ABSTRACT:

Harmful algal blooms (HABs) have become more prevalent within Lake Erie since the mid-1990s. Microcystin is one of the most common and harmful toxins associated with HABs, yet little is known about its attenuation and fate in the environment. Microcystin is a cyclic heptapeptide with 2 variable L-amino acids, which differentiate between the over 60 variants of microcystin known. Variants have differing toxicity profiles, the most toxic being microcystin-LR, which contains leucine (L) and arginine ® amino acids. The goal of this thesis research was to determine whether wave-driven benthic exchange accelerates the attenuation of microcystin in shallow coastal waters using laboratory wave tank experiments. Sediment was collected from Western Lake Erie and incorporated into a 110-gallon tank. A solution consisting of both a conservative chloride tracer and microcystin-LR stock dissolved in water was added to surface water at the start of both a Wave Trial and a Non-Wave Trial, and concentrations were monitored over time in surface water and shallow pore water. Results show that wave conditions had a significant impact on exchange rates of conservative chloride, mixing the system over 30 times faster than stagnant conditions. Microcystin concentration in surface water and pore water decreased faster than chloride, likely due to sorption to sediments, degradation, or both. It is crucial to better understand microcystin attenuation and mechanisms responsible in order to accurately predict the severity, duration, and extent of algal toxin plumes, which negatively affect the health of coastal ecosystems and economies.

ABSTRACT:

Subsurface drainage is known to adversely impact the water quality and contribute to the formation of harmful algal blooms (HABs). In early August of 2014, a HAB developed in the western Lake Erie Basin and resulted in over 400,000 people being unable to drink their tap water. HAB development is aided by excess nutrients from agricultural fields, which are transported through subsurface tile and enter the watershed. Compounding the issue, the trend has been to increase the installation of tile drains in both total extent and density. Due to the immense area of drained fields, it is necessary to establish a cost-effective technique to monitor tile installations and their associated impacts.
This thesis aimed at developing an automated method in order to identify subsurface tile locations from high resolution aerial imagery by applying an object based image analysis (OBIA) approach utilizing eCognition. This process was accomplished through a set of algorithms and image filters, which segment and classify image objects by their spectral and geometric characteristics. The algorithms utilized were based on the relative location of image objects and pixels in order to maximize the robustness and transferability of the final rule-set. These algorithms were coupled with convolution and histogram image iv filters to generate results for a 10km² study area located within Clay Township in Ottawa County, Ohio.
The eCognition results were compared to previously collected tile locations from a concurrent project that applied heads-up digitizing. The heads-up digitized locations were used as a baseline for the accuracy assessment. The accuracy assessment generated a range of agreement values from 67.20% – 71.20%, and an average agreement of 69.76%. The confusion matrices calculated a range of kappa values from 0.273 – 0.416 with an overall K value of 0.382, considered fair in strength of agreement. This thesis provides a step forward in the ability to automatically identify and extract tile drains and will assist future research in subsurface drainage modeling.

ABSTRACT: Cyanobacterial harmful algal blooms (HABs) degrade water quality of western Lake Erie and create negative economic impacts on an annual basis. Public health is at the forefront of concern because these blooms are often toxic due to an abundance of Microcystis. This genus of cyanobacteria produces the toxin microcystin, which causes gastrointestinal illnesses, damages the liver, and is capable of promoting tumors or death of animals (Poste et al 2011). The World Health Organization (WHO) has set values for microcystin in drinking water, recreational contact, and total daily consumption, but no standards exist for concentrations of microcystin in food. Because microcystin can accumulate in fish tissues, and fishing and fish consumption are important economic and cultural practices in Lake Erie, there is a potential health risk to humans via consumption of fish inhabiting waters with high concentrations of microcystin. Walleye is one of the most significant sportfish of Lake Erie, and a previous study found this species can have greater microcystin concentrations than yellow perch and white perch studied in the same time period (Wituszynski 2014). For these reasons, this study quantified microcystin levels in walleye tissue using an enzyme-linked immunosorbent assay (ELISA) and compared to public health thresholds used by the Ohio Department of Natural Resources (ODNR). Samples were harvested at different times and from locations in attempt to understand the seasonal correlation between bloom intensity and microcystin concentration, and impacts of variations in bloom intensity at different locations. The effects of chronic exposure of fish to microcystin has not been widely studied for Lake Erie, and no studies presently exist which have examined year-to-year variation in microcystin content in fish. Thus, by comparing this study to a similar study conducted in 2013 (Wituszynski 2014), we can aid in identifying correlation between annual variation in HABS, determine if previous exposure has an effect on accumulation in fish, and understand when microcystin concentrations in fish tissues may be at its peak when compared to HAB intensity.

