A Fast Gas Chromatographic Method for Measuring C2-C6 Alkanes and Alkenes in Air

The Environmental Protection Agency is responsible for establishing, reviewing, and revising standards of performance for new stationary sources of air pollution. Since this federal program was authorized in 1970, standards of performance (commonly referred to as new source performance standards or NSPS) have been developed for 34 categories of stationary sources. These regulations have focused primarily on large new sources of particulate matter, NO _x , and SO₂ emissions. Recently, work has begun on NSPS for a number of source categories that emit volatile organic compounds. Environmental professionals in these industries and in many regulatory agencies have little direct experience with the NSPS program and are unaware of the detailed engineering, cost, and economic information available with each proposed rulemaking. This article, therefore, reviews the purposes, procedures, and benefits of the NSPS program. A summary of the NSPS that have been promulgated through February 1983 are presented in tabular form.     

Epilithic Lichen—Atmospheric Deposition Monitors of Trace Elements and Organohalogens?

ABSTRACT

Epilithic lichen (Xanthoria elegans in Canada, Lecanora muralis in Germany) were gathered from 17 locations in Ontario, Canada (from Lake Ontario to James Bay) and 43 locations in Germany (from the Alps to the North Sea and from the Baltic Sea to the Erzgebirge). Sample aliquots were digested in nitric acid and trace elements were analyzed by inductively coupled plasma-mass spectrom-etry techniques. The organohalogens were determined as absorbable organic halogens (AOXs) by coulometry. Concentration ranges from Germany for trace element samples and AOXs were determined. The lichen showed high spatial resolution in their element enrichment patterns. This allowed for differentiation between natural and anthropogenic dominance in ambient air concentrations. This biomonitoring method has proven to be very sensitive, fast, and reliable. No clear relationship could be found between trace element and AOX concentrations. The AOX values may reflect individual metabolic rates of the fungal partner in lichen symbionts.     

TRLFS characterization of Eu(III)-doped synthetic organo-hectorite

Europium(III) was coprecipitated with the clay mineral hectorite, a magnesian smectite, following a multi-step synthesis procedure. Different Eu(III) species associated with the proceeding synthetic hectorite were characterized by selectively exciting the 5D0-->7F0 transition at low temperature (T < 20 K). Fluorescence decay times indicated that Eu(III) ions may be incorporated in the octahedral layer of the brucite precursor as well as in the octahedral sheet of the clay mineral. The excitation spectra indicated that the substitution of the divalent Mg by the trivalent Eu induced local structural deformation. This investigation implements the molecular-level understanding of the f element structural incorporation into the octahedral layer of sheet silicates by coprecipitation with clay minerals from salt solutions at 100 degrees C.     

Environmental parameters affecting induction of hatching in halibut (Hippoglossus hippoglossus) embryos

The influence of some environmental parameters in the regulation of hatching of halibut (Hippoglossus hippoglossus) embryos is reported. The progress of hatching was observed when light, oxygen and turbulence were varied. Environmental parameters influenced the induction of hatching, while the exit mechanism of halibut embryos was unaltered. Light arrests hatching of halibut eggs, and transfer of such eggs to darkness resulted in rapid and synchronous hatching. Hatching under different oxic conditions shows that better oxygen availability does not postpone the time of hatching in halibut. Oxygen seems therefore to have a minor role in the regulation of hatching in halibut. Induction of hatching was delayed under hypoxic conditions (15 mm Hg) compared to higher oxygen levels, but this probably reflects a minimal oxygen level needed for metabolism during hatching. Non-stationary water conditions delayed hatching for 1.5 d both in eggs incubated in turbulence, and in eggs subjected to turbulence at the time of hatching. Turbulence had an immediate inhibitory effect on hatching, but this inhibition was reversible under stationary conditions, under which hatching resumed after 150 to 250 min. We conclude that hatching in halibut occurs after sensory input from environmental factors which are integrated by the embryo before proceeding to hatch.     

来自印度Adayar河的重金属:渗透进入相邻的地下水含水层

引言 Adayar河是一条很短的河流(40km长),向西南方向流去,流经Chennai(北纬13°05',东经80°15'),从这里蜿蜒曲折大约13km后汇入孟加拉湾(图1).在河口地带它变得很宽,河口宽达2km.汇水面积约有800km2,其中大多数地方地势平坦,有岩层的露头.     

Protective skin structures in shell-less marine gastropods

Skin and stomach epithelia of the four suborders of nudibranch gastropods (Mollusca, Opisthobranchia) are characterized by large intracellular ovoid disks, here called spindles. These spindles are an evolutionary novelty in the nudibranchs; in shell-less sacoglossan species they are missing. We here examined whether the distribution and occurrence of the spindles is consistent with the assumption of a protective role against discharging nematocysts of co-habiting and prey Cnidaria. Spindles were abundant in epidermal cells of regions exposed to nematocysts, such as the cerata, the lips, the edges of lamellate rhinophores, the surfaces of non-retractile gill-like organs, as well as in the stomach epithelium of eolid and dendronotacean species which feed on Cnidaria. While cells packed with spindles almost exclusively formed the epidermis of eolid and arminacean species, they were less numerous in the skin of dendronotacean and dorid species, where glandular cells predominated. The preponderance of either glandular or spindle cells suggests a dual complementary defense strategy, on the one side the production of mucus coats and aversive glandular secretions, on the other structural defensive devices that are cushion-like entities filled with inert grains.