Rhee J.,Climate Center |
Park S.,Ulsan National Institute of Science and Technology |
Lu Z.,Anchor QEA LLC
GIScience and Remote Sensing | Year: 2014
The relationship between land cover patterns and surface temperature was examined using random forest as well as simple linear regression for two urban sites in Denver, Colorado, USA. Among four land cover types of buildings, trees, grass, and roads and parking lots, only trees and roads and parking lots show significant spatial metrics affecting surface temperature using both the methods. For trees, total class area seems the most important factor affecting surface temperature (R2 = 0.47; percentage of increased mean standard error when mean patch area is excluded %IncMSE = 5.35 for Site B in July), followed by aggregation metrics measuring physical connectedness (R2 for patch cohesion index = 0.42) and patch isolation (%IncMSE for mean Euclidean nearest neighbor distance = 6.01 for Site A in July). For roads and parking lots, the existence of dominantly large patches is the most important factor (R2 for range in patch area = 0.40, for largest patch index = 0.40, for Site B in July), followed by total class area (R2 = 0.39 for Site B in July). Despite some limitations, the findings of this study provide useful information for alleviating urban heat stress especially during summer and reducing adverse impacts of urban drought. © 2014 Taylor and Francis.
Mebane C.A.,U.S. Geological Survey |
Dillon F.S.,CH2M HILL |
Hennessy D.P.,Anchor QEA LLC
Environmental Toxicology and Chemistry | Year: 2012
The authors conducted 150 tests of the acute toxicity of resident fish and invertebrates to Cd, Pb, and Zn, separately and in mixtures, in waters from the South Fork Coeur d'Alene River watershed, Idaho, USA. Field-collected shorthead sculpin (Cottus confusus), westslope cutthroat trout (Oncorhynchus clarkii lewisi), two mayflies (Baetis tricaudatus and Rhithrogena sp.), a stonefly (Sweltsa sp.), a caddisfly (Arctopsyche sp.), a snail (Gyraulus sp.), and hatchery rainbow trout (Oncorhynchus mykiss), were tested with all three metals. With Pb, the mayflies (Drunella sp., Epeorus sp., and Leptophlebiidae), a Simuliidae black fly, a Chironomidae midge, a Tipula sp. crane fly, a Dytiscidae beetle, and another snail (Physa sp.), were also tested. Adult westslope cutthroat trout were captured to establish a broodstock to provide fry of known ages for testing. With Cd, the range of 96-h median effect concentrations (EC50s) was 0.4 to >5,329μg/L, and the relative resistances of taxa were westslope cutthroat trout ≈ rainbow trout ≈ sculpin << other taxa; with Pb, EC50s ranged from 47 to 3,323μg/L, with westslope cutthroat trout
Texas environmental flow standards and the hydrology-based environmental flow regime methodology [Normes des débits environnementaux au Texas et méthodologie du régime de débit environnemental à base hydrologique]
Opdyke D.R.,Anchor QEA LLC |
Oborny E.L.,BIO WEST Inc. |
Vaugh S.K.,HDR |
Mayes K.B.,Texas Parks and Wildlife Department
Hydrological Sciences Journal | Year: 2014
In 2007, the Texas legislature created a program to identify environmental flow standards statewide through the coordinated efforts of scientific and stakeholder groups and rulemaking by the Texas Commission on Environmental Quality. To aid in this task, a Hydrology-based Environmental Flow Regime (HEFR) method was developed that combines a suite of user-customizable hydrologic statistics with an implementation framework. Following the concepts of the Natural Flow Paradigm, the methodology includes the separation of a long-term hydrograph into key flow components (e.g. subsistence, base, high-flow pulse and overbank) defined by the Texas Instream Flow Program. Seasonal, annual and inter-annual flow component statistics were then coupled with biology, water quality and geomorphology overlays, where available, and with implementation rules applied to example large-scale water supply projects to support development of environmental flow standards for use in water rights permit conditions. The HEFR methodology and resulting flow recommendations are compared to two contemporary in-stream flow studies and adopted environmental flow standards. Subsistence flows were fairly similar. Baseflows were in a similar range, but fewer than three seasonal levels have sometimes been specified in in-stream flow studies. Episodic events are quite different in terms of magnitude, frequency, duration and applicable number. Editor D. Koutsoyiannis; Guest editor M. AcremanCitation Opdyke, D.R. Oborny, E.L. Vaugh, S.K. and Mayes, K.B. 2014. Texas environmental flow standards and the hydrology-based environmental flow regime methodology. Hydrological Sciences Journal, 59 (3-4), 820-830. © 2014 © 2014 IAHS Press.
