Nutrient impact

As discussed earlier, most of the phosphorus entering wetlands accumulates within the system. Surface soils in nutrient-impacted wetlands are often enriched as a result of recent accumulation, decomposition processes, and remobilization of phosphorus from subsurface soils to surface through plant uptake and deposition as detritus material. Thus, total phosphorus content of surface soils is higher than that of subsurface soils. Similar total phosphorus profiles have been seen for many wetlands and aquatic systems. In the impacted site, subsurface total phosphorus content can also represent the background levels of phosphorus for these soils, assuming that the surface material is the result of recent accumulation. Much of this phosphorus accumulation is due to organic matter accretion (detrital matter deposition) associated with phosphorus sorption to particulate matter. 

Potential Water and Soil Quality Indicators for Assessing Nutrient Impacts in Wetlands... 

FIGURE 15.5 Total soil phosphorus of soils as a function of depth. A = soil core from reference condition B = soil core from transition zone C = soil core from nutrient-impacted zone. (From Reddy et ah, 1993.)... 

Monitoring soil properties as indicators may provide long-term integrated effects of nutrient impacts on wetlands, but may not be suitable to determine short-term temporal changes in the system. Detailed methodologies for determining soil indicators can be obtained from the following sources Klute (1986), Weaver et al. (1994), Sparks et al. (1996), and Dane and Topp (2002). 

Castro, H., S. Newman, K. R. Reddy, and A. Ogram. 2005. Distribution and stability of sulfate-reducing prokaryotic and hydrogenotrophic methanogenic assemblages in nutrient-impacted regions of the Florida Everglades. Environ. Microbiol. 71 2695-2704. 

DeBusk, W. F. and K. R. Reddy. 1998. Turnover of detrital organic carbon in a nutrient-impacted Everglades marsh. Soil Sci. Soc. Am. J. 62(5) 1460-1468. 

Grunwald, S., R. Corstanje, B. E. Weinrich, and K. R. Reddy. 2006a. Spatial patterns of labile forms of phosphorus in a subtropical wetland 10 years after a sustained nutrient impact. J. Environ. Qual. 35 378-389. 

Inglett, P. W, K. R. Reddy, and P. V. McCormick. 2004. Periphyton tissue chemistry and nitrogenase activity in a nutrient impacted Everglades ecosystem. Biogeochemistry 67 213-233. 

Mills, D., Fitzgerald, K., Litchfield, C., et al., A comparison of DNA profiling techniques for monitoring nutrient impact on microhial community composition during bioremediation of petroleum-contaminated sods, J Microbiol Meth, 54, 57, 2003. 

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