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581.
582.
随着中国养殖业的迅速发展,禽畜粪便的排放数量逐年增加。据统计,禽畜粪尿排放量每头牛为55kg/d~65 kg/d,每头猪为3.5 kg/d~11.0 kg/d,每只鸡为0.10 kg/d~0.15 kg/d,每只羊为2.66 kg/d。大量的禽畜粪便不经处理而排入环境,将会对地表水、地下水、土壤和空气造成严重的污染,并危及禽畜本身及人体健康。因此,实现禽畜粪便的减量化、无害化及资源化,防止和消除养殖场粪便的污染及其利用问题的研究,对于生态环境的保护、实施可持续发展战略都具有十分重要的意义。本试验利用日本JST赠送的生态厕所反应装置为试验设备,分别以木屑和木屑与秸秆混合物为微生物载体,对牛粪便进行减量化处理技术研究。旨在为研究中国农业的玉米作物秸秆是否可以替代木屑作为反应过程中的调理剂,达到对禽畜养殖业粪便良好的减量化处理效果,减轻对环境的污染,同时也为中国大量的农作物秸秆寻找另一条资源化利用途径。 相似文献
583.
Yao Chen Jinhui Li Huabo Duan Zhishi Wang 《Frontiers of Environmental Science & Engineering in China》2011,5(2):167-174
Mechanical waste-processing methods, which combine crushing and separation processes for the recovery of valuable materials,
have been widely applied in waste printed wiring board (PWB) treatment. However, both the high impact toughness and the tensile
and flexural strengths of whole PWB with a laminated structure result in great energy consumption and severe abrasion of the
cutters during multi-level crushing. In addition, the high temperatures occurring in continual crushing probably cause the
decomposition of the polymer matrix. A thermal-crack method using residual steam as the heating medium has been developed
to pre-treat waste PWBs. This treatment reduces the mechanical strength in order to improve the recovery rate of valuable
materials in subsequent mechanical recycling. The changes of the PWBs’ macro-mechanical properties were studied to evaluate
thermal expansion impacts associated with changes in temperature, and the dynamic dislocation micro-structures were observed
to identify the fracture mechanism. The results showed that thermal cracking with steam at the temperature of 500 K can effectively
attenuate the mechanical properties of waste PWBs, by reducing the impact, tensile and flexural strengths respectively, by
59.2%, 49.3% and 51.4%, compared to untreated PWB. Thermal expansion can also facilitate the separation of copper from glass
fiber by reducing peel resistance by 95.4% at 500 K. It was revealed that the flexural fracture was a transverse cracking
caused by concentrated stress when the heating temperature was less than 500 K, and shifted to a vertical cracking after exceeding
500 K. 相似文献
584.
Arsenic (As) is a pervasive and ubiquitous environmental toxin that has created catastrophic human health problems world-wide.
Chlamydomonas reinhardtii is a unicellular green alga, which exists ubiquitously in freshwater aquatic systems. Arsenic metabolism
processes of this alga through arsenate reduction and sequent store and efflux were investigated. When supplied with 10 mol/L arsenate,
arsenic speciation analysis showed that arsenite concentration increased from 5.7 to 15.7 mg/kg dry weight during a 7-day period,
accounting for 18%–24% of the total As in alga. When treated with different levels of arsenate (10, 20, 30, 40, 50 mol/L) for 7 days,
the arsenite concentration increased with increasing external arsenate concentrations, the proportion of arsenite was up to 23%–28%
of the total As in alga. In efflux experiments, both arsenate and arsenite could be found in the efflux solutions. Additionally, the efflux
of arsenate was more than that of arsenite. Furthermore, two arsenate reductase genes of C. reinhardtii (CrACR2s) were cloned and
expressed in Escherichia coli strain WC3110 (ΔarsC) for the first time. The abilities of both CrACR2s genes to complement the arsenatesensitive
strain were examined. CrACR2.1 restored arsenate resistance at 0.8 mmol/L. However, CrACR2.2 showed much less ability
to complement. The gene products were demonstrated to reduce arsenate to arsenite in vivo. In agreement with the complementation
results, CrACR2.1 showed higher reduction ability than CrACR2.2, when treated with 0.4 mmol/L arsenate for 16 hr incubation. 相似文献
585.
