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1.
湖北省2008年初低温雨雪冰冻过程气候特征分析   总被引:3,自引:0,他引:3  
2008年初,湖北省出现了严重的低温雨雪冰冻灾害,直接经济损失高达110亿元以上,有必要对灾害期间的气候特征进行系统、科学的分析和总结。对湖北省76个气象站2008年1月12日~2月3日气温、降水(雪)、日照以及低温持续日数等要素进行时空间差异分析及历史与同期比较,并选取10个代表站历史上所有低温雨雪天气过程,对其过程持续低温日数、最长连续雨雪日数、过程极端低温进行比较分析。结果表明:(1)此次过程的平均气温异常偏低,该省大部为-1~-2℃,比常年同期偏低4~6℃,为各站历史同期最低,其中主要是最高气温异常偏低所致,但极端低温并不低;(2)降雪过程频繁,雨雪量异常偏多;(3)低温冰冻持续时间长,该省大部在16~22 d,位于历史第一;(4)日照异常偏少。持续而稳定的大气环流异常形势是湖北省大范围低温雨雪天气的直接原因。  相似文献   
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Benthic macroinvertebrate communities in streams adjacent to cornfields, streams where cows had unrestricted access, and reference locations without agriculture were compared to examine the effects of local land use and land use/land cover in the watershed. At each local site, macroinvertebrates and a variety of habitat parameters were measured upstream, adjacent, downstream, and farther downstream of the local land use. A geographic information system (GIS) was used to calculate drainage basin area, land use/land cover percentages in each basin, and the distance from sample sites to the stream source. Three‐way analysis of covariance (ANCOVA) tests with date, site type, and sampling location as main effects were used to explore differences in macroinvertebrate metrics using median substrate size, percent hay/pasture area, and stream depth as covariates. The covariates significantly improved model fit and showed that multiple contributing factors influence community composition. Local impacts were greatest at sites where cows had access, probably because of sedimentation and embeddedness in the substrate. Differences between the upstream and the adjacent and downstream locations were not as great as expected, perhaps because upstream recolonization was reduced by agricultural impacts or because of differences in the intensity or proximity of agriculture to riparian areas in the watershed. The results underscore the importance of both local and watershed factors in controlling stream community composition.  相似文献   
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本文运用系统科学原理阐释了社会和谐的内涵,指出社会和谐须以人与自然和谐为基础,以人与人之间的平等、友爱和同合作为表征,其构建与实现应遵从人类社会的演化规律,依赖予在把握人类社会需求演绎、协同人与自然关系的基础上推动生产力的高效有序发展和自然资源、生态环境的可持续支持.进而从可持续发展角度,提出了人与自然和谐的"双剩余理论",以揭示其间的供瓣枧理和协同准则;推导出了社会收益分配的相对公平系数,以衡量人与人公平要求下的社会和谐.针对国情和战略目标要求,提出了以加强小城镇建设为轴心的城市、小城镇与农村人流、物流、财流和信息流合理聚散的"三元结构"发展模式,以促进我国和谐社会的建设和可持续发展战略的有序实践.  相似文献   
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Background, Aims and Scope Sediments of the Spittelwasser creek are highly polluted with organic compounds and heavy metals due to the discharge of untreated waste waters from the industrial region of Bitterfeld-Wolfen, Germany over the course of more than one century. However, relatively few data have been published about the chloroorganic contamination of the sediment. This paper reports on the content of different (chloro)organic compounds with special emphasis on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), and chlorobenzenes. Existing concepts for the remediation of Spittelwasser sediment include the investigation of natural attenuation processes, which largely depend on the presence of an intact microbial food web. In order to gain more insight in terms of biological activity, we analyzed the capacity of sediment microflora to degrade organic matter by measuring the activities of extracellular hydrolytic enzymes involved in the biogeochemical cycling of carbon, nitrogen, phosphorus and sulfur. Furthermore, the detection of physiologically active bacteria in the sediment, particularly of those known for their capability to reductively dehalogenate organochlorine compounds, illustrates the potential for intrinsic bioremediation processes. Methods PCDD/F and chlorobenzenes were analyzed by gas chromatography(GC)/mass spectrometry and GC/flame ionization detection, respectively. The activities of hydrolytic enzymes were determined from freshly sampled sediment layers using 4-methylumbelliferyl (MUF) or 7-amino-4-methylcoumarin-conjugated