Collins B.D.,University of Washington |
Montgomery D.R.,University of Washington |
Fetherston K.L.,R2 Resource Consultants |
Abbe T.B.,ENTRIX Inc.
Geomorphology | Year: 2012
A 'floodplain large-wood cycle' is hypothesized as a mechanism for generating landforms and influencing river dynamics in ways that structure and maintain riparian and aquatic ecosystems of forested alluvial river valleys of the Pacific coastal temperate rainforest of North America. In the cycle, pieces of wood large enough to resist fluvial transport and remain in river channels initiate and stabilize wood jams, which in turn create alluvial patches and protect them from erosion. These stable patches provide sites for trees to mature over hundreds of years in river valleys where the average cycle of floodplain turnover is much briefer, thus providing a future source of large wood and reinforcing the cycle. Different tree species can function in the floodplain large-wood cycle in different ecological regions, in different river valleys within regions, and within individual river valleys in which forest composition changes through time. The cycle promotes a physically complex, biodiverse, and self-reinforcing state. Conversely, loss of large trees from the system drives landforms and ecosystems toward an alternate stable state of diminished biogeomorphic complexity. Reestablishing large trees is thus necessary to restore such rivers. Although interactions and mechanisms may differ between biomes and in larger or smaller rivers, available evidence suggests that large riparian trees may have similarly fundamental roles in the physical and biotic structuring of river valleys elsewhere in the temperate zone. © 2011 Elsevier B.V.
Staley C.,University of South Florida |
Reckhow K.H.,ENTRIX Inc. |
Lukasik J.,Biological Consulting Services |
Harwood V.J.,University of South Florida
Water Research | Year: 2012
We investigated the potential for a variety of environmental reservoirs to harbor or contribute fecal indicator bacteria (FIB), DNA markers of human fecal contamination, and human pathogens to a freshwater lake. We hypothesized that submerged aquatic vegetation (SAV), sediments, and stormwater act as reservoirs and/or provide inputs of FIB and human pathogens to this inland water. Analysis included microbial source tracking (MST) markers of sewage contamination (Enterococcus faecium esp gene, human-associated Bacteroides HF183, and human polyomaviruses), pathogens (Salmonella, Cryptosporidium, Giardia, and enteric viruses), and FIB (fecal coliforms, Escherichia coli, and enterococci). Bayesian analysis was used to assess relationships among microbial and physicochemical variables. FIB in the water were correlated with concentrations in SAV and sediment. Furthermore, the correlation of antecedent rainfall and major rain events with FIB concentrations and detection of human markers and pathogens points toward multiple reservoirs for microbial contaminants in this system. Although pathogens and human-source markers were detected in 55% and 21% of samples, respectively, markers rarely coincided with pathogen detection. Bayesian analysis revealed that low concentrations (<45 CFU × 100 ml-1) of fecal coliforms were associated with 93% probability that pathogens would not be detected; furthermore the Bayes net model showed associations between elevated temperature and rainfall with fecal coliform and enterococci concentrations, but not E. coli. These data indicate that many under-studied matrices (e.g. SAV, sediment, stormwater) are important reservoirs for FIB and potentially human pathogens and demonstrate the usefulness of Bayes net analysis for water quality assessment. © 2012 Elsevier Ltd.
Qian S.S.,Duke University |
Qian S.S.,ENTRIX Inc. |
Cuffney T.F.,U.S. Geological Survey
Ecological Indicators | Year: 2012
The concept of evaluating multiple alternative models to determine ecological response form is over a century old and is ever more relevant as modern computing power allows ever more complicated models to be routinely used but often without a reasonable model verification process, particularly in fields where the ecological conceptual model is still developing. The emphasis for developing a statistical model is to test the validity of the hypothesis represented by the model. We present a framework of model identification and evaluation that includes exploratory data analysis and model diagnostics and evaluation. This framework emphasizes the importance of evaluating multiple alternative models when evaluating the validity of the model. This process is illustrated by using a model-building problem for quantifying the stream ecological response to urbanization using a data set from a large ecological study designed to understand how stream ecosystems respond to urbanization. The paper focuses on the question of whether a threshold model is appropriate, and demonstrates the importance of evaluating multiple alternative models in the detection of ecological thresholds, and illustrates how choosing an inappropriate model can lead to erroneous conclusion regarding the existence of thresholds. © 2011 Elsevier Ltd. All rights reserved.
