Hillsborough River Research Articles

Effects of hydrodynamics on the cross-sectional distribution and transport of plastic in an urban coastal river.

The mechanisms of plastic transport in rivers remain an important knowledge gap in global plastic pollution research and management. We investigated how river flows and plastics' properties affect transport with a five-point cross-sectional field study in the Hillsborough River in Tampa (Florida, USA) using a 500-µm Neuston net and an Acoustic Doppler Current Profiler. We conducted in-depth analysis of water velocity profiles as well as plastics' concentrations and properties, determining advective, vertical, and lateral transport fluxes. Under calm flow conditions, advective fluxes were two orders of magnitude higher than lateral and vertical fluxes. Under turbulent conditions, enhanced particle exchange in the cross-section resulted in a three to tenfold increase in lateral and vertical plastic fluxes. The impact of turbulence on plastic particles depended on properties such as size, shape, and composition. This study presents a unique assessment of flow conditions driving plastic pollution in an urban coastal river setting. PRACTITIONERS POINTS: Multipoint, cross-sectional sampling and onsite flow profile collection should be adopted as a common practice for plastic field data collection to reduce uncertainty. Varying flow conditions affect the drivers of plastic transport in rivers. Advective surface fluxes govern plastic transport under calm flow conditions, while turbulent flow conditions enhance cross-sectional mixing and particle exchange. Larger and more irregular-shaped plastics are more affected by turbulence.

Bayesian risk assessment model of human cryptosporidiosis cases following consumption of raw Eastern oysters (Crassostrea virginica) contaminated with Cryptosporidium oocysts in the Hillsborough River system in Prince Edward Island, Canada

Cryptosporidium spp. has been associated with foodborne infectious disease outbreaks; however, it is unclear to what extent raw oyster consumption poses a risk to public health. Control of Cryptosporidium in shellfish harvest seawater in Canada is not mandatory and, despite relay/depuration processes, the parasite can remain viable in oysters for at least a month (depending on initial loads and seawater characteristics). Risks of human infection and illness from exposure to oysters contaminated with Cryptosporidium oocysts were assessed in a Bayesian framework. Two data sets were used: counts of oocysts in oysters harvested in Approved, Restricted, and Prohibited zones of the Hillsborough River system; and oocyst elimination rate from oysters exposed to oocysts in laboratory experiments. A total of 20 scenarios were assessed according to number of oysters consumed in a single serving (1, 10 and 30) and different relay times. The median probability of infection and developing cryptosporidiosis (e.g. illness) due to the consumption of raw oysters in Prince Edward Island was zero for all scenarios. However, the 95th percentiles ranged from 2% to 81% and from 1% to 59% for probability of infection and illness, respectively. When relay times were extended from 14 to 30 days and 10 oysters were consumed in one serving from the Restricted zones, these probabilities were reduced from 35% to 16% and from 15% to 7%, respectively. The 14-day relay period established by Canadian authorities for harvesting in Restricted zones seems prudent, though insufficient, as this relay period has been shown to be enough to eliminate fecal coliforms but not Cryptosporidium oocysts, which can remain viable in the oyster for over a month. Extending relay periods of 14 and 21 days for oysters harvested in Restricted zones to 30 days is likely insufficient to substantially decrease the probability of infection and illness. The highest risk was found for oysters that originated in Prohibited zones. Our findings suggest that Cryptosporidium oocysts are a potential cause of foodborne infection and illness when consuming raw oysters from Hillsborough River, one of the most important oyster production bays on Prince Edward Island. We discuss data gaps and limitations of this work in order to identify future research that can be used to reduce the uncertainties in predicted risks.

