scholarly journals Effects of cadmium amendments on low-molecular-weight organic acid exudates in rhizosphere soils of tobacco and sunflower

2006 ◽  
Vol 21 (5) ◽  
pp. 479-488 ◽  
Author(s):  
Po-Neng Chiang ◽  
Ming Kuang Wang ◽  
Chih Yu Chiu ◽  
Shu-Yen Chou
Keyword(s):  
Molecular Weight ◽  
Organic Acid ◽  
Low Molecular Weight ◽  
Rhizosphere Soils

Modelling low molecular weight organic acid dynamics in forest soils

2005 ◽  
Vol 37 (3) ◽  
pp. 517-531 ◽  
Author(s):  
Patrick A.W. van Hees ◽  
David L. Jones ◽  
Lars Nyberg ◽  
Sara J.M. Holmström ◽  
Douglas L. Godbold ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Acid ◽  
Forest Soils ◽  
Low Molecular Weight

Oxalate-enhanced solubility of lead (Pb) in the presence of phosphate: pH control on mineral precipitation

2019 ◽  
Vol 21 (4) ◽  
pp. 738-747 ◽  
Author(s):  
Murray B. McBride ◽  
Sabrina E. Kelch ◽  
Michael P. Schmidt ◽  
Sonam Sherpa ◽  
Carmen Enid Martinez ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Acid ◽  
Ph Control ◽  
Low Molecular Weight ◽  
Mineral Precipitation ◽  
Enhanced Solubility ◽  
Ph Range

Here we study the precipitation of lead (Pb)-phosphate minerals over the pH range of 4.0 to 8.0 with and without oxalate, a ubiquitous and abundant low-molecular-weight organic acid derived from plants and microorganisms.

scholarly journals Understanding the primary emissions and secondary formation of gaseous organic acids in the oil sands region of Alberta, Canada

2017 ◽  
Vol 17 (13) ◽  
pp. 8411-8427 ◽  
Author(s):  
John Liggio ◽  
Samar G. Moussa ◽  
Jeremy Wentzell ◽  
Andrea Darlington ◽  
Peter Liu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Acids ◽  
Organic Acid ◽  
Oil Sands ◽  
Box Model ◽  
Chemical Mechanism ◽  
Formation Mechanisms ◽  
Low Molecular Weight ◽  
Airborne Measurements ◽  
Secondary Formation

Abstract. Organic acids are known to be emitted from combustion processes and are key photochemical products of biogenic and anthropogenic precursors. Despite their multiple environmental impacts, such as on acid deposition and human–ecosystem health, little is known regarding their emission magnitudes or detailed chemical formation mechanisms. In the current work, airborne measurements of 18 gas-phase low-molecular-weight organic acids were made in the summer of 2013 over the oil sands region of Alberta, Canada, an area of intense unconventional oil extraction. The data from these measurements were used in conjunction with emission retrieval algorithms to derive the total and speciated primary organic acid emission rates, as well as secondary formation rates downwind of oil sands operations. The results of the analysis indicate that approximately 12 t day−1 of low-molecular-weight organic acids, dominated by C1–C5 acids, were emitted directly from off-road diesel vehicles within open pit mines. Although there are no specific reporting requirements for primary organic acids, the measured emissions were similar in magnitude to primary oxygenated hydrocarbon emissions, for which there are reporting thresholds, measured previously ( ≈  20 t day−1). Conversely, photochemical production of gaseous organic acids significantly exceeded the primary sources, with formation rates of up to  ≈  184 t day−1 downwind of the oil sands facilities. The formation and evolution of organic acids from a Lagrangian flight were modelled with a box model, incorporating a detailed hydrocarbon reaction mechanism extracted from the Master Chemical Mechanism (v3.3). Despite evidence of significant secondary organic acid formation, the explicit chemical box model largely underestimated their formation in the oil sands plumes, accounting for 39, 46, 26, and 23 % of the measured formic, acetic, acrylic, and propionic acids respectively and with little contributions from biogenic VOC precursors. The model results, together with an examination of the carbon mass balance between the organic acids formed and the primary VOCs emitted from oil sands operations, suggest the existence of significant missing secondary sources and precursor emissions related to oil sands and/or an incomplete mechanistic and quantitative understanding of how they are processed in the atmosphere.

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