Background: Soil microorganisms play key roles in nutrient cycling and are distributed throughout the soil profile. Currently, there is little information about the characteristics of the microbial communities along the soil depth because most studies focus on microorganisms inhabiting the soil surface. To better understand the functions and composition of microbial communities and the biogeochemical factors that shape them at different soil depths, we analyzed microbial activities and bacterial and fungal community composition in soils up to a 120 cm depth at a fallow field located in central Korea. To examine the vertical difference of microbial activities and community composition, β-1,4-glucosidase, cellobiohydrolase, β-1,4-xylosidase, β-1,4-N-acetylglucosaminidase, and acid phosphatase activities were analyzed and barcoded pyrosequencing of 16S rRNA genes (bacteria) and internal transcribed spacer region (fungi) was conducted. Results: The activity of all the soil enzymes analyzed, along with soil C concentration, declined with soil depth. For example, acid phosphatase activity was 125.9 (± 5.7 (± 1 SE)), 30.9 (± 0.9), 15.7 (± 0.6), 6.7 (± 0.9), and 3.3 (± 0.3) nmol g −1 h −1 at 0-15, 15-30, 30-60, 60-90, and 90-120 cm soil depths, respectively. Among the bacterial groups, the abundance of Proteobacteria (38.5, 23.2, 23.3, 26.1,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], and 90-120 cm soil depths, respectively) and Firmicutes (12.8, 11.3, 8.6, 4.3,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], and 90-120 cm soil depths, respectively) decreased with soil depth. On the other hand, the abundance of Ascomycota (51. 2, 48.6, 65.7, 46.1, and 45.7% at 15, 30, 60, 90, and 120 cm depths, respectively), a dominant fungal group at this site, showed no clear trend along the soil profile. Conclusions: Our results show that soil C availability can determine soil enzyme activity at different soil depths and that bacterial communities have a clear trend along the soil depth at this study site. These metagenomics studies, along with other studies on microbial functions, are expected to enhance our understanding on the complexity of soil microbial communities and their relationship with biogeochemical factors.

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Carbon capture and storage (CCS) technology, a process consisting of the separation and capture of CO2 from point sources and injection into deep geological reservoirs for long‐term isolation from the atmosphere, is considered to be a promising technology that can mitigate global climate change. However, the risk of CO2 leakage from storage sites exists, and thus its impact on ecosystem functions needs to be understood for safe implementation of CCS. Plant and microbial parameters were monitored in artificial CO2 release experiments in the field and in greenhouses. In addition, plants and microorganisms were monitored in CO2 storage sites. We review the findings from these studies and suggest directions of future research for determining the impact of potential CO2 leakage from CCS sites on plants and microorganisms. Our review showed that under high levels of soil CO2, (i) plant stress response was visible within short period of time; (ii) dicots were more sensitive than monocots in most studies; and (iii) the responses of microorganisms were more diverse and harder to generalize than those of plants. Only a limited number of field and greenhouse experimental studies have been conducted so far, and thus more field and greenhouse experimental studies are needed to better understand the plant and microbial response to elevated soil CO2 levels and elucidate specific mechanisms underlying these responses. Determining the ecological impacts of geological CO2 storage and ensuring its environmental safety via such research will make CCS a more viable technology. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd

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This study was conducted to analyze CO 2 migration from a shallow CO 2 release experiment using a continuous soil CO 2 flux measurement system. Approximately 1.8 t CO 2 was injected from 1 to 30 June 2016 through the point sources with perforated release wells laid at 2.5-m soil depth. Using LI-8100A instruments, CO 2 concentration, CO 2 flux, soil temperature, soil moisture, relative humidity, and atmospheric pressure were continuously measured every 30 min at 0, 1.5, 3.0, 4.5, and 6.0 m from the well from 29 May to 4 August 2016. Typically sensors for soil temperature and moisture were installed at 5-cm depth, and CO 2 concentration, relative humidity, and atmospheric pressure were measured at the chambers. The CO 2 flux was not maximum directly above the release well. Carbon dioxide flux at 6.0 m from the well was similar to the background level. The relationship between CO 2 flux and environmental factors, described using a temporal correlation analysis, indicated that CO 2 flux was primarily driven by soil temperature and had the inverse correlation with relative humidity and atmospheric pressure. Heavy rainfall inhibited in-soil CO 2 migration by filling the soil pore with water. The anomalously high CO 2 flux detected at 1.5 m from the well may have been caused by the associated permeability structure, in which a permeability discrepancy leads to the vertical or horizontal flow of in-soil CO 2. These findings from this shallow CO 2 release experiment should be considered as basic information to characterize and model the in-soil CO 2 transport related to CO 2 leakage. 1 INTRODUCTION International concern about global warming is continually increasing because of its wide impacts on the envi-Abbreviations: CCS, carbon capture and storage; EIT, Environmental Impact Assessment Test Facility. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Major objectives of the study were to analyze chemical and biological influences of the river ecosystem on the artificial weir construction at three regions of Sejong-Weir (S j -W), Gongju-Weir (G j -W), and Baekje-Weir (B j -W) during 2008-2012. After the weir construction, the discharge volume increased up to 2.9 times, and biological oxygen demand (BOD) and electrical conductivity (EC) significantly decreased (p < 0.05). Also, the decrease of total phosphorus (TP) was also evident after the weir construction, but still hyper-eutrophic conditions, based on criteria by OECD (1982), were maintained. Multi-metric model of Index of Biological Integrity (IBI) showed that IBI values averaged 21.0 (range: 20-22; fair condition) in the B wc , and 14.3 (range: 12-18; poor condition) in the A wc . The model values of IBI in S j -W and G j -W were significantly decreased after the weir construction. The model of Self-Organizing Map (SOM) showed that two groups (cluster I and cluster II) of B wc and A wc were divided in the analysis based on the clustering map trained by the SOM. Principal Component Analysis (PCA) was similar to the results of the SOM analysis. Taken together, this research suggests that the weir construction on the river modified the discharge volume and the physical habitat structures along with distinct changes of some chemical water quality. These physical and chemical factors influenced the ecosystem health, measured as a model value of IBI.