Effects of River Hydrology and Physicochemistry on Anchovy Abundance and Cymothoid Isopod Parasitism

The flow regime of a river is an important driver of many ecosystem components. However, few studies explore how differences in flow rates and water chemistry can influence communities of parasites and their hosts. Here, we investigate the impact of dissolved oxygen, pH, salinity, water temperature, and river flow on the abundance and prevalence of cymothoid isopod parasitism (Lironeca ovalis) of the Bay Anchovy (Anchoa mitchilli) in the Alafia and Hillsborough rivers of Tampa Bay (Florida). We also explore seasonality by comparing monthly samples preserved throughout 2005-2007. Although both the Alafia and Hillsborough rivers had similar average water temperatures and salinity, and similar wet and dry season cycles, the upstream damming of the Hillsborough River had numerous negative effects on water flow rate, dissolved oxygen content, and acidity. This disruption in water quality corresponded with a lower abundance of anchovy hosts, fewer free-swimming cymothoids, and low prevalence of anchovy parasitism. Anchovies were much more abundant in the Alafia River, but flow negatively affected abundance-a negative effect that could be mitigated by positive changes in water temperature, salinity, and pH. Flow rates also negatively affected free-swimming cymothoid abundance; however, water flow was less important in predicting their parasitism of anchovies. In Alafia, fewer anchovies were parasitized when dissolved oxygen was high and water acidity was low, but more were parasitized during the wet season. These findings corroborate predictions that flow can moderate habitat stability and complexity which, in turn, can impact opportunities for parasitism of host communities.

The fate of urban springs: Pumping-induced seawater intrusion in a phreatic cave

Sulphur Springs Cave is an extensive phreatic cavity that produces a large, historic spring in the middle of metropolitan Tampa, Florida, USA. The city of Tampa extracts groundwater from the spring to supplement municipal water supply and to support low-salinity habitat in the estuarine Hillsborough River. Extraction at this site has occurred for many decades, but has intensified since the early 2000s, rapidly increasing the salinity of the spring and cave water. The purpose of this study was to address the potential sources and mechanisms of saltwater intrusion at this site using historical and current hydrochemical data published in the literature and online by government agencies. We also explored the cave to identify point-sources of intrusion, and collected water and biological samples from inside the cave to identify potential ecosystem impacts of increasing cave salinity. From 1946 to present, Sulphur Springs water shifted from being fresh (specific conductance <500 µS cm−1) and of calcium-sulfate type to being brackish (specific conductance ∼5000 µS cm−1 and higher) and of sodium-chloride type. We found numerous vents in the cave that issue saline, thermal, sulfidic water and host distinct microbial mat communities. These vents are likely connected to bedrock fractures that provide preferential flow-paths along which confined, deep-sourced saline water enters the freshwater portion of the aquifer, probably originating from the coastal mixing zone. Salinity increased at the spring during dry-season pumping activity and after wet-season recharge events, which likely increased artesian pressure in confined saline aquifer units. Salinization of Sulphur Springs may disrupt the cave microbe and stygobite communities and eventually make the spring unsuitable to maintain low-salinity habitat in the Hillsborough River.

Effects of rain events on Cryptosporidium spp. levels in commercial shellfish zones in the Hillsborough River, Prince Edward Island, Canada

A longitudinal study was conducted during the 2014 spring eastern oyster harvesting season in Prince Edward Island. The concentrations of Cryptosporidium oocysts were assessed in seawater and oyster samples taken from three commercial shellfish zones (Approved, Restricted, and Prohibited) one day before a rain event (of at least 15mm), and on days 1, 3, and 7 after the rain event. Two rain events were recorded during the study period. The first event (rain event 1) was characterized by precipitation of 15mm over 14h (low intensity) and the second event had 40mm in 14h (high intensity). Oocysts in 20L of seawater ranged from 0 to10, 0 to 7, and 1 to 15 in Approved, Restricted, and Prohibited zones, respectively, and in oysters, ranged from 0 to 30, 0 to 48, and 0 to 25 in Approved, Restricted, and Prohibited zones, respectively. A significant increase in Cryptosporidium spp. oocyst counts was observed in seawater samples after an intense rain event. Oocyst counts in seawater were almost two times higher after a high intensity rain event than after a low intensity event, but no effect was observed in oysters. However, positive samples (seawater and oysters) were still present seven days after a rain event. These findings suggest that authorities should consider monitoring for Cryptosporidium spp. in shellfish and their associated waters, especially after heavy rain events.

