Partitioning and removal of perfluorooctanoate during rain events: the importance of physical-chemical properties

The potential for airborne emissions to undergo long-range transport or to be removed from the atmosphere is influenced by their physical-chemical properties. When perfluorooctanate (PFO) enters the environment, its physical-chemical properties can vary significantly, depending on whether it exists as an acid, a salt, or a dissociated ion. A summary of the physical-chemical properties of the three most likely environmental states: ammonium perfluorooctanoate (APFO), perfluorooctanoic acid (PFOA) and the dissociated perfluorooctanoate anion (PFO(-)) is presented to illustrate the distinct environmental properties of each. The most volatile species, PFOA, is shown to have a pH-dependent air-water partitioning coefficient (K(aw)). The variability of K(aw) with pH influences the potential for vapor formation from aqueous environments, including rain events. Using the pH-dependent K(aw) and measured rain and air concentrations, it is shown that vapor-phase PFOA is not likely to be present above measurable levels of 0.2 ng m(-3) (12 parts per quadrillion v/v) during a rain event. Because rain concentrations determined in this work are comparable to measurements in other parts of North America, it is unlikely that rain events are a significant source of vapor-phase PFOA for the general North American region. It is shown that PFOA exists primarily in the particle phase in ambient air near direct sources of emissions and is efficiently scavenged by rain droplets, making wet deposition an important removal mechanism for emissions originating as either PFOA or APFO. Washout ratios of particle-associated PFO were determined to range between 1 x 10(5) and 5 x 10(5), in the same range as other semi-volatile compounds for which wet deposition is an important mechanism for atmospheric removal and deposition onto soils and water bodies.     

45,X/46,XY chromosome mosaicism detected by midtrimester amniocentesis in amniocyte clones

Amniocyte clones from a mid-trimester pregnancy disclosed 45,X/46,XY sex chromosome mosaicism. Because of the uncertainty concerning the phenotype of the fetus, the parents elected to terminate the pregnancy. Mixed (asymmetrical) gonadal dysgenesis was not found. The fetus appeared to have a normal male uro-genital system. No malformations of any type were detected, although as expected, the fetus did have 45,X/46,XY mosaicism.     

Influence of light on algal symbionts of the deep water coral Leptoseris fragilis

Photoadaptations of zooxanthellae living within the deep water coral Leptoseris fragilis taken from the Gulf of Aqaba (Red Sea) were studied. Specimens-collected in summer 1988 between 110 and 120 m depth —were transplanted to 70 and 160 m. At each depth individuals were exposed in their natural growth position (oral side facing the surface) or in a reverse growth position (oral side facing the bottom). After 1 yr of exposure the corals were collected and the zooxanthellae were isolated. As a function of the availability of light with depth and growth position several algal parameters showed changes which are related to photoadaptations. The relatively low density of zooxanthellae of 0.15x10⁶ cellsxcm^-2 at a natural growth depth of 116 m decreased to 0.0034x10⁶ cellsxcm^-2 (2%) at 160 m in specimens growing with a natural orientation. In corals with a downward-facing oral surface at the same depth (160 m) only degenerated algae could be observed. With respect to depth dependence the volume of the algae decreased from 728 m³ at 116 m to 406 m³ at a depth of 160 m and the content of pigments increased. The augmentation of peridinin per cell was low (two times at 160 m compared to 116 m). Chlorophyll a and in particular chlorophyll c ₂ concentrations per cell were enhanced. Compared to natural amounts at 116 m, chl a was five times and chl c ₂ eight times higher at 160 m. At all depths the chl c ₂ content per cell was higher than for chl a. The formation of chl a/chl c ₂ complexes as light harvestor is discussed. Light harvesting, with chl c ₂ prevailing may be explained as a special type of chromatic adaptation of L. fragilis in a double sense: (1) in the habitat light short wavelengths predominate. This light can be directly absorbed with pigments such as chl a and chl c ₂. (2) Host pigments absorb visible violet light and transform these wavelengths, less suitable for photosynthesis, into longer ones by means of autofluorescence. The emitted longer wavelengths fit the absorption maxima of the algal pigments. Thus the host supports photosynthesis of his symbionts. Corals exposed at 160 m depth with a downward facing oral surface were alive after 1 yr and the host wavelength transforming pigment system was still present, but zooxanthellae were absent or degenerated. The light field at 160 m seems therefore to be critical: the combined photoadaptations of host and symbionts, allowing photosynthesis under barren light conditions, seem to be exhausted. In L. fragilis the photoadaptive strategies of host and symbionts cooperate harmoniously. In addition, the adaptations are interlocked with the particular light situation of the habitat with respect to light quantity and quality. The cooperation of physical and organismic parameters examplifies how evolution and, in particular, coevolution has led to optimal fitness.     

Unsolved Problems with Flue-FED Incinerators

At the beginning of the federal program in 1955, air pollution was viewed as a technical challenge. While technical problems remain, emphasis is shifting toward the social challenge. The degree of federal assistance now available to states and municipalities, under the Clean Air Act, is of broadened scope and higher order of magnitude; it is not confined to technical considerations, but has been expanded to take cognizance of political and economic obstacles that often block the path toward better air pollution control.