Malczyk E.A.,Anchor QEA LLC |
Branfireun B.A.,University of Western Ontario
Science of the Total Environment | Year: 2015
Mercury pollution has not been well documented in the inland lakes or fishes of Mexico, despite the importance of freshwater fish as a source of protein in local diets. Total mercury and methylmercury in waters, sediments, and the commercial fish catch were investigated in Lake Zapotlán, Mexico. Concentrations of total and methylmercury were very high in runoff and wastewater inputs, but very low in sediments and surface waters of the open water area of the lake. Concentrations of total mercury in tilapia and carp were very low, consistent with the low concentrations in lake water and sediments. Particle settling, sorption, the biogeochemical environment, and/or bloom dilution are all plausible explanations for the significant reductions in both total mercury and methylmercury. Despite very high loading of mercury, this shallow tropical lake was not a mercury-impaired ecosystem, and these findings may translate across other shallow, alkaline tropical lakes. Importantly, the ecosystem services that seemed to be provided by peripheral wetlands in reducing mercury inputs highlight the potential for wetland conservation or restoration in Mexico. © 2015 Published by Elsevier B.V.
O'Day P.A.,University of California at Merced |
Vlassopoulos D.,Anchor QEA LLC
Elements | Year: 2010
Amending soils with mineral-based materials to immobilize contaminants is both old and new. Although mineral amendments have been used for decades in agriculture, new applications with a variety of natural and reprocessed materials are emerging. By sequestering contaminants in or on solid phases and reducing their ability to partition into water or air, amendments can reduce the risk of exposure to humans or biota. A variety of mineral types are commonly used to amend contaminated soils, with different modes of molecular-scale sequestration. Regulatory, social, and economic factors also influence decisions to employ mineral amendments as a treatment technology.
Kroll C.N.,402 Baker Laboratory |
Song P.,402 Baker Laboratory |
Song P.,Anchor QEA LLC
Water Resources Research | Year: 2013
Often hydrologic regression models are developed with ordinary least squares (OLS) procedures. The use of OLS with highly correlated explanatory variables produces multicollinearity, which creates highly sensitive parameter estimators with inflated variances and improper model selection. It is not clear how to best address multicollinearity in hydrologic regression models. Here a Monte Carlo simulation is developed to compare four techniques to address multicollinearity: OLS, OLS with variance inflation factor screening (VIF), principal component regression (PCR), and partial least squares regression (PLS). The performance of these four techniques was observed for varying sample sizes, correlation coefficients between the explanatory variables, and model error variances consistent with hydrologic regional regression models. The negative effects of multicollinearity are magnified at smaller sample sizes, higher correlations between the variables, and larger model error variances (smaller R2). The Monte Carlo simulation indicates that if the true model is known, multicollinearity is present, and the estimation and statistical testing of regression parameters are of interest, then PCR or PLS should be employed. If the model is unknown, or if the interest is solely on model predictions, is it recommended that OLS be employed since using more complicated techniques did not produce any improvement in model performance. A leave-one-out cross-validation case study was also performed using low-streamflow data sets from the eastern United States. Results indicate that OLS with stepwise selection generally produces models across study regions with varying levels of multicollinearity that are as good as biased regression techniques such as PCR and PLS. ©2013. American Geophysical Union. All Rights Reserved.
Koellmann D.S.,Anchor QEA LLC
Ports 2013: Success Through Diversification - Proceedings of the 13th Triennial International Conference | Year: 2013
Incorporating environmental commitments into the design process from the onset of a project allows for ports to address environmental considerations, provides for greater certainty for ports and contractors during the bid process, and assists in building positive agency relationships that can assist in streamlining the regulatory process for current and future projects. Due to the complexity of today's port projects and ever-increasing regulatory requirements, a multidisciplinary project team approach to designing, permitting, and implementing port projects is needed to ensure project designs are able to be both permitted and constructed. Understanding and addressing specific regulatory agency requirements can result in a streamlined permitting process and provide greater certainty related to costs and reporting requirements for environmental commitments for ports and the contractors they hire. This paper provides an overview of the recommended steps to ensure environmental commitments for port projects are successfully addressed. © 2013 American Society of Civil Engineers.
