determine upward evaporative flux effects on photolytic loss. They measured relative rates of photolytic loss in soil columns that were irradiated with ultraviolet lamps or sunlight under different moisture conditions. Sandy, near-saturated soil exposed to light lost 55% more PCP in 14 days compared with dark controls. Reducing moisture levels increased volatilization losses and reduced photolytic losses. The study concluded that translocating PCP to the sunlit surface in wet soil enhances photolytic losses while minimizing volatilization. (J. Environ. Qual. 1997 26 402-09)
Reducing bioavailability Certain toxic organic chemicals in soil become less available to microorganisms and more resistant to desorption over time, but little data are available on comparable changes in bioavailability to higher organisms. J. W. Kelsey and M. Alexander reported that uptake by higher organisms declined as well. Atrazine, phenanthrene, and naphthalene were added to sterile soils, and earthworms were introduced after the soils aged for up to 107 days. Uptake by earthworms diminished with soil aging, whereas the amount of chemical extracted was nearly constant The authors sut?t?est that regulations based on vigorous extractions overlook the declining bioavailability of toxic compounds Such regulations mav overestimate the actual risks to exposed populations (Environ Toxicol Chem 1997 16(3) 582-85)
TOCIXITY Aircraft de-icing fluids De-icing a large aircraft can require 1000 gal of glycol-based fluid that is released into the environment. Because ingredients in de-icing solutions are proprietary, concern exists that the fluids may be more toxic than the glycol alone, which comprises 80% of a typical fluid. D. A. Cancilla and co-workers isolated and identified individual components of aircraft de-icing and anti-icing fluids with a toxicity-based bioassay technique. Five fractions were separated and tested for toxicity to fluorescent bacteria. The most toxic ingredients in the fluids benzotriazole and tolyltriazoles which serve as corro-
High-aluminum levels in acidic water Earlier studies have failed to establish why high aluminum levels occur in surface waters receiving heavy inputs of acid-sulfate solution, such as acid rain and acid mine drainage. M. K. Ridley and colleagues performed solubility experiments to determine whether high aluminum levels result from increased dissolution of Al-bearing minerals, such as gibbsite. The studies were conducted at acidic pH and the low temperatures (5-10 °C) actually found in acidsensitive waters. Gibbsite dissolution rates were significantly greater in H S0 -NaCI than in HCI-NaCI media There were zero-order rate con stants for H S0 and HCI The authors conclude that enhanced dissolution of Al-containing minerals in the
HIV exposure Raw wastewater may contain HIV, the cause of AIDS, posing a potential health threat to treatment plant workers. L. W. Casson and colleagues investigated seeded HIV survival in water and wastewater. Results indicate that infectivity of cell-associated HIV declines rapidly after exposure to distilled water. Some virus did remain stable for 48 h and infectious for about 96 h. Cell-associated HIV infectivity was reduced more rapidly in nonchlorinated wastewater treatment plant secondary effluent than in distilled water The authors believe the low HIV concentration in wastewater minimizes the potential risk of infection to treatment plant personnel (Water Environ Res 1997 69 174-79)
Wetlands metal removal
Studies have documented the effectiveness of constructed wetlands in ceiving „ P i J o i i l f a t e inpiLts tFn\/i~ removing biochemical oxygen demand and suspended solids from rnn Qri TprhnnI ,hic I i s I I u ,Q99—9R\ municipal wastewater, but there is little evidence demonstrating their ability to remove metals. R. W. Crites sion inhibitors. Analytical methods and co-workers studied metal and for these compounds in environammonia removal from secondary mental samples are being developed. effluent wastewater at the Sacra{Environ. Toxicol. Chem. 1997, 16(3), mento Regional Wastewater Treat430-34) ment Plant's constructed wetland. They present data showing significant removal of 13 metals, including lead, and zinc. Significant WASTEWATER removal of ammonia also occurred but varied with seasonal conditions The authors conclude that the SacraBiodegradable flocculant mento project is operating effecA need exists for new flocculants tively and producing useful data on that are highly active yet biodegradremoval of metals and ammonia able and can be used in wastewater The data further document the eftreatment and industrial processes. fectiveness of constructed wetlands G. S. Kwon and colleagues reported in municipal wastpwater effluent isolation and characterization of a tprtiary treatment (Water Enviro new biopolymer flocculant from R 1997 69 m ? ! ^ l white rot fungus Pestalotiopsis sp. KCTC 8673P. The biopolymer was partially purified and named Pestan. Contributors: Michael Brauer, Analysis of Pestan revealed that it University of British Columbia, consisted mainly of glucose with Vancouver; Brian Eitzer, Connecticuc small amounts of glucosamine, gluAgricultural Experiment Station, New curonic acid and rhamnose. Tests Haven; Stephen Geiger, Remediation of the flocculating efficiency of PesTechnologies, ,nc.. King of Prussia, tan with kaolin particles showed that Pa.; Vincent Hand, Miami University, it had the highest flocculating activInstitute of Environmental Sciences, ity at a concentration of 1 mg/L Oxford, Ohio; Louis Kovach, Ecolife The flocculating activity was enAssociates, Wilmington, Dell; Geoffrey hanced bv the addition of cationic Nobes, McGiil University, Montreal; solutions Pestan also had good therRaewyn Town, Queen'' University of mal stability and remained active to Belfast, Northern Ireland; ;nd 70 °C (Bioterhnnl . Ptt .99fi 18 Margaret Whittaker, NSF 1459-64) International, Ann Arbor, Mich. presenrp of •siilfate may contrihnte to
the high Al
IPVeIQ
observed
VOL. 31, NO. 7, 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 3 0 3 A