Tormey D.,ENTRIX Inc.
Global and Planetary Change | Year: 2010
Glaciated mountains are among the most sensitive environments to climatic changes, and recent work has shown that large-scale glacial melting, including at the end of the Pleistocene, caused a significant increase in the incidence of large volcanic sector collapse and debris flows on then-active volcanoes. With current accelerated rates of glacial melting, glaciated active volcanoes are at an increasing risk of sector collapse, debris flow and landslide. These catastrophic events are Earth's most damaging erosion phenomenon, causing extensive property damage and loss of life.This paper illustrates these effects in well-studied settings, focusing on the end-Pleistocene to Holocene glaciovolcanic growth and destruction of the cone of the active volcano Planchon-Peteroa in the Andean Southern Volcanic Zone at latitude 35° 15' S, along the border between Chile and Argentina. The development of the volcano over the last 14,000. years illustrates how glacial melting and magmatic activity can trigger landslides and sector collapses. Planchon had a large sector collapse that produced a highly mobile and erosive debris avalanche 11,000. years BP, and other slope instabilities during the end-Pleistocene/early Holocene deglaciation. The summit amphitheater left after the sector collapse was subject to alternating periods of glaciation and melting-induced lake formation. Breaching of the moraine dams then formed lahars and landslides originating at the western edge of the summit amphitheater, and the deposits are preserved along the western flank of the volcano. Deep incision of moraine deposits further down the western slope of the volcano indicates that the lahars and landslides were water-rich and had high erosive power. As illustrated by Planchon-Peteroa, the interplay among glacial growth and melting, magmatic activity, and slope stability is complex, but must be accounted for in volcanic hazard assessment. Planchon-Peteroa currently has the southernmost temperate zone mountain glacier in the Andes. Accelerated glacial melting at present rates of climate change could lead to a recurrence of many of these post-Pleistocene events.A framework for augmenting hazard assessments and countermeasures is also proposed based on the types of hazards presented by accelerated glacial melting. Glacial melting may lead to volcanic hazards in areas not previously considered at risk, and hence there may be a low level of preparedness. Compared to the end-Pleistocene accelerated glacial melting and sector collapses, present-day glacial melting in volcanic terrain has the potential to affect large human populations. Human settlements, hydropower production, forestry, mining and wilderness tourism are all concentrated near some glaciated volcanic areas. For example, the area covered by the debris avalanche from Volcan Planchon currently supports a rich agricultural economy in Chile.Effective risk management is needed to address the issues of changing patterns in vulnerability, the nature and redistribution of hazards, and the potential socioeconomic consequences of glaciovolcanic events. Since these events are infrequent, local communities frequently do not have a memory of past occurrences, and therefore have a low awareness of the potential effects. Systematic and structured impact assessment allows objective risk analysis, uncertainty analysis, and a framework for balancing countermeasures and contingency measures with public need and acceptance. An impact assessment approach similar to that used in land use planning is presented here, with the following major elements: (i) hazard characterization; (ii) consequence characterization; (iii) risk assessment; (iv) risk control and countermeasures; and (v) risk communication. The emphasis is on effective risk communication, supported by facts, in order to address the increased hazards posed by accelerated glacial melting on volcanic cone stability. Decision makers must then weigh societal acceptance of the risk control and countermeasures against their costs and consequences. © 2010 Elsevier B.V.
Palhegyi G.E.,ENTRIX Inc.
