Evaluation of new surfactant expanded zirconium and titanium phosphates for polycyclic aromatic hydrocarbons extraction from waters

A newly synthesized family of materials prepared with surfactant as organic template were tested for the extraction of polycyclic aromatic hydrocarbons (PAHs) from water, using pyrene (Pyr) and benzo[a]pyrene (B[a]P) as PAHs representatives. Particular attention was paid to the evaluation of the recovery factors with dichloromethane as eluent in order to estimate their potential as adsorbing solid phases for PAH remediation or analysis. Eleven lamellar MCM-50 type materials incorporating n-alkyl- (n = 12, 16, 18) trimethylammonium bromide molecules with different concentrations and chain lengths and two hexagonal MCM-41 type materials incorporating octadecyl-trimethyl ammonium bromide were tested. Best results were obtained by preparing lamellar MCM-50 zirconium and titanium phosphates in the presence of n-dodecyl-trimethylammonium at a relative molar concentration (surfactant/phosphate) of 1.     

Heavy metal bioavailability and effects: I. Bioaccumulation caused by mining activities in the Gulf of Cádiz (SW, Spain)

The bioaccumulation of six metals (Fe, Mn, Zn, Cd, Pb and Cu) was studied as part of the monitoring of the Aznalcóllar mining spill (April 1998) on the Guadalquivir estuary and in other estuaries located in the Gulf of Cádiz. Fish, clams and oysters were collected during different seasonal periods along the years 2000 and 2001 in the Guadalquivir estuary to determine the bioaccumulation of the metals originated by the mining spill. Results were compared to the bioaccumulation of the same metals in fish and clams exposed in the laboratory to sediments collected in the same areas during autumn 2001. The bioaccumulation of these metals was compared to the concentration of metals measured in tissues of same taxas collected in the areas of the ria of Huelva and the Bay of Cádiz. Results show that the bioaccumulation of Zn and Cd in the organisms sampled in the Guadalquivir estuary was associated with the enrichment of these metals in the estuary from the mining spill and decreased along the time reaching the lowest values in autumn 2001. The metal Cu show different trends that are associated with other sources of contamination than the spill and related to the transport of this metal from Huelva to Guadalquivir estuary and/or to the use of this metal as plaguicide in the rice fields located in the area. The comparison between bioaccumulation results under field and laboratory conditions obtained in the different areas of study shows that these data can be used to discriminate between acute and chronic impacts associated with mining activities.     

High-mileage study of on-board diagnostic emissions

The 1990 Clean Air Act amendments require the U.S. Environmental Protection Agency (EPA) to set guidelines for states to follow in designing and running vehicle inspection and maintenance (I/M) programs. Included in this charge was a requirement to implement an on-board diagnostic (OBD) test for both basic and enhanced I/M programs. This paper provides the results to date of an ongoing EPA study undertaken to assess the durability of the OBD system as vehicles age and as mileage is accrued. The primary results of this effort indicate the points described below. First, the majority of high-mileage vehicles tested had emission levels within their certification limits, and their malfunction indicator light (MIL) was not illuminated, indicating that the systems are capable of working throughout the life of a vehicle. Second, OBD provides better air quality benefits than an IM240 test (using the federal test procedure [FTP] as the benchmark comparison). This statement is based on greater emissions reductions from OBD-directed repairs than reductions associated with IM240-identified repairs. In general, the benefits of repairing the OBD fails were smaller, but the aggregate benefits were greater, indicating that OBD tests find both the high-emitting and a number of marginally high-emitting vehicles without false failures that can occur with any tailpipe test. Third, vehicles that truly had high-tailpipe emissions as confirmed by laboratory IM240 and FTP testing also had illuminated MILs at a statistically significant level. Last, field data from state programs have demonstrated MIL illumination rates comparable with those seen in this work, suggesting that the vehicles sampled in this study were representative of the larger fleet. Nonetheless, it is important to continue the testing of high-mileage OBD vehicles into the foreseeable future to ensure that the systems are operating correctly as the fleet ages and as changes in emission certification levels take effect.     

Population differentiation in female sex pheromone and male preferences in a solitary bee

Population differentiation in female mating signals and associated male preferences can drive reproductive isolation among segregated populations. We tested this assumption by investigating intraspecific variation in female sex pheromone and associated male odour preferences among distant populations in the solitary bee Colletes cunicularius (L.) by using quantitative gas chromatography and by performing field bioassays with synthetic blends of key sex pheromone compounds. We found significant differences in sex pheromone blends among the bee populations, and the divergence in odour blends correlated positively with geographic distance, suggesting that genetic divergence among distant populations can affect sex pheromone chemistry. Our behavioural experiments, however, demonstrate that synthetic copies of allopatric female sex pheromones were cross-attractive to patrolling males from distant populations, making reproductive isolation by non-recognition of mating signals among populations unlikely. Our data also show that patrolling male bees from different populations preferred odour types from allopatric populations at the two sites of bioassays. These male preferences are not expected to select for changes in the female sex pheromone, but may influence the evolution of floral odour in sexually deceptive orchids of the genus Ophrys that are pollinated by C. cunicularius males.     

