History and evaluation of national-scale geochemical data sets for the United States

Six national-scale,or near national-scale,geochemical data sets for soils or stream sediments exist for the United States.The earliest of these,here termed the ＇Shacklette＇ data set,was generated by a U.S. Geological Survey（USGS） project conducted from 1961 to 1975.This project used soil collected from a depth of about 20 cm as the sampling medium at 1323 sites throughout the conterminous U.S.The National Uranium Resource Evaluation Hydrogeochemical and Stream Sediment Reconnaissance（NUREHSSR） Program of the U.S.Department of Energy was conducted from 1975 to 1984 and collected either stream sediments,lake sediments,or soils at more than 378,000 sites in both the conterminous U.S.and Alaska.The sampled area represented about 65%of the nation.The Natural Resources Conservation Service（NRCS）,from 1978 to 1982,collected samples from multiple soil horizons at sites within the major crop-growing regions of the conterminous U.S.This data set contains analyses of more than 3000 samples.The National Geochemical Survey,a USGS project conducted from 1997 to 2009,used a subset of the NURE-HSSR archival samples as its starting point and then collected primarily stream sediments, with occasional soils,in the parts of the U.S.not covered by the NURE-HSSR Program.This data set contains chemical analyses for more than 70,000 samples.The USGS,in collaboration with the Mexican Geological Survey and the Geological Survey of Canada,initiated soil sampling for the North American Soil Geochemical Landscapes Project in 2007.Sampling of three horizons or depths at more than 4800 sites in the U.S.was completed in 2010,and chemical analyses are currently ongoing.The NRCS initiated a project in the 1990s to analyze the various soil horizons from selected pedons throughout the U.S.This data set currently contains data from more than 1400 sites.This paper（1） discusses each data set in terms of its purpose,sample collection protocols,and analytical methods;and（2） evaluates each data set in terms of its appropriateness as a national-scale geochemical database and its usefulness for nationalscale geochemical mapping.

Historic,pre-stock enhancement,demographic conditions of exploited populations of dusky flathead,Platycephalus fuscus,in eastern Australia

Responsible stock enhancement initiatives require baseline data of wild population demographic conditions that can be used in testing management outcomes.This study provides the first fishery-independent assessment of length-and age-based biological characteristics of exploited populations of Platycephalus fuscus in eastern Australia prior to stock enhancement.Sampling was conducted over seven estuaries spanning seven degrees of latitude and the geographical range of proposed stock enhancements.Populations in all estuaries showed evidence of length and age truncation,especially those subject to commercial fisheries where young individuals of both sexes dominated populations.Maximum longevities were 12 and 11 years for females and males respectively,but few females>5 years and males>3 years were generally sampled.Females dominated populations,and on average,the mean lengths and ages of females were greater than males within each estuary and across all age classes.Sexually dimorphic variation in growth was evident across all estuaries,with females attaining greater maximum lengths than males.Estuary-specific differences in individual growth were not identified.On average,over 50%of females sampled in each estuary were>the minimum legal length(MLL),but the opposite was evident for males.In contrast,over 25%of males in each estuary were>the mean length at maturity(L50),whereas in all but one estuary<13%of the females were>the L50.Stocked male and female P.fuscus should recruit to the fishery in 2 and 3 years,and contribute to the spawning stock in 1.5 and 4.5 years,respectively.This study provides important historical baseline data that can contribute to testing stock enhancement outcomes on populations.