Intermediate storage of carbon dioxide in geological formations: A technical perspective

Enhanced oil recovery (EOR) through CO₂ flooding has been practiced on a commercial basis for the last 35 years and continues today at several sites, currently injecting in total over 30 million tons of CO₂ annually. This practice is currently exclusively for economic gain, but can potentially contribute to the reduction of emissions of greenhouse gases provided it is implemented on a large scale. Optimal operations in distributing CO₂ to CO₂-EOR or enhanced gas recovery (EGR) projects (referred to here collectively as CO₂-EHR) on a large scale and long time span imply that intermediate storage of CO₂ in geological formations may be a key component. Intermediate storage is defined as the storage of CO₂ in geological media for a limited time span such that the CO₂ can be sufficiently reproduced for later use in CO₂-EHR. This paper investigates the technical aspects, key individual parameters and possibilities of intermediate storage of CO₂ in geological formations aiming at large scale implementation of carbon dioxide capture and storage (CCS) for deep emission reduction. The main parameters are thus the depth of injection and density, CO₂ flow and transport processes, storage mechanisms, reservoir heterogeneity, the presence of impurities, the type of the reservoirs and the duration of intermediate storage. Structural traps with no flow of formation water combined with proper injection planning such as gas-phase injection favour intermediate storage in deep saline aquifers. In depleted oil and gas fields, high permeability, homogeneous reservoirs with structural traps (e.g. anticlinal structures) are good candidates for intermediate CO₂ storage. Intuitively, depleted natural gas reservoirs can be potential candidates for intermediate storage of carbon dioxide due to similarity in storage characteristics.     

Toxicity and hazard of a mixture of SSRIs to zooplankton communities evaluated in aquatic microcosms

The toxicity and hazard of a mixture of selective serotonin reuptake inhibitors (SSRIs), including fluoxetine, fluvoxamine, and sertraline, to zooplankton communities were evaluated using 120,00l outdoor microcosms. Acute (day 4) and chronic (day 35) zooplankton abundance and species richness were assessed for Rotifera, Cladocera, and Copepoda. For acute SSRI exposures, rotifers were the most sensitive zooplankton taxa to changes in abundance (predicted no effect concentration (PNEC)=19 nM); however, no effects in zooplankton species richness were observed for this treatment period. A decrease in Copepoda abundance and species richness was observed following chronic exposures of SSRIs (PNEC=9.1 nM). A 99th-centile predicted environmental concentration (PEC=0.51 nM) yielded HQs at least two orders of magnitude below 1. Therefore, mixtures of SSRIs do not appear to present a hazard to zooplankton communities at environmentally relevant concentrations.     

Guidance for the performance evaluation of three-dimensional air quality modeling systems for particulate matter and visibility

Guidance for the performance evaluation of three-dimensional air quality modeling systems for particulate matter and visibility is presented. Four levels are considered: operational, diagnostic, mechanistic, and probabilistic evaluations. First, a comprehensive model evaluation should be conducted in at least two distinct geographical locations and for several meteorological episodes. Next, streamlined evaluations can be conducted for other similar applications if the comprehensive evaluation is deemed satisfactory. In all cases, the operational evaluation alone is insufficient, and some diagnostic evaluation must always be carried out. Recommendations are provided for designing field measurement programs that can provide the data needed for such model performance evaluations.     

The relationship between perceived risk of being ticketed and self-reported seat belt use

PROBLEM: Twenty-nine percent of Americans failed to use their seat belts in 2000. Efforts to improve safety belt usage can be enhanced by identifying specific factors that motivate belt use. METHOD: Motorist survey data were used to examine the effect of Perceived Risk of being Ticketed (PRT) for a seat belt infraction on self-reported seat belt use. RESULTS: Analyses indicated that individuals and groups of individuals who have higher PRT typically report higher belt usage. Factorial analyses indicated that this perceived risk to belt use relationship holds both within groups with generally high (e.g., upper income) and generally low (e.g. young men) overall self-reported belt use. DISCUSSION: Applications of PRT to improve seat belt use are discussed. IMPACT ON INDUSTRY: Enforcement of existing laws, perhaps through selective traffic enforcement programs, and strengthening laws to create a higher perception of being ticketed by motorists should increase safety belt use thereby saving lives and reducing cost for individuals, government, and industry.     

Taking the Click It or Ticket model nationwide

Click It or Ticket is an occupant protection Selective Traffic Enforcement Program (sTEP) combining intensive paid and earned publicity with enforcement during a brief two to four week period. North Carolina demonstrated substantial increases in safety belt use associated with their implementation of the first statewide Click It or Ticket program in 1993. In 2000, Click It or Ticket was implemented in South Carolina. In 2001, Click It or Ticket was implemented across all eight states of the southeast. In 2002, ten states in various parts of the country implemented Click It or Ticket; four states implemented parts of the full Click It or Ticket program; and four states were used as comparisons. Belt use increases were greatest in the full implementation states. Click It or Ticket was implemented nationally in 2003. This paper presents a historical perspective on the implementation and evaluation of Click It or Ticket programs.     

