The application of sterol biomarkers to the study of the sources of particulate organic matter in the Solo River system and and Serayu River, Java, Indonesia

Abstract

Abstract. Sterols were analyzed in suspended particles collected in January 1991 in the Solo River system and in the Serayu River, Java, Indonesia. Free sterols were extracted from particles larger than 0.7 #im and analyzed, after derivatization into their trimethylsilyl esters, by GC and GC/MS. Concentrations of total sterols ranged from 438 to 7922 ng/l, or from 2.4 to 183.8 ng/mg of total suspendedmatter, which varied from 3.3 to 400 and 471 mg/I, respectively in the Serayu River and at the downstream station in the Solo River. POC concentrations also varied in a wide range, from 0.91 to 4.72 and 6.13% of TSM, respectively at the above stations, and were associated with sterol/POC values ranging from 0.15 to 1.75 ag/mg. Eleven structures of C27, C 28 and C 29 stenols and associated stanols were identified. 28A 22 was only found at downstream stations in the Solo River and in the Serayu River. This unique distribution, different from that of other C 27 , C 28 and C 29 sterols, suggests a predominantly autochthonous origin for these compounds associated with an increased planktonic biosynthesis near the estuary. Concentrations of 28A 5 , 29A 5 ' 2 and 29A 5 showed similar spatial distributions and increased downstream, reflecting the significant accumulation of organic matter originating from the vegetation of the various drainage basins.Values of the autochthonous versus terrigenous sterol index, defined as 27A 5 /29A 5 ' 2 2 + 29A 5 were in the 1.4-1.9 range at upstream stations, whereas at downstream stations lower values were found, 0.4-0.6, which also corresponded to higher concentrations of TSM and lower POC values.Insofar as the stanol/stenol values can be used to estimate the bacterial activity of oxic waters, simultaneous variations of C27 and C 29 stenol/stanol pairs suggest rather different bacterial degradation capacities of autochthonous versus allochthonous organic matter. The wide differencies between the values of the stenol/stanol pairs observed in one of the main tributaries and in downstream stations of the Solo River is evidence that allochthonous organic matter is much more resistant than autochthonous matter. The low index value observed in the Serayu River indicates the highly refractory nature of both autochthonous and allochthonous organic material.

Distribution and sources of phytosterols in coastal and river sediments of south central Chile

“…Considering all the biomarkers of organic matter source, a clear difference was observed between the organic matter in marine and river sediments, with more sitosterol and terrestrial markers in river sediments and a transition zone at the river mouth, which is consistent with studies from other ecosystems (Huang & Meinschein, 1979;Li et al, 1995;Hu et al, 2009). Our results are consistent with the argument that it is more appropriate to use simultaneously different biomarkers to assess the origin of sediment organic matter (Huang & Meinschein, 1979;Volkman, 1986;Canuel et al, 1995;Mudge & Norris, 1997;Seguel et al, 2001;Zimmerman & Canuel, 2001;Curiale & Harrison, 2007;Ali et al, 2009).…”

Dinosterols or dinocysts to estimate dinoflagellate contributions to marine sedimentary organic matter?

“…Although the major sterols synthesized by algae are stenols, stanols and stenones can also directly derive from specific sources of algae (Volkman et al 1998;Arzayus and Canuel 2004). Stanol : stenol ratios have however often been used as an indicator of the diagenetic status, or ''freshness,'' of organic matter in marine sediments (Li et al 1995;Arzayus and Canuel 2004). …”

Faecal sterols as indicators of sewage contamination in estuarine sediments of the Tay Estuary, Scotland: an extended baseline survey

“…A significant number of authors (Hatcher and McGillivary, 1979;Saliot and Tusseau, 1984;Venkatesan and Kaplan, 1990;Grimault et al, 1990;Tian et al, 1992;Jeng and Han, 1994;Quemeneur and Marty, 1994;Takada et al, 1994;Chalaux et al, 1995;Li et al, 1995;Fattore et al, 1996;Nichols et al, 1996;Chan et al, 1998) have therefore suggested that appropriate independent ratios are a better instrument for comparison and trend identification purposes (i.e. a normaliser for grain surface area effects).…”

“…Changes in the Chalaux index (Table 8) Used with caution (Gaskell and Eglinton, 1975), stanol/sterol ratios have the potential to estimate the degree of biohydrogenation efficiency, leading to the transformation of sterols into stanols (Saliot and Tusseau, 1984;Tian et al, 1992;Li et al, 1995). The indices required the assumptions that there was a higher stability of stanols versus sterols, with direct reduction of sterols under anoxic conditions and that biohydrogenation of sterols by microorganisms occurred in the water column and surface sediments (Lajat et al, 1990).…”

“…The indices required the assumptions that there was a higher stability of stanols versus sterols, with direct reduction of sterols under anoxic conditions and that biohydrogenation of sterols by microorganisms occurred in the water column and surface sediments (Lajat et al, 1990). Li et al (1995) reported on the simultaneous measurement of a C 27 pair (cholestanol/cholesterol) and a C 29 pair (stigmastanol/sitosterol) in the Serayu River system in Indonesia. They suggested that the low values (mean 0.3) for the 27 pair and less again for the 29 pair indicated that allochthonous organic matter was more resistant than autochthonous to degradation by microorganisms.…”