Application of colorimetric sensor in monitoring dissolved CO2 in natural waters.

Dissolved CO2 originating from underground structures at high concentrations may pose a threat to public and environmental health. Therefore, a convenient monitoring technique that allows fast detection of dissolved CO2 needs to be developed. In this study, a low-cost colorimetric CO2 sensor was applied for monitoring dissolved CO2. The sensor is composed of an acrylic reactor, cresol red pH indicator solution, and a gas-permeable membrane, and the performance of the sensor was tested for the detection of dissolved CO2 at the range of 2-800 mg CO2 L-1. Color change of the detection solution within the sensor was mainly dependent on CO2 dissolved in the water sample. This was analyzed using an RGB program that extracts the red, green, and blue intensity of a target color on a scale of 0-255. ΔGB, an index of CO2 concentration corresponding to the change in intensity of green (G) and blue (B) extracted by the RGB program, exhibited a linear relationship with dissolved CO2 concentrations (r2 > 0.95, p < 0.005). In the field, the sensor was able to measure dissolved CO2 between 10 and 411 mg CO2 L-1 within 1 min. Overall, our CO2 sensor has high potential to be used in detection of dissolved CO2 in groundwater and surface waters.

Large-scale solvothermal synthesis of fluorescent carbon nanoparticles.

The large-scale production of high-quality carbon nanomaterials is highly desirable for a variety of applications. We demonstrate a novel synthetic route to the production of fluorescent carbon nanoparticles (CNPs) in large quantities via a single-step reaction. The simple heating of a mixture of benzaldehyde, ethanol and graphite oxide (GO) with residual sulfuric acid in an autoclave produced 7 g of CNPs with a quantum yield of 20%. The CNPs can be dispersed in various organic solvents; hence, they are easily incorporated into polymer composites in forms such as nanofibers and thin films. Additionally, we observed that the GO present during the CNP synthesis was reduced. The reduced GO (RGO) was sufficiently conductive (σ ≈ 282 S m(-1)) such that it could be used as an electrode material in a supercapacitor; in addition, it can provide excellent capacitive behavior and high-rate capability. This work will contribute greatly to the development of efficient synthetic routes to diverse carbon nanomaterials, including CNPs and RGO, that are suitable for a wide range of applications.

Fluorescence microfluidic system for real-time monitoring of PS and PVC sub-micron microplastics under flowing conditions.

Plastics, recognized for their convenience, disposability, and recyclability, have emerged as a significant ecological challenge, particularly with the prevalence of microplastics (MPs, 1 µm - 5 mm) and sub-micron MPs (100 - 1000 nm) in natural environments. While extensive research has focused on their occurrence and environmental impacts, quantification methods developed for MPs exhibit limitations when applied to sub-micron MPs due to their smaller size. This study addresses these limitations by introducing a novel monitoring system that integrates fluorescence labeling with a microfluidic device and particle tracking software, enabling automated quantification and size measurement of both spherical and fragmented MPs of size in the sub-micrometer range. Results showed that the developed system enabled fast quantification and size measurement of 500- and 1000-nm polystyrene (PS) sub-micron MP beads and fragmented PS and polyvinyl chloride (PVC) sub-micron MPs. Additionally, fluorescence labeling enabled the real-time discrimination of PS and PVC sub-micron MPs. Lastly, the microfluidic system allowed the monitoring of sub-micron MPs within a small quantity of water samples. This automated system has a high potential for swift and real-time monitoring of sub-micron MPs in the environment. By enhancing our ability to detect and quantify sub-micron MPs, this study contributes to a more comprehensive understanding of their presence and distribution in environmental systems.

Analysis of micro(nano)plastics based on automated data interpretation and modeling: A review.

The widespread presence of micro(nano)plastics (MNPs) in the environment threatens ecosystem integrity, and thus, it is necessary to determine and assess the occurrence, characteristics, and transport of MNPs between ecological components. However, most analytical approaches are cost- and time-inefficient in providing quantitative information with sufficient detail, and interpreting results can be difficult. Alternative analyses integrating novel measurements by imaging or proximal sensing with signal processing and machine learning may supplement these approaches. In this review, we examined published research on methods used for the automated data interpretation of MNPs found in the environment or those artificially prepared by fragmenting bulk plastics. We critically reviewed the primary areas of the integrated analytical process, which include sampling, data acquisition, processing, and modeling, applied in identifying, classifying, and quantifying MNPs in soil, sediment, water, and biological samples. We also provide a comprehensive discussion regarding model uncertainties related to estimating MNPs in the environment. In the future, the development of routinely applicable and efficient methods is expected to significantly contribute to the successful establishment of automated MNP monitoring systems.

