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Components of Nutrition
Published in Christopher Cumo, Ancestral Diets and Nutrition, 2020
Structure divides phytochemicals into five classes. The largest polyphenols includes flavonoids, which impart color to plant parts as mentioned, likely an adaptation for attracting insects to pollinate flowers. Flavonoids in legume roots attract nitrifying bacteria. More generally, flavonoids may protect plants against pathogens and help transmit intracellular and extracellular messages. In the body, flavonoids are antioxidants, which appear to protect cells against free radicals. Free radicals are electrically neutral, reactive atoms or molecules.
Chemical Factors
Published in Michael J. Kennish, Ecology of Estuaries Physical and Chemical Aspects, 2019
Zooplankton excretion and decomposition recycle ammonia for phytoplankton growth.188 The turnover time for ammonia can be very short when phytoplankton production is high. During the summer months in the Pamlico estuary, for example, ammonia can be turned over in less than 1 day and urea in about 1 day.151 High phytoplankton production, therefore, may require rapid remineralization of nitrogen.189 As iterated by Lippson et al. (p. 10),180 “ammonia can be oxidized directly to nitrite and nitrate.” Helder and De Vries190 ascribed the importance of estuarine nitrifying bacteria in the turnover of nitrogen to their ability to oxidize ammonium to nitrate, with nitrite as an intermediate. Nutrient utilization by autotrophs and heterotrophic microorganisms, as well as denitrification processes, act as a sink for dissolved inorganic nitrogen. Denitrification processes, which yield free nitrogen (N2) or nitrous oxide (N2O), should not be underestimated in estuarine nitrogen budgets. Seitzinger et al.191 measured denitrification directly as a flux of N2 from Narragansett Bay sediments and stipulated that the amount of nitrogen involved in denitrification equaled 50% of the fixed inorganic nitrogen loading from rivers and sewage to the bay. An estimated 35% of the organic nitrogen mineralized in the sediments was removed as N2.
Chemical hazards *
Published in Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse, Routledge Handbook of Water and Health, 2015
Lisa Smeester, Andrew E. Yosim, Rebecca C. Fry
Nitrates occur naturally in both soil and water, with surface water concentrations ranging from 0 to 18 mg/L (WHO, 2011a). Globally, the mean concentration of nitrate in water has risen approximately 36 percent over the past two decades, with regions such as the Eastern Mediterranean and Africa experiencing contamination that has more than doubled. Nitrites may be introduced into drinking water via the distribution systems, either by oxidation of ammonia by nitrifying bacteria during stagnation in pipes or by an improper chloramination disinfection process (EPA, 1993).
Subsea tunnel reinforced sprayed concrete subjected to deterioration harbours distinct microbial communities
Published in Biofouling, 2018
Sabina Karačić, Britt-Marie Wilén, Carolina Suarez, Per Hagelia, Frank Persson
The ammonia-oxidising archaeon Nitrosopumilus sp. was observed at a particularly high abundance and ammonia-oxidising bacteria within the Nitrosomonadaceae were consistently detected. Nitrite-oxidising bacteria within Nitrospina, as well as Nitrospira, were also common, as were anammox bacteria within Ca. Scalindua. The autotrophic nitrogen converters were typically marine clades, well adapted to low substrate concentrations and able to tolerate low oxygen environments (Lücker et al. 2010; Park et al. 2010; Lücker et al. 2013) or anoxic conditions (Schmid et al. 2007), which may assist in explaining their abundance in the biofilms having a range of DO concentrations (Figure 8). Concrete deterioration associated with the activities of nitrifying bacteria has been observed in various concrete infrastructures (Cwalina 2008; Noeiaghaei et al. 2017). In the Oslofjord tunnel the nitrifiers may have contributed to the deterioration of the sprayed concrete, but only to certain degree given the low concentrations of nitrogen species in the water. Iron-oxidising bacteria of Mariprofundus sp. were detected in the biofilm at high abundance. They oxidise Fe(II) to Fe(III) at microaerophilic conditions and neutral pH, as was detected in the biofilm. During growth, Mariprofundus cells excrete extracellular stalks rich in polysaccharides and Fe(III). Such twisted stalks rich in iron were observed by SEM (Figure 7, Table 3), confirming their activity in the biofilm. The stalks are structures for deposition of metabolic products, which prevent cell encrustation and increase the solubility of Fe(II), thereby increasing the corrosion process (Chan et al. 2011; McBeth et al. 2011). The presence of Mariprofundus helps to explain the observed corrosion of the steel fibres in the sprayed concrete, the orange biofilm colour, and the high iron concentration in the biofilms (Table 2). The biofilm also contained high concentrations of precipitated manganese. However, no known manganese-oxidising bacteria were detected in the biofilms, as similarly observed in a preliminary investigation in the Oslofjord tunnel (Karačić et al. 2016). Yet, microorganisms resembling Leptothrix discophora were previously observed by SEM on samples collected at the Pump Station in 2005, when the water flow was much lower (Hagelia 2011a). Profound biogenic manganese oxidation has, however, been detected without identification of any known manganese-oxidising bacteria based on 16S rRNA gene sequences (Cao et al. 2015), suggesting that this trait is not only restricted to the phylogenetically diverse group of established manganese oxidisers. In addition, the biofilms contained a diversity of heterotrophic bacteria typically found in marine water and sediment including members of the marine benthic group JTB255 (Mußmann et al. 2017), Saprospiracae (McIlroy and Nielsen 2014), Kordiimonadaceae (Xu et al. 2014) and Marinicella (Rua and Thompson 2014). These organisms were presumably utilising the small bioavailable fraction of organic matter in the water as well as organic matter from internal cycling of biofilm components.