* not completed

. The largest source of carbon in the environment – including air, water and the terrestrial environment – is:

carbon dioxide correct incorrect

peat correct incorrect

fossil fuels correct incorrect

carbonate minerals correct incorrect

plants correct incorrect

* not completed

. Regarding organic matter in water, which of the following statements is/are true? (Please select all that apply)

Most carbon found in water is in the form of dissolved organic matter correct incorrect

Sunlight is essential to produce organic matter in the hydrosphere correct incorrect

Both particulate and soluble forms of organic matter are generated in situ in water correct incorrect

In water, most OM of natural origin is in the form of macromolecules, while that of human origin is made up of discrete small molecules correct incorrect

Some organic matter in water originates from the terrestrial environment correct incorrect

* not completed

. Regarding degradation of organic matter, which of the following statements is/are true? (Please select all that apply)

The complete oxidative decomposition of organic matter produces more carbon dioxide than the combustion of the same organic matter correct incorrect

Humin is a relatively stable intermediate in the degradation of natural organic matter correct incorrect

The oxygen content of fulvic acid is greater than that of humic acid correct incorrect

Typically, the relative proportion of humin to humic and fulvic acids increases with depth in a soil correct incorrect

Lignin can be a precursor of humic material correct incorrect

* not completed

. Regarding properties of humic material, which of the following statements is/are true? (Please select all that apply)

The elemental components of humic material are limited to carbon, hydrogen, oxygen and nitrogen correct incorrect

Some humic material is soluble in water at neutral pH values correct incorrect

Humic material in water can account for the difference between alkalinity and acid neutralizing capacity correct incorrect

In water at pH 7, both carboxyl and phenol groups present in humic material can act as proton acceptors correct incorrect

Humic material in near-neutral water has a net negative charge correct incorrect

* not completed

. Regarding degradation of organic matter, which of the following statements is/are true?  (Please select all that apply)

Soluble humic material can enhance the solubility of small organic molecules of anthropogenic origin correct incorrect

Hydrogen bonding is one mechanism that enables binding of humic material to soils or sediments correct incorrect

Salt linkage is a process by which sodium chloride is  bound to humic material correct incorrect

Hydrophobic interactions involve further disruption of the ordered water structure correct incorrect

Soluble humic material associates with metal ions via hydrophobic interactions correct incorrect

* not completed

. The DOC content of a swamp is 17 mg L^-1. The equivalent value expressed as DOM (in mg L^-1) is: (Please select all that apply)

10 correct incorrect

17 correct incorrect

34 correct incorrect

58 correct incorrect

29 correct incorrect

* not completed

. Which of the following statements regarding infra-red (IR) spectra of humic and fulvic acids is/are true? (Please select all that apply)

The IR spectra of humic and fulvic acids typically contain the same peaks correct incorrect

The carbonyl stretch around 1720 cm^-1 is usually readily identifiable in both humic and fulvic acids correct incorrect

The structural features of humic and fulvic acids can be readily quantified correct incorrect

Sulfur containing functional groups can be easily identified in humic and fulvic acids correct incorrect

The presence of a strong O-H stretch readily identifies that the sample is fulvic acid correct incorrect

* not completed

. Which of the following statements regarding carbon-13 nuclear magnetic resonance (NMR) spectra of humic and fulvic acids is/are true? (Please select all that apply)

Humic and fulvic acids can be distinguished by carbon-13 NMR spectra due to the nature of the signals obtained in the aliphatic region correct incorrect

Humic acids show a larger aliphatic carbon signal than fulvic acid correct incorrect

Fulvic acids show a larger  aliphatic carbon signal than humic acid correct incorrect

Most carbon functional groups are readily identified in carbon-13 NMR spectra correct incorrect

A quantitative measure of the number of carbonyl groups can be made on a sample of humic acid correct incorrect

* not completed

. Which of the following statements about humic material complexing metals ions is/are true? (Please select all that apply)

Humic material can form complexes with metal ions through ionic or covalent bonds correct incorrect

pH will affect the strength of complex formed correct incorrect

Metals complexes tend to precipitate once formed correct incorrect

K_f depends on the number of binding sites correct incorrect

K_f is a measure of stability of the complex formed correct incorrect

* not completed

. Which of the following statements about interactions between humic material and small organic molecues is/are true? (Please select all that apply)

Humic materials can interact through hydrogen bonding with pesticides correct incorrect

Humic materials can use an ion bridge to bond with pesticides correct incorrect

Hydrophobic interactions with humic materials can bind pesticides correct incorrect

Electrostatic forces can bind pesticides to humic materials correct incorrect

van der waals forces are always a source of weak interactions correct incorrect