Journal of Hydrologic Engineering | Year: 2010
This paper presents an approach for designing storm-water controls to promote sustainable ecosystems. The approach focuses on understanding and resolving impacts from storm-water discharges on geomorphic stability of stream channels. To develop effective controls, it is critical to understand performance with links to instream hydrology and geomorphology. Comparing work curves and erosion potential in receiving channels between pre- and posturban conditions is the preferred method to test effectiveness and define management criteria. Work incorporates the combined influence of flow, sediment, geometry, slope, and resistance of the channel boundary and can be used to measure the change in erosive energy resulting from urban discharges. Flow duration control can be used to design on-site storm-water controls because flow duration is directly linked to channel processes. Flow duration control also has the potential to "mimic" predevelopment hydrology and be protective of beneficial values. Examples are presented to illustrate the application of work, the erosion potential, and flow duration control as decision making and design criteria. © 2010 ASCE.
Palhegyi G.E.,ENTRIX Inc.
Journal of Hydrologic Engineering | Year: 2010
Low-impact development (LID), such as bioretention, is increasingly used as a best management practice (BMP) to manage storm-water runoff. With LID becoming an integral part of storm-water management plans, it is critical to understand the hydrologic performance of these devices and their positive impacts on downstream hydrology, geomorphology, and ecology. This paper focuses on presenting a model evaluation of bioretention using calibrated and verified algorithms and describes the application of flow duration control (FDC) as a design strategy. The goal of bioretention, like many LID-based controls, is to replicate natural hydrologic processes. Storm-water controls designed to match preproject flow duration characteristics demonstrate that they come close to mimicking the natural hydrologic cycle, thereby protecting beneficial uses and promoting long-term sustainable solutions. This work presents the FDC approach for sizing bioretention and other similar flow control BMPs. This paper concludes with a summary of the sizing requirements to meet the flow duration criteria. Results from this evaluation suggest that typical water quality design criteria can be effective for individual sites with 20-30% imperviousness. For areas draining 100% imperviousness, typical of LID strategies, storage requirements should be 5-10 cm (2-4 in.) with areas of 12-25% the catchment draining to the bioretention facility. However, storage and land area requirements should be sized based on watershed and site-specific characteristics. © 2010 ASCE.
Brown J.S.,Southern California Coastal Water Research Project |
Ackerman D.,ENTRIX Inc. |
Ackerman D.,Tetra Tech Inc. |
Stein E.D.,Southern California Coastal Water Research Project
Journal of Environmental Engineering (United States) | Year: 2012
Understanding the size distribution of stormwater particulates and the pollutants associated with each size fraction is becoming an increasingly important aspect of stormwater management. This paper evaluates the accuracy of the Laser In Situ Scattering and Transmissometry (LISST 100x) particle analyzer and describes the adaptation of the instrument for use in urban stormwater assessment. The accuracy of the instrument was evaluated with known particle size standards of 5, 20, and 100 μm. While the mode of the size distribution corresponded with the average particle size indicated by the manufacturer, the weighted mean was 131%-141% of the average particle size of the standards. Measured concentrations of screened natural sediment (<63-μm) ranged from 71 to 120% of the nominal value, with a variation in replicate measurements of 3% (coefficient of variation). The pumping regime used to transport stream water to the instrument gave results that compared well with those obtained using a depth-integrated grab sampler. Bubbles in the pumped samples, which could be interpreted by the instrument as particles, were reduced using a modified filter device. Transmission of the laser through the samples was greatly improved using a reduced-volume flow-through cell. Field results using the adapted technique compared well with those obtained with a laboratory Coulter Counter, with a median relative percent difference between the two techniques of 8% for the silt and clay fraction and 20% for very fine and fine sands. With application of protocols outlined in this study, the LISST provides a new tool for continuous in situ analysis of stormwater particulates. © 2012 American Society of Civil Engineers.
