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931.
932.
Sang Soo Lee Samy A.M. Abd El-Azeem Jung Eun Lim Anushka Upamali Rajapaksha Kwon-Rae Kim Young Han Lee 《Chemistry and Ecology》2013,29(6):501-510
Addition of plant residue into soils improves soil physiochemical properties and its fertility. Rapeseed residue is an emerging N source to paddy soils via rice-rape double-cropping practice. The objective of this study was to evaluate the effects of rapeseed residue and eggshell waste on chemical changes and enzyme activity in the rice paddy soil. The powdered eggshells at 0, 1, 3, and 5% were applied once to 7.0 kg paddy repacked soils in each pot treated with the rapeseed residue or the conventional N, P, and K fertilisers. Eight rice seedlings (Oriza sativa L. cv. Ilmibyeo) (40 days after sowing) were transplanted to the treated each pot. The contents of total C (TC) and N (TN), and organic matter (OM) were significantly increased in soils treated with the rapeseed residue compared to the N, P, and K fertilisers. With the addition of eggshell containing ~92% CaCO3, a considerable increase of soil pH was observed in soils treated with the rapeseed residue and the N, P, and K fertilisers, compared to the untreated soil. Activities of β-glucosidase, urease, and arylsulfatase enzymes were higher in soils treated with the rapeseed residue than soils treated with the N, P, and K fertilisers. The eggshell additions at 1, 3, and 5% into soils treated with the rapeseed residue increased enzyme activity mainly resulting from N mineralisation, whereas no change in enzyme activity was observed in the soils treated with the NPK fertiliser. The combined use of the rapeseed residue and the eggshells can be beneficial to improve soil environment. 相似文献
933.
Large quantities of herbicides are used on agricultural soils, but the effects of herbicides on the structure of the soil microbial community have not been well investigated. In this study, soil from three soybean fields was investigated. The herbicide imazethapyr was applied in one year to soil 1 and in two sequential years to soil 2. Control soil received no imazethapyr. Microbial biomass and community structure were characterised using chloroform fumigation–extraction and phospholipid fatty acid (PLFA) determination. The imazethapyr residue was 1.62 μ g·kg?1 in soil 1 and 1.79 μ g·kg?1 in soil 2. The microbial biomass carbon and total PLFAs for soil 2 were much higher than for the other soils. PLFA profiles showed that fatty acids for Gram-negative and Gram-positive bacteria, as well as total bacteria and total fungi in soil 2 were higher than in other samples. Principal component analysis of the PLFAs showed that the structure of the microbial community differed substantially among the three different soybean field soils. Application of the herbicide imazethapyr to soybean fields clearly changed the soil microbial biomass and shifted the structure of the microbial community. 相似文献
934.
洞庭湖湿地Cd富集植物蒌蒿(Artemisia selengensis)的耐性生理机制研究 总被引:1,自引:0,他引:1
采用盆栽植株和外源Cd胁迫的方法,分别对不同生长期蒌蒿植株根、叶组织中的抗氧化酶活性、可溶性蛋白及MDA含量进行测定,以揭示蒌蒿在Cd胁迫下的抗氧化机理和耐受机制。研究结果表明,Cd胁迫对上述生理指标均有显著影响:≤20mg·kg-1的Cd处理可使幼苗期植株器官中的可溶性蛋白含量增加16.5%~19.1%,100mg·kg-1的Cd含量水平则导致其含量减少近30%,可溶性蛋白含量的变化与植株的生物量积累关系密切;3种酶活性在0~10mg·kg-1的Cd处理下未显示出明显变化,幼苗期植株CAT、POD活性在10~80mg·kg-1的Cd胁迫下增加明显,高于此浓度范围则使酶蛋白受到破坏而失活,中等含量水平(≤40mg·kg-1)的Cd处理经过长时间作用可使植株逐渐适应胁迫环境,胁迫强度较大的Cd处理可显著提高SOD酶的活性;Cd胁迫过程中植株MDA积累量不断增加。3种抗氧化酶活性的增强在蒌蒿植株耐受Cd胁迫方面能起到较好的防御作用。 相似文献
935.
SUMMARY Sustainable indicators have become popular tools by which policymakers can assess progress towards a more sustainable agriculture. Varying approaches to defining sustainability lead to disagreement about the value of indicators and yet some form of measurement is required so that society can judge the effects of policy. Environmental and social problems and their causes span national boundaries. An international framework for assessing agricultural activities, their effects and the pressures that drive those activities is therefore required. However, a guiding principle of the UN Agenda for Sustainable Development is that global problems require local action. Thus, indicators must provide information for policymakers as well as guidance for farmers and other practitioners. Many indicator programmes currently proposed do not provide this level of guidance as no evaluation as to what level of activity is sustainable has been agreed. A model is presented, to show how scientific and political or participatory approaches may be combined to meet the multiple objectives of involving people, maintaining scientific integrity and providing guidance for policymakers and practitioners alike. 相似文献
936.
