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At least 1,441 records · Page 80Linked to original sources
USGS1994

Decade-scale trend in sea water salinity revealed through d18O analysis of Montastraea annularis annual growth bands

Stable oxygen isotope ratios (1)180) of coral skeletons are influenced by ambient water temperature and by the oxygen isotope ratio in the surrounding sea water, which, in turn, is linked to evaporation (salinity) and precipitation. To investigate this relationship more thoroughly, we collected hourly temperature data from the Hen and Chickens Reef in the Florida Keys between 1975 and 1988 and compared them to'the 1)180 of Montastraea annularis skeleton that grew during the same interval. To ensure that we obtained the correct oxygen isotopic range in the skeleton we typically sampled the coral at a resolution of 20-30 samples in 1 year; in 1 year we sampled the coral at a resolution of 70 samples·year-'. Despite our high-resolution sampling, we were unable to obtain the full temperature-induced 1)180 range in the skeleton. Our data suggest that, during the summer, evaporation causes isotopic enrichment in the water, partially masking the temperature-induced signal. Our data also show that oxygen isotopic composition of seawater at the reef has increased since 1981. This increase indicates that salinity has increased slightly during the past decade, perhaps as a result of increased evaporation in waters of Florida Bay and the Keys. This phenomenon is probably not caused by a decrease in the outflow of freshwater into Florida Bay from the Everglades but may be related to the measured deficit in precipitation that has occurred over the past decade.

Bulletin of Marine Science↗
USGS1990

Influence of seasonal growth, age, and environmental exposure on Cu and Ag in a bivalve indicator, Macoma balthica, in San Francisco Bay

Temporal and spatial variations in Cu and Ag in the deposit-feeding clam Macoma balthica and in surficial sediments were analysed at 8 stations in San Francisco Bay at near-monthly intervals for periods ranging from 3 to 10 yr during 1977 to 1986. Strong seasonal variations in metal concentrations of M. balthica were associated with seasonal variations in soft tissue weight. Aperiodic fluctuations in metal concentration appeared to be driven by changes in metal content of the soft tissues. Metal content of clams of standard shell length was less variable than tissue metal concentration, and generally followed changes in the concentrations of Cu and Ag in the sediments. Correlations between metal content and sediment concentrations were improved when content was standardized to age rather than shell length. Metal content of M. balthica displayed few consistent temporal trends among stations, evidently reflecting different sources of input and complex hydrologic and geochemical processes affecting metal availability in San Francisco Bay. Increases in Cu and Ag were noted at several stations in South Bay during 1977 to 1980. A continuous 10 yr record at one of these stations showed that the 1977 to 1980 increase and the subsequent decline beginning in 1981 coincided with fluctuations in metal inputs from a nearby source.

California↗
USGS1973

The concept of growth and maturity of ore-stage pyrite in roll-type uranium deposts

Roll-type uranium deposits contain both ore-stage pyrite and preore or diagenetic pyrite that was present in the host rock before the deposits began to form. Ore-stage pyrite forms as the result of redistribution and accretion from the preore pyrite. Accretion of the ore-stage pyrite seems to be governed by natural laws that limit its concentration to only a few times the concentration of the preore pyrite. Accumulations of ore-stage pyrite build up along the leading edge of a supergene oxidation zone which spreads through the host rocks, literally pushing the ore deposits ahead of it. The ore-stage pyrite probably progresses much as a wave that first grows to a nearly fixed amplitude and thereafter is steadily maintained as the mature deposit continues to advance.

Journal of Research of the U.S. Geological Survey↗
USGS2003

Conditions for growth and survival of bull trout in Beulah Reservoir, Oregon. Annual report 2002

The Bureau of Reclamation (BOR) constructed Agency Valley Dam on the North Fork of the Malheur River in 1934-35, creating Beulah Reservoir. The project is operated and maintained by the Vale Irrigation District for irrigation and downstream flood control. There is currently no formal agreement for a minimum pool level at Beulah Reservoir, but project operators of Agency Valley Dam and BOR are considering management alternatives. Although the project is not operated for fish and wildlife values, the reservoir supports a rainbow trout Oncorhynchus mykiss fishery and also seasonally harbors an adfluvial population of bull trout Salvelinus confluentus (Oregon Department of Fish and Wildlife [ODFW], unpublished data). Bull trout were listed by the USFWS as a threatened species throughout the Columbia and Klamath river basins in 1998, and Oregon has listed the North Fork Malheur River population “Of Special Concern”.

Oregon↗
USGS2002

Conditions for growth and survival of bull trout in Beulah Reservoir, Oregon. Annual report 2001

The Bureau of Reclamation (BOR) constructed Agency Valley Dam on the North Fork of the Malheur River in 1934-35, creating Beulah Reservoir. The project is operated and maintained by the Vale Irrigation District for irrigation and downstream flood control, with no minimum pool or outflow operational criteria. Although the project is not operated for fish and wildlife values, the reservoir supports a rainbow trout Oncorhynchus mykiss fishery and also seasonally harbors an adfluvial population of bull trout Salvelinus confluentus (Oregon Department of Fish and Wildlife [ODFW]; Burns Paiute Tribe). Bull trout were listed by the USFWS as a threatened species throughout the Columbia and Klamath river basins in 1998, and Oregon has listed the North Fork Malheur River population “Of Special Concern”.

Oregon↗