Energy deprivation affects nitrogen assimilation and fatty acid biosynthesis leading to leaf chlorosis under waterlogging stress in the endangered Abies koreana.

Energy deprivation triggers various physiological, biochemical and molecular changes in plants under abiotic stress. We investigated the oxidative damages in the high altitude grown conifer Korean fir (Abies koreana) exposed to waterlogging stress. Our experimental results showed that waterlogging stress led to leaf chlorosis, 35 days after treatment. A significant decrease in leaf fresh weight, chlorophyll and sugar content supported this phenotypic change. Biochemical analysis showed a significant increase in leaf proline, lipid peroxidase and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical content of waterlogged plants. To elucidate the molecular mechanisms, we conducted RNA-sequencing (RNA-seq) and de novo assembly. Using RNA-seq analysis approach and filtering (P < 0.05 and false discovery rate <0.001), we obtained 134 unigenes upregulated and 574 unigenes downregulated. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis placed the obtained differentially expressed unigenes in α-linoleic pathway, fatty acid degradation, glycosis, glycolipid metabolism and oligosaccharide biosynthesis process. Mapping of unigenes with Arabidopsis using basic local alignment search tool for nucleotides showed several critical genes in photosynthesis and carbon metabolism downregulated. Following this, we found the repression of multiple nitrogen (N) assimilation and nucleotide biosynthesis genes including purine metabolism. In addition, waterlogging stress reduced the levels of polyunsaturated fatty acids with a concomitant increase only in myristic acid. Together, our results indicate that the prolonged snowmelt may cause inability of A. koreana seedlings to lead the photosynthesis normally due to the lack of root intercellular oxygen and emphasizes a detrimental effect on the N metabolic pathway, compromising this endangered tree's ability to be fully functional under waterlogging stress.

Synthesis of monoclinic potassium niobate nanowires that are stable at room temperature.

We report the synthesis of KNbO(3) nanowires (NWs) with a monoclinic phase, a phase not observed in bulk KNbO(3) materials. The monoclinic NWs can be synthesized via a hydrothermal method using metallic Nb as a precursor. The NWs are metastable, and thermal treatment at ∼450 °C changed the monoclinic phase into the orthorhombic phase, which is the most stable phase of KNbO(3) at room temperature. Furthermore, we fabricated energy-harvesting nanogenerators by vertically aligning the NWs on SrTiO(3) substrates. The monoclinic NWs showed significantly better energy conversion characteristics than orthorhombic NWs. Moreover, the frequency-doubling efficiency of the monoclinic NWs was ∼3 times higher than that of orthorhombic NWs. This work may contribute to the synthesis of materials with new crystalline structures and hence improve the properties of the materials for various applications.

Experimental warming studies on tree species and forest ecosystems: a literature review.

Temperature affects a cascade of ecological processes and functions of forests. With future higher global temperatures being inevitable it is critical to understand and predict how forest ecosystems and tree species will respond. This paper reviews experimental warming studies in boreal and temperate forests or tree species beyond the direct effects of higher temperature on plant ecophysiology by scaling up to forest level responses and considering the indirect effects of higher temperature. In direct response to higher temperature (1) leaves emerged earlier and senesced later, resulting in a longer growing season (2) the abundance of herbivorous insects increased and their performance was enhanced and (3) soil nitrogen mineralization and leaf litter decomposition were accelerated. Besides these generalizations across species, plant ecophysiological traits were highly species-specific. Moreover, we showed that the effect of temperature on photosynthesis is strongly dependent on the position of the leaf or plant within the forest (canopy or understory) and the time of the year. Indirect effects of higher temperature included among others higher carbon storage in trees due to increased soil nitrogen availability and changes in insect performance due to alterations in plant ecophysiological traits. Unfortunately only a few studies extrapolated results to forest ecosystem level and considered the indirect effects of higher temperature. Thus more intensive, long-term studies are needed to further confirm the emerging trends shown in this review. Experimental warming studies provide us with a useful tool to examine the cascade of ecological processes in forest ecosystems that will change with future higher temperature.

