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991.
基于GCM_CB模型的土壤重金属污染评价 总被引:2,自引:0,他引:2
灰色聚类法已经运用于土壤重金属污染评价中,然而此法在确定聚类权重时仅考虑重金属浓度,忽略了衡量重金属毒性强弱的重要指标生物毒性指数。为了更客观和准确地反映土壤重金属的污染程度,将生物毒性指数引入到聚类指标权重中,构建GCM_CB(grey clustering method_concentration and biotoxicity)土壤重金属污染评价模型。通过对华东某地区的10个区域土壤重金属污染进行分析评价,并与常用评价方法对比研究,表明:其多数样点的评价结果基本一致,但针对样品4和样品9中的元素Hg,因其强毒性,使得评价等级由I级定为II级,从而提高了评价方法的灵敏度,更加符合该区域的实际土壤污染情况。 相似文献
992.
通过控制好氧区低DO浓度以及缩短好氧实际水力停留时间(actual hydraulic retention time,AHRT),在处理低C/N比实际生活污水的A2/O工艺中,成功启动并维持了短程硝化反硝化;系统亚硝酸盐积累率稳定维持在90%左右,氨氮去除率在95%以上。通过提取富集氨氧化菌(ammonia oxidizing bacteria,AOB)的基因组DNA,经两次常规PCR扩增和琼脂糖凝胶电泳,以纯化回收的DNA扩增片段作为实时荧光定量PCR检测AOB数量的DNA标准品,建立了检测AOB数量的实时荧光定量PCR标准曲线。利用实时荧光定量PCR技术比较了A2/O系统在不同运行条件及亚硝酸盐积累率情况下AOB菌群数量。结果表明,随着系统亚硝酸盐积累率的上升,系统内AOB菌群数量也大幅上升。全程硝化和短程硝化时,系统内的AOB菌群数量分别为5.28×109cells/g MLVSS和3.95×1010cells/g MLVSS。此外,亚硝酸盐积累率的下降相对于AOB菌群数量的下降有一定的滞后性。 相似文献
993.
某矿区土壤和地下水重金属污染调查与评价 总被引:3,自引:0,他引:3
为了解湘南某矿区土壤和地下水重金属污染状况,对该矿区东河流域附近重金属污染源进行了调查,同时,对地下水和土壤样品进行了采样分析,结果表明:(1)该矿区东河流域附近的主要污染源有18个,其中有色金属选厂、尾矿库、采矿场和冶炼厂是排放重金属较多的污染源;(2)20个采样点中土壤重金属Pb、Cd、Zn、As和Hg大部分超过国家土壤环境质量标准(GB15618-1995),综合污染指数P综〉1,该矿区主要的重金属污染元素为Cd、As和Hg,且土壤中Cd、Zn和As的含量两两之间存在着极显著的正线性相关关系;(3)重金属元素在土壤中的纵向迁移不明显,该矿区附近20个采样点的地下水并未受到污染,综合污染指数P综〈1。20个采样点地下水Pb、Cd、Zn、As、Hg浓度均能达到地下水质量标准(GB/T14848.9)中的Ⅲ类标准。 相似文献
994.
Rachana Bhatt K. C. Patel Ujjval Trivedi 《Journal of Polymers and the Environment》2010,18(2):141-147
An extracellular poly(3-hydroxybutyrate) (PHB) depolymerase produced by a thermotolerant fungal soil isolate, Aspergillus fumigatus 202, was purified and characterized. Maximum PHB depolymerase production was obtained at the end of 48 h with initial medium
pH 7.0 and 45 °C in Bushnell Haas Minerals medium containing PHB as sole source of carbon. The PHB depolymerase was purified
using size exclusion chromatography to a fold purification of 20.62 and 61.62% yield. SDS-PAGE and isoelectric focusing revealed
the molecular weight and pI of the purified enzyme as 63,744 Da and 4.2, respectively. N-terminal amino acid sequence of purified
enzyme was HAXDAYLVK. This non-glycosylated enzyme was most active at pH 9.0 and 45 °C. Purified enzyme was inactivated by
N-bromosuccinimide and dithiothreitol suggesting the involvement of tryptophan residues and disulfide bonds at its active
site. Nonionic detergents like Tween 20, Tween 80 and Triton X-100 inhibited the enzyme activity. Ions like Ca+2 and Mg+2 (5 mM) increased the enzyme activity 1.5 times. Fe+2 effectively inhibited the enzyme activity to 88% whereas Hg+2 completely inhibited the enzyme. 相似文献
995.
