Milagros S. Simmons

INFLUENCE OF HUMIC SUBSTANCES ON PHOTOLYSIS OF NITROAROMATIC COMPOUNDS IN AQUEOUS SYSTEMS

Results are reported for kinetic studies of the photolysis of 19 nitroaromatic compounds in water. The results indicate that dissolved humic substances in natural waters enhance the sunlight-induced photodegradation rates of nitrobenzenes, nitrotoluenes, and nitroxylenes compared to rates observed in distilled water. The largest enhancements, ranging from 2 to 26-fold, were observed for nitroaromatics that are methylated ortho to the nitro group. Similar enhancement effects were observed for humic substances obtained from a variety of terrigenous sources, including humus in natural waters and humus extracted from soils.

The production of bromophenols resulting from the chlorination of waters containing bromide ion and phenol

Abstract The formation of 2,4,6-tribromophenol is shown to result from the chlorination of water containing phenol and bromide ion at pH 7.4. Direct bromination with hypobromous acid is compared with bromination by hypochlorous acid and bromide ion. Under conditions where HOCl is not limiting, a higher yield of bromine substitution products can be expected from bromination by HOCl + Br− than by direct bromination by HOBr.

Effects of chlorinated benzenes on diatom fatty acid composition and quantitative morphology. II: 1,3,5-trichlorobenzene

Cells of the diatomCyclotella meneghiniana were exposed in a closed system to 0.245 ppm 1,2,4-trichlorobenzene. Response to this chlorinated benzene was monitored over a period of 5 days by quantitative ultrastructure and fatty acid percent composition. Over the time period examined, 41 significant morphological changes and 12 significant changes in fatty acid composition were observed. Autophagic-like vacuoles were frequently observed, indicating lysis of cellular constituents. In general, there was an increase in the C20:5 fatty acid, which may be indicative of photosynthetic impairment, since this fatty acid probably substitutes for linolenic acid in diatoms. The most significant numbers of changes were observed after 8 hr of exposure to this lipophilic toxicant, and these changes occurred in membranous organelles. It is suggested that the daily photoperiodic variation in lipid content of phytoplankton may be an important consideration in evaluating effects of lipohilic toxicants.

Effects of chlorinated benzenes on diatom fatty acid composition and quantitative morphology. IV: Pentachlorobenzene and comparison with trichlorobenzene isomers

Cells of the diatomCyclotella meneghiniana were exposed in a closed system to 0.095 ppm pentachlorobenzene over a period of 5 days. Changes in fatty acid and morphological percent composition were monitored to determine the effect of the toxicant. The greatest morphological change observed was an increase in lipid volume. Most morphological changes occurred in the 1 hour and 5 day sampling periods. Few changes in morphological characteristics or fatty acid percent composition were observed at eight hours, when the cells were in the dark. The C18∶1 and C20∶5 fatty acids were most variable with exposure to pentachlorobenzene. Results suggest that at sublethal doses, lipophilic toxicants exert effects that are biphasic. That is, immediately measurable effects are observed in the cells that include increases in storage products and changes in membranous organelles. Long-term effects are postulated to be the result of mobilization of lipophilic toxicants that have partitioned into lipid stores and are more available when lipids are metabolized. Although pentachlorobenzene has a higher octanol/water partition coefficient, it appears to exert fewer cellular changes than any trichlorobenzene isomer.

The effect of food consumption on the toxicokinetics of benzo(a)pyrene and 2,2′,4,4′,5,5′-hexachlorobiphenyl in

The relative importance of water and ingested food as possible avenues of contaminant accumulation was examined. Mysis relicta was exposed to two representative non-polar contaminants: benzo(a)pyrene (BaP) and 2,2′,4,4′,5,5′-hexachlorobiphenyl (HCB). The accumulation was examined kinetically in the presence and absence of two food types, Daphnia pulex (water flea) and Tabellaria flocculosa (a diatom). The availability of either food enhanced HCB accumulation and reduced BaP accumulation. Feeding did not affect HCB elimination but enhanced BaP elimination. The BaP was eliminated primarily as metabolites. Essentially all of the elimination occurred via the fecal route for both compounds. The fraction of the accumulation via ingestion of contaminated food was greater when mysids fed on Daphnia than Tabellaria and was greater for HCB than BaP.

