Complexes with Humic material

Silver(I) binding properties of Organic Soil Materials are Different from Those of Isolated Humic Substances, Kleja, D.B., S. Nakata, I. Persson, and J.P. Gustafsson, Environ. Sci. Technol., 2016, 50 (14), pp 7453–7460, Publication Date (Web): June 15, 2016 (Article), DOI: 10.1021/acs.est.6b00970.

In Chapter 13, Section 13.3, the subsection on ‘Complexes with Humic Material’ discusses many of the fundamental properties of humic substances binding with various types of metals. This paper discusses how the solubility of silver(I) in many soils is controlled by such complexation reactions with organic matter. However, the authors diligently compare the differences in results between the isolated humic and fulvic acid’s ability to bind silver(I) with that of mor and peat. This is a good reminder that when working with these operationally defined humic materials, that their ‘original’ properties are often compromised when extracted.  

 

Bioavailability of metal species

Biomonitoring of Cd, Cr, Hg and Pb in the Baluarte River basin associated to a mining area (NW Mexico), Ruelas-Inzunza J., C. Green-Ruiz, M. Zavala-Nevárez, M. Soto-Jiménez, Science of the Total Environment 409 (2011) 3527–3536 (Published by Elsevier, May 2011)

 This paper provides a snap shot of metal accumulation in fish and crustaceans and relates to the section in our book on metal species and bioavailability. The paper uses a biota-sediment accumulation factor (BSAF) and classifies each metal accordingly.

 

Humic material properties

Humic ion-binding model VII: a revised parameterisation of cation-binding by humic substances, Tipping E., S. Lofts and J. E. Sonke, Environ. Chem. 2011, 8, 225 (Published by CSIRO, June 2011)

Both Chapter 12 and Chapter 13 discuss binding of ions with humic materials and this paper provides a vast collection of data and interpretation of results to enhance our predictive capabilities.

 

Mercury geochemistry

Worldwide trend of atmospheric mercury since 1995,  Slemr, F., E.-G. Brunke, R. Ebinghaus and J. Kuss,  Atmos. Chem. Phys. 11 (2011) 4779–4787 (Published by the European Geosciences Union, 2011)

This article presents global data showing declining trends of mercury in the atmosphere over the past 15 years.  During this period, total median gaseous mercury levels in the northern atmosphere have fallen from values greater than 1.6 ng m-3 to less than 1.4 ng m-3 and in the southern hemisphere from about 1.4 ng m-3 to 0.9 ng m-3.  The authors surmise that these unexpected trends are in large part due to a diminishing legacy of residual mercury in soil and ocean reservoirs. Other less significant causes may include ocean acidification, climate change, excess nutrient input and pollution. This new information about the atmospheric component of mercury cycling adds to our brief discussion of mercury biogeochemistry.