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501.
Vestergaard Peter 《Journal of Coastal Conservation》2001,7(2):117-128
The initial recovery of vegetation after a wildfire in a coastal dune area in NW Jutland, Denmark, was studied over a 5-yr
period by means of permanent plots representing various dune communities along a topographical gradient.
The impact of the fire varied with the position of the plots. Fens and south-facing dunes were little affected while dune
heath plots were severely affected including loss of the O-horizon. Post-fire conditions included presence of remaining soil
organic matter, a soil seed bank and surviving below-ground plant parts. The soil surface remained stable during the study
period.
The initial five years of recovery comprised of an initial three-year recruitment phase during which cover and number of species
increased and the quantitative species composition changed markedly, followed by two years of a declining rate of change.
38 species of vascular plants were recorded, 35 are regular components in dune, dune heath and heath fen and were recruited
from the seed bank, from locally dispersed seeds and/or by sprouting from surviving vegetative parts. The remaining three
species were ‘aliens’, dispersed from sources outside the area. Crustose lichens had an important role in the initial recovery
by stabilizing the surface and probably inhibiting seed germination, whereas mosses mostly had a subordinate role.
The seral position of the plots, as well as the expected time needed for full recovery of pre-fire vegetation, vary with topography
and initial soil conditions. Five years after the fire the fen and the south-facing dune probably need less than a decade
for full recovery. The remaining plots are judged to be relatively early seral; their full recovery into mature dry or moist
dune heath vegetation and O-horizon is expected to need several centuries. 相似文献
502.
Effective environmental management requires documentation of ecosystem status and changes to that status. Without long-term
data, short-term natural variability can mask chronic and/or cumulative impacts, often until critical levels are reached.
However, a trade-off generally occurs between sampling in space and time. This study analyses a spatially and temporally nested
long-term (12 years) monitoring programme conducted on benthic macrofauna in a large harbour. Sampling was carried out at
six sites for 5.5 years, after which only two sites were sampled for the next 5 years. After this period, all six sites were
sampled for another 2 years. While ecology is frequently thought of being highly variable, this design was able to detect
trends, and cycles, in abundance, with only around 10% of species at each site exhibiting unpredictable temporal variability.
Sites exhibiting similar trends in the abundance of a species over the 12.5-year period were generally spatially contiguous,
and the spatial scale of change could be assessed. Continuous sampling at two sites identified whether changes in unsampled
sites were related to long-term cycles. Moreover, this sampling provided a long-term background of temporal fluctuations against
which to assess the ecological significance of observed changes. 相似文献
503.
The Avoidance Responses of Daphnia magna to the Exposure of Organophosphorus Pesticides in an On-Line Biomonitoring System 总被引:1,自引:0,他引:1
Zong-Ming Ren Zhi-Liang Li Jin-Miao Zha Kai-feng Rao Mei Ma Zijian Wang Rong-Shu Fu 《Environmental Modeling and Assessment》2009,14(3):405-410
In this study, avoidance behavior of the freshwater cladoceran Daphnia magna Straus was used as indicator to assess the early stress of accidental organophosphorus pesticide (OP) contamination. The
movement behavior was detected by a multi-species biomonitoring system. There was obvious concentration–response relationship
between the OP stress and the behavioral response even at sublethal exposure. A rising OP stress resulted in a significant
decrease of response time to escape (RTE; p<0.05). In comparison of different OPs, it was found that there was a power regression between RTE and the toxic unit of OPs.
Therefore, the avoidance behavior of D. magna was a sensitive indicator of sublethal OP stress, and the power relationship could be used to predict the early warning thresholds
of more OPs in the on-line biomonitoring system. 相似文献
504.
全二维气相色谱/飞行时间质谱联用监测环境空气中VOCs 总被引:2,自引:0,他引:2
采用全采样系统-全二维气相色谱/飞行时间质谱联用技术监测环境空气中的VOCs,优化了调制周期、升温程序、进样体积等分析条件.39种目标化合物在0 μg/m3~10.0 μg/m3范围内线性良好,检出限范围为0.03 μg/m3~0.09 μg/m3,标准气体平行测定的RSD为1.1% ~5.3%.应用于化工园区环境空气样品测定,与热脱附-气相色谱/质谱法相比,目标物的分离效果更佳. 相似文献
505.
从空气质量实时发布的发布接口、集成环节、发布要素三个方面建立空气质量实时发布协同服务体系,在此基础上建立了协同服务框架,对发布信息的统计计算、数据质控、数据聚合计算、数据自动化处理等功能进行阐述,由此保证了不同层次、不同接口间发布信息的质量和一致性,具有较大的实际应用价值。 相似文献
506.
507.
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509.
粘土衬垫的防渗性能和吸附阻滞性能对卫生填埋场防渗系统工作性能有着重要影响。通过建立一维对流-弥散模型,分析了渗透系数、扩散系数、入渗强度、吸附能力对渗漏量及衬垫击穿时间的影响。考虑实际工程的复杂性,建立能反映土体分层、土体非均质性、地下水运动及宏观弥散等复杂因素影响的污染物运移二维分析模型,并对各参数的敏感性进行分析。计算结果表明,保持填埋场在低渗滤液水位下运行,对提高衬垫的防渗效果及耐久性有重要意义;受材料本身性质、施工质量等因素的影响,粘土衬垫的渗透系数变异性往往较大,渗透系数提高一个数量级时,衬垫击穿时间显著缩短;渗透系数恒定时,衬垫击穿时间与材料阻滞因子成线性变化关系;地下水分布及运动情况对污染物运移及分布有重要影响,地下水位越低,竖向入渗越明显,入渗区下部土体的吸附性能发挥越充分,到达地下水及下部土体的污染物浓度越低。 相似文献
510.
Hao Cui Shu-Ping Wang Shu-Gang Jia Na Zhang Zhi-Qiang Zhou 《Journal of environmental science and health. Part. B》2013,48(10):869-877
In this study, the effect of ciprofloxacin (CIP) on the catabolic diversity of soil microbial communities was evaluated. Soil samples were spiked with ciprofloxacin (0, 1, 5 and 50 mg?kg?1) and were incubated for 1, 3, 9, 22 and 40 days. Untreated controls received only water. The functional diversity of the microbial community studied was characterized using a catabolic response profile (CRP). Six substrate groups were tested: carbohydrates, amino acids, carboxylic acids, aromatic chemicals, alcohols and polymers. After 40 days, the CIP concentrations in the soil samples ranged from 25% to 58% of the initial concentrations. Soil respiratory responses to the individual substrates D-glucose, lactose, D-mannose, L-glutamic, Na-citrate, malic acid and inosine were inhibited at the high CIP concentrations (5 and 50 mg·kg?1) in the soils and were increased at the lowest CIP concentration (1 mg·kg?1). Soil respiration was inhibited at all of the CIP concentrations after the addition of D-galactose and glycerol. The CIP concentration and incubation time explained 45.3% of the variance of the catabolic responses. The CRP analysis clearly discriminated among the different CIP concentrations. The results suggest that CIP strongly affects the catabolic diversities of soil microbial communities and that its effect is more significant than that of incubation time. 相似文献