Sarah A. Green

Quantifying the consensus on anthropogenic global warming in the scientific literature

We analyze the evolution of the scientific consensus on anthropogenic global warming (AGW) in the peer-reviewed scientific literature, examining 11 944 climate abstracts from 1991‐2011 matching the topics ‘global climate change’ or ‘global warming’. We find that 66.4% of abstracts expressed no position on AGW, 32.6% endorsed AGW, 0.7% rejected AGW and 0.3% were uncertain about the cause of global warming. Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming. In a second phase of this study, we invited authors to rate their own papers. Compared to abstract ratings, a smaller percentage of self-rated papers expressed no position on AGW (35.5%). Among self-rated papers expressing a position on AGW, 97.2% endorsed the consensus. For both abstract ratings and authors’ self-ratings, the percentage of endorsements among papers expressing a position on AGW marginally increased over time. Our analysis indicates that the number of papers rejecting the consensus on AGW is a vanishingly small proportion of the published research.

A kinetic model for H2O2/UV process in a completely mixed batch reactor

Abstract A dynamic kinetic model for the advanced oxidation process (AOP) using hydrogen peroxide and ultraviolet irradiation (H 2 O 2 /UV) in a completely mixed batch reactor (CMBR) is developed. The model includes the known elementary chemical and photochemical reactions, and literature reported photochemical parameters and chemical reaction rate constants are used in this model to predict organic contaminant destruction. Unlike most other kinetic models of H 2 O 2 /UV oxidation process, the model does not assume that the net formation rate of free radical species is zero (pseudo-steady state assumption). In addition, the model considers the solution pH decrease during the process as mineral acids and carbon dioxide are formed. The model is tested by predicting the destruction of a probe compound, 1,2-dibromo-3-chloropropane (DBCP) in distilled water with the addition of inorganic carbon. The new model developed in this work gives better predictions of the destruction of the target organic compound than the model based on the pseudo-steady state assumption. The model provides a comprehensive understanding of the impact of design and operational variables on process performance. Accordingly the ability of the model to select optimum process variables, such as hydrogen peroxide dosage, is illustrated.

Release of NOx from sunlight‐irradiated midlatitude snow

Photochemical production and release of gas-phase NOx (NO + NO2) from the natural snowpack at a remote site in northern Michigan were investigated during the Snow Nitrogen and Oxidants in Winter study in January 1999. Snow was collected in an open 34 L chamber, which was then sealed with a transparent Teflon cover and used as an outdoor flow and reaction chamber. Significant increases in NOx mixing ratio were observed in synthetic and ambient air pulled through the sunlit chamber. [NOx] enhancements were correlated to ultraviolet sunlight intensity, reaching ∼300 pptv under partially overcast midday, midwinter conditions. These findings are consistent with NOx production from photolysis of snowpack NO3−; the observed NOx release implies production of significant amounts of OH within the snow. Snowpack NO3− photolysis may therefore significantly alter boundary layer levels of both NOx and oxidized compounds over wide regions of the atmosphere.

Analysis and characterization of naphthenic acids by gas chromatography–electron impact mass spectrometry of tert.-butyldimethylsilyl derivatives

Abstract The renewed interest in naphthenic acid (NA) as a wood preservative has driven the need for analytical techniques to characterize commercial supplies of NA. The compositional heterogeneity of NA makes analytical characterization extremely difficult. Fluoride ion chemical ionization mass spectrometry (FI-MS) has proven to be an effective technique in NA characterization. However, FI-MS is very complicated and expensive to perform. In this paper, an alternative to the FI-MS technique is presented which offers similar results with a more widely available bench-top electron impact (EI) mass spectrometer. By derivatization of NA components to their tert. -butyldimethylsilyl analogs, the extent of molecular fragmentation is greatly decreased and strong base peaks representing the unfragmented NA constituents are obtained in the EI spectra. Molecular mass and tentative structures can be deduced based on sites of unsaturation.

Approaching storm: Disappearing winter bloom in Lake Michigan

ABSTRACT Between 1990 and 2001, late-winter phytoplankton blooms were common in parts of the lower Great Lakes (southern Lake Michigan, Saginaw Bay and southern Lake Huron, and western Lake Erie), providing resources for over-wintering Zooplankton. In Lake Michigan up to 2001, detailed remote sensing and ship studies documented well-developed late-winter blooms in the southern gyre (circular bloom termed the ‘doughnut’). However, from 2001 to 2008, the winter blooms in Lake Michigan also supported early season veliger larvae from the introduced, cold-water adapted “profunda” morph of quagga mussels (Dreissena rostriformis bugensis). Remote sensing and ship studies revealed that settled mussels caused an extraordinary increase in water transparency and a simultaneous decrease of Chl a in the late-winter bloom. Before quagga mussels in 2001, water transparency was 74–85% at deep-water sites, whereas it increased progressively to 89% by 2006 and 94–96% by 2008. Chlorophyll a concentrations in the gyre rings were 1.1–2.6 µg/L in 2001, declining to 0.5–1.7 µg/L by 2006 and 0.4–1.5 µg/L by 2008. The reduction of Chl a in the winter bloom rings from 2001 to 2008 was 56–78% for the western limb and 74–75% for the eastern limb. Zooplankton species abundance, composition and abundance also changed, as cyclopoid copepods became very scarce and overwintering omnivorous calanoid copepods declined. Reduction in late-winter phytoplankton and Zooplankton poses a serious threat to open-water food webs.

