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Measurement of environmental parameters in polar regions based on a ubiquitous sensor network
Chae, Namyi,Yang, Heekwon,Lee, Bang Yong,Lee, Chankil Elsevier 2016 Cold Regions Science and Technology Vol.123 No.-
<P><B>Abstract</B></P> <P>To estimate the spatial variation of soil CO<SUB>2</SUB> flux in a permafrost region, major environmental parameters were measured and analyzed using the proposed ubiquitous sensor network-based remote monitoring system (U-RMS). The use of techniques for power-efficient operation and network scalability that enable long-term use of a wireless sensor network (WSN) that can be deployed reliably and widely is described. The temporal and spatial variations in air temperature (Ta) and relative humidity (RH) near the surface at 16 locations and soil temperature (Ts) and soil water content (SWC) at 10 locations were measured to monitor the active permafrost layer in Alaska from September 2012 to January 2013 and from July to September 2013. The temporal variations in environmental parameters in the soil and near the surface depended on the thawing and freezing of the snow cover in the permafrost regions. The spatial patterns of Ts in the three periods were not similar because of the heterogeneous distribution of snow coverage and depth in winter. On the other hand, the spatial patterns of Ts and SWC had a negative relationship during summer. The spatial variations in Ts and SWC showed a high coefficient of variation (CV) that ranged from 20% to 40%, while the CV of Ta and RH was within 5% except in winter due to the spatially heterogeneous snow cover. The relationship between CO<SUB>2</SUB> efflux and Ts or SWC in 2012, which had a high CV, was examined to estimate the soil CO<SUB>2</SUB> efflux in 2013. The Ts explained ~60% (soil CO<SUB>2</SUB> efflux=0.066×exp<SUP>0.1443×Ts</SUP>, R<SUP>2</SUP> 0.59) of the variation in soil CO<SUB>2</SUB> efflux in a temperature range of 3 to 8°C. Therefore, the soil CO<SUB>2</SUB> efflux in 2013 was estimated in the range of 0.08mgm<SUP>−2</SUP> s<SUP>−1</SUP> to 0.47mgm<SUP>−2</SUP> s<SUP>−1</SUP>, and average CV was 25%. Using the camera sensor, the growth of vegetation and the operating appearance of the remote WSN were also monitored. In the long term, measurement of temporal and spatial variations in environmental parameters, based on U-RMS, is expected to contribute to the understanding of the carbon and water cycles in permafrost.</P>
Namyi Chae,Dongho Lee,Jong-Hwan Lim,Jinkyu Hong,Sinkyu Kang 한국기상학회 2009 Asia-Pacific Journal of Atmospheric Sciences Vol.45 No.2
Using leaf carbon isotope monitoring as an indicator, carbon and water exchanges and their inter-dependencies were examined in the Gwangneung forest on a complex landscape in Korea. Leaf carbon isotope compositions (δ <SUP>13</SUP>C) were measured for two dominant tree species, Quercus serrata and Carpinus laxiflora, from 2003 to 2005. Leafδ <SUP>13</SUP>C exhibited a consistent decrease in 2004 compared to that of 2003 and 2005 regardless of its species and growth heights. The decrease inδ <SUP>13</SUP>C (and therefore the increase of the ratio between intercellular and ambient CO₂, Ci/Ca) was assumed to be the consequence of reduced productivity of the year, which was supported by complementary leaf nitrogen, biometric,micrometeorological and satellite-basedmeasurements. The estimation ofwater use efficiency (WUE) fromleaf carbon isotope composition was hampered mostly by the uncertainties in vapor pressure deficit of the air, the temperature difference between the air and leaf surface during photosynthesis, and the turnover rate of photosynthates in the leaves.