Ikechukwu D. Anyaogu Paul M. Ejikeme John A. Ibemesi 《Journal of Polymers and the Environment》2010,18(2):104-115
Soybean oil (SBO) was dimerized and the crude dimer acid product reacted with 1,2-phenylene diamine at 210 ± 5 °C under inert
atmosphere to obtain fatty polyamide (FPA). The FPA was used to modify a commercial alkyd resin by reacting a mixture of the
alkyd resin with 5 wt% of FPA at 120 °C for 80 min under inert atmosphere. The FTIR spectrum of the FPA modified resin showed
evidence of higher degree of H-bonding than was found for the unmodified alkyd. White gloss coatings of 15, 20, 25, and 30%
solids were formulated from the modified and unmodified resins and examined for performance with respect to: leveling, sag
resistance, drying time, pigment settling, skinning tendency and film hardness. Results showed that the unmodified alkyd coatings
exhibited good leveling but poor sag resistance at all solid contents. In contrast, FPA modified alkyd coatings combined good
leveling with high sag resistance indicating their thixotropic nature. A strong tendency to pigment settling was observed
for unmodified alkyd coatings but was not observed in the FPA modified alkyd coatings. The modified alkyd coatings showed
skinning while the unmodified alkyd coatings did not skin. A 30% solids coating formulation of the FPA modified resin showed
shorter surface dry time but longer hard dry time than the unmodified alkyd resin coating. 相似文献
996.
Romeu Casarano Denise F. S. Petri Michael Jaffe Luiz H. Catalani 《Journal of Polymers and the Environment》2010,18(1):33-44
A new aliphatic block copolyester was synthesized in bulk from transesterification techniques between poly((R)-3-hydroxybutyrate)
(PHB) and poly(isosorbide succinate) (PIS). Additionally, other two block copolyesters were synthesized in bulk either from
transesterification reactions involving PHB and poly(l-lactide) (PLLA) or from ring-opening copolymerization of l-lactide and hydroxyl-terminated PHB, as result of a previous transesterification reactions with isosorbide. Two-component
blends of PHB and PIS or PLLA were also prepared as comparative systems. SEC, MALDI-TOF mass spectrometry (MALDI-TOFMS), 1H and 13C NMR spectroscopy, WAXD, solubility tests, and TG thermal analysis were used for characterization. The block copolymer structures
of the products were evidenced by MALDI-TOFMS, 13C NMR, and WAXD data. The block copolymers and the corresponding binary blends presented different solubility properties,
as revealed by solubility tests. Although the incorporation of PIS sequences into PHB main backbone did not enhance the thermal
stability of the product, it reduced its crystallinity, which could be advantageous for faster biodegradation rate. These
products, composed of PHB and PIS or PLLA sequences, are an interesting alternative in biomedical applications. 相似文献
997.
Afforestation of agricultural lands has been one of the major land use changes in China in recent decades. To better understand
the effect of such land use change on soil quality, we investigated selected soil physical, chemical and microbial properties
(0–15 cm depth) in marginal agricultural land and a chronosequence of poplar (Populus
euramericana cv. ‘N3016’) plantations (5-, 10-, 15- and 20-years old) in a semi-arid area of Northeast China. Soil bulk density significantly
declined after conversion of agricultural lands to poplar plantations. Soil total organic carbon (TOC) and nitrogen (TN) concentrations,
microbial biomass C (MBC) and potential N mineralization rate (PNM) decreased initially following afforestation of agricultural
lands, and then increased with stand development. However, soil metabolic quotient (qCO2) exhibited a reverse trend. In addition, soil particulate organic matter C (POM-C) and N (POM-N) concentrations showed no
significant changes in the first 10 years following afforestation, and then increased with stand age. These findings demonstrated
that soil quality declined initially following afforestation of agricultural lands in semi-arid regions, and then recovered
with stand development. Following 15 years of afforestation, many soil quality parameters recovered to the values found in
agricultural land. We propose that change in soil quality with stand age should be considered in determining optimum rotation
length of plantations and best management practices for afforestation programs. 相似文献
998.
