窄叶鲜卑花灌丛土壤硝态氮和铵态氮含量具有明显的季节动态。整个生长季节,土壤硝态氮含量呈先增加后降低的趋势,而铵态氮含量均表现为一直增加的趋势。在生长季初期和中期,各处理土壤硝态氮含量均显著高于铵态氮含量,而在生长季末期土壤硝态氮含量均显著低于铵态氮含量,说明该区域土壤氮转化过程在生长季初期和中期以硝化作用为主,而在生长季末期以氨化作用为主。不同时期土壤硝态氮和铵态氮含量对增温和去除植物的响应不同:增温对硝态氮的影响主要发生在生长季中期和末期,且因植物处理的不同而有显著差异,增温仅在生长季中期使不去除植物样方铵态氮含量显著升高。去除植物对土壤硝态氮的影响仅表现在对照样方(不增温),去除植物显著提高了生长季初期和中期土壤硝态氮含量,显著降低了生长季末期土壤硝态氮含量;同时去除植物显著降低了增温样方生长季中期土壤铵态氮含量。灌丛植被在生长季初期和中期可能主要吸收土壤硝态氮,其吸收过程不受土壤增温的影响