4,211 research outputs found
Heavy metal concentrations in water and surface sediments of Wilgreen Lake, Madison County, Kentucky
Heavy metal pollution remains a problem in natural waters, particularly for localities near plausible anthropogenic sources. We assayed the level of heavy metals in surface waters and within surface sediments of Wilgreen Lake, whose watershed drains industrial, urban, and residential areas near Richmond, Kentucky.
Water samples were treated according to Environmental Protection Agency (EPA) protocols and digested with trace-metal-grade nitric and hydrochloric acids. Sediment samples were collected with a grab sampler and digested using established EPA procedures with hydrogen peroxide and trace-metal-grade nitric acid. Both water samples and sediment samples were sent to Activation Laboratories for analysis, and were measured via ICP/MS and ICP/OES, respectively.
All water samples had heavy metal concentrations far below the safety limit for drinking water as determined by the EPA and Kentucky Division of Water (KDW). At several sampling stations, cadmium, lead, and nickel were elevated above chronic criteria for aquatic habitat as established by the KDW. Several metals (cadmium, lead) showed increases in concentration in deeper, anoxic waters compared to oxygenated, surface samples, implying their diffusion out of the sediments. In surface sediments of the lake, heavy metal concentrations show no systematic increase or decrease at stations distributed across the lake. However, two stations located near the inflow of Taylor Fork, showed considerably higher concentrations of arsenic, chromium, cobalt and lead than other grab samples; we are investigating this anomaly
Concentration of heavy metals in the waters and surface sediments of Wilgreen Lake, Madison County, Kentucky
Heavy metal pollution remains a problem in natural waters, particularly for localities near plausible anthropogenic sources. We assayed the level of heavy metals in surface waters and within surface sediments of Wilgreen Lake, whose watershed drains industrial, urban, agricultural, and residential areas near Richmond, Kentucky. We sampled both surface (oxic) and deep waters (anoxic) when the lake was stratified over Summer 2010. Water samples were treated according to U.S. Environmental Protection Agency (EPA) protocols and were digested with trace-metal-grade nitric and hydrochloric acids. Sediment samples were collected with a grab sampler and digested using established EPA procedures with trace-metal-grade nitric acid and hydrogen peroxide. Both water and sediment samples were sent to Activation Laboratories for analysis, and were measured via ICP/MS and ICP/OES, respectively.
All water samples had heavy metal concentrations far below the safety limit for drinking water as determined by the EPA and Kentucky Division of Water (KDW). Lead and nickel were elevated above chronic criteria for aquatic habitat as established by the KDW, or 1.273 and 0.8 mg/L, respectively. Several metals - lead, thorium, and thallium - showed increases in concentration in deeper, anoxic waters compared to oxygenated, surface samples, implying their diffusion out of anoxic sediments. Water-borne lead concentration spiked up to 3 mg/L in anoxic waters of station TF-3; the acute exposure threshold for lead is 1.273 mg/L, with 2 additional samples exceeding this value.
In surface sediments, heavy metal concentrations mostly show no systematic increase or decrease at stations distributed across the lake. However, two stations, M2 and TF-1, located near the inflow of Taylor Fork, showed considerably higher concentrations of lead, chromium, and cobalt than other grab samples. For example, the background lead concentration within surface sediments is about 30 mg/L, but lead levels at stations M2 and TF-1 were 70 and 110 mg/L, respectively. Elevated metal concentrations within sediments in the upper reaches of Taylor Fork can occur from two very different sources. Metals may have originated in the watershed from upstream industrial sources and accumulated within sediments, or they may have entered the lake from septic systems and/or runoff from adjacent residential areas. We continue to investigate these possibilities
Heavy metal concentrations in water and surface sediments of Wilgreen Lake, Madison County, Kentucky
Heavy metal pollution remains problematic in natural waters, particularly for localities near plausible anthropogenic sources. We assayed the level of heavy metals in surface waters and within surface sediments of Wilgreen Lake, whose watershed drains industrial, urban, agricultural, and residential areas near Richmond, Kentucky. Water samples were treated according to Environmental Protection Agency (EPA) protocols and digested with trace-metal-grade nitric and hydrochloric acids. Sediment samples were collected with a grab sampler and digested using established EPA procedures with hydrogen peroxide and trace-metal-grade nitric acid. Both water samples and sediment samples were sent to Activation Laboratories for analysis, and were measured via ICP/MS and ICP/OES, respectively.
