Nitrate deposition in northern hardwood forests and the nitrogen metabolism of Acer saccharum marsh

It is generally assumed that plant assimilation constitutes the major sink for anthropogenic Nitrate NO 3 − deposited in temperate forests because plant growth is usually limited by nitrogen (N) availability. Nevertheless, plants are known to vary widely in their capacity for NO 3 − uptake and assimilation, and few studies have directly measured these parameters for overstory trees. Using a combination of field and greenhouse experiments, we studied the N nutrition of Acer saccharum Marsh. in four northern hardwood forests receiving experimental NO 3 − additions equivalent to 30 kg N ha −1 year −1 . We measured leaf and fine-root nitrate reductase activity (NRA) of overstory trees using an in vivo assay and used 15 N to determine the kinetic parameters of NO 3 − uptake by excised fine roots. In two greenhouse experiments, we measured leaf and root NRA in A. saccharum seedlings fertilized with 0–3.5 g NO 3 − −N m −2 and determined the kinetic parameters of NO 3 − and NH 4 + uptake in excised roots of seedlings. In both overstory trees and seedlings, rates of leaf and fine root NRA were substantially lower than previously reported rates for most woody plants and showed no response to NO 3 − fertilization (range = non-detectable to 33 nmol NO 2 − g −1 h −1 ). Maximal rates of NO 3 − uptake in overstory trees also were low, ranging from 0.2 to 1.0 μmol g −1 h −1 . In seedlings, the mean V max for NO 3 − uptake in fine roots (1 μmol g −1 h −1 ) was approximately 30 times lower than the V max for NH 4 + uptake (33 μmol g −1 h −1 ). Our results suggest that A. saccharum satisfies its N demand through rapid NH 4 + uptake and may have a limited capacity to serve as a direct sink for atmospheric additions of NO 3 − .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47695/1/442_2004_Article_BF00334659.pd

Meeting unique requirements: Community consultation and public disclosure for research in emergency setting using exception from informed consent

BackgroundException from informed consent (EFIC) regulations for research in emergency settings contain unique requirements for community consultation and public disclosure. These requirements address ethical challenges intrinsic to this research context. Multiple approaches have evolved to accomplish these activities that may reflect and advance different aims. This scoping review was designed to identify areas of consensus and lingering uncertainty in the literature.MethodsScoping review methodology was used. Conceptual and empirical literature related to community consultation and public disclosure for EFIC research was included and identified through a structured search using Embase, HEIN Online, PubMed, and Web of Science. Data were extracted using a standardized tool with domains for major literature categories.ResultsAmong 84 manuscripts, major domains included conceptual or policy issues, reports of community consultation processes and results, and reports of public disclosure processes and results. Areas of consensus related to community consultation included the need for a two‐way exchange of information and use of multiple methods. Public acceptance of personal EFIC enrollment is commonly 64% to 85%. There is less consensus regarding how to assess attitudes, what “communities” to prioritize, and how to determine adequacy for individual projects. Core goals of public disclosure are less well developed; no metrics exist for assessing adequacy.ConclusionsMultiple methods are used to meet community consultation and public disclosure requirements. There remain no settled norms for assessing adequacy of public disclosure, and there is lingering debate about needed breadth and depth of community consultation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/170817/1/acem14264_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/170817/2/acem14264.pd