Lake sediment samples

Kraft mill that had used elemental chlorine historically Microbial community and diatom species in lake sediments sampled from 2-8 cm depths Drop in the ATP content, depressed butyrate-esterase activity indicating toxicity to microorganisms, and reduction in diatom species richness Mika et al., 1999 [31]... 

Phosphorus is not a TE but a major nutrient element. Nevertheless, fractionation of this element is essential for environmental studies, and hence it seems reasonable to highlight here some relevant SEPs. Four different procedures for the fractionation of P in lake sediment samples have been tested in an interlaboratory study in the framework of the SM T program (Ruban et al., 1999). As a result, a novel scheme based on the Williams protocol (Williams et al., 1976) has been developed aimed at the restoration of lake sediments. The scheme comprises three separate assays (1) sequential extraction of NaOH-extractable (Fe- and Al-bound) and HCl-extractable (Ca-bound) fractions, (2) sequential extraction of inorganic and organic phosphorus and (3) single extraction, after calcination, of concentrated HCl-extractable (total P) fraction (see Table 12.3 for further details). Further discrimination of specific compounds is made feasible by the use of chromatographic and capillary separation techniques as reviewed by Spivakov et al. (1999). 

This chapter details the technical procedures used to prepare and analyze lake sediment samples for cellulose carbon and oxygen isotope composition, considers important factors in the interpretation of cellulose isotope data, briefly highlights key results from recent applications, and outlines future research needs and directions. 

Methods for lake sediment sample preparation for cellulose carbon and oxygen isotope analyses have been developed at the University ofWaterloo - Environmental Isotope Laboratory (UW-EIL), (Heemskerk Diebolt, 1994 Edwards et al, 1997 Elgood et al., 1997). 

Following removal of carbonate and freeze-drying, lake sediment samples are sieved to <500/rm to eliminate macrofossil plant debris (which may be of terrestrial origin). Scattered fragments may be removed with tweezers. 

Carbon isotope analysis on lake sediment cellulose may be performed by routine breakseal combustion (Boutton et al, 1983 Boutton, 1991a) or by continuous flow — isotope ratio mass spectrometry (CF-IRMS). Comparison of lake sediment samples analyzed by both methods at the UW-EIL show excellent agreement. 

Plasticizers have also been detected in river and lake sediment samples (Table 18.7). Because adsorption is a major fate mechanism for many plasticizers (see 18.2.5), it is expected that, depending on their organic carbon content, sediments can act as a sink for dissolved plasticizers. The largest reported concentration for di-n-butyl phthalate in river sediments (1,100 mg/kg) confirms this expectation. However, some of the sediment and soil samples may have been biased in that they were collected near chemical plants or in industrial areas, and hence, the results may reflect point sources rather than some type of background levels resulting from non-point mechanisms of dispersal. Kohli et al noted that it was difficnlt to determine background levels for phthalate esters because of their wide occurrence. 

Urmeneta, J., Mas-Castella, J. and Guerrero, R. (1995), Biodegradation of poly-P-hydroxyalkanoates in a lake sediment sample increases bacterial sulfate reduction , Appl. EnviroTL Microbiol. 61(5), 2046-2048. 

PHA synthesis has been advanced as an energy-producing mechanism in anaerobic syntrophic (H2-producing, acetogenic) bacteria [159]. Extracellular PHBV degradation concurrent with sulfate reduction in anoxic lake-sediment samples was seen by Urmeneta et al. [160] as an indication that PHAs could serve as carbon and electron sources. 

Figure 9.13 Mass spectrum in lake sediment sample by magnetic sector-CP-MS.

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