All water samples had heavy metal concentrations far below the safety limit for drinking water as determined by the EPA and Kentucky Division of Water (KDW). Lead and nickel were elevated above chronic criteria for aquatic habitat as established by the KDW. Several metals lead, thorium, and thallium showed increases in concentration in deeper, anoxic waters compared to oxygenated, surface samples, implying their diffusion out of the sediments. In surface sediments of the lake, heavy metal concentrations show no systematic increase or decrease at stations distributed across the lake. However, two stations M-2 and TF-1 located near the inflow of Taylor Fork showed considerably higher concentrations of lead, chromium, and cobalt than other grab samples. Elevated metal concentrations within sediments in the upper reaches of Taylor Fork can occur from two very different sources. Metals may have originated in the watershed from industrial sources and accumulated within sediments, or they may have entered the lake from septic systems or runoff from the residential areas
Intellectual property as complex innovation projects component
The materials presented the possibilities development of intellectual property complex innovation projects modern highly effective science-based problems of improving the use of wastes of different industries on a complex enterprise that can provide all its energy needs alone. Some features of the possibilities of solving evidence-based problems of development of mechanisms for identifying syner-gistic processes, their scientific justification improving the use of wastes of different industries on a complex enterprise. The problem of wastes utilization and recycling is present as complex synergetic processes research and analysis of energy- and resource saving process-es for treatment of polymer wastes of various origin. The research focused on the study of issues such as the development of models of waste-modifying polymer. The investigation are focused in researching such problems as selection of scientific based methods of wastes to be utilized or recycled; the development of appropriated process flow sheets and choice of modifications additives and equipment for polymers waste recycling. The choice of appropriate plants with selected energy resources is very important for projects realization
Actors and factors - bridging social science findings and urban land use change modeling
Recent uneven land use dynamics in urban areas resulting from demographic change, economic pressure and the cities’ mutual competition in a globalising world challenge both scientists and practitioners, among them social scientists, modellers and spatial planners. Processes of growth and decline specifically affect the urban environment, the requirements of the residents on social and natural resources. Social and environmental research is interested in a better understanding and ways of explaining the interactions between society and landscape in urban areas. And it is also needed for making life in cities attractive, secure and affordable within or despite of uneven dynamics.\ud
The position paper upon “Actors and factors – bridging social science findings and urban land use change modeling” presents approaches and ideas on how social science findings on the interaction of the social system (actors) and the land use (factors) are taken up and formalised using modelling and gaming techniques. It should be understood as a first sketch compiling major challenges and proposing exemplary solutions in the field of interest
Two-phonon 1- state in 112Sn observed in resonant photon scattering
Results of a photon scattering experiment on 112Sn using bremsstrahlung with
an endpoint energy of E_0 = 3.8 MeV are reported. A J = 1 state at E_x =
3434(1) keV has been excited. Its decay width into the ground state amounts to
Gamma_0 = 151(17) meV, making it a candidate for a [2+ x 3-]1- two-phonon
state. The results for 112Sn are compared with quasiparticle-phonon model
calculations as well as the systematics of the lowest-lying 1- states
established in other even-mass tin isotopes. Contrary to findings in the
heavier stable even-mass Sn isotopes, no 2+ states between 2 and 3.5 MeV
excitation energy have been detected in the present experiment.Comment: 10 pages, including 2 figures, Phys. Rev. C, in pres
Non-equilibrium phase transitions in biomolecular signal transduction
We study a mechanism for reliable switching in biomolecular
signal-transduction cascades. Steady bistable states are created by system-size
cooperative effects in populations of proteins, in spite of the fact that the
phosphorylation-state transitions of any molecule, by means of which the switch
is implemented, are highly stochastic. The emergence of switching is a
nonequilibrium phase transition in an energetically driven, dissipative system
described by a master equation. We use operator and functional integral methods
from reaction-diffusion theory to solve for the phase structure, noise
spectrum, and escape trajectories and first-passage times of a class of minimal
models of switches, showing how all critical properties for switch behavior can
be computed within a unified framework
Warren McCulloch and the British cyberneticians
Warren McCulloch was a significant influence on a number of British cyberneticians, as some British pioneers in this area were on him. He interacted regularly with most of the main figures on the British cybernetics scene, forming close friendships and collaborations with several, as well as mentoring others. Many of these interactions stemmed from a 1949 visit to London during which he gave the opening talk at the inaugural meeting of the Ratio Club, a gathering of brilliant, mainly young, British scientists working in areas related to cybernetics. This paper traces some of these relationships and interaction
Can filesharers be triggered by economic incentives? Results of an experiment
Illegal filesharing on the internet leads to considerable financial losses for artists and copyright owners as well as producers and sellers of music. Thus far, measures to contain this phenomenon have been rather restrictive. However, there are still a considerable number of illegal systems, and users are able to decide quite freely between legal and illegal downloads because the latter are still difficult to sanction. Recent economic approaches account for the improved bargaining position of users. They are based on the idea of revenue-splitting between professional sellers and peers. In order to test such an innovative business model, the study reported in this article carried out an experiment with 100 undergraduate students, forming five small peer-to-peer networks.The networks were confronted with different economic conditions.The results indicate that even experienced filesharers hold favourable attitudes towards revenue-splitting.They seem to be willing to adjust their behaviour to different economic conditions
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