Excitation−emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize dissolved organic matter (DOM) in water and soil. However, interpreting the >10,000 wavelength-dependent fluorescence intensity data points represented in EEMs has posed a significant challenge. Fluorescence regional integration, a quantitative technique that integrates the volume beneath an EEM, was developed to analyze EEMs. EEMs were delineated into five excitation−emission regions based on fluorescence of model compounds, DOM fractions, and marine waters or freshwaters. Volumetric integration under the EEM within each region, normalized to the projected excitation−emission area within that region and dissolved organic carbon concentration, resulted in a normalized region-specific EEM volume (Φi,n). Solid-state carbon nuclear magnetic resonance (13C NMR), Fourier transform infrared (FTIR) analysis, ultraviolet−visible absorption spectra, and EEMs were obtained for standard Suwannee River fulvic acid and 15 h...

Fluorescence excitation-emission matrix regional integration to quantify spectra for dissolved organic matter.

Biochar as a sorbent for contaminant management in soil and water: a review.

Characterization of marine and terrestrial DOM in seawater using excitation-emission matrix spectroscopy

Climate change 2014 - Synthesis Report

Rapid turnover of organic matter leads to a low efficiency of organic fertilizers applied to increase and sequester C in soils of the humid tropics. Charcoal was reported to be responsible for high soil organic matter contents and soil fertility of anthropogenic soils (Terra Preta) found in central Amazonia. Therefore, we reviewed the available information about the physical and chemical properties of charcoal as affected by different combustion procedures, and the effects of its application in agricultural fields on nutrient retention and crop production. Higher nutrient retention and nutrient availability were found after charcoal additions to soil, related to higher exchange capacity, surface area and direct nutrient additions. Higher charring temperatures generally improved exchange properties and surface area of the charcoal. Additionally, charcoal is relatively recalcitrant and can therefore be used as a long-term sink for atmospheric CO2. Several aspects of a charcoal management system remain unclear, such as the role of microorganisms in oxidizing charcoal surfaces and releasing nutrients and the possibilities to improve charcoal properties during production under field conditions. Several research needs were identified, such as field testing of charcoal production in tropical agroecosystems, the investigation of surface properties of the carbonized materials in the soil environment, and the evaluation of the agronomic and economic effectiveness of soil management with charcoal.

http://www.css.cornell.edu/faculty/lehmann/publ/BiolFertSoils%2035,%20219-230,%202002%20Glaser.pdf

Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal – a review

Long term effects of a brown coal-based amendment on the properties of soil humic acids

Chemical and spectroscopic characteristics of humic acids and dissolved organic matter along two Alfisol profiles.

Properties of dissolved organic matter in forest soils: Influence of different plant covering

Fractal humic acids in aqueous suspensions at various concentrations, ionic strengths, and pH values

Organic matter content is ascertained to be the major factor for alachlor adsorption in soils. Limited knowledge exists, however, as to the effects of structural and chemical properties of soil organic matter on the mechanisms and extent of alachlor adsorption. The binding mechanisms and adsorption isotherms for alachlor have been measured onto three humic acids (HA) originating from a municipal sewage sludge, a sludge-amended soil, and a control soil. Spectroscopic techniques, including Fourier-transform infrared, fluorescence and electron spin resonance analyses, and high-pressure liquid chromatography have been used. The magnitude of alachlor adsorption and the type of binding mechanism involved depended on the nature and chemical properties of the HA. Soil HA exhibited linear isotherms and higher alachlor adsorption at low concentration, whereas sludge humic acid featured an S-shaped isotherm and increasing adsorption at higher alachlor concentration. Multifunctional hydrogen bonds and charge-transfer bonds were preferentially involved in the adsorption of alachlor at low concentration, especially onto well humidified, highly aromatic soil humic acids rich in O-containing groups. Hydrophobic bonding appeared to predominate at higher alachlor concentration, especially onto low-humified, highly aliphatic sludge HA. A reliable quantitative evaluation of the extent of adsorption of alachlor to HA in the experimental range of concentration used could be provided by the use of both the Freundlich K-values and the distribution coefficients, Kd.

Nicola Senesi

Papers

Long term effects of a brown coal-based amendment on the properties of soil humic acids

Chemical and spectroscopic characteristics of humic acids and dissolved organic matter along two Alfisol profiles.

Properties of dissolved organic matter in forest soils: Influence of different plant covering

Fractal humic acids in aqueous suspensions at various concentrations, ionic strengths, and pH values

Adsorption of Alachlor by Humic Acids from Sewage Sludge and Amended and Non-Amended Soils