The theory behind,and the challenges of,conserving nature's stage in a time of rapid change

Most conservation planning to date has focused on protecting today's biodiversity with the assumption that it will be tomorrow's biodiversity. However, modern climate change has already resulted in distributional shifts of some species and is projected to result in many more shifts in the coming decades. As species redistribute and biotic communities reorganize, conservation plans based on current patterns of biodiversity may fail to adequately protect species in the future. One approach for addressing this issue is to focus on conserving a range of abiotic conditions in the conservation‐planning process. By doing so, it may be possible to conserve an abiotically diverse “stage” upon which evolution will play out and support many actors (biodiversity). We reviewed the fundamental underpinnings of the concept of conserving the abiotic stage, starting with the early observations of von Humboldt, who mapped the concordance of abiotic conditions and vegetation, and progressing to the concept of the ecological niche. We discuss challenges posed by issues of spatial and temporal scale, the role of biotic drivers of species distributions, and latitudinal and topographic variation in relationships between climate and landform. For example, abiotic conditions are not static, but change through time—albeit at different and often relatively slow rates. In some places, biotic interactions play a substantial role in structuring patterns of biodiversity, meaning that patterns of biodiversity may be less tightly linked to the abiotic stage. Furthermore, abiotic drivers of biodiversity can change with latitude and topographic position, meaning that the abiotic stage may need to be defined differently in different places. We conclude that protecting a diversity of abiotic conditions will likely best conserve biodiversity into the future in places where abiotic drivers of species distributions are strong relative to biotic drivers, where the diversity of abiotic settings will be conserved through time, and where connectivity allows for movement among areas providing different abiotic conditions.     

Biomarkers of end of shift exposure to disinfection byproducts in nurses

Increased disinfectant use commonly takes place in hospitals and other health care settings. A cross-sectional study among active nurses in two Cypriot public hospitals (n = 179) was conducted to examine the prevalence of exposure to disinfection byproducts (DBPs), such as trihalomethanes (THMs) using both self-reported information and biomarker measurements. The objectives of this study were to: i) quantify the magnitude and variability of occupational exposure to disinfectants/DBPs in nurses, ii) generate job exposure matrices (JEM) and job task exposure matrices (JTEM) for disinfectants, and iii) assess the major determinants of urinary THMs in nurses. End of shift urinary total THM values showed high variability among the nurses, but did not differ between hospitals. The disinfectant group of alcohols/phenols was used by > 98% of nurses, followed by octenidine (82%), iodine and chlorine (39%, each), chlorhexidine (25%), formaldehyde (12%), hydrogen peroxide (11%), and peracetic acid/ammonia/quaternary ammonium compounds (QACs), all being < 8% each. Chlorine use during the past 24 hr was associated with significantly (p < 0.05) lower brominated THMs (BrTHMs) after adjusting for age, gender and BMI, while a positive association was shown for TCM and the sum of all THMs (TTHMs), albeit not significant. Nurses were exposed to nearly double the levels of TTHMs and BrTHMs (median and IQR, 1027 [560, 2475] ng/g and 323 [212, 497] ng/g, respectively) when compared to those of the general population (552 [309,989] ng/g and 152 [87,261] ng/g, respectively). This was the first occupational health dataset reporting measurements of biomarkers of end of shift exposures to disinfectants/DBPs.     

Soil carbon sequestration in tropical agroforestry systems: a feasibility appraisal

Agroforestry is recognized as a strategy for soil carbon sequestration (SCS) under the afforestation/reforestation activities, but our understanding of soil carbon (C) dynamics under agroforestry systems (AFS) is not adequate. Although some SCS estimates are available, many of them lack scientific rigor. Several interrelated and site-specific factors ranging from agroecological conditions to system management practices influence the rate and extent of SCS under AFS, so that generalizations tend to become unrealistic. Furthermore, widely and easily adoptable methodologies are not available for estimating the SCS potential under different conditions. In spite of these, there is an increasing demand for developing “best-bet estimates” based on the current level of knowledge and experience. This document presents an attempt in that direction. The appraisal validates the conjecture that AFS can contribute to SCS, and presents indicative ranges of SCS under different AFS in the major agroecological regions of the tropics. The suggested values range from 5 to 10 kg C ha^?1 in about 25 years in extensive tree-intercropping systems of arid and semiarid lands to 100–250 kg C ha^?1 in about 10 years in species-intensive multistrata shaded perennial systems and homegardens of humid tropics.