Archive for the ‘Environmental Science & Technology’ Category

Pesticides in U.S. Streams and Rivers: Occurrence and Trends during 1992–2011

September 12, 2014 Comments off

Pesticides in U.S. Streams and Rivers: Occurrence and Trends during 1992–2011
Source: Environmental Science & Technology

During the 20 years from 1992 to 2011, pesticides were found at concentrations that exceeded aquatic-life benchmarks in many rivers and streams that drain agricultural, urban, and mixed-land use watersheds. Overall, the proportions of assessed streams with one or more pesticides that exceeded an aquatic-life benchmark were very similar between the two decades for agricultural (69% during 1992−2001 compared to 61% during 2002−2011) and mixed-land-use streams (45% compared to 46%). Urban streams, in contrast, increased from 53% during 1992−2011 to 90% during 2002−2011, largely because of fipronil and dichlorvos. The potential for adverse effects on aquatic life is likely greater than these results indicate because potentially important pesticide compounds were not included in the assessment. Human-health benchmarks were much less frequently exceeded, and during 2002−2011, only one agricultural stream and no urban or mixed-land-use streams exceeded human-health benchmarks for any of the measured pesticides. Widespread trends in pesticide concentrations, some downward and some upward, occurred in response to shifts in use patterns primarily driven by regulatory changes and introductions of new pesticides.

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Brominated and Chlorinated Flame Retardants in Tree Bark from Around the Globe

January 8, 2013 Comments off

Brominated and Chlorinated Flame Retardants in Tree Bark from Around the Globe
Source: Environmental Science and Technology

Brominated and chlorinated flame retardants were measured in about 40 samples of tree bark from 12 locations around the globe. The analytes were polybrominated diphenyl ethers (PBDE), Dechlorane Plus (DP), decabromodiphenylethane (DBDPE), hexabromocyclododecane (HBCD), hexabromobenzene (HBB), pentabromoethylbenzene (PBEB), pentabromobenzene (PBBz), and tetrabromo-p-xylene (pTBX). The highest concentrations of these compounds were detected at an urban site in Downsview, Ontario, Canada. Total PBDE and DP concentrations ranged from 2.1 to 190 ng/g lipid weight and from 0.89 to 48 ng/g lipid weight, respectively. Relatively high levels of DP (46 ± 4 ng/g lipid weight) were found at a remote site at Bukit Kototabang in Indonesia. The concentrations of total PBDE, DP, PBEB, and HBCD in the tree bark samples were significantly associated with human population in the nearby areas (r2 = 0.21–0.56; P < 0.05). In addition, the concentrations of total PBDE and DP were significantly associated (r2 = 0.40–0.64; P < 0.05). with the corresponding atmospheric concentrations of these compounds over a concentration range of 2–3 orders of magnitude.

See: Flame Retardant Pollutants Found at Far-Flung Locations, Including Indonesia, Nepal and Tasmania (Science Daily)

Vacuum Cleaner Emissions as a Source of Indoor Exposure to Airborne Particles and Bacteria

January 6, 2012 Comments off

Vacuum Cleaner Emissions as a Source of Indoor Exposure to Airborne Particles and Bacteria
Source: Environmental Science & Technology

Vacuuming can be a source of indoor exposure to biological and nonbiological aerosols, although there are few data that describe the magnitude of emissions from the vacuum cleaner itself. We therefore sought to quantify emission rates of particles and bacteria from a large group of vacuum cleaners and investigate their potential determinants, including temperature, dust bags, exhaust filters, price, and age. Emissions of particles between 0.009 and 20 μm and bacteria were measured from 21 vacuums. Ultrafine (<100 nm) particle emission rates ranged from 4.0 × 106 to 1.1 × 1011 particles min–1. Emission of 0.54–20 μm particles ranged from 4.0 × 104 to 1.2 × 109 particles min–1. PM2.5 emissions were between 2.4 × 10–1 and 5.4 × 103 μg min–1. Bacteria emissions ranged from 0 to 7.4 × 105 bacteria min–1 and were poorly correlated with dust bag bacteria content and particle emissions. Large variability in emission of all parameters was observed across the 21 vacuums, which was largely not attributable to the range of determinant factors we assessed. Vacuum cleaner emissions contribute to indoor exposure to nonbiological and biological aerosols when vacuuming, and this may vary markedly depending on the vacuum used.

See: Older, Cheaper Vacuum Cleaners Release More Bacteria and Dust (Science Daily)

Oil Biodegradation and Bioremediation: A Tale of the Two Worst Spills in U.S. History

September 17, 2011 Comments off

Oil Biodegradation and Bioremediation: A Tale of the Two Worst Spills in U.S. History
Source: Environmental Science & Technology

The devastating environmental impacts of the Exxon Valdez spill in 1989 and its media notoriety made it a frequent comparison to the BP Deepwater Horizon spill in the popular press in 2010, even though the nature of the two spills and the environments impacted were vastly different. Fortunately, unlike higher organisms that are adversely impacted by oil spills, microorganisms are able to consume petroleum hydrocarbons. These oil degrading indigenous microorganisms played a significant role in reducing the overall environmental impact of both the Exxon Valdez and BP Deepwater Horizon oil spills.


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