CCS scenarios optimization by spatial multi-criteria analysis: Application to multiple source sink matching in Hebei province

A method, based on spatial analysis of the different criteria to be taken into consideration for building scenarios of CO₂ capture and storage (CCS), has been developed and applied to real case studies in the Hebei province. Totally 88 point sources (42 from power sector, 9 from iron and steel, 18 from cement, 16 from ammonia, and 3 from oil refinery) are estimated and their total emission amounts to 231.7 MtCO₂/year with power, iron and steel, cement, ammonia and oil refinery sharing 59.13%, 25.03%, 11.44%, 3.5%, and 0.91%, respectively. Storage opportunities can be found in Hebei province, characterised by a strong tectonic subsidence during the Tertiary, with several kilometres of accumulated clastic sediments. Carbon storage potential for 25 hydrocarbon fields selected from the Huabei complex is estimated as 215 MtCO₂ with optimistic assumption that all recovered hydrocarbon could be replaced by an equivalent volume of CO₂ at reservoir conditions. Storage potential for aquifers in the Miocene Guantao formation is estimated as 747 MtCO₂ if closed aquifer assumed or 371 MtCO₂ if open aquifer and single highly permeable horizon assumed. Due to poor knowledge on deep hydrogeology and to pressure increase in aquifer, injecting very high rates requested by the major CO₂ sources (>10 MtCO₂/year) is the main challenge, therefore piezometry and discharge must be carefully controlled. A source sink matching model using ArcGIS software is designed to find the least-cost pathway and to estimate transport route and cost accounting for the additional costs of pipeline construction due to landform and land use. Source sink matching results show that only 15–25% of the emissions estimated for the 88 sources can be sequestrated into the hydrocarbon fields and the aquifers if assuming sinks should be able to accommodate at least 15 years of the emissions of a given source.     

Combination of ion exchange system and biological reactors for simultaneous removal of ammonia and organics

A novel process for a simultaneous removal of ammonia and organics was developed on the basis of ion exchange and biological reactions. From batch experiments, it was found out that NH₄⁺ could be removed effectively by combining cation exchange and biological nitrification showing 0.98 mg N/m²?s of a maximum flux. On the other hand, the removal of NO₃⁻ was 3.5 times faster than NH₄⁺ and the maximum flux was calculated to be 3.4 mg N/m²?s. The systems for NH₄⁺ and NO₃⁻ removal were combined for establishing the IEBR process. When the process was operated in a continuous mode, approximately 95.8% of NH₄⁺ was removed showing an average flux of 0.22 mg N/m²·s. The removal efficiency of total nitrogen was calculated as 94.5% whereas that of organics was 99.5%. It was concluded that the IEBR process would be effectively used for a simultaneous removal of NH₄⁺ and organics.     

Low-impact development for impervious surface connectivity mitigation: assessment of directly connected impervious areas (DCIAs)

Urbanization increases directly connected impervious area (DCIA), the impervious area that is hydraulically connected to downstream drainage by closed pipelines. Although the benefits of low-impact development (LID) have been examined in other studies, its effect on alleviating DCIA levels has seldom been assessed. This study measured the DCIA of urban watersheds in Houston, TX, USA. Five land-use types were categorized and the contribution of LID facilities to reducing DCIA in each type was estimated by using Sutherland's equations. The results showed (1) DCIA in commercial areas was greater than that in residential areas, especially for big-box retailers; (2) the percentage of DCIA reduction by LID varied by land-use type; and (3) optimal combinations of LID application could maximize the effectiveness of DCIA reduction. The results contribute to prioritizing land-use type for implementing LID practices and providing local governments with a useful measure to estimate runoff volume.     

Cranes,Crops and Conservation: Understanding Human Perceptions of Biodiversity Conservation in South Korea’s Civilian Control Zone

South Korea’s Civilian Control Zone (CCZ), a relatively untouched area due to tight military oversight since the end of Korean War, has received considerable attention nationally and internationally for its rich biodiversity. However, the exclusion of local communities from the process of defining problems and goals and of setting priorities for biodiversity conservation has halted a series of biodiversity conservation efforts. Through qualitative research, we explored CCZ farmers’ views of key problems and issues and also the sources of their opposition to the government-initiated conservation approaches. Key findings include the farmers’ concerns about the impact of conservation restrictions on their access to necessary resources needed to farm, wildlife impacts on the value of rice and other agricultural goods they produce, and farmers’ strong distrust of government, the military, and planners, based on their experiences with past conservation processes. The findings regarding farmers’ perceptions should prove useful for the design of future participatory planning processes for biodiversity conservation in the CCZ. This case highlights how conservative measures, perceived to be imposed from above—however scientifically valuable—can be undermined and suggests the value that must be placed on communication among planners and stakeholders.     