model compounds and kinetic fluorescence measurements. Physiologically active bacteria from different sediment layers were microscopically visualized by fluorescence in situ hybridization (FISH). Specific bacteria were identified by 16S rRNA gene amplification and sequencing. Results and Discussion The PCDD/F congener profile was dominated by dibenzofurans. In addition, the presence of specific tetra and pentachlorinated dibenzofurans supported the assumption that extensive magnesium production was one possible source for the high contamination. A range of other chloroorganic compounds, including several isomers of chlorobenzenes, hexachlorocyclohexane and 1,1,1-trichloro-2,2-bis (p-chloro-phenyl)ethane (DDT), was present in the sediment. Activities of extracellular hydrolytic enzymes showed a strong decrease in those sediment layers that were characterized by high contents of absorbable organic halogen (AOX), indicating disturbed organic matter decay. Interestingly, an abnormal increase of cellulolytic enzyme activities below the organochlorine-rich layers was observed, possibly caused by residual cellulose from discharges of sulfite pulping wastes. FISH revealed physiologically active bacteria in most sediment layers from the surface down to the depth of about 60 cm, including members of Desulfitobacterium (D.) and Sulfurospirillum. The presence of D. dehalogenans was confirmed by its partial 16S rRNA gene sequence. Conclusions Results of chemical sediment analyses demonstrated high loads of organochlorine compounds, particularly of PCDD/F. Several years after stopping the waste water discharge to Spittelwasser creek, this sediment remains a main source for pollution of the downstream river system by way of the ongoing mobilization of sediment during high floods. As indicated by our enzyme activity measurements, the decomposition potential for organic matter is low in organochlorine-rich sediment layers. In contrast, the comparably higher enzyme activities in less organochlorine-polluted sediment layers as well as the presence of physiologically active bacteria suggest a considerable potential for natural attenuation. Recommendations and Perspectives From our data we strongly recommend to explore the degradative capacity of sediment microorganisms and the limits for in situ activity towards specific sediment pollutants in more detail. This will give a sound basis for the integration of bioremediation approaches into general concepts to reduce the risk that permanently radiates from this highly contaminated sediment. Submission Editor: Dr. Henner Hollert (Henner.Hollert@urz.uniheidelberg.de)  相似文献   
6.
We report the prenatal diagnosis at 16 weeks' gestation of bilateral split-hand/split-foot malformation (SHSFM) with severe lobster claw deformity of hands and feet in a male fetus without associated malformations. A minor manifestation of SHSFM was present in the father with only mild bilateral foot involvement (syndactyly I–II; cleft II–III; left cutaneous syndactyly III–IV). Mutation analysis of the p63 gene on chromosome 3q27 showed a missense mutation 577A→G (predicting amino acid substitution K193E) in the father. This mutation has not been reported so far in SHSFM but resembles the previously reported 580A→G (predicting amino acid substitution K194E) in a family with SHSFM. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
7.
Summary The leaf gland volatile oils of ten sweet gale plants from a Scottish population were extracted in early summer. The results differed notably from reports of other populations in respect of the sesquiterpenes, -elemenone and germacrone, which were major components of the volatile oil. Three dihydrochalcones were also detected in the volatile oil. Variation within the population existed, particularly with respect to the relative importance of germacrone. Five plants were resampled in late summer and exhibited a marked reduction in -elemenone, a lesser reduction in germacrone and changes in the proportions of some monoterpenes.  相似文献   
8.