ABSTRACT:

Ultrasound (US) was studied as an alternative method to remediate contaminated sediments. Different ultrasonic systems were designed and characterized to fundamentally understand ultrasonic effects in porous sediment and to strategically improve the ultrasonic remediation process. These include a flow-through packed-media column coupled with US, the combination of US and persulfate (PS), and a scaled-up design of a multi-stepped horn.

First, 20 kHz US waves propagating in a flow-through column packed with porous media were characterized. Sound penetration and location of cavitation were measured by a hydrophone; enhanced pore flow velocity and faster bromide tracer breakthroughs were observed. In particular, US pressure decreased exponentially with distance from the US source due to wave absorption and scattering by porous media resulting in localized cavitation close to the horn tip. A Darcy model incorporating ultrasonic effects (i.e., acoustic pressure and cavitational heating) revealed that acoustic pressure increased flow velocity at the beginning of sonication while reduced water viscosity due to cavitational heating was accounted for the enhanced pore flow in long-time sonication. Bromide breakthrough tests verified the US accelerated solute transport, as well as the dispersion of tracer in the porous media. Findings of this column study suggest that US may improve remediation through enhancing fluid flow and mass transfer in porous sediments.

To improve contaminant degradation in sediments, sonication combined with PS was examined. PS is an in-situ chemical oxidation (ISCO) method. An ultrasonic reactor coupled with an electron paramagnetic resonance (EPR) spectrometer through a flow-cell was used to gain insight into the mechanisms of ultrasonic activation of PS. The high hydroxyl radical (•OH) yield in the US-PS system was attributed to the rapid reaction between sulfate radical anion (SO4•‒) and water molecules at the bubble-water interface. Likewise, the high dissociation rate of PS, estimated from steady-state approximation, was expected at the high temperature interface. Modeling of temperature and reactivity distribution surrounding a single cavitation bubble indicated a much larger interfacial region as compared to previous results. Addition of tert-Butyl alcohol and nitrobenzene to the US-PS system verified the location of PS dissociation at the interface and elucidated the •OH activation of PS to SO4•‒. The mechanisms unveiled provide mechanistic support to implement US-PS system for sediment remediation.

In addition, a novel ultrasonic horn with a multi-stepped configuration and a cone-shaped tip was designed to enable scaled-up testing of sonication. Hydrophone and sonochemiluminescence experiments showed and verified multiple cavitation zones around the horn neck and tip. Calorimetry and dosimetry results demonstrated higher energy efficiency (31.3%) and faster hydroxyl radical formation rate (0.36 μM min-1) for the new horn, which led to faster degradation of aqueous phenanthrene, a model contaminant. Characterization of the designed horn using COMSOL modeling and acoustic pressure maps in a large water tank exhibited a much improved treatment capacity (~ 5 L) as compared to typical horn systems. The scale-up efforts allows a potential of large-scale performance with the designed horn for remediation of contaminated sediments.

ABSTRACT:

The growth and abundance of phytoplankton in freshwater lakes has long been
attributed to the concentration of phosphorus (P), and this idea of P-limitation has been a
paradigm accepted by limnologists. Hence, lake managers have relied on the strategy of
reducing P to restore water quality of eutrophic lakes. Recently however, several
researchers have proposed that nitrogen (N) is equally important as P, and have stated
that the P paradigm has eroded. These researchers suggest that both P and N inputs need
to be constrained. In spite of the evidence that suggests N-limitation, there are still
several researchers that hold onto the paradigm that only P regulates phytoplankton
biomass. Limnologists need more data to solve this hotly debate topic. The goal of this
dissertation is to provide insights into the dual nutrient management strategy controversy
by studying how western Lake Erie cyanobacteria responded to low concentrations of N
and P. In western Lake Erie nitrate concentrations decrease throughout the growing
season to very low levels. Nutrient enrichment bioassays conducted monthly during the
summers of 2010 and 2011 indicated that N (and not P) constrains cyanobacterial growth
during August and September when nitrate concentrations are very low. Experiments conducted during 2012 showed that N-limited cyanobacterial blooms are able to utilize
many forms of N. However, nutrient dilution assays indicated that N-limitation could not
be induced during early summer when P is the primary limiting nutrient. Following Nlimitation,
the cyanobacterial bloom shifted from Microcystis to the N-fixing Anabaena.
Furthermore, during 2011, the concentration of the cyanotoxin microcystin was highly
correlated with Anabaena biovolume. Genetic diversity of the Microcystis population
was assessed during 2011 and showed that diversity was very similar spatially and
temporally in spite of the wide range of N, indicating that Lake Erie Microcystis can
survive in low N waters. Finally, long-term data sets show that annual summer nitrate
concentrations in western Lake Erie have been declining since 1995, and yet
cyanobacterial blooms are prevalent. Overall the results suggest that additional N inputs
will likely exacerbate cyanobacterial blooms, however, reducing N inputs will not be
effective in ameliorating eutrophication.

ABSTRACT:

The Great Lakes region of North America, holding 20% of the world’s fresh water and home to ¼ of the U.S. population, can provide its 13 million K-12 learners with a relevant context for science learning, unique opportunities for exploring local environmental issues, and connections to global issues. By linking Great Lakes research scientists with educators, students, and the public, the COSEE (Centers for Ocean Sciences Education Excellence) Great Lakes pursues its goal of enhancing science and environmental literacy of both adults and students.
This doctoral research had a three-fold purpose in the COSEE Great Lakes context. First, this study aimed to characterize the population of Great Lakes scientists and K-12 teachers in the Great Lakes region targeted as potential audiences for activities of COSEE Great Lakes. Second, this study aimed to identify factors that may affect educational collaboration between teachers and scientists. Third, this study was conducted as a part of an ongoing process of evaluating overall COSEE program outcomes related to increasing educational collaborations.
This dissertation consists of three research reports on professional development and interprofessional collaboration of K-12 teachers and scientists. The first report in Chapter 2 investigates primary and secondary teachers’ views of collaboration with scientists and incorporates the findings of teacher surveys into discussions about
professional development programs for educators. From 180 schools randomly selected in the eight Great Lakes States, 194 primary and secondary educators responded to a mailed survey. Through the survey responses, the educators reported that while they have positive attitudes toward their collaboration with scientists, their professional preparation has not equipped them with enough understanding of the process of science and the professions of scientists. Regression analysis shows that five predictor variables account for a majority of the variance in explaining educators’ experience in collaboration with scientists (a combined predictive ability of 32%): attitudes towards collaboration, professional preparation (science competencies), teaching experience in years, contemporary views of science/science education and perceived institutional supports.
The second report in Chapter 3 is an attempt to reveal interactions in education by scientists whose research is focused on the Great Lakes, and incorporates the findings into discussions about scientists’ potential for the role of education partner. In this parallel study, marine and aquatic scientists were recruited to complete a survey at a conference on Great Lakes research in 2006. Through 94 scientist responses, scientists reported that they were involved in educational outreach more frequently as a “resource” than a “partner” in Morrow’s framework (2000). Professional training of scientists and their lack of knowledge in education may explain the ways in which scientists are involved in educational outreach. The results show that most scientists had little chance to obtain knowledge in professional education during their professional science training.
Scientists’ lack of knowledge in education was demonstrated by their unfamiliarity with key terms/concepts in education. Regression analyses shows that four predictor variables account for a majority of the variance in explaining scientists’ experience in collaboration with teachers (a combined predictive ability of 42%): familiarity with terms in education, professional training (educational competencies and collaborative cultures) and age.
The third report in Chapter 4 elaborates on the results and discussions in Chapters 2 and 3 by comparing the two groups and by identifying implications of the findings for teacher-scientist collaboration. Comparing responses from educators (n=194) and scientists (n=94), this study answers how educators differ in the perceptions of education collaboration from scientists, in addition to two other research questions: how do educators in the Great Lakes region collaborate with scientists, and what barriers may deter their participation in collaboration. Regression analyses for the two groups suggest that to foster mutual learning in teacher-scientist collaboration, further consideration must be given to increasing educators’ science competencies and scientists’ collaborative attributes when we develop professional development programs for educators and scientists.