Hillsborough River Bascule Bridge Vibration and Rehabilitation

Hillsborough River Bascule Bridge, located in Tampa, Florida, vibrates significantly under traffic loading, and discomforting noises have been reported, especially in recent years. The cause of such a significant vibration was investigated. The bridge is briefly described. Analytical theory is then presented, including the vehicle model, bridge model, road surface model, and numerical methods. A vehicle is simulated as a three-dimensional nonlinear model. The bridge is treated as a space structure consisting of three-dimensional frame elements. The road profile is modeled as a stationary Gaussian random process that is described by a power spectral density function. The free and forced vibration characteristics of the bridge were investigated with trucks traveling over a rough deck. The stiffness effects of the main girders, bracings, and floor beams were studied. Analytical results indicate that insufficient stiffness of lateral bracings and floor beams is a main factor causing the severe vibration. Some rehabilitation schemes for mitigating the severe vibration were investigated. The actual behaviors of the rehabilitated bridge indicate that research results were correct and applicable to bascule bridge design and rehabilitation.

Occurrence and antimicrobial resistance of Escherichia coli in oysters and mussels from Atlantic Canada.

Acquiring antimicrobial-resistant (AMR) bacteria through consuming contaminated animal food products is an emerging public health concern, though the sources of contamination are not always clear. This study characterized the occurrence of AMR in Escherichia coli from bivalve molluscs and assessed for the possible sources in the Hillsborough river complex of Prince Edward Island, Canada in areas overlapping with an oyster fishery. Multivariable statistical analysis indicated that the probability of detecting E. coli increased as the estimated dosage of animal effluent contamination decreased. Isolates with AMR were only found from sampling sites closest to untreated human effluent sources. Twenty-seven percent (n=6 of 22) of the isolates were pathogenic, with virulence factors consistent with extraintestinal E. coli of human origin. Though there is more evidence of contamination arising from human effluent, more research is needed to identify driving sources.

The Principal Beauty of “At the Fishhouses”

The Principal Beauty of “At the Fishhouses” Erica Dawson (bio) I love Elizabeth Bishop’s love of travel. I admire her ability to place us in a familiar environment and then, seamlessly, transport us somewhere exotic. I moved to Tampa, Florida, almost four years ago and still find it exotic, feral even, with its love bugs mating midair. I want to recreate the Gulf Coast in my writing, tracing its lines, feeling both the weight of where I am and my perceptions of it, my awareness and my invention. During my undergraduate years at Johns Hopkins, one of my first poetry instructors introduced me to what is now my favorite Bishop poem, “At the Fishhouses.” I recently shared it with a student of my own as an example of the power of Bishop’s images. The images in this poem may not introduce readers to the lush exoticism of the tropics, but Bishop still invites me to a physical place I don’t know—the shores of Nova Scotia—and to a mental space I struggle to find in my own poetry. I’ve only begun to discover Florida—but so much of it scares me. It’s as if there’s too much to perceive, let alone capture on paper. The Hillsborough River weaves through downtown Tampa; the Bay is always at my feet, the humidity on my back. It’s ironic that I find myself in a place so surrounded by water: I have an intense fear of fish. I don’t walk too close to the fish counter at the grocery store. When I visited Seattle this past February I was so scared of Pike Place Market and the fish flying through it, I took a step inside and stepped back out. It seems doubtful, then, that I could love a poem called “At the Fishhouses.” But the poem, unlike Bishop’s iconic “The Fish,” is less about the physical animal and more about observation transformed into imagination. The title itself indicates that the poem will focus on the surroundings of the animals rather than the animals themselves. To recreate the real-life sensation of observation through perception, Bishop downplays the physical presence of the speaker as well. We don’t actually see her moving, but rather witness the mind moving through the environment from one aspect of the setting to another. [End Page 33] The backdrop becomes the foreground of the poem. It illustrates what’s in the limelight of the speaker’s gaze. In the opening stanza, Bishop uses several strategies to put us in the mindset of the speaker. “At the Fishhouses” begins with this sentence: Although it is a cold evening,down by one of the fishhouses,an old man sits netting,his net, in the gloaming almost invisible,a dark purple brown,and his shuttle worn and polished. (lines 1–6) Inverted syntax (placing a dependent before an independent clause), along with multiple modifiers and prepositions in a single sentence, leads us away from the actual subject of the sentence, as do weak to be verb constructions and passive phrasing. The result is a poem lively but static, moving but still, as something changes inside the speaker rather than in the exterior world. The images I shared with my student aren’t simply powerful. They are transformative for both speaker and reader. We start with a wide shot, then briefly have a visual of the old man, the sentence’s only independent clause and declarative action. Bishop introduces us to the weather first, then the location, and then the subject of the sentence. But she doesn’t linger there for more than one line, instead moving to a description of his net—the object he holds, not the man himself. The sentence only contains the to be verb when she writes about the man. She only implies the presence of is in the other places where it belongs: his net is a dark purple brown; his shuttle is worn and polished. By omitting the verb, Bishop removes the sense of agency. It’s not about agency. It’s about perception of what already exists. Farther down in the first stanza, Bishop writes...

