Abstract. Agriculture and urban activities are major sources of phosphorus and nitrogen to aquatic ecosystems. Atmospheric deposition further contributes as a source of N. These nonpoint inputs of nutrients are difficult to measure and regulate because they derive from activities dispersed over wide areas of land and are variable in time due to effects of weather. In aquatic ecosystems, these nutrients cause diverse problems such as toxic algal blooms, loss of oxygen, fish kills, loss of biodiversity (including species important for commerce and recreation), loss of aquatic plant beds and coral reefs, and other problems. Nutrient enrichment seriously degrades aquatic ecosystems and impairs the use of water for drinking, industry, agriculture, recreation, and other purposes.Based on our review of the scientific literature, we are certain that (1) eutrophication is a widespread problem in rivers, lakes, estuaries, and coastal oceans, caused by overenrichment with P and N; (2) nonpoint pollution, a major source of P and N to surface waters of the United States, results primarily from agriculture and urban activity, including industry; (3) inputs of P and N to agriculture in the form of fertilizers exceed outputs in produce in the United States and many other nations; (4) nutrient flows to aquatic ecosystems are directly related to animal stocking densities, and under high livestock densities, manure production exceeds the needs of crops to which the manure is applied; (5) excess fertilization and manure production cause a P surplus to accumulate in soil, some of which is transported to aquatic ecosystems; and (6) excess fertilization and manure production on agricultural lands create surplus N, which is mobile in many soils and often leaches to downstream aquatic ecosystems, and which can also volatilize to the atmosphere, redepositing elsewhere and eventually reaching aquatic ecosystems.If current practices continue, nonpoint pollution of surface waters is virtually certain to increase in the future. Such an outcome is not inevitable, however, because a number of technologies, land use practices, and conservation measures are capable of decreasing the flow of nonpoint P and N into surface waters.From our review of the available scientific information, we are confident that: (1) nonpoint pollution of surface waters with P and N could be reduced by reducing surplus nutrient flows in agricultural systems and processes, reducing agricultural and urban runoff by diverse methods, and reducing N emissions from fossil fuel burning; and (2) eutrophication can be reversed by decreasing input rates of P and N to aquatic ecosystems, but rates of recovery are highly variable among water bodies. Often, the eutrophic state is persistent, and recovery is slow.
The integration of a cooperative learning technique (Student Team Achievement Divisions or STAD) into a sophomore-level organic chemistry course is described. Students were assigned to Learning Teams according to their performance in the two terms of general chemistry and on a General Chemistry Review Sheet written by the author and administered on the first day of the organic chemistry class. Extra credit points applied to the students' exam scores were earned by Learning Team members if all members improved on their own past performance. The methods used to assign students to Learning Teams and to determine the amount of extra credit earned are presented. Student opinion surveys indicate that students support the use of the technique in organic chemistry.
A safety course unique in its pedagogy and student composition. Lecture topics: Risk assessment; Federal, state, and local agencies regulating chemicals; lab and personal safety equipment; labeling; fire; chemical storage; hazardous waste disposal; first aid and accident prevention; legal case studies.
The Summer Chemistry Workshop at Armstrong Atlantic State University is a graduate course designed to meet a broad spectrum of needs of in-service secondary science teachers. The workshop addresses multiple challenges faced by in-service science teachers and provides them with the tools required for effective laboratory instruction. It incorporates a number of topics related to laboratory instruction, including keeping chemistry content current and highlighting its universal relevance, learning (usually for the first time) how to safely store and dispose of hazardous chemicals, and establishing a synergistic relationship between secondary and university science faculty. An overview of the workshop and its advantages are presented.
Extending the usefulness of the instruments we have has never been more important. The current economic crisis has prompted all of us to re-examine how money is spent and to try to minimize our expenditures because of future uncertainties. Already the economy has affected the replacement of equipment (1), and at least in academia, "there is little flab left to cut" (2). Simultaneously, we are encouraged to be more "green", which, in its encouragement of minimizing electronic waste, should prompt less abandonment of instrumentation that is still usable and relevant. We have been able to breathe new life into an aging 60 MHz NMR spectrometer used by hundreds of undergraduates each year in the second-year organic chemistry sequence. In addition to extending the instrument's life, the updated look of the instrument may positively affect student attitudes about its usefulness (3).A department value at this university is that students should use instruments to collect their own data as early and as often as possible in the chemistry curriculum. For this reason, the 60 MHz spectrometer was obtained nearly 20 years ago through the (obsolete) NSF-ILI program. It is used entirely by second-year students and we estimate that thousands of students have used it; each student using it half a dozen times over the two-semester lab sequence. Having said this, no doubt minor repairs have been necessary over the years, but we hit a seemingly insurmountable obstacle about a year ago when the plotter that came with the Hitachi model 1200 rapid-scan correlation instrument became nonfunctional.The high level of "student traffic" coupled with the minimal chemical maturity of those students precluded simply switching to using the JEOL 300 MHz instrument also available in our department. We were at a crossroads: Do we abandon our commitment to early and frequent student use of instrumentation or do we find a way to keep the old 60 MHz machine going? We chose the latter and would like to share how we modernized our instrument and have successfully extended the already long life of this workhorse NMR. SolutionThe attached plotter received output in the form of Hewlett-Packard graphics language, and we were unable to find an affordable printer to serve as a replacement. Software solutions were also cost-prohibitive. Because our NMR also has an oscilloscope display, we realized that we could tap into that feature and read the voltages controlling the x and y positions of the beam. We estimated that we would require a two-channel data acquisition (DAQ) device with a sample rate of several kHz or more.Our upper-level physics laboratories have used National Instruments USB-600x DAQ modules for some time, so our familiarity with them suggested we employ a USB-6009 (approximately $250). The USB-6009 is shipped with several simple programs suitable for use in a variety of programming languages. One of these is used to gather data from both channels at 5000 Hz for 2 s, requiring user input only to choose a file name and start the acquisition.The dat...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.