Prognostic Modeling Studies of the Keweenaw Current in Lake Superior. Part I: Formation and Evolution

Abstract The formation and evolution of the Keweenaw Current in Lake Superior were examined using a nonorthogonal-coordinate primitive equation numerical model. The model was initialized by the monthly averaged temperaturefield observed in June and September 1973 and run prognostically under different forcing conditions with and without winds. As a Rossby adjustment problem, the model predicted the formation of a well-defined coastal current jet within an inertial period of 16.4 h after the current field adjusted to the initial temperature field. The magnitude and direction of this current jet varied with the cross-shelf temperature gradient and wind velocity. It tended to intensify during northeastward (downwelling favorable) winds, and to lessen, or even reverse, during southwestward to northwestward (upwelling favorable) or southeastward (downwelling favorable) winds. In a case with strong stratification and without external atmospheric forcings, a well-defined clockwise warm-core eddy formed near the ...

Noncovalent Functionalization of Boron Nitride Nanotubes with Poly(p-phenylene-ethynylene)s and Polythiophene

Boron nitride nanotubes (BNNTs) are functionalized and solubilized in organic solvents such as chloroform, methylene chloride, and tetrahydrofuran by using conjugated poly(p-phenylene ethynylene)s (PPEs) (polymers A and B) and polythiophene (polymer C) via a noncovalent functionalization approach through strong pi-pi stacking interactions between the conjugated polymers and BNNTs. The functionalization of BNNTs with PPEs enhanced planarization of PPEs with red shifts in both absorbance and emission of the composite materials with reference to free PPEs, whereas the functionalization of BNNTs with polythiophene disrupts the pi-conjugation, resulting in blue shifts in both the absorption and emission of the composite material.

Photochemical Transformation of Dissolved Organic Carbon in Lake Superior—An In-situ Experiment

A direct solar irradiation experiment was conducted for Lake Superior water (initial [DOC] = 2.49 mgC/L) and Sturgeon River water (initial [DOC] = 33.95 mgC/L) in Lake Superior on 22–23 August 1999. Water samples were sealed in quartz tubes and suspended in the lake at 0 m, 6 m, and 24 m. Samples were collected after 5.5 h and 15.5 h of exposure to sunlight. The dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) concentrations, UV-vis absorbance, and 3D fluorescence were measured on all samples. For irradiated lake water, DIC was photoproduced at a rate of 1.3 to 5.6 M DIC hr−1 for the first day and 1.3 to 2.1 × 102 nM DIC hr−1 for the second day, normalized to 1 mg DOC/L, and long wavelength absorbance decreased as a function of irradiation time. For both river and lake samples, integral fluorescence also decreased systematically and the fluorescence quantum yield decreased after photoirradiation. In addition, new fluorescence peaks at short wavelengths appeared in irradiated lake samples, suggesting the formation of new chromophores. After irradiation, DOC concentrations in surface samples were lower than those in deep samples. Rate constants for all processes measured decreased during the irradiation time. Rate constants for loss of fluorophores were greater than those for chromophores, which, in turn, were greater than the rate constants for loss of DOC.

Prognostic Modeling Studies of the Keweenaw Current in Lake Superior. Part II: Simulation

The Keweenaw Current, observed along the coast of the Keweenaw Peninsula in Lake Superior during July 1973, was simulated using a 3D, nonorthogonal coordinate transformation, primitive equation coastal ocean model. The model domain covered the entire lake with a high resolution of 250‐600 m in the cross-shelf direction and 4‐6 km in the alongshelf direction along the peninsula. The model was initialized using the monthly averaged temperature field observed in June 1973 and was run prognostically with synoptic wind forcing plus monthly averaged heat flux. Good agreement was found between model-predicted and observed currents at buoy stations near Eagle Harbor. Comparison of the model results with and without inclusion of heat flux suggested that combined wind and heat fluxes played a key role in the intensification of the Keweenaw Current during summer months. The model-predicted relatively strong near-inertial oscillations occurred episodically under conditions of a clockwise-rotating wind. These oscillations intensified at the surface, were weak near the coast, and increased significantly offshore.

Controlled Knoevenagel reactions of methyl groups of 1,3,5,7-tetramethyl BODIPY dyes for unique BODIPY dyes

Formyl groups at 6- and 2,6-positions initiated Knoevenagel reactions of the methyl groups at the 7, and 1,7-positions of 1,3,5,7-tetramethyl BODIPY dyes with aromatic aldehydes. Formation of vinyl bonds at the 7-, and 1,7-positions facilitates further Knoevenagel reactions of the methyl groups at the 3,5-positions. This approach offers fast, facile and versatile ways to prepare potential novel building blocks of BODIPY dyes for conjugated oligomers, dendrimers, and highly water-soluble, near-infrared emissive sensing materials.