• Title/Summary/Keyword: environmental science

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Carbon stocks and its variations with topography in an intact lowland mixed dipterocarp forest in Brunei

  • Lee, Sohye;Lee, Dongho;Yoon, Tae Kyung;Salim, Kamariah Abu;Han, Saerom;Yun, Hyeon Min;Yoon, Mihae;Kim, Eunji;Lee, Woo-Kyun;Davies, Stuart James;Son, Yowhan
    • Journal of Ecology and Environment
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    • v.38 no.1
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    • pp.75-84
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    • 2015

  • Tropical forests play a critical role in mitigating climate change, and therefore, an accurate and precise estimation of tropical forest carbon (C) is needed. However, there are many uncertainties associated with C stock estimation in a tropical forest, mainly due to its large variations in biomass. Hence, we quantified C stocks in an intact lowland mixed dipterocarp forest (MDF) in Brunei, and investigated variations in biomass and topography. Tree, deadwood, and soil C stocks were estimated by using the allometric equation method, the line intersect method, and the sampling method, respectively. Understory vegetation and litter were also sampled. We then analyzed spatial variations in tree and deadwood biomass in relation to topography. The total C stock was 321.4 Mg C $ha^{-1}$, and living biomass, dead organic matter, and soil C stocks accounted for 67%, 11%, and 23%, respectively, of the total. The results reveal that there was a relatively high C stock, even compared to other tropical forests, and that there was no significant relationship between biomass and topography. Our results provide useful reference data and a greater understanding of biomass variations in lowland MDFs, which could be used for greenhouse gas emission-reduction projects.

  • https://doi.org/10.5141/ecoenv.2015.008 인용 PDF KSCI KPUBS HTML

Toxicity Monitoring of Endocrine Disrupting Chemicals (EDCs) Using Freeze-dried Recombinant Bioluminescent Bacteria

  • Kim, Sung-Woo;Park, Sue-Hyung;Jiho Min;Gu, Man-Bock
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.5 no.6
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    • pp.395-399
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    • 2000

  • Five different freeze-dried recombinant bioluminescent bacteria were used for the detection of cellular stresses caused by endocrine disrupting chemicals. These strains were DPD2794 (recA::luxCDABE), which is sensitive to DNA damage, DPD2540 (fabA::luxCDABE), sensitive to cellular membrane damage, DPD2511 (katG::luxCDABE), sensitive to oxidative damage, and TV1061 (grpE::luxCDABE), sensitive to protein damage. GC2, which emits bioluminescence constitutively, was also used in this study. The toxicity of several chemicals was measured using GC2. Damage caused by known endocrine disrupting chemicals, such as nonyl phenol, bisphenol A, and styrene, was detected and classified according to toxicity mode, while others, such as phathalate and DDT, were not detected with the bacteria. These results suggest that endocrine disrupting chemicals are toxic in bacteria, and do not act via an estrogenic effect, and that toxicity monitoring and classification of some endocrine disrupting chemicals may be possible in the field using these freeze-dried recombinant bioluminescent bacteria.

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Simultaneous Measurements of Gaseous Nitrous Acid and Particulate Nitrite Using Diffusion Scrubber/Steam Chamber/Luminol Chemiluminescence

  • Chang, Won-Il;Choi, Jung-Ho;Hong, Sang-Bum;Lee, Jai H.
    • Bulletin of the Korean Chemical Society
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    • v.29 no.8
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    • pp.1525-1532
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    • 2008

  • An instrument was developed for the simultaneous determination of gas- and aerosol-phase nitrous acid (HONO). Gaseous HONO (HONO(g)) was sampled by a diffusion scrubber and particulate nitrite ($NO_2\;^-$(p)) was collected by a particle growth chamber. The collected samples were analyzed in time-sharing manner, based on the peroxynitrite-induced luminol chemiluminescence. The automated system was found to be sensitive with 13 pptv of detection limit, fast with 4 min. of sampling frequency, and simple and affordable to construct and operate. The system was optimized by adjusting the experimental parameters. The system was applied to the field measurement of gas- and particle-phase HONO during the springtime of 2004 in Gwangju, South Korea. HONO(g) concentrations varied diurnally from 200 pptv around 3 P.M. to 800 pptv at 5 A.M. The variation of $NO_2\;^-$(p) was not significant with the maximum of 240 pptv at 11 P.M. and the minimum of 170 pptv at 4 P.M., not displaying distinct characteristics.

  • https://doi.org/10.5012/bkcs.2008.29.8.1525 인용 PDF KSCI