Amniote faunal revision of the Pictou Group (Permo-Carboniferous), Prince Edward Island, Canada

The amniote faunal assemblages from the Pictou Group (Prince Edward Island, Canada) are re-evaluated for the first time in 50 years. Fossils recovered from formations within this group (Orby Head, Hillsborough River, and Kildare Capes) indicate the presence of a parareptile, representing the first occurrence of a non-synapsid amniote from the PEI redbeds. The amniote taxa from PEI are re-described within the context of current research, providing the basis for an updated faunal list for the vertebrate-bearing formations within the Pictou Group. The presence of a parareptile, diadectid, and possibly two synapsids (caseid and/or varanopid), together with the absence of edaphosaurids and definitive ophiacodontids, suggests similarities with the upland Bromacker and Richards Spur localities of Germany and Oklahoma, respectively. However, more research and new fossil discoveries are needed to confidently resolve the systematics and palaeoecology of amniotes from the Lower Permian of Atlantic Canada.

Water Quality and Land Use Changes in the Alafia and Hillsborough River Watersheds, Florida, USA1

Abstract: Spatial distribution of land use can have a substantial effect on surface and groundwater quality. Our objective was to test for trends in flow components and water quality related to changes in land use in the Alafia and Hillsborough River watersheds in Florida, USA, over the period 1974‐2007. In addition, water quality statistics were evaluated in the perspective of numeric water quality criteria and proposed reclassification of segments of the Alafia River. Trends in 10 water quality parameters and three discharge variables were evaluated using a nonparametric trend detection test. Results of land use analysis indicated substantial urbanization and loss of agricultural land in the study area. Discharge variables did not exhibit significant trends, whereas trends in the majority of water quality concentrations were negative or nonsignificant with total nitrogen and total Kjeldahl nitrogen as exceptions showing positive trends. Changes in nutrient pathways could not be clearly identified. Considering recently promulgated numeric nutrient criteria and standards for dissolved fluoride, much of the Alafia River was found to be out of compliance. While there were land use changes and changes in water quality over the study period, it was difficult to identify a direct cause‐effect relationship. Responses to regulatory efforts, such as the Clean Water Act and improvements in phosphate mining practices, may have had greater impacts on water quality than changes in land use.

Relationship Between Watershed Land-Cover/Land-Use Change and Water Turbidity Status of Tampa Bay Major Tributaries, Florida, USA

The extent and change of land cover/land use (LCLU) across the Tampa Bay watershed, Florida, was characterized for the time period between 1996 and 2006. Likewise, the water turbidity trend was determined at a site near the Bay for each of four major tributaries to Tampa Bay (Hillsborough River, the Alafia River, the Little Manatee River, and the Manatee River). This study identifies consistent changes in LCLU across the Tampa Bay watershed and a decrease in water turbidity. LCLU change analysis as a percent of the total Tampa Bay watershed revealed an increase of 2.6% in developed area followed by a 0.9% in bare land and a 0.6% in water cover. A decrease of 1.8% of the total Tampa Bay watershed was found in agriculture, followed in order by 1.1% in wetland and 1.4% in scrub/shrub. Other land classes changed less than 0.2% of the total watershed. A linear mixed model (SAS procedure PROC MIXED) revealed an overall decreasing trend in water turbidity (p = 0.003, slope estimate = −0.02) across the four major Tampa Bay tributaries considered. This study suggests that development (urbanization) could be associated with decreasing water turbidity in Tampa Bay. Finally, although these results may help explain similar effects on other water bodies with similar conditions of adjacent urbanization and low slope, more analysis are needed considering a larger number of watersheds with similar scales and longer time period in order to confirm that the findings of this study are generally evident.