This work was undertaken to analyze nutrient contents of vegetation in an alpine meadow—Tungnath, North-West Himalaya, India.
The study pertains to the uptake, transfer and release of four main macronutrients (organic carbon, total nitrogen, total
potassium and total phosphorus) in grazed (exposed to extensive grazing by cattles) and ungrazed (grazing completely prohibited)
communities. Mineral concentration was recorded higher for the ungrazed sites compared to the grazed sites, and maximum standing
state of nutrients was found in roots. Belowground compartment (roots) contributed maximum share of mineral elements to soil.
Litter nutrients release was low because of low microbial activity and continuous removal of phytomass. Observations reveal
that there was very little amount of nutrient release from phytomass and vegetation in alpine are very poor source of mineral
recycling. Low transfer rate of minerals from one compartment to other is adequate for greater amount of these minerals that
are translocated back into the storage organs. A small proportion get removed through rain splash or through the removal of
hay during grazing as relatively high release rates in ungrazed sites when compared to grazed sites was observed. This translocation
can be considered as an important adaptation in alpine plants for survival during adverse environmental conditions, against
all types of biotic pressures and also for regeneration in the forthcoming growing season. 相似文献
999.
Ruchi Badola Syed Ainul Hussain Bidyut Kumar Mishra Bidyarani Konthoujam Sneha Thapliyal Parag Madhukar Dhakate 《The Environmentalist》2010,30(4):320-329
This paper examines the economic value of selected ecosystem services of Corbett Tiger Reserve, India. The direct cost was
derived from secondary sources, and indirect and opportunity costs through socioeconomic surveys. For recreational value the
individual approach to travel cost method was used, and to assess carbon sequestration the replacement cost method was used.
The maintenance cost of the reserve was estimated as US $2,153,174.3 year−1. The indirect costs in terms of crop and livestock depredation by wild animals ranged from US $2,153,174.3 year−1. The indirect costs in terms of crop and livestock depredation by wild animals ranged from US 2,408 to US $37,958 village−1 over a period of 5 years. The dependence of local communities was for fuel wood (US $37,958 village−1 over a period of 5 years. The dependence of local communities was for fuel wood (US 7,346 day−1), fodder (US $5,290 day−1), small timber, and other nontimber forest products. The recreational value of the reserve was estimated as US $5,290 day−1), small timber, and other nontimber forest products. The recreational value of the reserve was estimated as US 167,619 year−1. With the cost per visitor being US $2.5, the consumers’ surplus was large, showing the willingness of visitors to pay for
wildlife recreation. The forests of the reserve mitigate carbon worth US $2.5, the consumers’ surplus was large, showing the willingness of visitors to pay for
wildlife recreation. The forests of the reserve mitigate carbon worth US 63.6 million, with an annual flow of US $65.0 ha−1 year−1. The other benefits of the reserve include US $65.0 ha−1 year−1. The other benefits of the reserve include US 41 million through generation of electricity since 1972. The analysis reveals
that, though the benefits outweigh costs, they need to be accrued to local communities so as to balance the distribution of
benefits and costs. 相似文献
1000.
By means of environmental education, teachers are supposed to intervene in pupils’ awareness and concern of environmental
issues. Teachers’ environmental attitudes, however, have rarely been studied. We analysed 367 German pre- and in-service teachers’
environmental attitudes for their structure and socio-economic correlates within the frame of a European project. Thus, we
retrieved for adults the two-dimensional model of ecological values (2-MEV) presented for adolescents by Bogner and Wiseman
(Sci Educ Int 15(1):27–48, 2004). For the two domains, Preservation and Utilisation, the psychometric structure was confirmed and discriminative correlations
with age, gender and teaching subject were unveiled. Further research is needed to deduce the implications for teaching practice. 相似文献