Department of Civil and Environmental Engineering

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The mission of the Department of Civil and Environmental Engineering at the University of Delaware is to provide a culturally diverse and intellectually stimulating environment for the discovery and application of knowledge in civil and environmental engineering, the education of our students to their fullest potential, and service to the public through outreach and professional activities.

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1988 Sediment Monitoring Program In The Southern Chesapeake Bay
(1989-06) Burdige, David J.
A Bacillus velezensis strain shows antimicrobial activity against soilborne and foliar fungi and oomycetes
(Frontiers in Fungal Biology, 2024-02-23) Wockenfuss, Anna; Chan, Kevin; Cooper, Jessica G.; Chaya, Timothy; Mauriello, Megan A.; Yannarell, Sarah M.; Maresca, Julia A.; Donofrio, Nicole M.
Biological control uses naturally occurring antagonists such as bacteria or fungi for environmentally friendly control of plant pathogens. Bacillus spp. have been used for biocontrol of numerous plant and insect pests and are well-known to synthesize a variety of bioactive secondary metabolites. We hypothesized that bacteria isolated from agricultural soil would be effective antagonists of soilborne fungal pathogens. Here, we show that the Delaware soil isolate Bacillus velezensis strain S4 has in vitro activity against soilborne and foliar plant pathogenic fungi, including two with a large host range, and one oomycete. Further, this strain shows putative protease and cellulase activity, consistent with our prior finding that the genome of this organism is highly enriched in antifungal and antimicrobial biosynthetic gene clusters. We demonstrate that this bacterium causes changes to the fungal and oomycete hyphae at the inhibition zone, with some of the hyphae forming bubble-like structures and irregular branching. We tested strain S4 against Magnaporthe oryzae spores, which typically form germ tubes and penetration structures called appressoria, on the surface of the leaf. Our results suggest that after 12 hours of incubation with the bacterium, fungal spores form germ tubes, but instead of producing appressoria, they appear to form rounded, bubble-like structures. Future work will investigate whether a single antifungal molecule induces all these effects, or if they are the result of a combination of bacterially produced antimicrobials.
A Hyperelastic Bounding Surface Plasticity Model for Unsaturated Granular Soils
(Geosciences, 2024-05-30) Kadivar, Mehdi; Manahiloh, Kalehiwot Nega; Kaliakin, Victor N.
In this paper, a state-dependent, bounding surface plasticity model that simulates the behavior of unsaturated granular soils is presented. An unsaturated, soil mechanics-compatible elastoplastic response is adopted in which no part of the response occurs in a purely elastic fashion. To create an appropriate hydro-mechanical coupling, a newer generation stress framework, consisting of the Bishop-type effective stress and a second stress variable, is used in conjunction with a soil-water characteristic curve function. Details regarding the model development, parameter estimation, and assessment of the model’s predictive capabilities are outlined. With a single set of parameter values, the model realistically simulates the main features that characterize the shear and volumetric behavior of unsaturated granular soils over a wide range of matric suction, density, and net confining pressure.
Abiotic reduction of 3-nitro-1,2,4-triazol-5-one (NTO) and other munitions constituents by wood-derived biochar through its rechargeable electron storage capacity
(Environmental Science: Processes and Impacts, 2022-01-17) Xin, Danhui; Girón, Julián; Fuller, Mark E.; Chiu, Pei C.
The environmental fate of 3-nitro-1,2,4-triazol-5-one (NTO) and other insensitive munitions constituents (MCs) is of significant concern due to their high water solubility and mobility relative to legacy MCs. Plant-based biochars have been shown to possess a considerable electron storage capacity (ESC), which enables them to undergo reversible electron transfer reactions. We hypothesized biochar can act as a rechargeable electron donor to effect abiotic reduction of MCs repeatedly through its ESC. To test this hypothesis, MC reduction experiments were performed using wood-derived biochars that were oxidized with dissolved oxygen or reduced with dithionite. Removal of aqueous NTO, an anion at circumneutral pH, by oxidized biochar was minimal and occurred through reversible adsorption. In contrast, NTO removal by reduced biochar was much more pronounced and occurred predominantly through reduction, with concomitant formation of 3-amino-1,2,4-triazol-5-one (ATO). Mass balance and electron recovery with ferricyanide further showed that (1) the amount of NTO reduced to ATO was relatively constant (85–100 μmol per gram of biochar) at pH 6–10; (2) the fraction of biochar ESC reactive toward NTO was ca. 30% of that toward ferricyanide; (3) the NTO-reactive fraction of the ESC was regenerable over multiple redox cycles. We also evaluated biochar transformation of other MCs, including nitroguanidine (NQ), 2,4-dinitroanisole (DNAN), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). While mass and electron balances could not be established due to sorption, DNAN and RDX reduction by reduced biochar was confirmed via detection of multiple reduction products. In contrast, NQ was not reduced under any of the conditions tested. This study is the first demonstration of organic contaminant degradation through biochar's rechargeable ESC. Our results indicate biochar is a regenerable electron storage medium and sorbent that can remove MCs from water through concurrent reduction and sorption, and is thus potentially useful for pollution control and remediation at military facilities.
