Journal - American Water Works Association | Year: 2012
Nitrosamine data reported from the first rounds of samples collected under the second Unregulated Contaminants Monitoring Rule (UCMR2) were reviewed to assess the frequency and magnitude of occurrence and the effect of disinfectant type and other treatment factors on reported nitrosamine concentrations. N-nitrosodimethylamine (NDMA) was detected in drinking water at concentrations above the UCMR2 minimum reporting level of 2 ng/L in 1 of every 10 samples, primarily in systems using chloramines. Other nitrosamines (i.e., N-nitrosodiethylamine [NDEA], N-nitrosopyrrol idine [NPYR], N-nitroso-di-n- butylamine [NDBA], and N-nitrosodimethylethylamine [NMEA]) were rarely detected. Followup survey results from 45 water systems generally followed expected trends based on the literature. NDMA occurrence was more frequent, and concentrations were higher in water systems having long contact times with chloramines and with no preoxidation step.
Meyer J.S.,Arcadis |
Adams W.J.,Rio Tinto Alcan
Environmental Toxicology and Chemistry | Year: 2010
The U.S. Environmental Protection Agency's (U.S. EPA) water quality criteria for Cu were tested to determine whether they protect fish against neurophysiological impairment. From published studies with rainbow trout (Oncorhynchus mykiss), Chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), and fathead minnows (Pimephales promelas), 20% inhibition concentrations (IC20s) were calculated for avoidance of Cu-containing water and for impairment of electroencephalogram (EEG) and electro-olfactogram (EOG) responses to natural odorants in Cu-containing water. Additionally, a Cu-olfactory biotic ligand model (BLM) that fits the coho salmon EOG data was parameterized by changing the sensitivity parameter in the ionoregulatory-based BLM. The IC20s calculated from reported Cu avoidance, EEG, and EOG data and IC20s predicted by the olfactory BLM were compared with acute and chronic Cu criteria calculated using U.S. EPA's BLM 2007 or hardness-adjustment equations. The BLM-based chronic criteria were protective in all 16 exposure water-species combinations used in avoidance and olfaction experiments. Additionally, the BLM-based acute criteria were protective in all 11 exposure water-species combinations in which comparisons could be made with olfactory BLM-predicted IC20s but not in two of the 16 exposure water-species combinations in which comparisons could be made with the reported IC20s (which were ≤8% lower than but did not differ significantly from the BLM-based acute criteria; p>0.05). In effect, the olfactory BLM factored out the relatively high variability in the reported IC20s. It is concluded that the U.S. EPA's BLM-based water quality criteria for Cu protect against these types of neurophysiological impairment in the six species-endpoint combinations analyzed in this paper. However, the U.S. EPA's hardness-based criteria for Cu sometimes were considerably underprotective and sometimes were much less protective than the BLM-based criteria. © 2010 SETAC.
International Journal of Rock Mechanics and Mining Sciences | Year: 2016
This paper presents the solution based on Finite Difference Method for the analysis of passive bolts reinforcement around a circular opening. Linked to the classical convergence-confinement method, the solution provides a framework to the ground and passive bolts responses and can be applied to the elastoplastic models such as Mohr-Coulomb and Generalized form of Hoek-Brown failure criterions. The passive bolt and rock mass interaction is incorporated through the results of pullout tests and the reinforcement mechanism is illustrated through parameters studies. The proposed solution is validated with known analytical results for the unbolted case. Numerical examples of bolted tunnels are also provided to demonstrate significant advantage and efficacy of the proposed solution for practical applications. © 2015 Elsevier Ltd.
Farley K.J.,Manhattan College |
Environmental Toxicology and Chemistry | Year: 2015
A comparison of 4 metal mixture toxicity models (that were based on the biotic ligand model [BLM] and the Windermere humic aqueous model using the toxicity function [WHAM-FTOX]) was presented in a previous paper. In the present study, a streamlined version of the 4 models was developed and applied to multiple data sets and test conditions to examine key assumptions and calibration strategies that are crucial in modeling metal mixture toxicity. Results show that 1) a single binding site on or in the organism was a useful and oftentimes sufficient framework for predicting metal toxicity; 2) a linear free energy relationship (LFER) for bidentate binding of metals and cations to the biotic ligand provided a good first estimate of binding coefficients; 3) although adjustments in metal binding coefficients or adjustments in chemical potency factors can both be used in model calibration for single-metal exposures, changing metal binding coefficients or chemical potency factors had different effects on model predictions for metal mixtures; and 4) selection of a mixture toxicity model (based on concentration addition or independent action) was important in predicting metal mixture toxicity. Moving forward, efforts should focus on reducing uncertainties in model calibration, including development of better methods to characterize metal binding to toxicologically active binding sites, conducting targeted exposure studies to advance the understanding of metal mixture toxicity, and further developing LFERs and other tools to help constrain the model calibration. © 2014 SETAC.
Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: SEC-2012.2.1-1 | Award Amount: 5.29M | Year: 2013
The overall objective of the ELASSTIC project is to improve the security and resilience of large scale multifunctional building complexes to natural and man-made disasters by providing a methodology and tools which enable to include security and resilience from the early design and planning phase of such projects. The ELASSTIC concept proposed is based upon the following key features: 1) A comprehensive approach for designing safe, secure and resilient large scale built infrastructures 2) A set of tools to enable architects, structural engineers and building installation engineers to assess the safety, security and resilience of designs and to optimize the integral design 3) Coupling and integration of these tools into Building Information Modelling (BIM) technology resulting in extended BIM technology (BIM\) 4) Smart and reinforced building elements, to measure the actual building condition combined with an increased bearing capacity and resistance 5) Coupling and integration of BIM and BMS (Building Management System) 6) Real time information on the safety, security and resilience of infrastructure Validation of the approach and developed tools will be done by evaluation the design of a multifunctional, resilient, large scale urban complex (anno 2020), called the ELASSTIC complex. This large multifunctional complex combines housing, shopping centre, transport node, business centre and entertainment centre. The ELASSTIC complex will not only be secure and resilient to disasters, it will also be designed to ensure fast and efficient evacuation in case of a disaster. For a crowded complex comprising a large number of people, the design of a smart evacuation system should be included at the start of the design of the complex. Taking evacuation and safety installations into account in the design phase will increase safety and is less expensive compared to an evacuation system integrated after the complex is build or at the final design stage.