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101.
Tracing carbon transfer and assimilation by invertebrates and fish across a tropical mangrove ecosystem using stable isotopes 下载免费PDF全文
Nguyen Tai Tue Tran Dang Quy Mai Trong Nhuan Luu Viet Dung Nguyen Dinh Thai 《Marine Ecology》2017,38(5)
Mangroves are highly productive ecosystems that exhibit a diverse range of habitats, including tidal creeks and flats, forest gaps and interior forest with varying understory light intensity, tidal dynamics, geomorphological settings, and overall biological production. Within mangrove ecosystems, invertebrates and fish feed on heterogeneous food sources, the occurrence of which is unevenly distributed across the system. This provides a basis for testing models of carbon transfer across mangrove ecosystems. We hypothesized that the carbon transfer and assimilation by fish and invertebrates will vary across the different mangrove habitats and that such variations can be predicted by their stable isotope compositions. We analysed δ13C and δ15N signatures of consumers and their potential organic carbon sources across a tropical mangrove ecosystem in Vietnam. The δ13C values of crabs and snails significantly decreased from the tidal flat to interior forest, indicating that variations in carbon transfer and assimilation occurred at small scales <30 m. Reduced variation in δ13C of suspension‐feeding bivalves suggested that tidal water was a vector for large‐scale transport of carbon across the mangrove ecosystem. An analysis of co‐variance using habitat as a fixed factor and feeding habit and movement capacity of consumers as co‐variates indicated that habitat and feeding types were major features that affected the δ13C values of invertebrates and fish. The findings demonstrate that carbon transfer and assimilation across mangrove ecosystems occur as a diverse combination of small (<30 m) and large (>30 m) scale processes. 相似文献
102.
Wei Zhang XiaoPei Dong GuangXiu Liu GaoSen Zhang XiuKun Wu XiSheng Tai HaoZhi Long BaoGui Zhang 《寒旱区科学》2012,4(2):0127-0131
Microorganisms in permafrost can live in cold environments due to coadapted physicochemical processes in this environment. In
this paper, the relation between microbial number and soil physicochemical properties at the headwaters area of the Urumqi River
is analyzed by using fluorescence microscopy counting and oligo-culture techniques. In total, 20 samples from a 200-cm permafrost
core were used as study materials. The study reveals that the number of culturable bacteria has a significantly positive correlation
with soil water content, total carbon and total nitrogen concentrations, and a significantly negative correlation with soil pH
value. In addition, the ratio of culturable bacteria to total cell number decreases with depths. The results demonstrate that the
number of culturable bacteria in permafrost is closely correlated with soil physicochemical properties and depositional age. 相似文献
103.
Livelihood differentiation between two villages in Yesanpo Tourism District in China 总被引:1,自引:0,他引:1
The rapidly developing rural tourism industry in China has deeply influenced the livelihoods of rural households. This study compares the impact of rural tourism development in poor areas on the farmers’ livelihoods, based on the Sustainable Livelihoods Framework proposed by the United Kingdom’s Department for International Development. Gougezhuang, a tourist village, and Jiaojiekou, a non-tourist village, both located in Yesanpo Tourism District in the state-level povertystricken Laishui County, Hebei Province, were selected as case studies. The livelihood models of the two villages show great differentiation after 20 years of tourism development. Gougezhuang Village has been driven by the tourism industry and farmers are employed locally, enjoying a relatively higher-income life, with a developmental livelihood model. In contrast, farmers in Jiaojiekou Village earn their living mainly by leaving home to work in the city. They have a low income, with a survival livelihood model, supported by part-time business. Considering that the two villages are adjacent and have similar development backgrounds, the analysis results indicate that rural tourism has an apparent locationspecific effect on poverty alleviation and socioeconomic development, but the development of rural tourism is limited regarding large-scale poverty alleviation efforts in poor areas. To implement a propoor- tourism strategy and achieve sustainable development, it is necessary to implement comprehensive management measures to change the local conditions of rural settlements and make full use of the spillover effect of tourist consumption. 相似文献
104.
由中国地震学会和甘肃省地震局联合举办的“中国 8级大震研究及防震减灾学术讨论会”将于 2 0 0 1年 6月 2 5~ 2 7日在兰州市召开。会议活动安排有 1大会报告 ;2专题报告 ;3学术论文报告分组讨论会 ;4会后考察。会后考察为2个路线。 1线 :兰州—海原—古浪—敦煌 (6月2 8日~ 7月 3日 ) ;2线 :兰州—天水 (6月 2 8日~ 7月 1日 )。欲参会者请与中国地震学会有关专业委员会联系中国8级大震研究及防震减灾学术讨论会将于2001年6月25~27日在兰州召开@董泰 相似文献
105.