Abstract Book SETAC 19th Annual Meeting
(Society of Environment Toxicology and Chemistry (SETAC), 1998-11) SETAC, Staff
Acid-Base Metabolism And The Protein Condition
(Rand Corporation, 1967-12) Russell, C.D.
Adhesion Characterization and Enhancement between Polyimide-Silica Composite and Nodulated Copper for Applications in Next-Generation Microelectronics
(ACS Applied Materials & Interfaces, 2024-01-17) Doshi, Sagar M.; Barry, Alexander; Schneider, Alexander; Parambil, Nithin; Mulzer, Catherine; Yahyazadehfar, Mobin; Samadi-Dooki, Aref; Foltz, Benjamin; Warrington, Keith; Wessel, Richard; Zhang, Lei; Simone, Christopher; Blackman, Gregory S.; Lamontia, Mark A.; Gillespie, John W. Jr.
As the need for high-speed electronics continues to rise rapidly, printed wiring board (PWB) requirements become ever-more demanding. A typical PWB is fabricated by bonding dielectric films such as polyimide to electrically conductive copper foil such as rolled annealed (RA) copper and is expected to become thinner, flexible, durable, and compatible with high-frequency 5G performance. Polyimide films inherently feature a higher coefficient of thermal expansion (CTE) than copper foils; this mismatch causes residual thermal stresses. To attenuate the mismatch, silica nanoparticles may be used to reduce the CTE of PI. A nodulated copper surface can be used to enhance the Cu/PI adhesion by additional bonding mechanisms that could include a type of mechanical bonding, which is a focus of this study. In this investigation, a 90° peel test was used to measure the peel strength in copper/polyimide/copper laminates containing nodulated copper and polyimide reinforced with 0, 20, and 40 wt % silica nanoparticles. The influence of silica nanoparticles on the peel strength was quantitatively evaluated. Laminates incorporating polyimide films lacking silica nanoparticles had a ∼3.75× higher peel strength compared with laminates reinforced with 40% silica. Their failure surfaces were analyzed by using scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy to identify the mode of failure and to understand bonding mechanisms. The key bonding mechanism, mechanical interlocking, was achieved when the polyimide surrounded or engulfed the copper nodules when the laminate was created. Post-testing failure surface analysis revealed the presence of copper on the polyimide side and polyimide on the copper side, indicating mixed mode failure. An analytical model was developed to determine the impact of applied pressure, temperature, and time on the polyimide penetration and mechanical interlocking around the copper nodules. The model was validated by measuring the peel strength on another set of specimens fabricated using increased temperature and pressure that showed a 3× increase in peel strength compared to lower temperature/pressure processing conditions. This enhanced adhesion resulted from the lower polymer material viscosity at higher temperatures, which fosters deeper and more complete penetration around the copper nodules during processing at higher pressures for longer durations. The methodology of combining peel testing, viscosity and CTE measurement, SEM/EDX, surface chemical analysis, and penetration depth calculation developed herein enables the calculation of the desired processing parameters to enhance functionality and improve adhesion.
An Age Dependent Model Of PCB In A Lake Michigan Food Chain
(1981-09-30) Thomann, Robert V.; Connolly, John P.