Scales of heterogeneity of water quality in rivers: Insights from high resolution maps based on integrated geospatial, sensor and ROV technologies

While the spatial heterogeneity of many aquatic ecosystems is acknowledged, rivers are often mistakenly described as homogenous and well-mixed. The collection and visualization of attributes like water quality is key to our perception and management of these ecosystems. The assumption of homogeneity can lead to the conclusion that data collection from discrete, discontinuous points in space or time provide a comprehensive estimate of condition. To counter this perception, we combined high-density data collection with spatial interpolation techniques to created two-dimensional maps of water quality. Maps of four riverine transitions and habitats – wetland to urban, river to reservoir, river to estuary and a groundwater intrusion – were constructed from the continuous data. The examples provided show that the most basic water quality parameters - temperature, conductivity, salinity, turbidity, and chlorophyll florescence - are heterogeneous at spatial scales smaller than those captured by common point sampling statistical strategies. The 2-dimensional, interpolation-based maps of the Hillsborough River (Tampa, FL) show significant influences of a variety of geographic features including tributary confluences, submarine groundwater inflow, and riparian interfaces. We conclude that many sampling strategies do not account for the type of patchy heterogeneity observed. The integration of existing in-situ sensors, inexpensive autonomous sampling platforms, and geospatial mapping techniques provides high resolution visualization that can adds a more comprehensive geographic perspective needed for environmental monitoring and assessment programs.

Linking a spatially explicit watershed model (SWAT) with an in‐stream fish habitat model (PHABSIM): A case study of setting minimum flows and levels in a low gradient, sub‐tropical river

AbstractAs changes in landuse and the demand for water accelerate, regulators and resource managers are increasingly asked to evaluate water allocation against the need for protection of in‐stream habitat. In the United States, only a small number of river basins have the long‐term hydrograph data needed to make these assessments. This paper presents an example of how to bridge the conceptual and physical divide between GIS‐based watershed modelling of basin‐discharge and in‐stream hydraulic habitat models. Specifically, we used a Soil and Water Assessment Tool (SWAT) model for the Hillsborough River to produce data for use in a Physical HABitat SIMulation (PHABSIM) model of the same river. This coupling of models allowed us to develop long‐term discharge data in ungauged river systems based on watershed characteristics and precipitation records. However this approach is not without important limitations. Results confirm that accuracy of the SWAT‐predicted hydrograph declines significantly when either the DEM resolution becomes too coarse or if DEM data are resampled to a coarser or finer resolution. This is due to both changes in the size and shape of the river basin with the varying DEMs and subsequent shifts in the proportions of land use, soils and elevation. Results show the use of 30 m DEMs produced hydrographic patterns amenable for using in‐stream habitat protocols like PHABSIM model, especially where little or no hydrographic and land use information exists. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Application of the Bacteria Decision-Support Tool in the Hillsborough River Watershed

Application of the Bacteria Decision-Support Tool in the Hillsborough River Watershed

Characterization and adsorption of arsenate and selenite onto Kemiron

Kemiron, a commercially available, porous iron oxide sorbent was evaluated in batch systems for arsenate (As(V)) and selenite (Se(IV)) removal from aqueous solutions as a function of pH, ionic strength, and particle size (< 38 μ m and between 250 and 425 μ m). BET surface area of Kemiron is 39.8 m2/g and Electron dispersive spectroscopy (EDS) studies found Kemiron to be 40.37% iron and 42.25% oxygen by mass. Langmuir isotherms best described the As(V) and Se(IV) removal at pH 7 with maximum adsorption capacity of 82 mg/g and 52 mg/g respectively. As(V) and Se(IV) sorption decreased as pH increased and both anions were unaffected by sodium nitrate (NaNO3) background electrolyte. As(V) sorption was not affected in surface water samples from the Hillsborough River. Batch kinetic models of the experimental data on the 250 to 425 μ m particle size yielded mass transfer coefficients of 0.0008 min−1 and 0.009 min−1 for As(V) and Se(IV) respectively.