High concentrations of single-walled carbon nanotubes lower soil enzyme activity and microbial biomass.

Nanomaterials such as single-walled carbon nanotubes (SWCNTs) may enter the soil environment with unknown consequences resulting from the development of nanotechnology for a variety of applications. We determined the effects of SWCNTs on soil enzyme activity and microbial biomass through a 3-week incubation of urban soils treated with different concentrations of SWCNTs ranging from 0 to 1000 µg g(-1) soil. The activities of cellobiohydrolase, ß-1,4-glucosidase, ß-1,4-xylosidase, ß-1,4-N-acetylglucosaminidase, L-leucine aminopeptidase, and acid phosphatase and microbial biomass were measured in soils treated with powder and suspended forms of SWCNTs. SWCNTs of concentrations at 300-1000 µg g(-1) soil significantly lowered activities of most enzymes and microbial biomass. It is noteworthy that the SWCNTs showed similar effects to that of multi-walled carbon nanotubes (MWCNTs), but at a concentration approximately 5 times lower; we suggest that this is mainly due to the higher surface area of SWCNTs than that of MWCNTs. Indeed, our results show that surface area of CNTs has significant negative relationship with relative enzyme activity and biomass, which suggests that greater microorganism-CNT interactions could increase the negative effect of CNTs on microorganisms. Current work may contribute to the preparation of a regulatory guideline for the release of CNTs to the soil environment.

Effects of different sizes of polystyrene micro(nano)plastics on soil microbial communities.

Micro(nano)plastic (MNP) pollution in soil environments is a major concern, but the effects of different sizes of MNPs on soil microbial communities, which are crucial in nutrient cycling, has not been well investigated. In this study, we aimed to determine the effects of polystyrene (PS) MNPs of different sizes (0.05-, 0.5-, and 5-µm) on soil microbial activity and community composition. Changes in inorganic N concentration, microbial biomass, and extracellular enzyme activities were determined in soils treated with 100 and 1000 µg PS MNPs g-1 soil during a 40-d incubation experiment. Soil microbial biomass was significantly lowered when soils were treated with 0.5- or 5-µm MNPs at 100 and 1000 µg PS MNPs g-1 soil. NH4+ concentration was higher in soils treated with 5-µm MNPs at 100 and 1000 µg g-1 soil than in the control soils at day 1, suggesting that MNPs inhibited the soil nitrification in short term. In contrast, extracellular enzyme activity was not altered by MNPs. The composition of microbial communities analyzed by Illumina MiSeq sequencing changed; particularly, the relative abundance of several bacteria related to N cycling, such as the genus Rhizomicrobium belonging to Alphaproteobacteria was decreased by 0.5- and 5-µm MNPs. Our study shows that the size of MNPs is an important factor that can determine their effects on soil microbial communities. Therefore, the size effects need to be considered in assessing the environmental impacts of MNPs.

Resistance random access memory based on a thin film of CdS nanocrystals prepared via colloidal synthesis.

We demonstrate that resistance random access memory (RRAM) can be fabricated based on CdS-nanocrystal thin films. A simple drop-drying of the CdS-nanocrystal solution leads to the formation of uniform thin films with controlled thickness. RRAMs with a Ag/Al(2) O(3) /CdS/Pt structure show bipolar switching behavior, with average values of the set voltage (V(Set) ) and reset voltage (V(Reset) ) of 0.15 V and -0.19 V, respectively. The RRAM characteristics are critically influenced by the thickness of the Al(2) O(3) barrier layer, which prevents significant migration of Ag into the CdS layer as revealed by Auger electron spectroscopy (AES). Interestingly, RRAM without an Al(2) O(3) layer (i.e., Ag/CdS/Pt structure) also shows bipolar switching behavior, but the polarity is opposite to that of RRAM with the Al(2) O(3) layer (i.e., Ag/Al(2) O(3) /CdS/Pt structure). The operation of both kinds of devices can be explained by the conventional conductive bridging mechanism. Additionally, we fabricated RRAM devices on Kapton film for potential applications in flexible electronics, and the performance of this RRAM device was comparable to that of RRAMs fabricated on hard silicon substrates. Our results show a new possibility of using chalcogenide nanocrystals for RRAM applications.

