[Reflections on construction of the experimental course system for environmental science in colleges and universities].

The training effects of experimental courses determine the practical abilities of undergraduate students. Therefore, it is essential to establish a comprehensive experimental course system that adapts to the undergraduate education of environmental science. Here, we introduce the "basic-specialized-comprehensive" experimental course system of Xiamen University, which is established following the principles of being systematic, comprehensive, and modular. To establish this course system, we first increased the investment of lab facilities and enhanced the management of student labs. Then, we improved the contexts of teaching and training according to the requirements of industry and society. Showing how this course system is developed stepwise and the training effects of this system, we hope to provide a reference for the experimental courses of environmental science in colleges and universities.

Measuring of time-series concentrations of nutrients in surface waters using osmotic sampler with air bubble segmentation and preservative addition.

The analysis of time-series concentrations (CTS) is of great importance when investigating the biogeochemical processes of nutrients in aquatic environments. However, obtaining CTS of nutrients remains a challenge using current sampling techniques. In this study, a novel in situ sampler was constructed using reverse osmosis membrane (ROM) osmotic pumps (OP) (ROM-OP sampler), and was used to obtain the CTS of nutrients in surface waters. The sampler consisted of a sampling OP, sample storing coil, filter, bubble injection module, and preservative adding module. When deployed, the sampling OP continuously draws ambient water through the filter into the sample storing coil, while simultaneously the preservative adding module continuously delivers preservative (H2SO4 solution) into the water flow. The bubble injection module periodically injects air bubbles into the sample storing coil, to segment the sample and create time stamp indicators that allow the sample age to be defined. Upon retrieval, the sample segments in the coil are sequentially pumped out of the sample storing coil and transferred into different vials for further analysis. The sampler was applied to measure the CTS of various nutrients, including dissolved total nitrogen, dissolved total phosphorus, dissolved reactive phosphorus, and nitrate in a river over a 20 day period and in municipal sewage treatment plant effluent for a 36 h period. Results showed that the ROM-OP sampler successfully obtained CTS of nutrients, capturing nutrient variations at a high temporal resolution. This sampler is relatively low-cost (~USD 300), small in size, lightweight, robust and does not require an external power source, showing high promise as an effective and efficient tool for monitoring nutrient CTS in aquatic environments.

[Study on ratiometric determination of peroxynitrite and its scavenger based on synchronous fluorescence spectroscopy].

A ratiometric fluorimetry is proposed for the determination of peroxynitrite (ONOO-) and the evaluation of its scavenger based on synchronous fluorescence spectroscopy. L-tyrosine, an intrinsic fluorescent aminoacid, reacts with peroxynitrite and carbon dioxide, yielding a highly fluorescent dimer of tyrosine in pH 8.5 PBS buffer solution. By synchronous fluorescence scanning, both monomer and dimer emission bands of L-tyrosine appeared at 364 and 406 nm, respectively. The ratio of F406/ F364 is quantitatively related to the concentration of peroxynitrite, where F406 represents the intensity of synchronous emission band of dimer and F364 represents that of monomer. The method has been showing merit of being insensitive to the changes in experimental parameters and offers a higher sensitivity and a broader responding linear range of the analyte concentration, compared to fluorimetric method, giving a LOD of 1.84 X 10(-8) mol x L(-1) and a linear range of 1.60 X 10(-7) mol x L(-1)-6.00 X 10(-6) mol x L(-1) for ONOO-, respectively, with a deviation of 2.4% for 1.00 X 10(-6) mol x L(-1) ONOO- (n = 8). A IC50 of 0.065 microg x mL(-1) for mitoxantrone, an antioxidant and anticancer drug, was also obtained. This method has proved to be simple and speedy. It would be easily used in the determination of ONOO- and its scavenger.

Probing the hydroxyl radical-mediated reactivity of peroxynitrite by a spin-labeling fluorophore.

The decomposition of peroxynitrite at physiological pH yielded a hydroxyl radical, which reacted rapidly with dimethyl sulfoxide (DMSO) to produce a methyl radical (*CH3), which was then trapped by a spin-label fluorophore nitroxide-linked naphthalene (NTEMPO), a carbon-centered radical probe with a low fluorescence intensity, and transformed to a stable diamagnetic O-alkoxyamine, a high-fluorescence compound. The fluorescence increment was proportional to the concentration of the hydroxyl radical, and then to the concentration of peroxynitrite. NTEMPO therefore was demonstrated to be capable of detecting hydroxyl radicals generated from peroxynitrite, and the method was proved to be simple and sensitive. The hydroxyl radical-mediated reactivities of peroxynitrite to several amino acids, such as tyrosine, phenylalanine and histidine, were then evaluated by the spin-labeling fluorophore NTEMPO at pH 7.4 and, 37 degrees C. The obtained data were in good agreement with the reference values, respectively.