An age-dependent food chain model that considers species bioenergetics and toxicant exposure through water and food is developed. It is successfully applied to PCB contamination of the Lake Michigan lake trout food chain represented by phytoplankton, Mysis, alewife, and lake trout. The model indicates that for the top predator lake trout, PCB exposure through the food chain can account for greater than 99 percent of the observed body burden. A simple steady-state computation indicates that ratios of chemical concentration in predators to that in prey in feeding experiments may be as low as 0.2 and still result in significant food chain transfer. It is estimated that a criterion specifying that PCB concentrations of all ages of lake trout be at or below 5 ug/g (wet weight) in the edible portion would require that dissolved PCB concentrations be reduced to somewhere between 0.5 and 2.5 ug/R. The range reflects uncertainty in the PCB assimilation efficiency of the species and the dissolved PCB concentration. This report was submitted in fulfillment of Cooperative Agreement No. CR805916010 by Manhattan College under the sponsorship of the U.S. Environmental Protection Agency. This report covers the project period May 1, 1978 to September 30, 1981.
Aggregated Zero-Knowledge Proof and Blockchain-Empowered Authentication for Autonomous Truck Platooning
(IEEE Transactions on Intelligent Transportation Systems, 2023-05-10) Li, Wanxin; Meese, Collin; Guo, Hao; Nejad, Mark
Platooning technologies enable trucks to drive cooperatively and automatically, providing benefits including less fuel consumption, greater road capacity, and safety. To establish trust during dynamic platooning formation, ensure vehicular data integrity, and guard platoons against potential attackers in mixed fleet environments, verifying any given vehicle’s identity information before granting it access to join a platoon is pivotal. Besides, due to privacy concerns, truck owners may be reluctant to disclose private vehicular information, which can reveal their business data to untrusted third parties. To address these issues, this is the first study to propose an aggregated zero-knowledge proof and blockchain-empowered system for privacy-preserving identity verification in truck platooning. We provide the correctness proof and the security analysis of our proposed authentication scheme, highlighting its increased security and fast performance. The platooning formation procedure is re-designed to seamlessly incorporate the proposed authentication scheme, including the 1st catch-up and cooperative driving steps. The blockchain performs the role of verifier within the authentication scheme and stores platooning records on its digital ledger to guarantee data immutability and integrity. In addition, the proposed programmable access control policies enable truck companies to define who is allowed to access their platoon records. We implement the proposed system and perform extensive experiments on the Hyperledger platform. The results show that the blockchain can provide low latency and high throughput, the aggregated approach can offer a constant verification time of 500 milliseconds regardless of the number of proofs, and the platooning formation only takes seconds under different strategies. The experimental results demonstrate the feasibility of our design for use in real-world truck platooning.
Analysis By Migration In The Presence Of Chemical Reaction
(Rand Corporation, 1962-06) Shapiro, Norman
Analytical Approach for Modeling Axisymmetric Levee Underseepage
(American Society of Civil Engineers., 2014) Benjasupattananan, Sittinan; Meehan, Christopher L.; Meehan, Christopher L., Benjasupattananan, Sittinan; Meehan, Christopher L. (orcid.org/0000-0002-9721-6275); Benjasupattananan, Sittinan
A variety of real-world levee underseepage problems can best be modeled using an axisymmetric analysis approach. In current practice, axisymmetric levee underseepage analyses are performed using numerical modeling approaches, such as the FEM. In contrast, levee underseepage analyses of planar cross sections are often analyzed using a blanket theory analytical approach, which is quicker and more convenient than numerical modeling. To address this problem, this paper provides a derivation of a series of closed-form blanket theory analytical equations that can be used to perform an axisymmetric levee underseepage analysis. This derivation begins from the governing equation of semiconfined uid ow beneath a levee in a shallow semiconfined aquifer. The equations that result from this derivation can be used to calculate the total head in the pervious foundation layer and the seepage quantity that passes through the levee foundation over time. Different equations are presented for different seepage directions relative to the axis of rotation and different model boundary conditions. A typical example problem is used to compare results from the axisymmetric analytical equations that are derived with those from axisymmetric finite-element analyses. For this example problem, the analytical equations yield results that are equal to or more conservative than those from the finite-element analysis, where conservative results correspond to greater seepage under the levee and higher heads at the levee toe.
