The role of optimality in characterizing CO2 seepage from geologic carbon sequestration sites

Storage of large amounts of carbon dioxide (CO₂) in deep geologic formations for greenhouse-gas mitigation is gaining momentum and moving from its conceptual and testing stages towards widespread application. In this work we explore various optimization strategies for characterizing surface leakage (seepage) using near-surface measurement approaches such as accumulation chambers and eddy covariance towers. Seepage characterization objectives and limitations need to be defined carefully from the outset especially in light of large natural background variations that can mask seepage. The cost and sensitivity of seepage detection are related to four critical length scales pertaining to the size of the: (1) region that needs to be monitored; (2) footprint of the measurement approach, and (3) main seepage zone; (4) region in which concentrations or fluxes are influenced by seepage. Seepage characterization objectives may include one or all of the tasks of detecting, locating, and quantifying seepage. Each of these tasks has its own optimal strategy. Detecting and locating seepage in a region in which there is no expected or preferred location for seepage nor existing evidence for seepage requires monitoring on a fixed grid, e.g., using eddy covariance towers. The fixed-grid approaches needed to detect seepage are expected to require large numbers of eddy covariance towers for large-scale geologic CO₂ storage. Once seepage has been detected and roughly located, seepage zones and features can be optimally pinpointed through a dynamic search strategy, e.g., employing accumulation chambers and/or soil-gas monitoring. Quantification of seepage rates can be done through measurements on a localized fixed grid once the seepage is pinpointed. Background measurements are essential for seepage detection in natural ecosystems. Artificial neural networks are considered as regression models useful for distinguishing natural system behavior from anomalous behavior suggestive of CO₂ seepage without need for detailed understanding of natural system processes. Because of the local extrema in CO₂ fluxes and concentrations in natural systems, simple steepest-descent algorithms are not effective and evolutionary computation algorithms are proposed as a paradigm for dynamic monitoring networks to pinpoint CO₂ seepage areas.     

Occurrence of residues of the veterinary drug malachite green in eels caught downstream from municipal sewage treatment plants

Residues of malachite green (MG), a veterinary drug illegally used for the treatment of aquacultured fish, have been found in wild eels caught from surface waters downstream from the sewers of different municipal sewage treatment plants (STPs). MG and its metabolite leucomalachite green (LMG) were detected with total concentrations up to 0.765 microg kg(-1) fresh weight in the tissues of 25 out of 45 eels caught from different lakes, a river and a canal in Berlin, Germany. In all cases, the occurrence of the residues could directly be linked to the presence of discharges by municipal STPs into the receiving surface waters. MG is a multiple-use compound that is also used to color materials. Thus, it appears to be reasonable that the residues of MG found in the eel samples originate from such uses, e.g. by wash off from clothes or paper towels colored with MG. Additional loads from legal uses of MG as veterinary drug for the treatment of ornamental fish (private aquaria) are possible. The results obtained from this study are the first proof of background contaminations of a veterinary drug found in samples of fish not intentionally treated with such agents. MG and LMG are regarded as potential genotoxic carcinogens making it impossible to establish a tolerable daily intake. A margin of exposure (MOE) approach was applied to evaluate the human health risk associated with the consumption of the eels investigated in this study. With a MOE of 3.4 million the chronic risk was classified as being very low. Nevertheless, due to their potential to act as genotoxic carcinogens, any oral exposure to residues of MG and LMG should be avoided. According to European Union law, zero tolerance applies to all residues of MG and LMG found in food for human consumption as MG is not registered for use as veterinary drug.     

Contamination by polybrominated diphenyl ethers of sediments from the Lake Maggiore basin (Italy and Switzerland)

Polybrominated diphenyl ethers (PBDEs) are characterized by chemical properties and toxicological profiles similar to other POPs (persistent organic pollutants) included in the EU Priority Pollutant List (2455/01/CE). However, limited data have been available for these compounds thus far for Italian freshwater abiotic matrices. Lake Maggiore basin, a heavily industrialized and densely populated area, was selected for studying PBDE contamination in Italy. PBDEs and OCs (organochlorine compounds) in the basin were quantified by analysing both sediment cores collected in 2005 from the lake and grab samples from the main tributaries and the emissary. Fourteen PBDEs, from tri-BDE to hepta-BDE congeners and BDE209, were compared with some organochlorine POPs (PCBs and DDTs) characterizing Lake Maggiore basin contamination. Analyses of tri-to hepta-BDEs, PCBs and DDTs were undertaken by GC-MS/MS, while BDE-209 was analysed by GC/ECD. Results showed a dominant presence of BDE-209 (>95% of SigmaBDE) and limited amounts of BDE-47, BDE-99, BDE-100, BDE-153 and BDE-154. Lake core profiles highlighted a decreasing trend in PCB concentrations starting from the year 2000, while PBDEs showed greater concentrations after the beginning of the 1990s (up to 30 ng g(-1)d.w.). Among the tributaries, the Bardello and Boesio rivers were the most PBDE-contaminated (up to 290 ng g(-1)d.w.).     

Evaluating policy options for managing diffuse source water quality in Lake Taupo,New Zealand

Environmental policy makers are interested in ways to prevent environmental degradation without significantly limiting economic and social development. Increasingly, market-based instruments are being incorporated into the suite of policy tools to accomplish these aims. However, the lack of information on market-based instruments accessible to non-economists limits understanding of how and when a market-based instrument can be integrated into a traditional policy regime. This paper aims to address the lack of accessible information using a generic screening process for policy instruments demonstrated through application to a non-point source pollution problem in Lake Taupo, New Zealand.     