Kim Dockyu,Chae Namyi,Kim Mincheol,Nam Sungjin,Kim Tai Kyoung,Park Ki-Tea,Lee Bang Yong,Kim Eungbin,Lee Hyoungseok 한국미생물학회 2022 The journal of microbiology Vol.60 No.12
Recent rapid air temperature increases across the northernlatitude tundra have prolonged permafrost thawing and snow melting periods, resulting in increased soil temperature (Ts) and volumetric soil water content (SWC). Under prolonged soil warming at 8°C, Alaskan tundra soils were incubated in a microcosm system and examined for the SWC differential influence on the microbial decomposition activity of large molecular weight (MW) humic substances (HS). When one microcosm soil (AKC1-1) was incubated at a constant SWC of 41% for 90 days (T = 90) and then SWC was gradually decreased from 41% to 29% for another T = 90, the initial HS was partly depolymerized. In contrast, in AKC1-2 incubated at a gradually decreasing SWC from the initial 32% to 10% for T = 90 and then increasing to 27% for another T = 90, HS depolymerization was undetected. Overall, the microbial communities in AKC1-1 could maintain metabolic activity at sufficient and constant SWC during the initial T = 90 incubation. In contrast, AKC1-2 microbes may have been damaged by drought stress during the drying SWC regimen, possibly resulting in the loss of HS decomposition activity, which did not recover even after re-wetting to an optimal SWC range (20–40%). After T = 90, the CO2 production in both treatments was attributed to the increased decomposition of small-MW organic compounds (including aerobic HS-degradative products) within an optimal SWC range. We expect this study to provide new insights into the early effects of warming- and topography-induced SWC variations on the microbial contribution to CO2 emissions via HS decomposition in northern-latitude tundra soil.
Dockyu Kim,Namyi Chae,Mincheol Kim,Sungjin Nam,Eungbin Kim,Hyoungseok Lee 한국미생물학회 2020 The journal of microbiology Vol.58 No.12
Recent increases in air temperature across the Antarctic Peninsula may prolong the thawing period and directly affect the soil temperature (Ts) and volumetric soil water content (SWC) in maritime tundra. Under an 8°C soil warming scenario, two customized microcosm systems with maritime Antarctic soils were incubated to investigate the differential influence of SWC on the bacterial community and degradation activity of humic substances (HS), the largest constituent of soil organic carbon and a key component of the terrestrial ecosystem. When the microcosm soil (KS1-4Feb) was incubated for 90 days (T = 90) at a constant SWC of ~32%, the initial HS content (167.0 mg/g of dried soil) decreased to 156.0 mg (approximately 6.6% loss, p < 0.05). However, when another microcosm soil (KS1-4Apr) was incubated with SWCs that gradually decreased from 37% to 9% for T = 90, HS degradation was undetected. The low HS degradative activity persisted, even after the SWC was restored to 30% with water supply for an additional T = 30. Overall bacterial community structure remained relatively stable at a constant SWC setting (KS1-4Feb). In contrast, we saw marked shifts in the bacterial community structure with the changing SWC regimen (KS1-4Apr), suggesting that the soil bacterial communities are vulnerable to drying and re-wetting conditions. These microcosm experiments provide new information regarding the effects of constant SWC and higher Ts on bacterial communities for HS degradation in maritime Antarctic tundra soil.
Park, Kyung-Min,Chae, Namyi,Jung, Jae-Ho,Min, Gi-Sik,Kim, Sanghee,Berger, Helmut Elsevier 2017 EUROPEAN JOURNAL OF PROTISTOLOGY Vol.60 No.-
<P><B>Abstract</B></P> <P>The morphology of <I>Keronopsis helluo</I> Penard, 1922, type species of <I>Keronopsis</I>, and <I>Paraholosticha pannonica</I> Gellért and Tamás, 1959, two little-known members of the Keronopsidae Jankowski, 1979, was described using standard methods. In addition, we sequenced the SSU rRNA of both species. <I>Keronopsis helluo</I> was isolated from a mossy soil from Robert Island (Antarctica) while <I>P. pannonica</I> was found in terrestrial moss from Alaska. Our data correspond very well with the original descriptions. The frontal ciliature of <I>K. helluo</I> is identical with that of <I>Paraholosticha</I> spp., indicating that some <I>Keronopsis</I> species (<I>K. tasmaniensis</I>, <I>K. dieckmanni</I>) are misclassified in the keronopsids. The type species has distinctly more transverse cirri (8–13) than <I>K. wetzeli</I> (1–3), type species of <I>Parakeronopsis</I>, which is thus perhaps a valid genus or subgenus. The phylogenetic analyses confirm the position of the keronopsids outside the Dorsomarginalia. The species sequenced so far (<I>K. helluo</I>, <I>Paraholosticha muscicola</I>, <I>P. pannonica</I>) emerge from a soft polytomy, which also comprises <I>Bistichella</I>-like species and a large cluster composed of amphisiellids, trachelostylids, and gonostomatids, that is, the method failed to resolve the relationships within the keronopsids. The Keronopsidae and the two species studied are characterized based on previous studies and our data.</P>