High-performance supercapacitors based on vertically aligned carbon nanotubes and nonaqueous electrolytes.

We demonstrate the high performance of supercapacitors fabricated with vertically aligned carbon nanotubes and nonaqueous electrolytes such as ionic liquids and conventional organic electrolytes. Specific capacitance, maximum power and energy density of the supercapacitor measured in ionic liquid were ~75 F g(-1), ~987 kW kg(-1) and ~27 W h kg(-1), respectively. The high power performance was consistently indicated by a fast relaxation time constant of 0.2 s. In addition, electrochemical oxidation of the carbon nanotubes improved the specific capacitance (~158 F g(-1)) and energy density (~53 W h kg(-1)). Both high power and energy density could be attributed to the fast ion transport realized by the alignment of carbon nanotubes and the wide operational voltage defined by the ionic liquid. The demonstrated carbon-nanotube- and nonaqueous-electrolyte-based supercapacitors show great potential for the development of high-performance energy storage devices.

All-solid-state flexible supercapacitors based on papers coated with carbon nanotubes and ionic-liquid-based gel electrolytes.

All-solid-state flexible supercapacitors were fabricated using carbon nanotubes (CNTs), regular office papers, and ionic-liquid-based gel electrolytes. Flexible electrodes were made by coating CNTs on office papers by a drop-dry method. The gel electrolyte was prepared by mixing fumed silica nanopowders with ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf(2)]). This supercapacitor showed high power and energy performance as a solid-state flexible supercapacitor. The specific capacitance of the CNT electrodes was 135 F g(-1) at a current density of 2 A g(-1), when considering the mass of active materials only. The maximum power and energy density of the supercapacitors were 164 kW kg(-1) and 41 Wh kg(-1), respectively. Interestingly, the solid-state supercapacitor with the gel electrolyte showed comparable performance to the supercapacitors with ionic-liquid electrolyte. Moreover, the supercapacitor showed excellent stability and flexibility. The CNT/paper- and gel-based supercapacitors may hold great potential for low-cost and high-performance flexible energy storage applications.

The effect of multi-walled carbon nanotubes on soil microbial activity.

Nanomaterials such as multi-walled carbon nanotubes (MWCNTs) are applied to various industrial products and thus may be released to soils, but their potential environmental impacts remain largely undetermined. We investigated the short-term effect of MWCNTs on the activity and biomass of microorganisms inhabiting two different soil types in an incubation study. Up to 5000 µg MWCNT g(-1) soil was applied and the activities of 1,4-ß-glucosidase, cellobiohydrolase, xylosidase, 1,4-ß-N-acetylglucosaminidase, and phosphatase and microbial biomass were measured. In both soil types, most enzyme activities showed a tendency to be repressed under 500 µg MWCNT g(-1) soil, and all enzymatic activities as well as microbial biomass C and N were significantly lowered under 5000 µg MWCNT g(-1) soil. Our results suggest that high concentrations of MWCNTs could lower the microbial activity and biomass in soils, and they may serve as an important guideline in regulating the release of MWCNTs to the soil environment.

Effects of Graphene Oxide on Germination and Early Growth of Plants.

Owing to its excellent material properties such as large surface area and superb mechanical and thermal characteristics, graphene oxide (GO) is likely to be applied in a variety of environmental fields. These applications may lead to the entrance of GO in terrestrial ecosystems, but there is little research regarding the impact of GO on plants upon such entrances. To analyze the effects of GO on the germination and growth of various plants, the changes in lettuce, radish, perennial ryegrass, alfalfa, and cucumber seeds under GO treatment was studied. Germination rate and growth were analyzed after the seeds were exposed to GO at 0, 0.2, 0.4, 0.8, and 1.6 mg ml-1. For lettuce, the germination rate decreased with GO concentration. However, no significant effects were observed on the germination rate of other plants. On the other hand, the growth of lettuce, alfalfa, and radish decreased under GO treatment. For example, at 1.6 mg ml-1 of GO, the length of shoot and root of lettuce was shortened by 87% and 86%, respectively. Such results indicate that the germination and early growth of plants can be negatively affected in a species-specific manner under high concentrations of GO. Hence, we anticipate that our results may assist in supplementing the legal regulations for the proper disposal of nanomaterials.

