Views
3 years ago

Isotopic evidence for the source and fate of phosphorus in ...

Isotopic evidence for the source and fate of phosphorus in ...

Isotopic evidence for the source and fate of phosphorus in

Applied Geochemistry 26 (2011) 688–695 Contents lists available at ScienceDirect Applied Geochemistry journal homepage: www.elsevier.com/locate/apgeochem Isotopic evidence for the source and fate of phosphorus in Everglades wetland ecosystems Xin Li a,b , Yang Wang b,⇑ , Jennifer Stern b,c , Binhe Gu d a Institute of Hydrobiology, Jinan University, Guangzhou, Guangdong 510632, China b Department of Earth, Ocean and Atmospheric Science, Florida State University & National High Magnetic Field Laboratory, Tallahassee, FL 32306-4100, USA c NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA d Everglades Division, South Florida Water Management District, West Palm Beach, FL 33406, USA article info abstract Article history: Received 26 November 2009 Accepted 11 January 2011 Available online 15 January 2011 Editorial handling by W.B. Lyons Phosphorus has historically been a limiting nutrient in the Florida Everglades. Increased P loading to the Everglades over the past several decades has led to significant changes in water quality and plant communities. Stormwater runoff that drains agricultural lands and enters the Water Conservation Areas (WCAs) are known to contain elevated levels of P, but the exact source of this P has not been fully determined. Here the results of an O isotope study of dissolved inorganic phosphate (DIP) in both polluted and relatively pristine (or reference) areas of the Everglades are reported. The data reveal spatial and temporal variations in the d 18 O signature of DIP, reflecting the source and the degree of cycling of P. The d 18 O values of DIP collected from the Everglades National Park were close or equal to the predicted d 18 O values of DIP formed in situ in equilibrium with ambient water, indicating that P is quickly cycled in the water column in oligotrophic ecosystems with very low P concentrations. However, most DIP samples collected from areas impacted by agricultural runoff yielded d 18 O values that deviated from the predicted equilibrium DIP–d 18 O values based on the d 18 O of water and water temperature, suggesting that biological cycling of P was not rapid enough to remove the fertilizer d 18 O signature in the DIP pool from areas receiving high P loading. The d 18 O signature of DIP in impacted areas reflects a mixing of fertilizer P and biologically cycled P, where the relative proportions of biologically cycled vs. fertilizer DIP are controlled by both biological (microbial activities and plant uptake) and hydrologic factors (loading rate and residence time). Using a two-end-member (i.e., fertilizer P and biologically cycled P) mixing model, fertilizers were estimated to contribute about 15–100% of the DIP pool in the highly impacted areas of the northern Everglades, whereas the DIP pool in the reference (i.e., relatively pristine) wetlands in the Everglades National Park was dominated by biologically cycled P. The study shows that O isotopic measurements of dissolved PO 3 4 can be a useful tool for tracing the fertilizer P inputs to freshwater ecosystems. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Nutrient loading in wetlands is the subject of much concern due to human dependence on the benefits offered by a healthy wetland. Wetlands serve to store and filter water, provide habitats for a diverse array of species, and support recreational activities such as fishing. Many coastal and freshwater wetlands have experienced eutrophication due to poor land-use and the contributions of excessive nutrients from agricultural or urban runoff upstream (Carpenter et al., 1998). Eutrophication of freshwater wetlands is problematic as it causes a reduction of biodiversity and the invasion of exotic species (Sklar et al., 2005). While the sources of these excess nutrients can sometimes be traced, the fate of these nutrients upon entering the wetland system is poorly understood. ⇑ Corresponding author. Fax: +1 850 644 0827. E-mail address: ywang@magnet.fsu.edu (Y. Wang). Phosphorus is a limiting nutrient in most freshwater ecosystems (Jickells, 1998). Unlike C and N, P added to an aquatic ecosystem or released during the decomposition of organic matter usually stays within the system, resulting in an enrichment of P in detritus and surface soil/sediment (Reddy et al., 1999). Phosphorus is present in the water column as particulate organic P (POP), dissolved organic P (DOP), and dissolved inorganic P (DIP). DIP is the most bioavailable form of P and may be quickly taken up by organisms. It may also be sequestered in sediments/soils by adsorption to or reaction with Fe, Al, Ca and Mg minerals. Soil P undergoes various transformations as it cycles through inorganic P pools (associated with Fe, Al, Ca and Mg minerals) and organic P pools (including plants, animals, microbes, and soil organic matter) (Richardson, 1999). Microbes transform organic P from decaying organic matter into bioavailable inorganic P. These processes are largely governed by nutrient content (C, N and P) of the soil and water as well as by the size of the microbial pool (Richardson, 1999; Reddy et al., 1999). 0883-2927/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.apgeochem.2011.01.027

CSI Chicago: Tracking the Sources and Fate of Phosphorus in ...
Phosphorus Transformation in Soil Phosphorus Transformation in Soil
Peak Phosphorus - SuSanA
Carbon and hydrogen isotopic evidence for the origin of combustible ...
Using Stable Isotope Geochemistry Tools for Nutrient Source Tracking
Chemical and carbon isotopic evidence for the source and fate of ...
Phosphorus Fertilization - Sources and Efficiency
Phosphorus Sources for Corn Fertilization - Iowa State University ...
Commercial Phosphorus Fertilizer…Know Your Sources
The Oceanic Phosphorus Cycle
Geochemical and Nd isotopic evidence for sedimentary-source ...
Phosphorus Sources for Field Crops - Cornell University Nutrient ...
Geochemical and Pb isotopic evidence for sources and dispersal of ...
Rapid biologically mediated oxygen isotope exchange between ...
Phosphorus Basics – The Phosphorus Cycle - Cornell University ...
Dissolved inorganic phosphorus, dissolved iron, and ...
The Fate of Phosphorus Along Estuarine Salinity Gradients A ...
feasibility of using isotopes as tracers of the sources of dissolved ...
Evaluation of Phosphorus Fertilizer Type on Plugging of Drip ...
Magnitudes and sources of dissolved inorganic phosphorus inputs ...
MODELLING PHOSPHORUS FLOWS IN SOILS - Optimus Verlag
Sourcing drugs with stable isotopes
Chemical and isotopic evidence for secondary alteration of natural ...
Experimental evidence for diel variations of the carbon isotope ...
Spatial and seasonal sediment phosphorus species and its relation ...
The Story of Phosphorus - DiVA
Phosphorus 101 - Indiana CCA Program
Phosphorus Requirements for Sustainable ... - Jatropha.pro