Annulus Void Fill Material for Rehabilitated Sliplined Culverts
(The University of Akron, 2023-03) Patnaik, Anil; Alzlfawi, Abdullah; Das, Shagata
Sliplining is a method used by transportation agencies to rehabilitate deteriorated culverts. In recent years, ODOT discovered a number of sliplined culverts that did not have their annulus void spaces completely filled. Such culverts experience distortion and settlement as well as reduced structural capacity. Field inspections of several sliplined culverts in Ohio in this study confirmed that the lack of complete annulus void filling is a prevalent problem. Filler grout properties, particularly poor flow characteristics, would prevent the grout from completely filling annulus voids. This led to the investigation of grout properties that are most important to achieve good flow and fillability. New mixture proportions of a controlled low-strength material (CLSM) and cellular grout C40 were developed based on extensive laboratory testing. These improved grouts were also mixed in a batching plant at a larger scale and were pumped over a 200-ft length at an upslope of 2.5% to determine the suitability of these grouts in practical applications. Grouting of the annulus voids of 20-foot-long sections was verified using a 36-inch liner pipe sliplined within a 48-inch host pipe. A suggested basis for changes to the relevant ODOT specifications in SS 837 is recommended.
Application of New Lubricant and Modifier Formulations for the Reduction of Wheel Squeal Noise Under Freight and Passenger Service
(American Railway Engineering Association, 1999-09) Zarembski, Allan M.; Chiddick, Kelvin S.
Wheel sequel noise on curved track is a serious problem in residential areas where the tracks are near or adjacent to homes and residences. This was the case in a Southern California community that was adjacent to a Southern Pacific Railroad mainline that carried both freight and passenger traffic. The specific wheel squeal problem was associated with the negotiation of the moderate curved track by the mix of traffic at a range of speeds and operating conditions. While significant noise levels were recorded by all of the traffic, to include commuter and inter-urban passenger traffic, the highest levels of noise were recorded by intermodal freight equipment, both trailer and container carrying. These n0ise levels were of significant magnitude and resulted in numerous complaints as well a'$ follow up lawsuits from the residents. In order to address this noise problem, the dynamics of the wheel/rail interaction mechanism was examined and a two part solution applied. The solution consisted of using a low coefficient of friction modifiers on the gage face of the high rail of the curve(s) in conjunction with a high positive coefficient of friction modifiers on the top of the rail head on both the high and low rails. In this configuration, lateral slip of the wheel tread across the rail head was significantly reduced, together with the more traditional flanging effects 011 the gage face of the high rail. The result was a significant reduction in the level of noise generated by all of the traffic types. In order to achieve this dual application at specific locations on the rail head, a high rail vehicle mounted application system was developed and utilized. The hi-rail based system allowed for a uniform and accurate application of the friction modifiers onto the rail. However, the friction modifiers deteriorated with time and traffic (as a function of the number of axle passes), and as such had to be reapplied on a regular and ongoing basis. This paper describes the development and application of this combination of friction modifiers to the high noise curve(s) as well as the determination of the rate of degradation of the friction modifiers under traffic. The testing of the Friction Modifiers (Lubricants) performance led to the development of a well defined friction modifier effectiveness degradation curve which served as the basis for an ongoing program of friction modifiers aimed at keeping the level of noise below a defined threshold. In addition, the need for a "reasonably long" interval between friction modifier applications led to the development of an extended life version of the friction modifiers that made them appropriate for use in an ongoing maintenance application.
Application Of The Telegraph Equation To Oceanic Diffusion: Another Mathematic model
(1971-03) Okubo, Akira
The solution of the conventional diffusion equation has an obvious shortcoming; that is, the substance concentration will rise instantaneously everywhere when substance is introduced at some point in the sea. Although such instantaneous propagation of substance makes a negligibly small contribution to the concentration at large distances from the source, it might cause serious error in predicting water pollution, micro-organism distributions, etc. A diffusion equation which overcomes this difficulty is the telegraph equation characterized by a finite propagation velocity. An ad hoc derivation of the telegraph equation from a set of hydromechanical equations identifies the parameters involved in the equation. Thus, the propagation velocity is related to the correlation tensor of turbulent velocity. As a result, the one-particle dispersion law by Taylor and the relative diffusion law by Richardson can be deduced from the telegraph equation.