Effects of NO,NO<Subscript>2</Subscript>, CO and SO<Subscript>2</Subscript> on NO oxidation over Pt/TiO<Subscript>2</Subscript> for hybrid fast SCR process

The selective catalytic reduction (SCR) rate of NO with N-containing reducing agents can be enhanced considerably by converting part of NO into NO₂. The enhanced reaction rate is more pronounced even at lower temperatures by using an equimolar mixture of NO and NO₂ (fast SCR reaction). The oxidation characteristics of NO over catalyst Pt/TiO₂ have been determined in a fixed bed reactor (8 mm-ID) with different concentrations of oxygen, nitric oxide and nitrogen dioxide in the presence of 8% water. The conversion of NO to NO₂ increases with increasing oxygen (O₂) concentration from 3 to 12%, but it levels off at higher O₂ concentrations. The NO conversion to NO₂ decreases with increasing NO concentration and it also decreases by an addition of NO₂ in the feed stream. Therefore, the oxidation of NO over Pt/TiO₂ catalyst could be auto-inhibited by the reaction product of NO₂. The effects of CO and SO₂ on NO oxidation characteristics have also been determined. In fact, the presence of SO₂ significantly suppresses oxidation of NO but due to the less stability of sulfate on anatase structure in TiO₂, it becomes less significant. On the other hand, the presence of CO increases NO oxidation significantly due to the auto-inhibition effect by CO. Moreover, the effect of SO₂/CO on NO oxidation has also been determined and it was observed that NO oxidation decreases with the increase in SO₂/CO ratio.     

Habitat and Biodiversity of On-Farm Water Storages: A Case Study in Southeast Queensland, Australia

On-farm water storages (locally known as farm dams or farm ponds) are an important part of many agricultural landscapes, as they provide a reliable source of water for irrigation and stock. Although these waterbodies are artificially constructed and morphologically simple, there is increasing interest in their potential role as habitat for native flora and fauna. In this article, we present results from a case study which examined the habitat characteristics (such as water physical and chemical parameters, benthic metabolism, and macrophyte cover) and the macrophyte and macroinvertebrate biodiversity of eight farm ponds on four properties in the Stanley Catchment, Southeast Queensland, Australia. Each landowner was interviewed to allow a comparison of the management of the ponds with measured habitat and biodiversity characteristics, and to understand landowners’ motivations in making farm pond management decisions. The physical and chemical water characteristics of the study ponds were comparable to the limited number of Australian farm ponds described in published literature. Littoral zones supported forty-five macroinvertebrate families, with most belonging to the orders Hemiptera, Coleoptera, Odonata, and Diptera. Invertebrate community composition was strongly influenced by littoral zone macrophyte structure, with significant differences between ponds with high macrophyte cover compared to those with bare littoral zones. The importance of littoral zone macrophytes was also suggested by a significant positive relationship between invertebrate taxonomic richness and macrophyte cover. The landowners in this study demonstrated sound ecological knowledge of their farm ponds, but many had not previously acknowledged them as having high habitat value for native flora and fauna. If managed for aquatic organisms as well as reliable water sources, these artificial habitats may help to maintain regional biodiversity, particularly given the large number of farm ponds across the landscape.     

Source identification and characterization of the accumulating non-biodegradable organics in Korean reservoirs

An increase in the chemical oxygen demand (COD) has been noticed in most Korean reservoirs. Therefore, this research systematically investigated the causes of organic accumulation. Samples of soil affecting the quality of water of reservoirs were collected at various sources and analyzed for their organic characteristics. The COD to biochemical oxygen demand (BOD) ratio was used as the key parameter in the evaluation of non-biodegradable (NBD) organic accumulation in the reservoirs. Soil samples containing plant roots were agitated, with the supernatant showing COD/BOD ratios of less than 2.8, while those of the composted tree leaves were greater than 5.0, suggesting that humic substances produced in forest areas are a major cause of NBD organic accumulation in reservoirs. In addition, the organic fractionation of the leachate from leaching tests showed that of the various types of hydrophobic natural organic matter (NOM), the larger molecular weight humic acid makes a greater contribution than fulvic acid to the increase in the NBD COD in Korean reservoirs.     

