This work treats one of the possible degradation pathways of organic compounds in the natural marine environment. Goethite is the prevailing species of iron minerals in marine sediments. The hydroxyl radicals, one of the most efficient oxydizing agents, are formed in the presence of this mineral under the influence of solar light. The presence of organic ligands, which enable the photoreduction of iron ions after the adsorption on the goethite surface, is necessary for this process. Results of the absorption on goethite and subsequent photodegradation of two naturally occurring carboxylic acids are presented in this work. This is the first step of a process, which can lead to the degradation of other organic compounds, including pollutants, in the natural waters.
COBISS.SI-ID: 2325327
In the last few years, several multimetrics, combining diversity indices and indicator taxa indices, have been proposed with the aim of providing a better picture of the response of benthic communities to disturbance gradients. In order to understand how different responses of diversity measures may affect the responses of multimetric indices, several biotic indices, including multimetrics, were calculated for a set of Mediterranean coastal ecosystems affected by different ranges of organic matter content. Diversity measures did not show monotonic patterns of response to the gradient of organic content, particularly at the low end of its range, while strong correlations were found between indicator taxa indices and this pressure indicator gradient. The multimetric used in the study (M-AMBI) was more correlated with its diversity components (H′ and S) than with its indicator taxa component (AMBI) and, consequently, M-AMBI was always less correlated with the gradient of organic content than AMBI. In Mediterranean coastal water ecosystems naturally poor in sediment organic matter content, indicator taxa indices, such as MEDOCC, BOPA, AMBI or BENTIX, seem to give a more reliable picture of the response of benthic communities to moderate increments of organic content than diversity indices.
COBISS.SI-ID: 2430799
We present a method for in situ monitoring of phytoplankton composition changes in a marine environment. The method is based on delayed fluorescence excitation spectra analyzed with CHEMTAX software, which is generally used for determination of phytoplankton communities with HPLC pigment data. Delayed fluorescence (DF) can only be measured in living cells and algal DF excitation spectra are group-specific. The DF excitation spectra (DFS) and HPLC pigment compositions of the mixtures were analyzed with CHEMTAX software. The prediction power of DFS–CHEMTAX method was comparable to HPLC–CHEMTAX.
COBISS.SI-ID: 2299983