University of Rhode Island

About: University of Rhode Island is a education organization based out in Kingston, Rhode Island, United States. It is known for research contribution in the topics: Population & Bay. The organization has 11464 authors who have published 22770 publications receiving 841066 citations. The organization is also known as: URI & Rhode Island College of Agriculture and the Mechanic Arts.

A Guide to the Proper Use of Factor Analysis in the Conduct and Reporting of Research: Pitfalls to Avoid

Abstract: Suggestions for proper procedures to use and pitfalls to avoid are offered to prospective authors of manuscripts on studies using factor analysis methods.

Evolutionary potential of marine phytoplankton under ocean acidification.

Abstract: Marine phytoplankton have many obvious characters, such as rapid cell division rates and large population sizes, that give them the capacity to evolve in response to global change on timescales of weeks, months or decades. However, few studies directly investigate if this adaptive potential is likely to be realized. Because of this, evidence of to whether and how marine phytoplankton may evolve in response to global change is sparse. Here, we review studies that help predict evolutionary responses to global change in marine phytoplankton. We find limited support from experimental evolution that some taxa of marine phytoplankton may adapt to ocean acidification, and strong indications from studies of variation and structure in natural populations that selection on standing genetic variation is likely. Furthermore, we highlight the large body of literature on plastic responses to ocean acidification available, and evolutionary theory that may be used to link plastic and evolutionary responses. Because of the taxonomic breadth spanned by marine phytoplankton, and the diversity of roles they fill in ocean ecosystems and biogeochemical cycles, we stress the necessity of treating taxa or functional groups individually.

Replacing the Nile: Are Anthropogenic Nutrients Providing the Fertility Once Brought to the Mediterranean by a Great River?

Abstract: Prior to construction of the Aswan High Dam, the annual Nile flood delivered about 7–11 × 103 t of biologically available phosphorus (P), at least 7 × 103 t of inorganic nitrogen (N), and 110 × 103 t of silica (Si) to the Mediterranean coastal waters off Egypt. These nutrients stimu-lated a dramatic “Nile bloom” of diatoms which supported a productive fishery. After closure of the dam in 1965, flow from the Nile was reduced by over 90%, and the fishery collapsed. It remained unproductive for about 15 years. The fishery began a dramatic recovery during the 1980s, coincident with increasing fertilizer use, expanded agri-cultural drainage, increasing human population, and dra-matic extensions of urban water supplies and sewage collection systems. Calculations of the potential anthro-pogenic contribution of nutrients (P and N, but not Si) are consistent with the hypothesis that human sewage and agricultural drainage now support the fertility once provided by the Nile, though the nature of the product...

Photochemistry of HOx in the upper troposphere at northern midlatitudes

Abstract: The factors controlling the concentrations of HOx radicals (= OH + peroxy) in the upper troposphere (8–12 km) are examined using concurrent aircraft observations of OH, HO2, H2O2, CH3OOH, and CH2O made during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment (SONEX) at northern midlatitudes in the fall. These observations, complemented by concurrent measurements of O3, H2O, NO, peroxyacetyl nitrate (PAN), HNO3, CH4, CO, acetone, hydrocarbons, actinic fluxes, and aerosols, allow a highly constrained mass balance analysis of HOx and of the larger chemical family HOy (= HOx + 2 H2O2 + 2 CH3OOH + HNO2 + HNO4). Observations of OH and HO2 are successfully simulated to within 40% by a diel steady state model constrained with observed H2O2 and CH3OOH. The model captures 85% of the observed HOx variance, which is driven mainly by the concentrations of NOx (= NO + NO2) and by the strength of the HOx primary sources. Exceptions to the good agreement between modeled and observed HOx are at sunrise and sunset, where the model is too low by factors of 2–5, and inside cirrus clouds, where the model is too high by factors of 1.2–2. Heterogeneous conversion of NO2 to HONO on aerosols (γNO2 = 10−3) during the night followed by photolysis of HONO could explain part of the discrepancy at sunrise. Heterogeneous loss of HO2 on ice crystals (γice_HO2 = 0.025) could explain the discrepancy in cirrus. Primary sources of HOx from O(1D)+H2O and acetone photolysis were of comparable magnitude during SONEX. The dominant sinks of HOy were OH+HO2 (NOx 50 pptv). Observed H2O2 concentrations are reproduced by model calculations to within 50% if one allows in the model for heterogeneous conversion of HO2 to H2O2 on aerosols (γHO2 = 0.2). Observed CH3OOH concentrations are underestimated by a factor of 2 on average. Observed CH2O concentrations were usually below the 50 pptv detection limit, consistent with model results; however, frequent occurrences of high values in the observations (up to 350 pptv) are not captured by the model. These high values are correlated with high CH3OH and with cirrus clouds. Heterogeneous oxidation of CH3OH to CH2O on aerosols or ice crystals might provide an explanation (γice_CH3OH ∼ 0.01 would be needed).