ABSTRACT:

This dissertation explores the physical and economic aspects of agricultural
externalities and the economic value of marine and stream recreational fishing. The
effects of pesticide use and tillage practice on water treatment costs and pesticide
contamination in treated water are empirically investigated in the first essay. The
economic value of marine recreational fishing, the value of access to fishing sites and
fishing quality improvements, is examined in the second essay. The third essay examines
the economic value of stream recreational fishing: the value of fishing trips and water
quality improvements. To evaluate the value of recreational fishing, both second and
third essays use benefit transfer techniques.
The first essay, Empirical Investigation of Agricultural Externalities: Effects of
Pesticide Use and Tillage System on Surface Water Quality and Treatment Costs, focuses
on the off-farm water quality and water treatment cost effects of upstream and nearby
agricultural practices (pesticide use and tillage system), specifically on the pesticide
contamination in finished public surface water and water treatment costs in the Maumee
River Basin, a major tributary to Lake Erie, located in northwestern Ohio, northeastern
Indiana, and southeastern Michigan. Pesticide contamination level in treated surface
water and average chemical cost of treating surface water are related to farming
practices and other environmental variables. Findings indicate significant relationships
between farming practices and both surface water quality and treatment costs. Average
chemical cost per million gallons of water decreases by 1.95% for a 1% reduction in
pesticide application, while pesticide contamination level decreases by 4.32% for a 1%
more adoption of conservation tillage in a typical watershed area in the Maumee River
Basin.
The second essay, The Economic Value of Marine Recreational Fishing: Applying
Benefit Transfer to Marine Recreational Fisheries Statistics Survey (MRFSS), conducts a
comprehensive survey of benefit transfer techniques including historical background,
methodologies, and procedures. Then, benefit transfer technique is applied to the
estimation of access value to fishing sites and willingness to pay for better fishing
experience in a marine recreational fishing environment of the coastal states in the
Northeast and Southeast U.S. Using 1994 Northeast and 1997 Southeast MRFSS data,
benefit transfer estimates are compared with original value estimates to empirically
examine the validity of benefit transfer. Although benefit transfer error could go up to
over 400% of original estimates for some cases, the magnitude of benefit transfer error is
less than 100% of original estimates for most cases. Since two data sets used for benefit
transfer exercise are from different regions and years, whether regional or temporal
variation is more responsible for benefit transfer error can not be determined with current
data.
The third essay, Recreational Fishing Value Estimation of Water Quality
Improvements in Western Ohio Using Benefit Transfer, presents methods for estimating
the value of recreational fishing trips and water quality improvements in two watersheds
supporting a warm freshwater recreational fishery, the Stillwater River Watershed and
Maumee River Basin, in western Ohio using benefit transfer. These two watersheds are
further disaggregated into several local stream segments within the watersheds to provide
regional results for larger watersheds and to help local policy makers target their efforts
more efficiently and effectively. Findings are that annual recreational fishing benefits of
water quality improvements are $2,255,616 ($2,759,225 or $3,966,716) and $6,236,853
($5,395,609 or $7,171,617) with about $44 ($54 or $77) and $58 ($50 or $66) of annual
per angler benefits using average value transfer (two function transfer) estimates in the
Stillwater River Watershed and Maumee River Basin respectively. These estimates along
with disaggregated results in terms of local stream segments and angler types could serve
as an initial set of approximated recreational benefits of any local environmental policy
involving water quality improvement in inland streams and rivers, at least in terms of
recreational fishing.
The measurements of both agricultural externalities and recreational fishing value
can be used to help policy makers manage available resources more efficiently and
effectively in administrating conservation and/or environmental programs. As is always
the case with any non-market valuation technique, careful professional judgments and
efforts should be practiced before adopting externality measurements of agricultural
practices and benefit transfer estimates of any recreation activity at any stage of policy
formulation.