Fabrication of monolithic polymer nanofluidic channels using nanowires as sacrificial templates.

We report a facile and reliable method to fabricate polymer-based monolithic nanofluidic channels. The nanochannels are obtained via three main steps: (1) fabrication of nanowire-transistor like structures, which are silver or zinc oxide nanowires horizontally bridging two electrodes made of zinc oxide on SiO(2)/Si substrates; (2) casting and curing polyimide solution on the nanowire structures; and (3) selective etching of the nanowire and electrode templates against the polyimide substrates. This process leads to the production of nanochannels with a diameter down to ∼ 50 nm. Our method is based on nanowires that are chemically synthesized whereas nanopattern fabrication conventionally relies on expensive equipment. Moreover, the polymer nanochannels are fabricated monolithically while a process of bonding two different materials is required in traditional methods where leakage problems are often identified at the interface. Construction of nanofluidic circuitry could be expected in the future based on the current work.

Highly efficient colorimetric CO2 sensors for monitoring CO2 leakage from carbon capture and storage sites.

Carbon capture and storage (CCS) technology used for reducing anthropogenic CO2 emissions involves the capture of CO2 from industrial sources and its injection into geological sinks, such as oil reservoirs and abandoned gas fields. To ensure environmental and public safety in implementing CCS technology, efficient CO2-monitoring technology must be developed to detect potential CO2 leakage from CCS sites. Conventional CO2 sensors used for monitoring CCS sites are typically high in cost and require professional staff for maintenance. In this study, we developed a portable and low-cost colorimetric CO2 sensor with high soil CO2 detection efficiency for CCS sites. The sensor consists of a detection solution that contains the pH indicator cresol red encapsulated with a gas-permeable membrane. When CO2 enters the sensor through the membrane, the color of the pH indicator changes and this was quantified using an RGB (red, green, blue) application (app), an app that measures the RGB values of a given color. The change in G and B values of the detection solution showed a significant linear relationship with soil CO2 concentration determined via non-dispersive infra-red (NDIR) CO2 sensor (r2 = 0.98, p = 0.001), and thus these values were used for quantification of CO2 concentration. Tests using CO2-injection chamber showed that the optical CO2 sensors can detect soil CO2 concentration of 0.1 to 30% within a few minutes. Field studies conducted at a natural CO2 vent and an artificial CO2 leakage site showed that the optical CO2 sensors can be applied in analyzing surficial CO2 leakage patterns. The advantage of this optical CO2 sensor when applied to field monitoring is that it is inexpensive and has few installation restrictions. Therefore, this optical CO2 sensor has a strong potential for use in monitoring CO2 leakages from CCS sites.

Effects of silver-graphene oxide on seed germination and early growth of crop species.

Due to its excellent material properties, silver-graphene oxide (Ag-GO) is being studied for diverse applications, such as antimicrobial agents, catalysts and absorbents. Such use of Ag-GO may lead to its release into terrestrial ecosystems, but little is known about the impact of Ag-GO on plants. In the present study, we determined the effects of Ag-GO on seed germination and early growth of crop species by analyzing the germination rate, growth of roots and shoots, hydrogen peroxide (H2O2) accumulation, and the uptake of Ag in alfalfa, radish and cucumber treated with 0.2-1.6 mg mL-1 of Ag-GO. Ag-GO treatment increased the shoot growth of radish at 0.2-1.6 mg mL-1 but decreased that of cucumber at 0.8 mg mL-1. In addition, Ag-GO enhanced the root elongation of radish at 0.2 mg mL-1 but inhibited that of alfalfa at 0.2, 0.8 and 1.6 mg mL-1. Ag-GO treatment induced H2O2 production in alfalfa, radish and cucumber in a concentration-dependent manner. Larger amounts of Ag accumulated in the seedlings as the concentration of Ag-GO increased, and such accumulation suggests that Ag may be transferred to higher trophic levels when plants are exposed to Ag-GO in ecosystems. Our study can, thus, serve as an important basis for setting guidelines for the release of nanomaterials into the environment.

Effects of graphene oxides and silver-graphene oxides on aquatic microbial activity.