Assessing Iron Complexation by Dissolved Organic Matter Using Mediated Electrochemical Oxidation
(ACS Earth and Space Chemistry, 2024-08-14) Hudson, Jeffrey M.; Luther, George W., III; Chin, Yu-Ping
FeII is an abundant reductant in the environment that participates in numerous biogeochemical cycles and pollutant attenuation. FeII in aquatic environments can exist as a complex with dissolved organic matter (DOM), where organic ligands in DOM can modulate iron’s redox potential (EH) and henceforth reactivity as a reductant. Previous studies have assessed the reactivity of FeII-complexes using probe compounds, although these compounds are limited in their ability to profile FeII oxidation across multiple thermodynamic conditions (i.e., both pH and EH) and fail to validate the EH of Fe(II)-complexes via their direct measurement. This study elucidated the redox potentials of FeII-DOM complexes via mediated electrochemical oxidation (MEO) and assessed the extent of FeII oxidation at two different applied EH and pH regimes. Furthermore, we used a Nernstian-based model calibrated with a training set between known iron-ligand thermodynamic stability constants and their respective measured potentials to indirectly determine the stability constants of both FeII and FeIII-DOM complexes as a function of EH and pH. This work highlights the versatility of MEO as an electrochemical technique and is the first to assess stability constants of Fe-complexes with aquatic DOM isolates. We also discuss linkages between speciation modeling and redox reactivity of FeII.
Backed-Up, Saturated, and Stagnant: Effect of Milldams on Upstream Riparian Groundwater Hydrologic and Mixing Regimes
(Water Resources Research, 2022-09-28) Sherman, Melissa; Hripto, Johanna; Peck, Erin K.; Gold, Arthur J.; Peipoch, Marc; Imhoff, Paul; Inamdar, Shreeram
How milldams alter riparian hydrologic and groundwater mixing regimes is not well understood. Understanding the effects of milldams and their legacies on riparian hydrology is key to assessing riparian pollution buffering potential and for making appropriate watershed management decisions. We examined the spatiotemporal effects of milldams on groundwater gradients, flow directions, and mixing regime for two dammed sites on Chiques Creek, Pennsylvania (2.4 m tall milldam), and Christina River, Delaware (4 m tall dam), USA. Riparian groundwater levels were recorded every 30 min for multiple wells and transects. Groundwater mixing regime was characterized using 30-min specific conductance data and selected chemical tracers measured monthly for about 2 years. Three distinct regimes were identified for riparian groundwaters—wet, dry, and storm. Riparian groundwater gradients above the dam were low but were typically from the riparian zone to the stream. These flow directions were reversed (stream to riparian) during dry periods due to riparian evapotranspiration losses and during peak stream flows. Longitudinal (parallel to the stream) riparian flow gradients and directions also varied across the hydrologic regimes. Groundwater mixing varied spatially and temporally between storms and seasons. Near-stream groundwater was poorly flushed or mixed during storms whereas that in the adjacent swales revealed greater mixing. This differential groundwater behavior was attributed to milldam legacies that include: berm and swale topography that influenced the routing of surface waters, varying riparian legacy sediment depths and hydraulic conductivities, evapotranspiration losses from riparian vegetation, and runoff input from adjoining roads. Key Points: - Milldams raise riparian groundwater levels, decrease hydraulic gradients, and cause reversals in groundwater flow - Milldam legacies contribute to reduced groundwater mixing in near-stream sediments - Altered groundwater regimes due to milldams could affect riparian water quality processes Plain Language Summary: Riparian zones can buffer streams from upland nitrogen pollution and are thus considered as important water quality management practices. How the presence of milldams affects groundwater flow paths and their buffering capacity is not known. This study showed that milldams back up stream water above dams, reduce the groundwater gradients from the upland to the stream, and also result in their reversal during summer dry conditions and floods. Milldams reduced the mixing of groundwaters for near-stream sediments. This response was attributed to the topographic and sediment conditions associated with the milldams.
Beyond the Wedge: Impact of Tidal Streams on Salinization of Groundwater in a Coastal Aquifer Stressed by Pumping and Sea-Level Rise
(Water Resources Research, 2024-09-27) Hingst, M. C.; Housego, R. M.; He, C.; Minsley, B. J.; Ball, L. B.; Michael, H. A.