Bever A.J.,Anchor QEA LLC |
Macwilliams M.L.,Anchor QEA LLC
Hydrological Processes | Year: 2016
Secondary circulation is the component of three-dimensional (3D) flow in river channels perpendicular to the primary flow direction. Secondary circulation calculated from acoustic Doppler current profiler (ADCP) transects is sensitive to the calculation method and is affected by the transect angle relative to the mean flow direction and variations in the flow direction along a transect. To quantify bounds on transect alignment relative to river flow for field data collection and examine tidal time-scale variability in secondary circulation, the 3D hydrodynamic model UnTRIM was applied to simulate the hydrodynamics in the lower reach of the Sacramento River (CA, USA). Secondary circulation was calculated using the Rozovskii and the zero net discharge methods on repeated transects extracted from the model results in regions of both relatively uniform and complex flows. When the depth-averaged flow direction along a transect varied by more than about 5°, occurring when the transect was as little as 10 to 20° out of normal to the mean flow direction, the Rozovskii method produced more realistic secondary circulation than the zero net discharge method. Analysis indicated that ADCP transects should be within 20° of perpendicular to the mean flow direction when calculating secondary circulation. Secondary circulation strength around two tidally influenced bends generally increased with increasing flow and broke down near slack water. However, the strength of the secondary circulation was not only a function of the flow magnitude, but also depended on the direction of the water flow and the transect location relative to the river curvature, which varied with the tidal flow direction. © 2016 John Wiley & Sons, Ltd.
Israelsson P.H.,Anchor QEA LLC |
Quadrini J.D.,Anchor QEA LLC |
Connolly J.P.,Anchor QEA LLC
Estuaries and Coasts | Year: 2014
The fate and transport of hydrophobic organic chemicals (HOCs) is particularly complex in estuaries because of bidirectional longitudinal currents, density stratification, the tendency to trap sediments, and significant dilution in the downstream bay or ocean. Investigations of HOCs in estuaries are further complicated because HOCs typically enter from multiple sources. The distribution of contaminants in estuarine sediment beds reflect a time integration of a complex balance of time- and space-variable fate and transport processes and loading history. A unique opportunity to study HOC fate and transport exists in the Lower Passaic River (LPR), where a pesticide manufacturer was the dominant source of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) to the estuary and the distribution of this "tracer of opportunity" provides insights about fate and transport processes in estuarine systems. This paper presents observed sediment 2,3,7,8-TCDD patterns within the LPR and the adjacent Newark Bay, and interprets them in terms of fate and transport processes that likely distributed the contaminant from its dominant source, drawing upon other physical datasets as needed. Major observations include that estuarine transport processes have distributed 2,3,7,8-TCDD approximately 18 km upstream of the source and downstream across Newark Bay, and that, generally, HOC trapping processes within the LPR have been highly effective, particularly near the 2,3,7,8-TCDD source and in downstream areas. The present LPR surface sediment 2,3,7,8-TCDD distribution indicates spatially variable recovery, which appears broadly driven by historical net sedimentation patterns, though the dominant processes may be shifting as the system continues to evolve. © 2013 The Author(s).
Wang T.,Anchor QEA LLC
Ports 2013: Success Through Diversification - Proceedings of the 13th Triennial International Conference | Year: 2013
The Whatcom Waterway is located on the Bellingham Bay waterfront in Bellingham, Washington, and is currently managed by the Port of Bellingham (Port). The Whatcom Waterway site includes aquatic areas that have been impacted by contaminants historically released from industrial waterfront activities, including mercury discharges from a former Georgia Pacific (GP) chlor-alkali plant, wood waste and degradation products from historical log rafting activities, and phenolic compounds from pulp mill wastewater discharges, as well as other industrial releases. A remedial investigation/feasibility study (RI/FS) effort was completed in 2007 with the Washington State Department of Ecology (Ecology), and the first phase of cleanup is currently in the final stages of remedial design and permitting. Cleanup activities will be completed in two phases of work. Phase 1 cleanup activities, the focus of this paper, will commence in the summer of 2013 and include structure demolition, shoreline debris removal, shoreline stabilization, new bulkhead construction, remedial dredging, and placement of engineered sediment caps and dredge residuals management cover material. In total, approximately 111,000 cubic yards (85,000 cubic meters) of contaminated sediment and debris will be removed from the Whatcom Waterway during Phase 1 cleanup. This paper discusses key challenges associated with waterfront cleanup at the Whatcom Waterway site, with a focus on the remedial basis of design that was developed to meet cleanup objectives for the project. Specific topics discussed include: integration of cleanup requirements with navigation and existing tenant operational uses; design of shoreline capping and stabilization to meet geotechnical, coastal engineering, and remedial criteria; engineered capping design criteria to accommodate existing and future vessel use; and integration of aquatic habitat mitigation needs. This paper will provide an overview of the complexities associated with a multi-phase cleanup approach at the Whatcom Waterway site, including recontamination potential within the Phase 1 cleanup areas, and coordination with private and public landowners to preserve existing operational site use and account for potential future waterway use changes. © 2013 American Society of Civil Engineers.