A simplified procedure using diffusion and a sulfide ion selective electrode is described for measuring acid‐volatile sulfides (AVS) in sediment This method yielded at least 10% more AVS than the more common purge‐and trap method The quantity of AVS (based on dry mass of sediment) was found to be dependent on acid concentration and on mass of wet sediment The mean recovery of known additions of sodium sulfide was 93 8 ± 6 7%

Three forms of volatile sulfides (free hydrogen sulfide, acid‐volatile sulfides [AVS] and a new form, heat‐volatile sulfides [HVS]), were measured and their relationships discussed. Purging of some contaminated sediments with nitrogen at 22°C failed to remove all of the free H2S, even after 6 h. With freshly H2S‐spiked uncontaminated sediment, purging of H2S was complete after 2 h; however, if the spiked sediment was allowed to stand for 53 d, H2S continued to be purged, even after 43 h. The H2S likely originates from equilibrium reactions involving reduced sulfur species in the sediment. Uncontaminated sediment spiked with H2S was found to be highly toxic using a sediment‐contact bioassay employing Photobacterium phosphoreum. Addition of Fe3+, which sequesters the S2−, reduced the toxicity. Two other bioassays (ATP‐TOX and Toxi‐Chromotest), both involving a DMSO/methanol extract of the spiked sediment, showed greatest toxicity with spiked sediment that had been standing for 22 d. The results indicate that reduced sulfur species in sediment may be a cause of toxicity observed in contaminated anoxic sediments.

The I3C spectra of 21 methyl-and halo-substituted 2-propenols have been determined. The shielding data are discussed with particular emphasis on their dependence on the orientation of the 3-halo substituents. Linear regression analyses of the results gave sets of additive parameters which correlate the shieldings with reasonable precision ( < 1 p.p.m.). A similar set of parameters has been generated from the published data for acyclic alkenes: these parameter sets are intercompared. The results of complete analysis of the proton spectra of most of the alcohols are also presented.On a determine le spectre au 13C de 21 derives methyles et halogenes du 2-propenol. On discute des donntes de blindage en insistant particulierement sur leur effet dans I'orientation des substituants halogenes en position-3. Les analyses de regression lineaire des rCsultats ont don& des ensembles de paramttres additifs qui nous fournissent les blindages avec une precision raisonnable (< l p.p.m.). Un ensemble similaire de paramttres a CtC tire des donnCes publikes pour les alctnes acycliques: on compare ces parametres avec ceux qu'on a obtenus. On presente aussi les resultats de I'analyse compltte des spectres de protons de la plupart des alcools.Canadian Journal of Chemistry, 50. 1361 (1972) IntroductionIn an earlier part of this series, 13C n.m.r. spectra of several unsaturated aliphatic systems were discussed and the results of an examination of a$-unsaturated carboxylic acids and esters compared with earlier data (1). These results clearly showed that olefinic 13C shieldings exhibit a marked dependence on the orientation of substituents bonded to the olefinic carbons. Furthermore, these shieldings were correlated by a linear expression entirely analogous to that employed for acyclic saturated hydrocarbons(2),

A simplified procedure using diffusion and a sulfide ion selective electrode is described for measuring acid‐volatile sulfides (AVS) in sediment This method yielded at least 10% more AVS than the more common purge‐and trap method The quantity of AVS (based on dry mass of sediment) was found to be dependent on acid concentration and on mass of wet sediment The mean recovery of known additions of sodium sulfide was 93 8 ± 6 7%

Three forms of volatile sulfides (free hydrogen sulfide, acid-volatile sulfides [AVS] and a new form, heat-volatile sulfides [HVS]), were measured and their relationships discussed. Purging of some contaminated sediments with nitrogen at 22°C failed to remove all of the free H,S, even after 6 h. With freshly H,S-spiked uncontaminated sediment, purging of H,S was complete after 2 h; however, if the spiked sediment was allowed to stand for 53 d, H,S continued to be purged, even after 43 h. The H,S likely originates from equilibrium reactions involving reduced sulfur species in the sediment. Uncontaminated sediment spiked with H S was found to be highly toxic using a sediment-contact bioassay employing Photobacterium phosphoreum. Addition of Fe3+f which sequesters the S2-, reduced the toxicity. Two other bioassays (ATP-TOX and Toxi-Chromotest), both involving a DMSOhethanol extract of the spiked sediment, showed greatest toxicity with spiked sediment that had been standing for 22 d. The results indicate that reduced sulfur species in sediment may be a cause of toxicity observed in contaminated anoxic sediments.