) and microplankton community respiration (CR, size fraction < 300 µm, 2 to 90 mg C m -3 d -1) was conducted in the inlet and outlet of Taiwan Nuclear Power Plant II (TNP-II). In addition, 3 transect surveys were conducted across the warm plume outside the TNP-II outlet. All measurements except dissolved organic carbon (DOC, 18 to 45 g C m -3 ) varied seasonally and spatially with temperature. On average, BR constituted 41% of the total CR. The BR/CR ratios were negatively correlated with CR, the first observation of this trend that we are aware of. The positive temperature responses of rate and/or biomass-normalized rate parameters indicated a very low probability of bottom-up (substrate supply) control on the growth of heterotrophic organisms in these systems. The Q 10 (i.e. the increase of rate with a temperature increase of 10°C) values for BR, CR, biomass-normalized bacterial respiration (0.07 to 1.31 d ) ranged from 1.3 to 3.7. Similar Arrhenius expressions of heterotrophic processes in the field surveys and short-term temperature-manipulation experiments showed that, in this high DOC system, most planktoners were eurythermal and that their respiration increased with temperature up to > 35°C. Such a phenomenon might be related to a temperature-substrate interaction.
Seawater storage at ambient temperature is necessary when freezing facilities are unavailable for the preservation of samples collected for the determination of soluble reactive phosphate (SRP), nitrite (
NO2−), and nitrate plus nitrite (N + N)—notably, during small boat operations. Here, we report that samples may be preserved at ambient temperature by the addition of NaOH at sampling to induce the precipitation of Mg(OH)2, and then returned to a shore base laboratory for further processing. In the laboratory, SRP, which has been sequestered in the precipitate, is analyzed by the MAGnesium‐induced co‐precipitation method.
NO2− and N + N are quantitatively retained in the supernatant liquid and they are analyzed by the standard methods after a pH adjustment. The samples may be stored for up to at least 2 months and they yield concentrations that are indistinguishable from those in frozen samples. Internally added SRP,
NO2−, and N + N to seawater samples can be recovered quantitatively after storage. This storage method also offers clear advantages over the preservation of samples at ambient temperature by the addition of HgCl2 as NaOH is a less toxic and less environmentally hazardous chemical and it does not interfere in the determination of N + N. It also allows low level SRP to be determined as part of the analytical routine as a pre‐concentration of SRP has been built into the storage scheme.
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