Brown R.L.,ENTRIX Inc. |
Naeth M.A.,University of Alberta
Restoration Ecology | Year: 2014
Mining disturbs large forested areas around the world, including boreal forests after oil sands mining in Canada. Industrial companies are expected to reclaim degraded land to ecosystems with equivalent land capability. This research showed the value of woody debris for reclamation of dramatically disturbed landscapes with a forest ecosystem end land use. Adding woody debris during reclamation can facilitate recovery of flora, soil nutrient cycling and water and nutrient holding capacity. Combined with forest floor material, woody debris can provide native plant propagules that would be otherwise commercially unavailable. Sites with and without woody debris on forest floor material containing identifiable litter (L), fragmented and fermented litter (F), and humus (H) (LFH), and peat mineral soil mix (peat) cover soils were studied. Within 2 years, woody debris decreased bare ground and created microsites which were positively associated with greater vegetation cover and woody plant density. Woody debris treatments had lower soil available nitrate and soil under woody debris had a lower temperature range and higher soil volumetric water content than control treatments without woody debris. Woody debris did not affect first year microbial biomass carbon or mycorrhizae, but both were greater on LFH than peat cover soil. LFH was associated with lower bare ground and greater vegetation cover, species richness, and soil phosphorus and potassium than peat cover soil, which had greater soil sulfate. © 2013 Society for Ecological Restoration.
Jayasundara N.,Duke University |
Van Tiem Garner L.,Duke University |
Van Tiem Garner L.,ENTRIX Inc. |
Meyer J.N.,Duke University |
And 2 more authors.
Toxicological Sciences | Year: 2015
Polycyclic aromatic hydrocarbons (PAHs) induce developmental defects including cardiac deformities in fish. The aryl hydrocarbon receptor (AHR) mediates the toxicity of some PAHs. Exposure to a simple PAH mixture during embryo development consisting of an AHR agonist (benzo(a)pyrene-BaP) with fluoranthene (FL), an inhibitor of cytochrome p450 1(CYP1)-a gene induced by AHR activation-results in cardiac deformities. Exposure to BaP or FL alone at similar concentrations alters heart rates, but does not induce morphological deformities. Furthermore, AHR2 knockdown prevents the toxicity of BaP+FL mixture. Here, we used a zebrafish microarray analysis to identify heart-specific transcriptomic changes during early development that might underlie cardiotoxicity of BaP+FL. We used AHR2 morphant embryos to determine the role of this receptor in mediating toxicity. Control and knockdown embryos at 36h post-fertilization were exposed to DMSO, 100 μg/l BaP, 500 μg/l FL, or 100 μg/l BaP+500 μg/l FL, and heart tissues for RNA were extracted at 2, 6, 12, and 18 h-post-exposure (hpe), prior to the appearance of cardiac deformities. Data show AHR2-dependent BaP+FL effects on expression of genes involved in protein biosynthesis and neuronal development in addition to signaling molecules and their associated molecular pathways. Ca2+-cycling and muscle contraction genes were the most significantly differentially expressed category of transcripts when comparing BaP+FL-treated AHR2 morphant and control embryos. These differences were most prominent at 2 and 6 hpe. Therefore, we postulate that BaP+FL may affect cellular Ca2+ levels and subsequently cardiac muscle function, potentially underlying BaP+FL cardiotoxicity. © The Author 2014. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved.
ENTRIX Inc. | Date: 2011-10-28
A method for providing the recharge of water into underground aquifers while preventing the mobilization of trace metals. The recharge water may be used for storage and subsequent withdrawal, or to regain or increase the long term beneficial use of an aquifer. The recharge water may be also be used to influence the groundwater flow in the aquifer. Water is treated and recharged by the addition of a small amount of a sulfide compound to remove dissolved oxygen and prevent dissolution of negative valence sulfur bearing minerals, such as pyrite, in the subsurface. The recharged water may increase the pressure head in the aquifer, alter the groundwater flow pattern to prevent the encroachment of objectionable quality water, or to segregate water of different quality. The recharge water may be fresh or brackish depending on the specific objectives of the application.