Plant conversion experience: ozone BAC process installation and disinfectant residual control

The David L. Tippin Water Treatment Facility in Tampa, Fla., treats Hillsborough River water, which has relatively high organic matter content, especially during high‐rainfall seasons. In 2001, ozonation and biologically activated carbon (BAC) filtration were implemented along with a few additional modifications to the existing conventional process. After the start of the new process, unexpectedly low monochloramine formation efficiency and rapid decay of monochloramine residual in treated waters were observed. By changing the sequence of free chlorine and ammonia injection and by providing sufficient mixing and reaction time for free chlorine, monochloramine formation efficiency was dramatically increased. Among several factors that might affect monochloramine decay rate, the particulate matter produced from the BAC filters, presumably because of microbial activities, was found to be primarily responsible for the monochloramine demand. The filter backwashing practice was modified to successfully enhance filter performance and stabilize monochloramine in treated waters.

Colored dissolved organic matter in Tampa Bay, Florida

Absorption and fluorescence of colored dissolved organic matter (CDOM) and concentrations of dissolved organic carbon (DOC), chlorophyll and total suspended solids in Tampa Bay and its adjacent rivers were examined in June and October of 2004. Except in Old Tampa Bay (OTB), the spatial distribution of CDOM showed a conservative relationship with salinity in June, 2004 ( a CDOM(400) = − 0.19 × salinity + 6.78, R 2 = 0.98, n = 17, salinity range = 1.1–32.5) with little variations in absorption spectral slope and fluorescence efficiency. This indicates that CDOM distribution was dominated by mixing. In October, 2004, CDOM distribution was nonconservative with an average absorption coefficient ( a CDOM(400), ∼ 7.76 m − 1 ) about seven times higher than that in June (∼ 1.11 m − 1 ). The nonconservative behavior was caused largely by CDOM removal at intermediate salinities (e.g., a CDOM(400) removal > 15% at salinity ∼ 13.0), which likely resulted from photobleaching due to stronger stratification. The spatial and seasonal distributions of CDOM in Tampa Bay showed that the two largest rivers, the Alafia River (AR) and Hillsborough River (HR) were dominant CDOM sources to most of the bay. In OTB, however, CDOM showed distinctive differences: lower absorption coefficient, higher absorption spectral slopes, and lower ratios of CDOM absorption to DOC and higher fluorescence efficiency. These differences may have stemmed from (1) changes in CDOM composition by more intensive photobleaching due to the longer residence time of water mass in OTB; (2) other sources of CDOM than the HR/AR inputs, such as local creeks, streams, groundwater, and/or bottom re-suspension. Average CDOM absorption in Tampa Bay at 443 nm, a CDOM(443), was about five times higher in June and about ten times higher in October than phytoplankton pigment absorption, a ph(443), indicating that blue light attenuation in the water column was dominated by CDOM rather than by phytoplankton absorption throughout the year.

Spatial and temporal chemical variability in the Hillsborough River system

The Hillsborough River originates in the Green Swamp, a principal recharge area of the Floridan Aquifer system. As the river flows to Tampa Bay, its chemistry is influenced by a variety of natural and anthropogenic inputs. Spatial and temporal variations in the river's major ion concentrations, CO 2-system chemistry, and nutrients were examined in a two-year study between 1999 and 2001. At thirteen sampling stations along approximately 87 km of the river, water samples were collected in surroundings that ranged from pristine to urban. Concentrations of major ions were lowest in the river's headwaters, showed only minor spatial variations mid-river, and sharply increased in tidally influenced waters below the dam on the lower river. The mid-river major ion composition is relatively constant in large part because two of the river's most compositionally distinctive inputs, Blackwater Creek and Crystal Springs, are located well upstream. Below the confluence of Blackwater Creek and river water that is largely derived from Crystal Springs, concentrations of Na +, K +, Mg 2+, Ca 2+, HCO 3 −, F −, Cl − and PO 4 3− showed spatial variations that were smaller than +/− 30%. Only SO 4 2− and NO 3 − exhibited strong downstream variations. Sulfate concentrations increased by more than a factor of two, and NO 3 − decreased by more than an order of magnitude. In contrast to spatial variations in the river's chemistry, temporal variations were quite large. Concentrations of major ions decreased during the rainy season (June–September) by as much as a factor of 3–5, and phosphate concentrations increased by approximately an order of magnitude. The river's CO 2-system also showed strong seasonal variations. River pH and CaCO 3 saturation state decreased sharply during periods of high precipitation. CaCO 3 supersaturation was observed during the exceptionally dry periods of the study, and undersaturation was observed during periods of high rainfall. Overall, the Hillsborough River's delivery of solutes to Tampa Bay is greatly influenced by temporal variations in river hydrology, and distinct chemical signatures from the river's tributaries, groundwater sources, and anthropogenic inputs. The river's output of phosphate to the bay, which is exceptionally high during periods of high river-flow, is especially notable.

