Much of our understanding of factors influencing stream chemistry comes from studies of montane forests, whereas far less work has focused on streams of coastal areas that integrate a homogeneous, flat topography and interactions with the bodies of water into which they drain, especially involving tidal fluxes. Fewer still do so in the context of an urban interface, especially that of a college campus. This study assessed the water quality of Thompson Bayou, a freshwater stream entering the University of West Florida campus in a wetland after flowing through the urban property with impacted water quality. We measured temperature, pH, dissolved O2 (DO), and specific conductivity (SC) for one year at eight sites along Thompson Bayou from campus to the Escambia River. All variables, except temperature, varied spatially, with consistent increases in DO and SC toward the river of 10% and 75%, respectively. Variables exhibited temporal patterns of significant seasonal variation, especially temperature, increasing from a January minimum of 14 °C to a summer maximum of 28 °C. These results suggest that, in general, the biogeochemistry of coastal streams such as Thompson Bayou can be influenced by numerous factors, including (1) wetland processes, (2) interactions of the stream channel with forested uplands, and (3) tidal fluxes.

Stream chemistry effectively integrates watershed ecosystem processes on both spatial and temporal scales. Streams of coastal areas integrate a more homogeneous, flat topography wherein there can be interactions between the stream and the body of water into which it drains, especially where tidal fluxes occur. The present study assessed water quality of Thompson Bayou, which comes to the campus of the University of West Florida in a wetland after flowing through 4 km of commercial and private property with associated impacts on water quality. Sampling was carried out for one year at eight discrete sites along Thompson Bayou from the UWF campus to the Escambia River. We used a portable field meter to measure temperature, pH, dissolved O2 (DO), and specific conductivity (SC). Except for temperature, all variables exhibited a spatial pattern of significant variation with distance, with consistent increases in DO and SC as the stream approached the river. These variables also exhibited a temporal pattern of significant seasonal variation, including—and especially—temperature. Data suggest that spatial and temporal patterns of water quality of Thompson Bayou are determined by (1) processing of water by the wetland, (2) interactions of the stream channel with upland forest stands, and (3) the tidal hydrology of the Escambia River.

An air-entrained high-performance concrete (HPC) mixture design for prestressed bridge beams was developed in an attempt to interest the Tennessee Department of Transportation. The mixture contained locally available, 19-mm maximum-size limestone as the coarse aggregate and a manufactured limestone fine aggregate. A dense, combined aggregate gradation was used to lower water demand and thus enhance durability. Type II portland cement, microsilica, and Class C fly ash were used as binder materials. The resulting w/(c + p) was 0.22. Twelve 0.028-m3 batches of the HPC were mixed for the study. The mixture design produced an average air content of 4.1 percent and an average slump of 72 mm. Although it contained 4.1 percent air, the mixture remained very dense, with an average unit weight of 2422 kg/m3. Average compressive strengths of 72.6, 63.3, 84.8, and 92.9 MPa were achieved at simulated release at 7, 28, and 56 days, respectively. Measured static modulus of elasticity at 28 days agreed with ACI 363R-92 equations within 2 percent. Further, after 600 freezing and thawing cycles, the average durability factor of two prismatic specimens was 100, and visible damage was minimal.

Recent research demonstrates that personal mortality salience from annuity contemplation generates an avoidance response, reducing interest in purchasing annuities. However, theoretical models of mortality salience also predict an increased desire for investment in the future circumstances of surviving others (“symbolic immortality”), such as that provided by bequest provisions in an annuity contract. An experimental test confirms that those exposed to higher levels of personal mortality reminders exhibit a greater preference for an annuity paying lower income but with a bequest provision. Thus, the effects of mortality salience can drive annuity decisions, not only at the extensive margin (avoidance of any purchase), but also at the intensive margin (purchasing lower income by including a bequest provision).

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