Radioactive and radiogenic isotopes in sediments from Cooper Creek, Western Arnhem Land

Protection of the environment post-mining is a key objective of rehabilitation, especially where runoff and erosion from rehabilitated mine sites could potentially lead to contamination of the surrounding land and watercourses. As part of an overall assessment of the success of rehabilitation at the former Nabarlek uranium (U) mine, an appraisal of stable lead (Pb) isotopes, radionuclides and trace metals within sediments and soils was conducted to determine the off site impacts from a spatial and temporal perspective. The study found localised areas on and adjacent to the site where soils had elevated levels of trace metals and radionuclides. Lead isotope ratios are highly radiogenic in some samples, indicating the presence of U-rich material. There is some indication that erosion products with more radiogenic Pb isotope ratios have deposited in sediments downstream of the former ore body. However, there is no indication that the radiogenic erosion products found on the mine site at present have significantly contaminated sediments further downstream of Cooper Creek.     

Radon concentrations in ground and drinking water in the state of Chihuahua, Mexico

This paper reports (222)Rn concentrations in ground and drinking water of nine cities of Chihuahua State, Mexico. Fifty percent of the 114 sampled wells exhibited (222)Rn concentrations exceeding 11Bq/L, the maximum contaminant level (MCL) recommended by the USEPA. Furthermore, around 48% (123 samples) of the tap-water samples taken from 255 dwellings showed radon concentrations over the MCL. There is an apparent correlation between total dissolved solids and radon concentration in ground-water. The high levels of (222)Rn found may be entirely attributed to the nature of aquifer rocks.     

Optimizing a dansylhydrazine (DNSH) based method for measuring airborne acrolein and other unsaturated carbonyls

The Passive Aldehydes and Ketones Sampler (PAKS) method has been developed to measure airborne carbonyls (aldehydes and ketones) by derivatizing the carbonyls with dansylhydrazine (DNSH) on a solid sorbent. The method collection efficiencies are approximately 100% for most saturated carbonyls, but are significantly lower for unsaturated carbonyls. In this study, we examined the mechanisms of DNSH reactions with unsaturated carbonyls, focusing on acrolein. With a better understanding of these mechanisms, we modified the sampling substrate conditions and HPLC analysis conditions of the original PAKS method, resulting in substantially improved collection efficiencies for acrolein and crotonaldehyde. Evaluated under a variety of conditions (temperature, humidity, presence of ozone), the modified PAKS method had a collection efficiency of 99%+/- 5% for acrolein (N= 36) and 96%+/- 20% for crotonaldehyde (N= 6). The acrolein-DNSH derivative was stable within 9.6% of the initial amount, after 14 days of storage at 4 degrees C, on the collection medium; and stable within 2.8% of the initial amount, after 16 days of storage at room temperature, in extract.     

Filamentous cyanophytes containing phycourobilin and in symbiosis with sponges and an ascidian of coral reefs

A study was made of the ultrastructure and pigment composition of filamentous cyanophytes living in symbiosis with several sponges and a colonial didemnid ascidian collected from the southern end of the Great Barrier Reef, Australia, between 1983 and 1986. The sponges were Dysidea herbacea Keller and several other encrusting sponges which have not been identified; the ascidian was Trididemnum miniatum Kott (1977). The cyanophyte Oscillatoria spongeliae (Shultz) Hauck was identified as the symbiont of several of the sponges, including D. herbacea. Two other unidentified Oscillatoria species were found in a bristly papillate sponge and in T. miniatum. Chlorophyll a, alone, was present in all the symbionts with the exception of T. miniatum, which contained the cosymbiont Prochloron and where chlorophyll b was also present. Two phycoerythrins were isolated by chromatography and chromatofocusing. Both resembled C-phycoerythrin, but one of the two carried the chromophore phycourobilin as well as phycoerythrobilin possibly on both the and subunits, which had apparent molecular masses of 18 and 20 kdaltons. No subunit was present. Ultrastructurally, the three Oscillatoria species were distinguished by an unusual type of parallel, longitudinal, thylakoid organisation; the arrangement was different in detail in each species.     

美国关于化学品事故预防、风险管理和固有安全性的观点

本文重点介绍近年来美国在化学品事故预防领域的主要成就,包括通过了旨在阻止危险物质事故性释放的立法.与我们的全球邻居、工业界、国家政府和地方政府的强有力伙伴关系减轻了法规实施的负担.也讨论了这个领域的未来活动.     

Photosynthetic oxygen production and PAM fluorescence in the brown algaPadina pavonica measured in the field under solar radiation

The effects of solar radiation on photosynthetic oxygen production, pulse amplitude-modulated (PAM) fluorescence and pigmentation were measured in the Mediterranean brown macroalgaPadina pavonica (Linnaeus) Lamouroux under field conditions and natural sunlight. Exposure of thalli to solar radiation for 1 h caused a dramatic decrease of their photosynthetic quantum yield, which recovered to initial levels after they had been placed in the shade for 3 h. Photoinhibition also occurred at the natural growth site ofP. pavonica during the hours of maximal solar irradiance. Photosynthetic oxygen production was also affected by high levels of solar radiation both in algae harvested from the surface and from 6 m depth; oxygen production started to decrease after a few minutes of exposure, and negative values were found after 1 h of solar exposure. Chlorophylla content inP. pavonica also decreased during the hours of maximal solar irradiation. These results suggest that photoinhibition ofP. pavonica occurs during part of a typical summer day on Mediterranean coasts.