Pharmaceutically active compounds in Atlantic Canadian sewage treatment plant effluents and receiving waters, and potential for environmental effects as measured by acute and chronic Aquatic Toxicity

Ten acidic and two neutral pharmaceuticals were detected in the effluents of eight sewage treatment plants (STPs) from across Atlantic Canada. Concentrations varied between nondetectable and 35 microg/L. The analgesic, nonsteroidal anti-inflammatory drugs ibuprofen and naproxen were predominant. Carbamazepine, a neutral compound used as an antiepileptic drug, was observed consistently at a median concentration of 79 ng/L. Acetaminophen was found in the effluents of the three largest mechanical STPs at a median concentration of 1.9 microg/L, but not in the lagoon treatment systems. The substantially longer hydraulic retention times may have contributed to more effective removal of acetaminophen in the lagoon treatment systems. Drugs generally were not detected at significant concentrations in the larger bodies of receiving water (Saint John River, Hillsborough River, and Bedford Bay, Canada). However, drug residues in the small receiving streams were 15 to 30% of the effluent median concentrations. Six compounds (caffeine, naproxen, salicylic acid, carbamazepine, metoprolol, and sotolol) were found to persist in a small stream for a distance of at least 17 km, suggesting that small stream exposure to pharmaceutically active residues may be relatively greater than that in large bodies of water. Bioassays assessing acute and chronic effects on four organisms were conducted on four high-use drugs: Acetaminophen, ibuprofen, naproxen, and salicylic acid (metabolite of acetyl salicylic acid). Results indicated no negative effects except for the chronic algal (Selanastrum capricornutum) growth test on ibuprofen (no-observed-effect concentration, 10 microg/L; lowest-observed-effect concentration, 32 microg/L). Effects of these four compounds on invertebrates and plants in the receiving environments are unlikely based on the concentrations measured.

Spectrophotometric Measurements of pH in-Situ: Laboratory and Field Evaluations of Instrumental Performance

Automated in-situ instrumentation has been developed for precise and accurate measurements of a variety of analytes in natural waters. In this work we describe the use of 'SEAS' (spectrophotometric elemental analysis system) instrumentation for measurements of solution pH. SEAS-pH incorporates a CCD-based spectrophotometer, an incandescent light source, and dual pumps for mixing natural water samples with a sulfonephthalein indicator. The SEAS-pH optical cell consists of either a liquid core waveguide (LCW, Teflon AF-2400) or a custom-made PEEK cell. Long optical path lengths allow use of indicators at low concentrations, thereby precluding large indicator-induced pH perturbations. Laboratory experiments show that pH measurements obtained using LCW and PEEK optical cells are indistinguishable from measurements obtained using conventional spectrophotometric cells and high-performance spectrophotometers. Deployments in the Equatorial Pacific and the Gulf of Mexico demonstrate that SEAS-pH instruments are capable of obtaining vertical pH profiles with high spatial resolution. SEAS-pH deployments at a fixed river-site (Hillsborough River, FL) demonstrate the capability of SEAS for observations of diel pH cycles with high temporal resolution. The in-situ precision of SEAS-pH is assessed as 0.0014 pH units, and the system's measurement frequency is approximately 0.5 Hz. This work indicates that in-situ instrumentation can be used to provide accurate, precise, and highly resolved observations of carbon-system transformations in the natural environment.