新太古-古元古代华北陆块构造演化的研究进展 总被引:7,自引:0,他引:7
在过去的二十年里 ,华北克拉通早期陆块形成和演化的研究进展是中国固体地球科学研究领域最为显著的成果之一。第一个十年代表性的工作包括深变质变形的层状岩系与块状岩系的识别与成因研究、高级区与绿岩带的划分、构造样式与变形序列研究、变质历史与变质动力学、年代学与地质事件的研究等。第二个十年的研究重点是如何认识和理解早期大陆地壳的性质和它们的形成与演化过程。代表性的进展包括均匀域与地质体的划分、古老微陆块的识别、残留洋壳与早期陆壳的形成、下地壳组成和性质、大陆拼贴机制、古地幔柱构造与前Rodinia超大陆旋回等。其中高压麻粒岩地体和退变质榴辉岩的发现 ,是华北早前寒武纪研究中最重要的进展 ,它为早期大陆的拼合机制、地壳的深部结构和古老下地壳与现代的对比等多个领域打开了新的研究思路。对新太古 -早元古代的重大地质事件的厘定已表明 ,华北主要的地壳生长期是在 2 9~ 2 7亿年 ,但 2 5和 18亿两期事件是重大的事件 ,虽然对其性质尚存争议 ,但越来越多的证据把它们与超大陆和地幔柱构造相联系。 相似文献
106.
Doreen Y. Tai Kenneth S. Turner Lisa A. Garcia 《Ground Water Monitoring & Remediation》1991,11(1):125-132
A standpipe system was developed for testing the reliability of ground water samplers. The unit consists of a stainless steel pipe 5 inches (13 centimeters) in diameter and 100 feet (30.5 meters) in height. It has 14 sampling ports from which control samples can be withdrawn at the same time and position as the samples are collected by a sampler lowered to that position. Test solutions were made in two mixing tanks, totaling 260 gallons (980 liters), by diluting the concentrate of five volatile chlorohydrocarbons in water at two levels of concentration: 10-to-30 and 100-to-200 parts per billion (micrograms per liter).
A gas chromatograph interfaced with a purge-and-trap system was used to perform the analyses. Comparisons of the control samples with the sampler-collected samples have indicated that the three non-pumping samplers had recoveries in the range of 92.4 to 103.5 percent and the three pumping samplers had recoveries ranging from 97.7 to 101.5 percent. 相似文献
A gas chromatograph interfaced with a purge-and-trap system was used to perform the analyses. Comparisons of the control samples with the sampler-collected samples have indicated that the three non-pumping samplers had recoveries in the range of 92.4 to 103.5 percent and the three pumping samplers had recoveries ranging from 97.7 to 101.5 percent. 相似文献
107.
本文分析了氧绿线强度剖面的半宽度与氧原子密度剖面的观测值,表明氧绿线强度与氧原子密度的关系,不是如Chapman机制所要求的J∞N3(O),而是J∞N2(O)。 相似文献
108.
Laboratory experiments were conducted to investigate the lethal and sublethal effects of suspended solids on the survival and physiological, behavourial and morphological changes of the green-lipped mussel Perna viridis collected from Tolo Harbour, Hong Kong. Results showed that P. viridis survived in all test conditions of suspended solids from 0 to 1200 mg/l over a period of 96 h. Physiological responses of the green-lipped mussel under 14-d exposure of suspended solids from 0 to 600 mg/l, followed by 14-d recovery in natural seawater, revealed no significant changes (p>0.05) in oxygen consumption and dry gonosomatic index for treatments in different concentrations of suspended solids and exposure time. Changes in clearance rate were only found to be significant (p<0.001) with exposure time. Responses in behavourial and morphological changes of the green-lipped mussel were also studied under similar experimental treatments and exposure time. Byssus production was significantly (p<0.001) related to exposure time. Gill damage, however, was significantly greater in treatments (p<0.001). Present findings suggested that P. viridis could tolerate a high level of suspended solids in the laboratory. There were dose-dependent effects of suspended solids on morphology of gill filaments. Implications of survival and responses of the green-lipped mussel to suspended solids in the marine environment are discussed. 相似文献
109.
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