ESEL Paper Review_20120109
 
By Hong Guo

1,Title and Author

Title: Rational for Control of Anthropogenic Nitrogen and Phosphorus to Reduce Eutrophication of Inland Waters

Journal: Environmental Science and Technology

Authors:

William M.Lewis,Jr1, Stephan Pfisher2, and Stefanie Hellweg3  

1.Cooperative Institute for Research in Environmental Science, Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado 80309-0216, United States
2.Department of Watershed Science and the Ecology Center, Utah State University , Logan, Utah 84322-5210, United States
3,Institute of Marine Science, University of North Carolina at Chapel Hill, Morehead City, North Carolina 28557, United States

2. Summary of Paper

In this paper, authors describe the importance of the dual control of the N and P for the eutrophication. As we know, restriction of the anthropogenic release of both N and P to inland waters is a means of controlling excessive algal growth.  The authors have a conclusion those lines of evidence that nutrient control based on both P and N offers a broader range of strategies and reduces the potential for corollary damage caused by anthropogenic mobilization of N. P regulation should be based on total P (for lakes) or total dissolved P (for flowing waters). N regulation should be based on bioavailable N rather than total N.

2.1 Comparisons of phosphorus and nitrogen as limiting nutrients in lakes
 
In order to controlling the excessive algal growth, it is important to know which element limits the expansion of algal population when their stops because of nutrient depletion. Nowadays, we give more attentions to the P limitation than N in the inland waters for following reasons: (1) Easily removed from anthropogenic sources (2)  N control is ineffective(N fixation by cyanobacteria) (3) the correlation between chlorophyll and  total P among lakes is stronger than the correlation between chlorophyll and total N

So if the main source of the phosphorus is waste effluent, it is effective strategy to use flocculation and sedimentation process to control the P. however,  it is infeasible of nonpoint  sources pollution. Moreover, nutrient enrichment experiments for lakes shows that nitrogen limitation is globally as common as phosphorus limitation. On the other words, the single regulation for P control is not unrealistic. When the limitation factors are both of P and N, authors found that growth repose ratios of freshwater phytoplankton are significantly increase.

2.2 Control of N, P or both

For the cost control, single P control is much less expensive than control of both N and P.  However P control may not provide enough phosphorus recovery to reduce algal biomass in the case of nonpoint phosphorus or background phosphorus sources are strong enough to sustain eutrophic conditions.  Moreover, allowing nitrogen to be released indiscriminately from on water body to another through the drainage network could cause wide spread simulation of algal growth by providing nitrogen to algal communities downstream that otherwise would be nitrogen limited. Thus, dual nutrient control has multiple advantages.

2.3 Strategies for limiting phosphorus and nitrogen in the environment.

Compare to P control , the concept of bioavailability suggests that water quality standards for N should be based on total N minus refractory DON, regulating total  N without adjusting for unavailable DON would be equally effective but would lower the feasibility and raise the cost of N control. 

3. Contribution:

This paper reviews the concept of controlling the nutrient growth in the lakes and streams. The most interesting for the paper is the dual control of N and P.  Generally, when we consider the eutrophication, we mostly talk about the regulation of the P control. And my research before also just focus on the P control. (Both of particle P and dissolved P) the authors give the dual control concept to us. 

4. Author information:
Email: lewis@spot.colorado.edu