Transport of Escherichia coli bacteria through laboratory columns of glacial-outwash sediments: estimating model parameter values based on sediment characteristics

Bacterial transport through cores of intact, glacial-outwash aquifer sediment was investigated with the overall goal of better understanding bacterial transport and developing a predictive capability based on the sediment characteristics. Variability was great among the cores. Normalized maximum bacterial-effluent concentrations ranged from 5.4x10(-7) to 0.36 and effluent recovery ranged from 2.9x10(-4) to 59%. Bacterial breakthrough was generally rapid with a sharp peak occurring nearly twice as early as the bromide peak. Bacterial breakthrough exhibited a long tail of relatively constant concentration averaging three orders of magnitude less than the peak concentration for up to 32 pore volumes. The tails were consistent with non-equilibrium detachment, corroborated by the results of flow interruption experiments. Bacterial breakthrough was accurately simulated with a transport model incorporating advection, dispersion and first-order non-equilibrium attachment/detachment. Relationships among bacterial transport and sediment characteristics were explored with multiple regression analyses. These analyses indicated that for these cores and experimental conditions, easily-measurable sediment characteristics--median grain size, degree of sorting, organic-matter content and hydraulic conductivity--accounted for 66%, 61% and 89% of the core-to-core variability in the bacterial effective porosity, dispersivity and attachment-rate coefficient, respectively. In addition, the bacterial effective porosity, median grain size and organic-matter content accounted for 76% of the inter-core variability in the detachment-rate coefficient. The resulting regression equations allow prediction of bacterial transport based on sediment characteristics and are a possible alternative to using colloid-filtration theory. Colloid-filtration theory, used without the benefit of running bacterial transport experiments, did not as accurately replicate the observed variability in the attachment-rate coefficient.     

Estimating willingness to pay for a hypothetical earthquake early warning systems

The development of reliable, accessible, and transparent earthquake early warning systems (EEWSs) for disaster reduction have been given increased priority at local, national, and international levels. Accurately quantifying the social and economic benefits accrued to households and businesses from EEWSs are a challenging and difficult task. In this paper, the Contingent Valuation Method (CVM) is used to evaluate the benefits of a hypothetical EEWS to the citizens of Tehran Metropolitan. This study clarifies public willingness to pay (WTP) for EEWS in Tehran, and the dominant factors involved in WTP through a CVM analysis. The survey, completed by more than 504 households, showed that on average households are willing to pay 367,471 Rials (38 US$) per month for the hypothetical EEWS. Those willing to pay the most for EEWS are households, which currently possess a fire alarm. Also the more educated the respondents and the more children the respondents have, the more willing they are to pay for EEWS. These results could be used by policy makers and technology firms in order to determine the optimal investments in early warning systems for earthquake disaster reduction.     

Environmental PCBs in Guánica Bay,Puerto Rico: implications for community health

Guánica Bay, located in southwestern Puerto Rico, has suffered oil spills and other pollution discharges since the 1960s. Previous research showed elevated concentrations of polychlorinated biphenyls (PCBs) in coral reef and sediment. This research examined PCB concentrations in sediment and fish. Sediment and fish sampling in the bay was facilitated by community members. This study identified the second highest reported PCB level (129,300 ng/g) in sediment in the USA. Fish samples also showed elevated concentrations (1623 to 3768 ng/g), which were higher than the thresholds of safe levels of PCBs in fish for human consumption. The alarmingly high concentration of PCBs calls for proactive community engagement to bring awareness about contamination of the bay and more extensive sampling to test for the concentration of PCBs in seafood and the people of Guánica. This study also underscores the value of the involvement of local communities during sampling design aimed at identifying hot spots of contaminants.     

New climate change information modifies frames and decisions of decision makers: an exploratory study in forest planning

Information helps decision makers to address and to decide about environmental problems. In the context of climate change adaptation, often knowledge is missing on how the available information from impact models affects the decision-making process. The main aim of this study was to explore the extent of ambiguity and how new climate change information influenced decision of forest planners. We investigated changes in decisions of planners about forestry actions representing species choice and forest tourism and expiry dates of these actions leading to environmental constraints in the provision of ecosystem services. Forest planners evaluated expiry dates using four forest ecosystem services: forest production, stand yield class, sequestered carbon, and potential tourism. Data were collected during workshops with eleven forest planners from three forest districts in Scotland. Presented climate change information modified the understanding and frames of planners about forestry actions assessed with accompanying expiry dates. Changes in the frames of planners often result in both earlier and later expiry dates. Ambiguity of planners was found to be dependent on diversity in frames and difficulty in evaluating multiple ecosystem services. These findings imply that due to ambiguity forest planners might find it hard to choose climate change adaptation measures and researchers can struggle to convince planners with new research findings.     

