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[Methods in Molecular Biology] || Total Nitrogen Determination by a Spectrophotometric Method
摘要： Being able to measure total nitrogen (TN) is important for following the nitrogen budget. In this chapter, we present the spectrophotometric method we use for determining TN. The method relies on oxidation and reduction steps, involving persulfate digestion of nitrogen compounds into nitrate followed by spectrophotometric determination.
关键词： Total nitrogen,Nutrient uptake
更新于2025-09-19 17:15:36
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Screening of microalgae and LED grow light spectra for effective removal of dissolved nutrients from cold-water recirculating aquaculture system (RAS) wastewater
摘要： Popularity of recirculating aquaculture systems (RAS) is increasing. Because of the high water recirculation rate, dissolved nutrients originating from fish feed are concentrated enough in RAS wastewater (WW) to enable growth of primary producers, e.g. microalgae. This study evaluated nitrate-nitrogen (NO3-N) and phosphate-phosphorus (PO4-P) removal efficiency of ten temperate zone freshwater microalgae species during their exponential growth phase in unfiltered RAS WW at 17 ± 0.5 °C. Growth and nutrient uptake efficiency of six green and four non-green microalgae strains were compared between WW and reference growth medium in batch monocultures. The effect of three different LED grow light spectra on growth and nutrient uptake efficiency were compared for four green microalgae in WW. The specific growth rate (SGR, 0.5-0.8 d-1) and removal of NO3-N (N%, 57–96%) and PO4-P (P%, 78–94%) of green microalgae in WW in 4 days were comparable to the results obtained in the reference medium (SGR, 0.6-0.9 d-1, N%, 59–99%; P%, 86–99%). In contrast, non-green microalgae had negligible growth (SGR, from -0.1 to 0.2 d-1) and poor nutrient removal (N%, 1–29%; P%, 0–34%) in both growth media after 9 days. The three LED spectra did not differ on their effect on growth and nutrient removal of three green microalgae in WW after 4 days, while the fourth tested species, Haematoccocus pluvialis, had its highest nutrient removal after 8 days under a specific LED spectrum. Current results show that RAS WW supports well green microalgae growth in batch cultures in temperatures common in Nordic RAS and that continuous spectrum LED grow lights can induce high removal of dissolved nutrients. Our findings lend support to the concept of using temperate zone microalgae for nutrient removal and recycling from RAS WW.
关键词： Wastewater treatment,Nitrate-nitrogen,Bioremediation,Nutrient uptake,Fish farming,Phosphate-phosphorus,Continuous light spectra,Coregonus lavaretus
更新于2025-09-12 10:27:22
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Red light means on for phosphorus
摘要： Light is a critical environmental factor that influences nutrient uptake in roots and the subsequent use of nutrients, which is necessary to sustain plant growth. The positive effect of red light on phosphorus uptake has now been defined, along with the pivotal role of the phytochrome-B signalling cascades that mediate this effect.
关键词： nutrient uptake,phosphorus,red light,plant growth,phytochrome-B
更新于2025-09-10 09:29:36