NUTRIENT CONTAMINATION FROM NON-POINT SOURCES: DISSOLVED PHOSPHATE IN SURFACE AND SUBSURFACE WATERS AT EKU MEADOWBROOK FARM, MADISON COUNTY, KENTUCKY

Abstract. The Arctic Ocean accounts for only 4% of the global ocean area but it contributes significantly to the global carbon cycle. Recent observations of seawater carbonate chemistry in shelf waters of the Western Arctic from 2009 to 2011 indicate that extensive areas of the benthos are exposed to bottom waters that are seasonally undersaturated with respect to calcium carbonate (CaCO3) minerals, particularly aragonite. Our observations indicate seasonal reduction of saturation states (Ω) for calcite (Ωcalcite) and aragonite (Ωaragonite) in the subsurface in the Western Arctic by as much as 0.9 and 0.6, respectively. Such data indicates that bottom waters of the Western Arctic shelves are already potentially corrosive for biogenic and sedimentary CaCO3 for several months each year. Seasonal changes in Ω are imparted by a variety of factors such as phytoplankton photosynthesis, respiration/remineralization of organic matter and air-sea gas exchange of CO2 – combined these processes either increase or enhance Ω in surface and subsurface waters, respectively. These seasonal physical and biological processes also act to mitigate or enhance the impact of Anthropocene ocean acidification (OA) on Ω in surface and subsurface waters, respectively. Future monitoring of the Western Arctic shelves is warranted to assess the present and future impact on Ω values from ocean acidification and seasonal biological/physical processes on Arctic marine ecosystems.

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Investigation of the activity of Rn-222 along a small stream in the Representative Basin of Juatuba - MG

RBRH ◽

10.1590/2318-0331.231820180009 ◽

2018 ◽

Vol 23 ◽

Cited By ~ 1

Author(s):

Vinícius Verna Magalhães Ferreira ◽

Cláudio José Chagas ◽

Rubens Martins Moreira ◽

Zildete Rocha ◽

Talita de Oliveira Santos ◽

...

Keyword(s):

Surface Waters ◽

Human Consumption ◽

Southeastern Part ◽

Small Stream ◽

Radon Activity ◽

Subsurface Waters ◽

Main Instrument ◽

Natural Tracer ◽

Effective Radiation ◽

Surface And Subsurface Waters

ABSTRACT For thousands of years, water has been the focus of experimentation toward solving the challenges associated with human water supply, navigation, irrigation, and sanitation. The use of tracers to study water resources is an efficient approach that can facilitate the modeling of many hydrological scenarios. The goal of this paper is to show results of research that tracked the presence of Rn-222, a natural tracer, in the surface waters of a small watercourse in southeastern part of Brazil. RAD 7, which is an electronic and portable radon detector, was the main instrument used in this survey. We analyzed 117 water samples and converted the radon activity results to effective radiation doses with respect to the hypothetical human consumption of these waters. We also analyzed the sediments of the watercourse. The obtained data showed that the radon activity in the studied waters varies between 0.52-76.96 Bq/m3. We determined the effective dose of all samples to be less than 1 mSv y−1, and its consumption to present no risk to human health. The existence of connections between surface and subsurface waters in the stream is possible, and radon peaks may indicate the existence of discharge zones into the surface water body.

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