Growth responses of low-alpine dwarf-shrub heath species to nitrogen deposition and management

Nitrogen deposition is a continuing problem in European alpine regions. We hypothesised that, despite climatic limitations, low-alpine Calluna heathland would respond to nitrogen addition with increased shoot growth and flowering and that fire and grazing would modify responses. In a five-year study, 0-50kgNha(-1)y(-1) were added, combined with burning (+/-) and clipping (+/-). Calluna vulgaris responded with increased shoot extension, but effects on flowering were variable. Burning enhanced the positive effect of nitrogen addition and negative effects of clipping. Sub-dominant shrubs generally did not respond to nitrogen. C. vulgaris shoot extension was stimulated by nitrogen addition of 10kgNha(-1)y(-1) (above background) supporting suggestions that alpine heathlands are sensitive to low levels of nitrogen deposition. Increased C. vulgaris growth could negatively impact on important lichen components of this vegetation through increased shading and competition. Climatic factors constrain productivity in this community, but do not prevent rapid responses to nitrogen deposition by some species.     

PCDD/Fs in ambient air in north-east Italy: The role of a MSWI inside an industrial area

The stack gases of a municipal solid waste incinerator (MSWI), and ambient air were sampled in four locations around the plant for the analysis of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs). The sampling area was close to an industrial area near Trieste, in north-east Italy. The purpose of the study was to estimate the impact of the MSWI emissions and to distinguish the contribution of these emissions from other potential emission sources in the industrial area.PCDD/F atmospheric concentrations were similar to those generally detected in urban–rural areas with one location about 2–3 times more contaminated than the others. Since the most contaminated location was inside the industrial area but upwind of the MSWI, principal component analysis (PCA) was used to establish whether other sources were the cause. This analysis clearly showed that a local steel plant’s emission was the main source of PCDDs/Fs in ambient air. This study highlights the usefulness of multivariate data analysis such as PCA to identify, among different potential emission sources, the one really responsible for the contamination.     

Survey of arsenic and its speciation in rice products such as breakfast cereals, rice crackers and Japanese rice condiments

Rice has been demonstrated to be one of the major contributors to arsenic (As) in human diets in addition to drinking water, but little is known about rice products as an additional source of As exposure. Rice products were analyzed for total As and a subset of samples were measured for arsenic speciation using high performance liquid chromatography interfaced with inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). A wide range of rice products had total and inorganic arsenic levels that typified those found in rice grain including, crisped rice, puffed rice, rice crackers, rice noodles and a range of Japanese rice condiments as well as rice products targeted at the macrobiotic, vegan, lactose intolerant and gluten intolerance food market. Most As in rice products are inorganic As (75.2-90.1%). This study provides a wider appreciation of how inorganic arsenic derived from rice products enters the human diet.     

Using multiple indices to evaluate scenarios for the remediation of contaminated land: the Porto Marghera (Venice,Italy) contaminated site

Background, aim, and scope  

The management of contaminated sites requires the investigation of different involved aspects (from socioeconomic to risk and technological issues) and the presentation of useful and condensed information to decision makers. For this purpose, indices are more and more recognized as effective and valuable tools. This paper presents specific indices created within the DEcision Support sYstem for REhabilitation of contaminated sites (DESYRE).     

Occurrence of pharmaceutically active and non-steroidal estrogenic compounds in three different wastewater recycling schemes in Australia

The discovery that natural and synthetic chemicals, in the form of excreted hormones and pharmaceuticals, as well as a vast array of compounds with domestic and industrial applications, can enter the environment via wastewater treatment plants and cause a wide variety of environmental and health problems even at very low concentrations, suggests the need for improvement of water recycling. Three Australian wastewater recycling schemes, two of which employ reverse osmosis (RO) technology, the other applying ozonation and biological activated carbon filtration, have been studied for their ability to remove trace organic contaminants including 11 pharmaceutically active compounds and two non-steroidal estrogenic compounds. Contaminant concentrations were determined using a sensitive analytical method comprising solid phase extraction, derivatization and GC with MS using selected ion monitoring. In raw wastewater, concentrations of analgesics and non-steroidal anti-inflammatory medications were comparable to those found in wastewaters around the world. Remarkably, removal efficiencies for the three schemes were superior to literature values and RO was responsible for the greatest proportion of contaminant removal. The ability of RO membranes to concentrate many of the compounds was demonstrated and highlights the need for continued research into monitoring wastewater treatment, concentrate disposal, improved water recycling schemes and ultimately, safer water and a cleaner environment.     

Water quality indices across Europe--a comparison of the good ecological status of five river basins

The European Water Framework Directive (WFD) requires the definition of near-natural reference conditions to determine the extent of water bodies' deviation from "good ecological status" caused by stress gradients. However, the classification of ecological quality depends on the assessment method applied and the stressor concerned. While assessment methods that are generally applicable would be favourable, many European countries employ the locally developed water quality metrics that assess the impact of organic pollution (including eutrophication) and the associated decrease in dissolved oxygen. These indices do not specifically address stress from organic toxicants, such as pesticides. The aim of this study was to examine the performance of presently used assessment methods to identify reference conditions of non-contaminated streams in five selected European river basins, covering the geographical region from Spain to Finland, as a crucial prerequisite to indicate toxic gradients. The analysis comprised the Belgium biotic index (BBI), the biological monitoring working party (BMWP) scoring system and the revised German saprobic index. For comparison, we included an adaptation of the recently developed SPEAR index. In two previous field studies, this metric highly correlated with measured pesticide gradients. In this study, SPEAR was the only indicator that was generally applicable to all monitoring data and capable of determining "high ecological status" of reference conditions in all basins. Thus, based upon previous and own results, the authors suggest the species at risk (SPEAR) index to be potentially useful as a European-wide index to address deviations from "good ecological status" due to organic toxicants and recommend it for consideration in integrated water-resource evaluations under the WFD.