Graphene oxide (GO) and silver-graphene oxide (Ag-GO) are used in various fields, such as biotechnology and environmental engineering, due to their unique material properties, including hydrophilicity, high surface area, mechanical strength, and antibacterial activity. With the increase in the usage of such nanomaterials, they are likely to enter the aquatic environment during the manufacturing process, product use, and disposal. However, the effects of GO and Ag-GO on aquatic microbial activities are not well understood. In this study, we aimed to determine the effects of GO and Ag-GO on the aquatic microbial communities inhabiting a river and a lake located in Seoul, South Korea. Unfiltered natural surface water samples were exposed to GO and Ag-GO at a final concentration of 10 to 100 mg L-1 for 48 h. The activity of leucine aminopeptidase was significantly lowered within 1 h of GO and Ag-GO treatments and nitrification rate was significantly lowered. An increase in intracellular lactate dehydrogenase levels of up to 5% was observed in natural waters under GO and Ag-GO treatments compared to the control (0%), indicating cell membrane damage. In addition, generation of intracellular reactive oxygen species increased up to 184% under 100 mg GO L-1 and 102% under 100 mg Ag-GO L-1 treatment compared to the control (0%). Our results indicate that the activities of microorganisms inhabiting natural surface waters may have been inhibited by oxidative stress and cell membrane damage induced by GO and Ag-GO. We believe that our results may contribute to the development of regulatory guidelines on the release of emerging engineered nanomaterials to the environment.

Effects of silver-graphene oxide nanocomposites on soil microbial communities.

Due to the application of silver-graphene oxide (Ag-GO) in diverse fields, it is important to investigate its potential impacts on the environment including soils. In this study, the response of microbial communities in soils treated with Ag-GO synthesized by glucose reduction was determined by analyzing enzyme activities, biomass, and inorganic N concentrations and by pyrosequencing. In soils treated with 0.1-1 mg Ag-GO g-1 soil, the activities of ß-glucosidase, cellobiohydrolase, and xylosidase decreased up to 80% and NO3- concentration decreased up to 82% indicating inhibited nitrification. Within the bacterial community, the relative abundance of Acidobacteria and Cyanobacteria in soils treated with Ag-GO were lower than that in control soil. Meanwhile, the relative abundance of AD3 and Firmicutes tended to increase under Ag-GO treatments. These changes in bacterial community composition reflected lowered activities associated with C and N cycling. On the other hand, microbial biomass showed no distinct change in response to Ag-GO treatment. Our study can serve as important basis in establishing guidelines for regulating the release of nanocomposites such as Ag-GO to the soil environment.

Increased N2O emission by inhibited plant growth in the CO2 leaked soil environment: Simulation of CO2 leakage from carbon capture and storage (CCS) site.

Atmospheric carbon dioxide (CO2) concentrations is continuing to increase due to anthropogenic activity, and geological CO2 storage via carbon capture and storage (CCS) technology can be an effective way to mitigate global warming due to CO2 emission. However, the possibility of CO2 leakage from reservoirs and pipelines exists, and such leakage could negatively affect organisms in the soil environment. Therefore, to determine the impacts of geological CO2 leakage on plant and soil processes, we conducted a greenhouse study in which plants and soils were exposed to high levels of soil CO2. Cabbage, which has been reported to be vulnerable to high soil CO2, was grown under BI (no injection), NI (99.99% N2 injection), and CI (99.99% CO2 injection). Mean soil CO2 concentration for CI was 66.8-76.9% and the mean O2 concentrations in NI and CI were 6.6-12.7%, which could be observed in the CO2 leaked soil from the pipelines connected to the CCS sites. The soil N2O emission was increased by 286% in the CI, where NO3--N concentration was 160% higher compared to that in the control. This indicates that higher N2O emission from CO2 leakage could be due to enhanced nitrification process. Higher NO3--N content in soil was related to inhibited plant metabolism. In the CI treatment, chlorophyll content decreased and chlorosis appeared after 8th day of injection. Due to the inhibited root growth, leaf water and nitrogen contents were consistently lowered by 15% under CI treatment. Our results imply that N2O emission could be increased by the secondary effects of CO2 leakage on plant metabolism. Hence, monitoring the environmental changes in rhizosphere would be very useful for impact assessment of CCS technology.