Relationship of Toxicokinetic Parameters to Respiration Rates in Mysis Relicta

The uptake of organic xenobiotics from water was compared to the respiration rate of the Great Lakes invertebrate, Mysis relicta. Xenobiotic clearance was compared with oxygen clearance. Uptake clearance is defined as milliliters of water stripped of contaminant or oxygen per mass of organism per hour. M. relicta were exposed to benzo(a)pyrene (BaP) and 2,2′,4,4′,5,5′-hexachlorobiphenyl (HCBP). The respiration rate for M. Relicta declined logarithmically when measured for periods ranging from 3 to 48 h. The respiration rate ranged from 1.4 (1.24–1.48) μg O2 mg–1 wet weight h’ for a 3 h period to 0.25 ± 0.023 μg O2 • mg−1 wet weight • h−1 for a 48 h period. Neither the presence of the methanol carrier nor the methanol carrier plus xenobiotics produced significant changes in respiration compared to those of the control organisms in lake water only. The clearances of oxygen and the two xenobiotics were each inversely correlated to organism weight. The slopes of the clearance regressions with organism weight were not significantly different among the different measures of xenobiotic or oxygen clearance. There was a near constant ratio of xenobiotic clearance to oxygen clearance of 1.25 ± 0.01 (mean ± SE, n = 29) for BaP and 1.37 ± 0.12 (r = 29) for HCBP. These findings suggest that the accumulation of organic xenobiotics may be linked to the accumulation of oxygen for M. relicta.

Distribution coefficients for chemical components of a coal-oil/water system

Distribution coefficients (KDS) were measured by equilibrating a coal oil comparative reference material (CRM-1) with water and then separating the oil and water phases. Aqueous phase concentrations were determined by direct analysis of this phase, while organic phase concentrations were determined from the original oil composition by difference. The log K o values obtained for acidic and basic components were generally <3, while those for the neutral components ranged from 3 to 6. For aromatic hydrocarbons, strong correlations were observed between log KD and log Sw (water solubility), and between log K o and log Kow (octanol/water partition coefficient). Alkylated benzenes had significantly higher Kos than did unsubstituted aromatics of similar molecular weight. Examination of homologs revealed an increase of 0.307 IOg KD units per additional carbon atom for polynuclear aromatic hydrocarbons having from 10 to 16 carbons. Alkyl substituent effects determined for various sets of homologs ranged from 0.391 to 0.466 log K~ units per --CH 2- group added.

Distribution of Water Masses in and Near the Straits of Mackinac

Abstract Three cruises in the Straits of Mackinac area were conducted from 30 August to 8 October 1973. Samples were taken from up to 11 depths during each cruise and analyzed for silica, nitrate, total and soluble phosphorus, chlorophyll a , pH, water temperature, and specific conductance. Cluster analyses were used to visualize the relationship between stations for each depth on all cruises. The clearest relationships observed were from 0, 5, and 10 m depths, while clusters of data from other depths were not as useful in describing water masses. Analyses of 0 - 10 m depths showed a consistent homogeneous water mass extending through the northern edge of the Straits proper, past the western edge of Mackinac Island, to south of Bois Blanc Island. This cluster of stations was found during most wind conditions at the three depths considered. The last cruise, 6-8 October, occurred during a period of light winds from the southeast which partially disrupted this cluster. Relationships between the variables were defined by factor analysis which showed silica and nitrate increased with decreasing water temperature and pH, and partly as a function of depth. Secchi disc values tended to vary independently of most other variables, implying these readings had little value in explaining water quality in the Straits region.

Microanalysis of Aqueous Samples for Phenols and Organic Acids

Abstract A method for determining carboxylic acids and phenols from aqueous solution is described. Trace concentrations in the parts per billion levels of these pollutants are determined. This is accomplished by a concentration step using macroreticular resins with pyridine elution, subsequent derivatization with Bis-trimethylsilyl acetamide (BSA), and analysis by gas chromatography. The method gives good recovery for several phenols and acids of environmental importance.

Routine Determination of Particulate Silica in Water

Abstract A method is described for the determination of particulate silica in water or biogenic material. The decomposition of the sample is satisfactorily achieved by treatment with a mixture of hydrofluoric and nitric acids. After standing at room temperature overnight, the mixture is then treated with boric acid taken up with water and analyzed for silicon by atomic absorption spectrophotometry using nitrous oxide-acetylene flame. The reproducibility of the decomposition method is ± 5%. Recovery after addition of known amounts of pure SiO2 standards to the lakewater samples is 90 - 95%.