The use of pump-out facilities by recreational boaters in Maryland

Because of the intense interest in the water quality of the Chesapeake Bay, the State of Maryland sponsored a survey of 500 Maryland boaters to determine their use of marina facilities to discharge sewage from portable toilets or holding tanks. We report results of that survey as well as examine some of the factors that contribute to the use of pump-out facilities. Presently, with under 10% of Maryland’s marinas having facilities available to pump out holding tanks or portable toilets, less than one in twenty boaters has ever used such a facility. Moreover, less than one in three boats equipped with holding tanks or portable toilets has ever used such a facility. Using a discrete choice behavioral model, we found that boaters with portable toilets were more likely to use facilities than ones with holding tanks, especially if the holding tanks were equipped with macerating devices. The price of using the pump-out facility negatively influenced pump-out use. We also found that vessels in transition were less likely to use marina facilities. Finally, the availability of a pump-out facility at a boater’s marina increased the likelihood of pumping by twofold. In Maryland reduction of boat-generated pollution will likely require a policy of both extensive pump-out services and low costs for the services.     

The Spectral Irradiance Monitor: Measurement Equations and Calibration

The Spectral Irradiance Monitor (SIM) is a satellite-borne spectrometer aboard the Solar Radiation and Climate Experiment (SORCE) that measures solar irradiance between 200 and 2700 nm. This instrument employs a Fèry prism as a dispersing element, an electrical substitution radiometer (ESR) as the primary detector, and four additional photodiode detectors for spectral scanning. Assembling unit level calibrations of critical components and expressing the sensitivity in terms of interrelated measurement equations supplies the instrument's radiant response. The calibration and analysis of the spectrometer's dispersive and transmissive properties, light aperture metrology, and detector characteristics provide the basis for these measurement equations. The values of critical calibration parameters, such as prism and detector response degradation, are re-measured throughout the mission to correct the ground-based calibration.     

Multi-scale risk assessment of stream pollution by wastewater of olive oil mills in Kolymvari,Crete

In the streams of the Mediterranean island of Crete (Greece), olive mill wastewater (OMW) has been reported to reduce biodiversity up to 85 %. Mere conduction of impact assessment based on pollutant concentrations, however, cannot reveal how impacted areas may be connected to the pollution sources. In this study, we developed a new methodology which allows for a dynamic cause-effect linking of pollution sources and impacted areas through the pathways of OMW. Risk is hierarchically assessed and mapped at three different scales and more specifically, at the source scale (targeting olive mill units and their waste tanks), at the receptor scale (targeting potential impacted sites in the streams) and at the watershed scale (which is the scale of overall water management). The approach is based mainly on remote sensing data without taking account of groundwater regimes or field measurements. Involvement of local experts for recognizing spatial features of interest and selecting appropriate risk parameters was proved necessary and efficient in order to model the stream pollution risk realistically. Potential impacted sites in the stream network were occasionally verified by a field survey. The results comprise a set of risk maps at the three different scales. The constructed digital geo-database can be updated or modified and thus is considered to be a dynamic tool for future environmental management in the service of the local community.     

Application of discriminant analysis and manova to grain-size data on a study of the distribution and movement of dredged sediment

A dredged material disposal operation was monitored at a location in Lake Erie, 8 km offshore at Ashtabula, Ohio, in 1975. Approximately 200 sediment cores were collected from 12 experimental and 4 control locations before and after dredging and analyzed for the grain-size distribution and related heavy-metal content. The dredged sediments were similar to those from the lake bottom at the disposal and control sites. Because of this similarity, it was extremely difficult to distinguish between the dredged material and the lake bottom sediments without tagging the material with dyes or radioactive isotopes. A sequence consisting of a linear discriminant analysis followed by a univariate and multivariate analysis of variance was successfully applied to discriminate between the dredged and the original lake sediments. Results indicate that 4 months after the disposal operation some stations had returned to predisposal conditions, a probable result of currents stripping dredged material off the lake bottom. The analysis of variance indicated that the clay-size fraction was responsible for initial changes in the grain-size distribution. Storm induced scouring caused an eventual return of the grain-size distribution to predisposal conditions. In support of this observation, the concentrations of iron and zinc, which were statistically correlated to the clay size fraction, also exhibited the same trends.     

The energetics of natural garnet solid solution

Approximate mixing properties of the end-member components of the quarternary garnet solid solution, (Fe,Mg,Ca,Mn)₃Al₂Si₃O₁₂, have been derived through theoretical analysis of observational data, combined with certain experimental results and crystal chemical considerations. The results suggest that the mixing of pyrope with grossularite, spessartite, and almandine would involve significant positive excess free energies of mixing leading to the critical mixing temperatures of 694±55, 535±140, and 479±63 °C respectively. Spessartite would mix with almandine nearly ideally, and with grossularite with small positive deviation from ideality. The quarternary solution reduces essentially to a ternary mixture of pyrope, grossularite, and almandine + spessartite. The solid solubility relation, and tie line coordinates in this ternary system has been calculated as a function of temperature; the solid solution is found to be intrinsically stable for practically all ternary compositions at 600 °C.     

Principles of quantitative absorbance measurements in anisotropic crystals

The accurate measurement of absorbance (A=-log T; T=I/I ₀) in anisotropic materials like crystals is highly important for the determination of the concentration and orientation of the oscillator (absorber) under investigation. The absorbance in isotropic material is linearly dependent on the concentration of the absorber and on the thickness of the sample (A=?·c·t). Measurement of absorbance in anisotropic media is more complicated, but it can be obtained from polarized spectra (i) on three random, but orthogonal sections of a crystal, or (ii) preferably on two orthogonal sections oriented parallel to each of two axes of the indicatrix ellipsoid. To compare among different crystal classes (including cubic symmetry) it is useful to convert measured absorbance values to one common basis (the total absorbance A _tot), wherein all absorbers are corrected as if they were aligned parallel to the E-vector of the incident light. The total absorption coefficient (a _tot=A _tot/t) is calculated by $$\left( {\text{i}} \right)a_{{\text{tot}}} = \sum\limits_{i = 1}^3 {(a_{\max ,i} + a_{\min ,i} )} /2, {\text{or}} {\text{by}} {\text{(ii) }}a_{{\text{tot}}} = a_x + a_y + a_z .$$ Only in special circumstances will unpolarized measurements of absorbance provide data useful for quantitative studies of anisotropic material. The orientation of the absorber with respect to the axes of the indicatrix ellipsoid is calculated according to A _x/A _tot=cos² (x < absorber), and analogously for A _yand A _z. In this way, correct angles are obtained for all cases of symmetry. The extinction ratio of the polarizer (Pe=I _crossed/I _parallel) has considerable influence on the measured amplitude of absorption bands, especially in cases of strong anisotropic absorbance. However, if Pe is known, the true absorbance values can be calculated even with polarizers of low extinction ratio, according to A _max=?log[(T _max,obs?0.5·Pe·T _min,obs)/(1?0.5·Pe)], and similar for A _min. The theoretical approach is confirmed by measurements on calcite and topaz.