碳源-碳汇特征的研究是建设低碳小区的先决条件。论文分别使用了物料均衡法和生物量统计法对周家泉小区碳源-碳汇进行了计算分析,并对按居住区能源供应标准计算的排放值与实际排放值进行了对比。结果显示:(1)实际排放中,直接排放量占小区总排放量的47.1%,其中煤炭消耗排放量最大。间接排放占小区排放总量的52.9%,其中电力消耗排放占到了93.6%,为小区能源消耗的最大排放源。(2)按居住区燃气供应指标为小区居民提供能源能在充分满足居民需求的前提下有效减少CO2排放量。按电力供应指标计算的CO2排放量大于实际电力消耗排放。供水及污水处理技术是减少用水排放的关键因素。(3)绿化带是小区主要碳汇要素,仅通过实现国家规定的30%的绿地率并不能满足小区碳汇需求。在小区碳源碳汇研究的基础上提出了控制和减少小区CO2的对策建议,以期为低碳小区建设提供参考。 相似文献
586.
587.
The SO2 emission sources of the Chengdu-Chongqing economic zone were divided into 556 emissions units according to four different categories, which are city, industry, point sources, and area sources. The CALPUFF model was used to calculate the contribution of each unit, and consequently obtain an influence-transferring matrix. To ensure that the SO2 concentrations of 46 cities and counties in the Chengdu-Chongqing economic zone meet air quality standards, an emission optimization model was developed to calculate optimal emissions of each emission unit under different development scenarios. The result showed the optimal emissions of SO2 by different provinces and industries. To achieve the target of restricting and optimizing development, corresponding planning programs were developed for every district. 相似文献
588.
589.
Methane emissions during storage of different treatments from cattle manure in Tianjin 总被引:2,自引:0,他引:2
Many studies on methane emissions from animal manure have revealed that animal manure is a major source of methane emissions to the atmosphere that can have negative consequences for people,animals and environment.In general,the release of methane can be influenced by the type of feed taken by animals,temperature,manure characteristics and so on.This study aimed at quantifying and comparing methane release from dairy manure with different piling treatments.Four treatments were designed including manure piling height 30,45,60 cm and adding 6 cm manure every day until the piling height was 60 cm.Static chamber method and gas chromatography were adopted to measure the methane emissions from April to June in 2009.Methane emission rates of all four manure treatments were low in the first week and then increased sharply until reaching the peak values.Subsequently,all the methane emission rates decreased and fluctuated within the steady range till the end of the experiment.Wilcoxon nonparametric tests analysis indicated that methane emission rate was greatly influenced by manure piling height and manner.There were no significant relationships between methane emission rates and the temperatures of ambience and heap.However,regression analysis showed that the quadratic equations were found between emission rates of all treatments and the gas temperature in the barrels. 相似文献
590.
天津滨海盐碱湿地土壤种子库特征研究 总被引:2,自引:0,他引:2
对天津滨海新区典型盐碱湿地土壤种子库进行了研究。通过选取三个标准样地进行野外调查,采用种子萌发实验确定土壤种子库的活性、种类及数量;对土壤种子库的物种组成和数量、物种多样性指数、相似性指数及时空分布等特征进行分析,结果表明,滨海新区盐碱湿地土壤种子库共有26植物,种子库的密度在6809~30644粒/m2之间;种子库的生态优势度在0.51~0.81之间,多样性指数相对较低,其中Shannon-Wiener指数最高为1.78;土壤种子库与地面植被之间的相似性指数较低,最低为0.21;种子库的垂直分布特征较为明显,其中0~5cm层种子数量最多,种子数量层间差异显著或极显著;此外,还研究了土壤种子库萌发随时间变化的规律,得出其萌发数量随时间变化的曲线,为今后土壤种子库应用于植被恢复提供了参考。 相似文献