Development of Soils and Communities of Plants and Arbuscular Mycorrhizal Fungi on West Virginia Surface Mines

Surface mining followed by reclamation to pasture is a major driver of land use and cover change in Appalachia. Prior research suggests that many aspects of ecosystem recovery are either slow or incomplete. We examined ecosystem structure—including soil physical and chemical properties, arbuscular mycorrhizal fungal (AMF) infectivity and community composition, and plant diversity and community composition—on a chronosequence of pasture-reclaimed surface mines and a non-mined pasture in northern West Virginia. Surface mining and reclamation dramatically altered ecosystem structure. Some aspects of ecosystem structure, including many measures of soil chemistry and infectivity of AMF, returned rapidly to levels found on the non-mined reference site. Other aspects of ecosystem structure, notably soil physical properties and AMF and plant communities, showed incomplete or no recovery over the short-to-medium term. In addition, invasive plants were prevalent on reclaimed mine sites. The results point to the need for investigation on how reclamation practices could minimize establishment of exotic invasive plant species and reduce the long-term impacts of mining on ecosystem structure and function.     

Biomass of Speckled Alder on an Air-Polluted Mountain Site and its Response to Fertilization

The article summarizes outcomes of a biomass study conducted in a young speckled alder plantation on a cold mountain site. At this location, the previously existing old forest was clear felled because of damage from air pollution, and present-day surface humus is in need of restoration. The intention of this study was to quantify the biomass and nutrients accumulated by alders and their components and assess whether the initial fertilization resulted in increased biomass production and nutrient accumulation in the biomass. Besides the control, two fertilized treatments were installed. In the surface treatment (SUT), the amendment was applied as a base dressing in small circles around trees. In the planting-hole treatment (PHT), the amendment was incorporated into soil inside the planting holes. Five growth seasons after planting and fertilization, six alders from each treatment were harvested including roots. Their biomass was quantified and analyzed for macroelements. The greatest pool of dry mass (DM) was branches in the control and stem wood in the fertilized treatments. The greatest pools of macroelements were leaves and branches. The most pronounced effects of fertilization were recorded in the DM and consequently in the absolute quantities of nutrients. The DM of an average tree in the control, SUT, and PHT was 85, 226, and 231 g, respectively. The absolute contents of nutrients per tree in the fertilized treatments showed the following increases, as compared with the control: (N) 2.5–2.6 times; (P) 1.6–2.4 times; (K) 1.8–2.1 times; and (Mg) 1.8–2.0 times, respectively. Speckled alder responded positively to fertilization.     

Quantification of carbon dioxide and methane emissions in urban areas: source apportionment based on atmospheric observations

Anthropogenic emissions of carbon dioxide (CO₂) and methane (CH₄) in the atmosphere constitute an important component of the related carbon budget. The main source of anthropogenic CO₂ is burning of fossil fuels, especially in densely populated areas. Similar emissions of CH₄ are associated with the agricultural sector, coal mining, and other human activities, such as waste management and storage and natural gas networks supplying methane to large urban, industrial centers. We discuss several methods aimed at characterizing and quantifying atmospheric loads and fluxes of CO₂ and CH₄ in Krakow, the second largest city in Poland. The methods are based on atmospheric observations of mixing ratios as well as isotopic composition of the investigated gases. Atmospheric mixing ratios of CO₂ and CH₄ were measured using gas chromatography (GC) and cavity ring-down spectroscopy (CRDS). The isotopic composition of CO₂ and CH₄ was analyzed using isotope ratio mass spectrometry (IRMS), accelerator mass spectrometry (AMS), and CRDS techniques. These data, combined with auxiliary information characterizing the intensity of vertical mixing in the lower atmosphere (height of the nocturnal boundary layer [NBL] and atmospheric ²²²Rn concentration), were further used to quantify emission rates of CO₂ and CH₄ in the urban atmosphere of Krakow. These methods provide an efficient way of quantifying surface emissions of major greenhouse gases originating from distributed sources, thus complementing the widely used bottom-up methodology based on emission statistics.

     

Dynamics of dust explosions suppression by means of extinguishing powder in various industrial conditions

In industrial conditions, there are different kinds of installations endangered by an explosion of dust–gas mixtures. In order to prevent them from any consequences of potential explosions, active protection systems which use extinguishing powders, as the suppressing material, are more and more widely applied. It often happens that the industrial installations are additionally endangered by an action of mechanical vibrations. In the above-mentioned conditions, the extinguishing powder tends to aggregate, making the process of dispersing it in the protected areas more difficult.

The results of research into optimization of the shape, number of igniters and miniaturization of the explosive charge mass are presented. In case of occurrence of the mechanical vibrations in the installations that cause aggregation of the suppressing powder, the best solution was modification of the perforated combustion chamber located inside the extinguisher. As a result of that, a certain amount of gases generated in the course of combustion of the main charge is directed over the membrane, where the gases crash a layer of aggregated powder. Thus, the process of pushing the powder out from a container towards the dispersing head improves considerably and consequently increases the efficiency of the explosion-suppressing process.