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A substantial increase in the number of studies using the optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) as a proxy for its chemical properties in estuaries and the coastal and open ocean has occurred during the last decade. We are making progress on finding the actual chemical compounds or phenomena responsible for DOM’s optical properties. Ultrahigh resolution mass spectrometry, in particular, has made important progress in making the key connections between optics and chemistry. But serious questions remain and the last major special issue on DOM optics and chemistry occurred nearly 10 years ago. Controversies remain from the non-specific optical properties of DOM that are not linked to discrete sources, and sometimes provide conflicting information. The use of optics, which is relatively easier to employ in synoptic and high resolution sampling to determine chemistry, is a critical connection to make and can lead to major advances in our understanding of organic matter cycling in all aquatic ecosystems. The contentions and controversies raised by our poor understanding of the linkages between optics and chemistry of DOM are bottlenecks that need to be addressed and overcome.

CDOM --- dissolved organic matter --- Absorbance --- fluorescence --- biomarkers --- Stable isotopes --- Mass Spectrometry --- dissolved organic carbon --- CDOM --- dissolved organic matter --- Absorbance --- fluorescence --- biomarkers --- Stable isotopes --- Mass Spectrometry --- dissolved organic carbon

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A substantial increase in the number of studies using the optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) as a proxy for its chemical properties in estuaries and the coastal and open ocean has occurred during the last decade. We are making progress on finding the actual chemical compounds or phenomena responsible for DOM’s optical properties. Ultrahigh resolution mass spectrometry, in particular, has made important progress in making the key connections between optics and chemistry. But serious questions remain and the last major special issue on DOM optics and chemistry occurred nearly 10 years ago. Controversies remain from the non-specific optical properties of DOM that are not linked to discrete sources, and sometimes provide conflicting information. The use of optics, which is relatively easier to employ in synoptic and high resolution sampling to determine chemistry, is a critical connection to make and can lead to major advances in our understanding of organic matter cycling in all aquatic ecosystems. The contentions and controversies raised by our poor understanding of the linkages between optics and chemistry of DOM are bottlenecks that need to be addressed and overcome.

CDOM --- dissolved organic matter --- Absorbance --- fluorescence --- biomarkers --- Stable isotopes --- Mass Spectrometry --- dissolved organic carbon

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Microorganisms (bacteria, archaea, microeukaryotes) in marine environments secrete a diverse array of exopolymeric substances that facilitate attachment to surfaces, the formation of organic colloids and larger aggregations of cells (marine snow), and that can influence many ocean, as well as global, processes. The aim of this Research Topic is to highlight recent advances in the sources, chemistry and function of these microbial-produced macromolecules. We encouraged original research and reviews on exopolymeric substances, from their sources, chemico-physiological properties, functions and ecosystem effects, and including their role in the Gulf of Mexico following the Deepwater Horizon oil spill disaster.

marine oil snow (MOS) --- exopolymers --- marine environment --- biological pump --- phytoplankton --- marine snow --- oceans --- marine bacteria --- exopolysaccharide substances (EPS) --- organic carbon --- marine oil snow (MOS) --- exopolymers --- marine environment --- biological pump --- phytoplankton --- marine snow --- oceans --- marine bacteria --- exopolysaccharide substances (EPS) --- organic carbon

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Microorganisms (bacteria, archaea, microeukaryotes) in marine environments secrete a diverse array of exopolymeric substances that facilitate attachment to surfaces, the formation of organic colloids and larger aggregations of cells (marine snow), and that can influence many ocean, as well as global, processes. The aim of this Research Topic is to highlight recent advances in the sources, chemistry and function of these microbial-produced macromolecules. We encouraged original research and reviews on exopolymeric substances, from their sources, chemico-physiological properties, functions and ecosystem effects, and including their role in the Gulf of Mexico following the Deepwater Horizon oil spill disaster.

marine oil snow (MOS) --- exopolymers --- marine environment --- biological pump --- phytoplankton --- marine snow --- oceans --- marine bacteria --- exopolysaccharide substances (EPS) --- organic carbon

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A geometallurgical approach was adopted by Goldcorp Peñasquito poly-metallic mine, which produces lead and zinc concentrates with payable amounts of gold and silver, to characterize the variability and metallurgical response of sedimentary ores with high organic carbonaceous material content. For this purpose a sequential rougher test was designed to simulate the final configuration of the industrial plant for characterization and variability testing. A proxy test was designed to provide organic carbonaceous material concentrates using a representative small size sample for rapid characterization of the material. Three different leach test procedures were developed as well as a preg robbing potential test to characterize the sequential rougher test product’s response to a leach circuit. Analysis tools used included optical microscopy, SEM EDS analysis and principal component analysis. The results indicated that the sequential rougher test designed produced partially positive results with acceptable distributions of organic carbonaceous material, lead and zinc sulfide minerals. Improvement on the recovery of iron sulfides can still de done through the recommendations suggested in this report. The proxy test presented good results comparable to those of the sequential rougher test but improvements have also been suggested to result in the production of higher grade organic carbonaceous material concentrates. The leach tests designed for this project did not produce acceptable results and further test work is suggested. Principal component analysis aided for preliminary class definition.

geometallurgy --- organic carbon --- sedimentary rocks --- pre-flotation --- principal component analysis --- variability characterization --- Ingénierie, informatique & technologie > Géologie, ingénierie du pétrole & des mines