Remote sensing was used to assess the impacts of tourism development on temporal land-cover changes in the Lugu Lake region, home to the Mosuo people. The ecological and economic significance of the Lugu Lake area derives from the existence of a unique matriarchal system and the success of tourism development. Temporal land-cover changes between 1990 and 2005 were evaluated using digital interpretation of multitemporal Landsat TM images. Pairwise comparison methods were used to quantify changes in land-cover during three periods: 1990 to 1995, 1995 to 2001, and 2001 to 2005. The areas surveyed in each period were 10,226 ha, 7,727 ha and 9,344 ha, respectively. The annual rate of land-cover change for farmland, forest, grassland and wetland were 2.86%, 5.85%, 3.95%, 6.28%, respectively. Farmland and wetland have decreased, whereas forest, grassland and residential areas have increased. The land-cover changes could be explained by the success of tourism development and ecosystem management in Lugu Lake region. The impact of tourism on land cover and the community environment were assessed. The results show that most farmers actively left farms for off-farm jobs and took measures to protect forest, grassland and wetland by developing tourism in the study area. However, construction in residential areas has proceeded in a disorderly fashion. In future, the potential impacts of tourism on the lake ecosystem need to be re-assessed and monitored. 相似文献
937.
碳纳米管以其独特的结构和性能,在生物医药和电子等领域广泛应用,而其生态安全性也成为科学界关注的焦点。为探究多壁碳纳米管(MWCNTs)诱导的细胞毒性机制,将小鼠肺泡巨噬细胞(RAW264.7)暴露于6个浓度梯度(0、25、50、100、150和200μg.mL-1)的MWCNTs中,应用噻唑蓝(MTT)法测定细胞存活率,用2’,7’-二氯荧光素二乙酸(DCFH-DA)荧光染色法测定细胞内活性氧的生产量,用流式细胞方法测定MWCNTs对细胞周期的影响。同时使用抗氧化剂氮乙酰半胱氨酸(NAC)验证MWCNTs诱导的细胞氧化损伤的作用机理。结果显示,MWCNTs对RAW264.7的细胞毒性呈剂量依赖性。暴露于不同浓度的MWCNTs(25、50、100、150和200μg.mL-1)下24h后,细胞活力分别为对照的74%、62%、59%、51%和45%。MWCNTs对RAW264.7的周期阻滞作用主要发生在G0/G1期。200μg.mL-1的MWCNTs处理3h后活性氧较对照组上升6.6倍。NAC对MWCNTs细胞毒作用有明显的抑制作用,且NAC能减弱MWCNTs对RAW264.7的细胞周期阻滞作用。研究表明,活性氧能够介导MWCNTs对小鼠巨噬细胞RAW264.7的损伤,并且MWCNTS通过细胞周期G0/G1期的阻滞,诱导细胞凋亡。 相似文献
938.
Hua?Bai Siyu?Zeng Xin?Dong Jining?ChenEmail author 《Frontiers of Environmental Science & Engineering》2013,7(5):746-755
This paper discusses the use of substance flow analysis (SFA) as a tool to support quantified research on urban drainage systems. Based on the principle of mass balance, a static substance flow model is established to describe and examine the routes and intensities of water, chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) for a representative hypothetical city (RH city) in China, which is a devised and scaled city using statistical characteristics of urban circumstances at the national level. It is estimated that the annual flux of water, COD, TN and TP through the urban drainage system in 2010 was 55.1 million m3, 16037.3 t, 1649.5 t and 209.7 t, respectively. The effluent of wastewater treatment plant (WWTP) was identified as the most important pathway for pollutant emissions, which contributed approximately 60% of COD, 65% of TN and 50% of TP to receiving water. During the wastewater treatment process, 1.0 million m3, 7042.5 t, 584.2 t and 161.4 t of the four studied substances had been transmitted into sludge, meanwhile 3813.0 t of COD and 394.0 t of TN were converted and emitted to the atmosphere. Compared with the representative hypothetical city of 2000, urban population and the area of urban built districts had expanded by approximately 90% and 80% respectively during the decade, resulting in a more than threefold increase in the input of substances into the urban drainage system. Thanks to the development of urban drainage systems, the total loads of the city were maintained at a similar level. 相似文献
939.
940.