Saltwater intrusion (SWI) is a well-studied phenomenon that threatens the freshwater supplies of coastal communities around the world. The development and advancement of numerical models has led to improved assessment of the risk of salinization. However, these studies often fail to include the impact of surface waters as potential sources of aquifer salinity and how they may impact SWI. Based on field-collected data, we developed a regional, variable-density groundwater model using SEAWAT for east Dover, Delaware. In this location, major users of groundwater from the surficial aquifer are the City of Dover and irrigation for agriculture. Our model includes salinized marshland and tidal streams, along with irrigation and municipal pumping wells. Model scenarios were run for 100 years and included changes in pumping rates and sea-level rise (SLR). We examined how these drivers of SWI affect the extent and location of salinization in the surficial aquifer by evaluating differences in chloride concentration near surface waters and the subsurface freshwater-saltwater interface. We found the presence of the marsh inverts the typical freshwater-saltwater wedge interface and that the edge of the interface did not migrate farther inland. Additionally, we found that tidal streams are the dominant pathways of SWI at our site with salinization from streams being exacerbated by SLR. Our results also show that spatial distribution of pumping affects both the magnitude and extent of salinization, with an increase in concentrated pumping leading to more intensive salinization than a more widely distributed increase of the same total pumping volume. Key Points - Presence of a saltmarsh inverts the freshwater-saltwater interface in our study location - Tidal streams contribute substantially to salinization of inland groundwater - Concentrated pumping led to more intensive salinization than widespread pumping
Biochar and zero-valent iron sand filtration simultaneously removes contaminants of emerging concern and Escherichia coli from wastewater effluent
(Biochar, 2023-07-19) Zhu, Linyan; Chattopadhyay, Suhana; Akanbi, Oluwasegun Elijah; Lobo, Steven; Panthi, Suraj; Malayil, Leena; Craddock, Hillary A.; Allard, Sarah M.; Sharma, Manan; Kniel, Kalmia E.; Mongodin, Emmanuel F.; Chiu, Pei C.; Sapkota, Amir; Sapkota, Amy R.
Advanced treated municipal wastewater is an important alternative water source for agricultural irrigation. However, the possible persistence of chemical and microbiological contaminants in these waters raise potential safety concerns with regard to reusing treated wastewater for food crop irrigation. Two low-cost and environmentally-friendly filter media, biochar (BC) and zero-valent iron (ZVI), have attracted great interest in terms of treating reused water. Here, we evaluated the efficacy of BC-, nanosilver-amended biochar- (Ag-BC) and ZVI-sand filters, in reducing contaminants of emerging concern (CECs), Escherichia coli (E. coli) and total bacterial diversity from wastewater effluent. Six experiments were conducted with control quartz sand and sand columns containing BC, Ag-BC, ZVI, BC with ZVI, or Ag-BC with ZVI. After filtration, Ag-BC, ZVI, BC with ZVI and Ag-BC with ZVI demonstrated more than 90% (> 1 log) removal of E. coli from wastewater samples, while BC, Ag-BC, BC with ZVI and Ag-BC with ZVI also demonstrated efficient removal of tested CECs. Lower bacterial diversity was also observed after filtration; however, differences were marginally significant. In addition, significantly (p < 0.05) higher bacterial diversity was observed in wastewater samples collected during warmer versus colder months. Leaching of silver ions occurred from Ag-BC columns; however, this was prevented through the addition of ZVI. In conclusion, our data suggest that the BC with ZVI and Ag-BC with ZVI sand filters, which demonstrated more than 99% removal of both CECs and E. coli without silver ion release, may be effective, low-cost options for decentralized treatment of reused wastewater. Graphical Abstract available at: https://doi.org/10.1007/s42773-023-00240-y Highlights - The efficacy of BC, Ag-BC, and ZVI sand filtration, and their combinations, in removing contaminants from reused water was evaluated. - Ag-BC, ZVI, BC with ZVI and Ag-BC with ZVI demonstrated > 90% removal of E. coli. - BC, Ag-BC, BC with ZVI and Ag-BC with ZVI demonstrated efficient removal of selected contaminants of emerging concern.
The Biogenic Structure of Lower Chesapeake Bay Sediments
(U.S. Enviromental Protection Agency, 1982-08) Nilson, Karl J.; Diaz, Robert J.; Schaffner, Linda C.; Boesch, Donald F.; Bertelsen, Rodney; Kravitz, Michael
This study was designed to obtain Information on the animal-sediment relationships in the Chesapeake Bay as a means of assessing the relative importance of benthic macroinvertebrates in determining the distribution and fate of sediment-borne toxic substances. Large volume box cores for biological examination were collected simultaneously with cores taken by Maryland Geological Survey for interstitial water chemistry. Vertical distribution of organisms within the cores was utilized as a means of determining the depth of biological mixing. The vertical distribution of organisms has been found to be correlated to the depth of mixing. Employed was an x-ray technique to determine the relative amounts of mixing in different areas of the estuary as well as the types of biogenic structure produced by resident organisms.
Biological Field And Laboratory Methods For Measuring The Quality Of Surface Waters And Effluents
(1973-07) Weber, Cornelius

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