Analysis of the nitrifying bacterial community in BioCube sponge media using fluorescent in situ hybridization (FISH) and microelectrodes

There is growing interest in the development of more cost-effective and retrofit technologies for the upgrade and expansion of existing wastewater treatment plants with extreme space constraints. A free-floating sponge media (BioCube) process, using a 24L lab scale reactor, was operated to study the nitrification profiles and microbial community. The COD removal efficiencies were maintained, at an average of 95%, with the mixed liquor suspended solids (MLSS) inside the BioCube sponge media maintained at 12,688mg/L. The nitrification removal efficiencies were between 92% and 100%, with an average value of 99%. From the results of microelectrode measurements, the ammonium ion concentration was found to rapidly decrease from the surface of the BioCube sponge media to a depth of 2mm due to chemical reactions carried out by ammonia oxidizing bacteria (AOB) species. Multi-fluorescence in situ hybridization (FISH) has been used to investigate the spatial distributions of various microbial activities within reactors. Microbial communities were targeted using different oligonucleotide probes specific to AOB and nitrite oxidizing bacteria (NOB). There were a large number of AOB populations, but these were not uniformly distributed in the biofilm compared to the NOB populations.     

Effects of calibration on L-THIA GIS runoff and pollutant estimation

Urbanization can result in alteration of a watershed's hydrologic response and water quality. To simulate hydrologic and water quality impacts of land use changes, the Long-Term Hydrologic Impact Assessment (L-THIA) system has been used. The L-THIA system estimates pollutant loading based on direct runoff quantity and land use based pollutant coefficients. The accurate estimation of direct runoff is important in assessing water quality impacts of land use changes. An automated program was developed to calibrate the L-THIA model using the millions of curve number (CN) combinations associated with land uses and hydrologic soil groups. L-THIA calibration for the Little Eagle Creek (LEC) watershed near Indianapolis, Indiana was performed using land use data for 1991 and daily rainfall data for six months of 1991 (January 1-June 30) to minimize errors associated with use of different temporal land use data and rainfall data. For the calibration period, the Nash-Sutcliffe coefficient was 0.60 for estimated and observed direct runoff. The calibrated CN values were used for validation of the model for the same year (July 1-December 31), and the Nash-Sutcliffe coefficient was 0.60 for estimated and observed direct runoff. The Nash-Sutcliffe coefficient was 0.52 for January 1, 1991 to December 31, 1991 using uncalibrated CN values. As shown in this study, the use of better input parameters for the L-THIA model can improve accuracy. The effects on direct runoff and pollutant estimation of the calibrated CN values in the L-THIA model were investigated for the LEC. Following calibration, the estimated average annual direct runoff for the LEC watershed increased by 34%, total nitrogen by 24%, total phosphorus by 22%, and total lead by 43%. This study demonstrates that the L-THIA model should be calibrated and validated prior to application in a particular watershed to more accurately assess the effects of land use changes on hydrology and water quality.     

Natural and anthropogenic influences on heavy metals in airborne particles over the Korean Peninsula

Six monitoring stations were selected to characterize the variations in airborne concentrations of heavy metals in South Korea between 1999 and 2012. Three stations represented higher concentrations, and three represented lower concentrations. The heavy metals monitored at these stations include cadmium, chromium, copper, iron (Fe), lead, manganese (Mn), and nickel. During the study period, concentrations of heavy metals at many stations, including those around the Seoul metropolitan area, showed a decreasing trend. However, concentrations of Mn and Fe that are primarily of crustal origin increased at four of the six stations. Some stations were significantly affected by emissions from the local industrial complex (IC), and heavy metal concentrations at those stations were relatively high even in summer. Many heavy metal concentrations were higher in spring than in winter, but wintertime concentrations of Cr and Pb were higher at the stations representing lower concentrations due to the dominant influence of combustion emissions. At stations less affected by emissions from the IC, concentrations of Fe and Mn that are predominantly crustal in origin were higher in spring, when Asian dust (AD) events are most frequent. Although Mn concentrations were also high at stations within the steelmaking IC during AD periods, they were much higher during non-AD periods due to local emissions. Variations in heavy metal concentrations, which are heavily influenced by emissions from the IC, warrant individual analysis because their emission characteristics differ from those of typical cases.