Daily Archives: September 25, 2014

Carbon Dioxide Emissions Not the Cause of Warming the US West Coast

James A. Johnstone and Nathan J. Mantua. Atmospheric controls on northeast Pacific temperature variability and change, 1900–2012. PNAS doi: 10.1073/pnas.1318371111

Over the last century, northeast Pacific coastal sea surface temperatures (SSTs) and land-based surface air temperatures (SATs) display multidecadal variations associated with the Pacific Decadal Oscillation, in addition to a warming trend of ∼0.5–1 °C. Using independent records of sea-level pressure (SLP), SST, and SAT, this study investigates northeast (NE) Pacific coupled atmosphere–ocean variability from 1900 to 2012, with emphasis on the coastal areas around North America. We use a linear stochastic time series model to show that the SST evolution around the NE Pacific coast can be explained by a combination of regional atmospheric forcing and ocean persistence, accounting for 63% of nonseasonal monthly SST variance (r = 0.79) and 73% of variance in annual means (r = 0.86). We show that SLP reductions and related atmospheric forcing led to century-long warming around the NE Pacific margins, with the strongest trends observed from 1910–1920 to 1940. NE Pacific circulation changes are estimated to account for more than 80% of the 1900–2012 linear warming in coastal NE Pacific SST and US Pacific northwest (Washington, Oregon, and northern California) SAT. An ensemble of climate model simulations run under the same historical radiative forcings fails to reproduce the observed regional circulation trends. These results suggest that natural internally generated changes in atmospheric circulation were the primary cause of coastal NE Pacific warming from 1900 to 2012 and demonstrate more generally that regional mechanisms of interannual and multidecadal temperature variability can also extend to century time scales.

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Israel Officially Bans Addition of Fluoride to Drinking Water, Other Countries Should Follow

“On Tuesday of this week (Aug. 26), Israel officially stopped adding fluoride to its water supplies. The decision has “been lauded by various rights groups, but criticized by many in the medical and dental communities as a serious mistake,” as the Times of Israel put it.” click here

The so called “medical” and “dental” groups should stop complaining and get on with the task of actually doing something positive to affect dental health rather then hide behind the facade that communal fluoridation will take of the problem.

Performance Evaluation of a Parabolic Solar Still

Shiva Gorjian, Barat Ghobadian, Teymour Tavakkoli Hashjin, Ahmad Banakar. Experimental performance evaluation of a stand-alone point-focus parabolic solar still. Desalination Volume 352, 3 November 2014, Pages 1–17

A stand-alone point-focus parabolic solar still (PPSS) was designed and fabricated for desalination of seawater or brackish water and purification of non-potable water. The system consists of a parabolic dish concentrator; a two axis sun tracker based on programmable logic controllers (PLCs) and two plate heat exchangers (PHEs) to preheat the salt water before entering the absorber located at the focal point as well as condense the generating steam. Distillate productivity of the PPSS was measured along with evaluation of the effects of environmental and operational parameters that includes: beam solar insolation, wind speed, air temperature, absorber wall temperature and raw water salinity under the climatic conditions of Tehran during October. The maximum productivity of 5.12 kg within 7 h in a day was measured with the maximum average solar insolation of 626.8 W/m2 and the absorber wall temperature of 150.7 °C. However, no significant effect of air temperature, wind speed, and water salinity on the productivity was observed. The maximum daily efficiency of 36.7% was calculated with a maximum hourly output of 1.5 kg/h. The quality of lab-prepared salt water samples was analyzed before and after desalination and the results comply with the WHO guidelines for drinking water quality.

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Lake Turnover Causes Severe Taste and Odor Problems

“As hot days become cool nights in the Fall, water from the bottom of Lake Thunderbird rises to the top. It’s a process called “turning over,” now several Norman-ites are turning away from H20.st tastes terrible when this happens. But believe it or not the can still be safe to drink.” click here

 

Conventional Treatment Compared with Nanofiltration

N. García-Vaqueroa, Eunkyung Leeb, R. Jiménez Castañedac, Jaeweon Chod, J.A. López-Ramíreza. Comparison of drinking water pollutant removal using a nanofiltration pilot plant powered by renewable energy and a conventional treatment facility. Desalination Volume 347, 15 August 2014, Pages 94–102

In this paper, drinking water pollutant removal between a conventional drinking water treatment and a nanofiltration (NF) pilot plant powered by renewable energy is compared. This kind of plant can be very useful for isolated locations with water quality problems. Energy consumption and related CO2 emissions and the occurrence of synthetic organic compounds in drinking water sources are important environmental and public health issues. NF membranes were used to improve drinking water quality from a holistic point of view. Compared to conventional drinking water treatment, membranes efficiently removed color and turbidity (100%), DOC (93%), ions (97%), and metals and metalloids (ranging from 80% to 100%), but not boron (17%) or pharmaceuticals (Ph’s) (varied from 15% to 100%, but still always above conventional treatment). Moreover, NF membranes removed 53% of the trihalomethanes (THMs) present in conventionally treated water. Analyses of 93 persistent organic compounds (VOCs, BTEXs, PAHs, DEs, pesticides…) were carried out, but none of the compounds were detected in the three types of water analyzed (reservoir, conventionally treatment and NF permeate). Reservoir water has a strong hydrophilic composition due to protein-like substances that can promote biofouling. NF membranes effectively removed the hydrophobic fraction (66%).

Click here for full paper (fee).