不同低碳氮比废水中好氧颗粒污泥的长期运行稳定性   总被引:2,自引:2,他引:0  
袁强军  张宏星  陈芳媛 《环境科学》2020,41(10):4661-4668
为了研究好氧颗粒污泥系统处理低碳氮比废水的长期运行稳定性,采用低碳氮比(C/N)条件下逐步增加碳氮负荷的进水方法,分别在反应器A和B中接种好氧颗粒污泥,考察其长期运行过程中的理化性质、处理性能及应对冲击负荷的稳定性.其中A反应器的碳氮比一直维持在2,而B则由4逐步降至2.结果表明,在4℃存储30d的好氧颗粒污泥,经过25d的培养,其活性基本恢复,A、B反应器化学需氧量(COD)和氨氮(NH4+-N)的去除效率均达到90%以上.在其后的稳定阶段,B反应器COD和NH4+-N去除率达到90%以上,实现了完全硝化;而A反应器COD去除率仅80%左右,虽然NH4+-N去除率最终也达到90%以上,但仅实现短程硝化.在冲击负荷阶段,A和B反应器COD去除率仍维持在80%以上,但是NH4+-N去除受到很大冲击.A反应器NH4+-N去除效率恶化,B反应器仅实现了部分硝化.整个运行过程,好氧颗粒污泥的物理性质受到的影响不大,A和B反应器的污泥容积指数(SVI30)分别维持在60 mL ·g-1和75 mL ·g-1左右,混合液悬浮固体(MLSS)在5g ·L-1和3.7g ·L-1左右.颗粒污泥微生物群落分析表明,B反应器相对于A反应器丰富度和多样性更高.同时B反应器具有更高丰度的Zoogloea属,在颗粒中能产生更多的胞外蛋白促使颗粒结构更稳定,保证系统的长期稳定运行.以上结果表明,与C/N为2的好氧颗粒污泥系统相比,C/N为4的系统脱碳硝化效果好,抗冲击负荷能力强,更有利于颗粒污泥的长期稳定运行.  相似文献   
9.
华北区域点冬季二次有机气溶胶特征与影响因素   总被引:2,自引:0,他引:2  
为探明二次有机气溶胶(SOA)的污染特征和影响因素,本研究于2018年11月—2019年1月对华北区域点(德州市郊区点)细颗粒物(PM_(2.5))的化学组成进行了在线测量,并分析了PM_(2.5)中有机碳(OC)、元素碳(EC)和水溶性离子组分的污染特征及PM_(2.5)与气象要素之间的相关性.结果表明,观测期间德州PM_(2.5)污染严重,平均质量浓度为(115.6±24.6)μg·m~(-3);其中,有机碳和元素碳是PM_(2.5)的主要成分,平均质量浓度分别为(8.2±5.8)μg·m~(-3)和(2.6±2.2)μg·m~(-3),占PM_(2.5)总质量的7.1%和2.2%;PM_(2.5)与风速呈负相关,与相对湿度呈正相关,与气温的相关性较差,偏北风对PM_(2.5)浓度影响较大.同时,本研究利用EC示踪OC/EC比值法对PM_(2.5)中的二次有机碳(SOC)进行了估算,通过估算得到的SOC结果表明,华北区域点冬季SOC是OC的重要组成部分,平均浓度为(4.0±2.9)μg·m~(-3),占OC的45.7%,SOC在白天占比较高(62.7%),早晚由于有局地生物质燃烧影响,SOC占比降低,约占OC的42.7%.本研究还分析了SOC生成的影响因素,分析了德州市冬季O_3、含水量、酸度与SOC的相关性.结果表明,SOC受臭氧浓度影响,但在白天和夜晚表现出不同的相关关系,可能存在不同的生成机制.最后,利用ISORROPIA模型估算了颗粒物的含水量和酸度,发现SOC在高含水量和低含水量下存在不同的关系,高含水量更能促进SOC生成;在高含水量下SOC与H~+具有显著相关性,但在低含水量下则不相关,表明颗粒物含水量较高、H~+浓度较高情况下液相酸催化反应可能对SOC具有重要贡献.  相似文献   
10.
焦化废水处理过程中产生的焦油、污泥和结晶杂盐等固相物质,既有资源属性,又有污染特性,但目前缺乏基于能源、经济及环境影响方面的评估.本研究阐述了3类固相物质的形成机制,建立了质量当量计算及处置方法评价模型.以宝武集团韶关钢铁股份有限公司焦化厂(二期)焦化废水处理工程的A/O/H/O(厌氧/好氧/水解/好氧)流化床工艺作为考察对象,利用工程运行参数和水质统计数据进行固相物质的产量推算,结果发现,焦油、物化污泥、生物污泥(含水率为80%)和工业杂盐的产率分别为0.186、5.80、4.24和1.97 kg·m-3.通过处置方法评价模型明确了焦油焚烧、污泥热解、结晶杂盐分盐提纯后工业应用是最佳处置方案,在60 m3·h-1废水处理规模的固相物质处置过程中,每年约产生1177 MWh的能源,获得135.0万元的经济效益,排放627.0 t CO2,表明能源回收、经济效益和环境影响的协同存在.  相似文献   
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