Accumulation Of Hydrogen Sulfide Research Articles

The importance of sulfate reduction associated with Ulva lactuca thalli during decomposition: a mesocosm experiment

The decay of the macroalga Ulva lactuca was followed for 54 days in a controlled laboratory experiment. The experiment focused on the activity of sulfate reducers in different compartments (water, thalli and sediment) of the experimental system. In addition to sulfate reduction, the concentrations of sulfide, carbon dioxide, sulfate, carboxylic acids and pH were determined at regular intervals. Interestingly, 90% of the system-integrated sulfate reduction was carried out in the water column by thallus-associated sulfate reducers. The sediment accounted for about 10% of the integrated sulfate reduction activity, while sulfate reduction carried out by free-living sulfate reducers was insignificant and represented less than 1% of total sulfate reduction. Sulfate reduction rates in the water column were below the detection limit at the beginning of the experiment and were detected after 1 week of incubation. Sulfate reduction rates associated with thalli were measurable immediately after the experiment was started and increased very rapidly, reaching extremely high rates after 1 week of incubation. Sediment sulfate reduction rates had increased to twice the initial value by day 30 after which they remained constant. Thallus-associated sulfate reduction rates (SRR) were of the same level in all layers of the algal mat throughout the experiment. Our results indicate that sulfate-reducing bacteria were present on the thalli when the experiment was initiated and that the water column colonization by sulfate-reducing bacteria from the sediment was less important. This would explain the rapid accumulation of hydrogen sulfide in the water column during macroalgal decay events in coastal marine environments.

Habitat characterization and nutritional strategies of the endosymbiont-bearing bivalve Lucinoma aequizonata

A population of the lucinid bivalve Lucinorna aequizonata, with sulfur-oxidizing endosymbiotic bacteria in the gills, is restricted to a narrow depth range (500 -f10m) on the slope of the Santa Barbara Basin, California, USA. In this zone, the seawater just above the substratum is sub-oxic ([02] < 2 0 FM). The organically rich sediments in which these clams live are well mixed by bioturbation, which appears to maintain a redox condition Limiting the extensive accumulation of hydrogen sulfide. However, thiol levels in the blood of the clams indicate an exposure to significant amounts of sulfide and/or thiosulfate apparently from randomly &spersed short-lived pockets of sulfidic mud that can be reached by the clam's burrowing vermiform foot. When the bivalves are incubated in the presence of hydrogen sulfide, thiosulfate is concentrated in the blood and apparently utilized by the bacteria for metabohc energy and the production of intracellular elemental sulfur. Laboratory growth experiments demonstrated that sulfide concentrations greater than 10 FM were detrimental to the host, even though the bacteria continued to accumulate elemental sulfur. The utilization of thiosulfate under near anaerobic conditions and the accumulation of intracellular elemental sulfur by the endosymbiotic bacteria coupled with the high availability of environmental nitrate and low molecular oxygen suggests a metabolic strategy analogous to the free-living sulfur oxidizer Thlobacillus denjtrificans. The 6 ' 3 ~ values of the purified endosymbiont bacteria (-34.0 5 0.8%) were significantly lighter than those of the host tissue (-29.0 + 0.7 %) suggesting that in addition to the nutrition provided by the bacteria, over 25 % of the host carbon may be attributed to exogenous dissolved carbon which is in high concentrations in its natural habitat.

The EI Cajon Reservoir: Developing Management Strategies for a Tropical Impoundment

ABSTRACT In 1984, a 94 km2 reservoir started to form behind the highest arch dam on the American continent, EI Cajon in Honduras. Pre-impoundment programs established to assess the environmental aspects of this hydroelectric project have developed into a post-impoundment research unit that is undertaking management-oriented studies on the reservoir and its watershed. Information from this research provides an excellent case history of the evolution of a tropical reservoir and associated management challenges. Accumulation of hydrogen sulfide in the anoxic hypolimnion has resulted in some corrosion problems in the power generation facility. The fisheries, which appear to have a substantial potential for contributing to employment and food supply in the region, are currently underexploited. However, as the regional social infrastructure develops, utilization of the fisheries production is expected to increase. As population pressure in the EI Cajon basin increases, the economic and environmental consequence...

Depletion of epilimnetic oxygen and accumulation of hydrogen sulfide in the hypolimnion of Onondaga Lake, NY, U.S.A.

The depletion of epilimnetic DO during fall, and the accumulation of H2S in the hypolimnion during summer, are documented for polluted hypereutrophic Onondaga Lake, NY, U.S.A. The fall epilimnetic DO depletion is so severe that in many, if not all years, the New York State standard for minimum DO of 4 mg- L−1 is violated for periods as long as 1 mo. The depletion is caused by the transport of O2 demanding species, particularly H2S, from the hypolimnion into the epilimnion. Hydrogen sulfide accumulates progressively through the summer, mostly via SO inf4 sup2− reduction, to unusually high concentrations; a maximum of 1.65 mM has been observed. These conditions are apparently manifestations of hypereutrophy, and thus may be subject to remediation through P management efforts.

SOME CONSEQUENCES OF BRINE POLLUTION IN THE BAHÍA FOSFORESCENTE, PUERTO RICO

Brine pollution from a sea‐salt works occasionally flows into Bahía Fosforescente causing stagnation, severe anoxia and accumulation of hydrogen sulfide (89 ml/liter) with consequent toxic effects on local flora and fauna. The bottom brine (salinity 57‰) constitutes a lethal trap which accumulates and kills phytoplankton so that the water turns yellow‐green and reaches a chlorophyll a (actually pheophytin) content of about 2,000 µg/liter as compared with chlorophyll levels of about 4 µg/liter in the normal surface water. Colonization of the bay bottom by benthic plants and animals may have been prevented by limited light and intermittent brine pollution since the adjacent salt works was established in 1937.