Ozone is applied to the recirculation aquaculture system to reduce bacteria and parasites. Besides the sterilization effects, it is known that ozone has oxidizing effects on some water quality parameters. Therefore, oxidizing effects of ozone on ammonia (NH 4 -N), nitrite (NO 2 -N), nitrate (NO 3 -N), and dissolved organic carbon were tested in this study. During the test, ozone effects on pH, dissolved oxygen (DO) and bromination were also monitored. Ozone concentrations were originally set to 0.05, 0.1, 0.15, 0.2, and 0.25 ppm, but actual treatment concentrations were maintained at 0.04, 0.11, 0.15, 0.19, and 0.23 ppm. The 5 ppm of NH 4 -N was oxidized within 12 h in all concentrations of ozone treatments, with the average oxidizing rate of 0.65 ± 0.28 mg NH 4 -N/L per h. The 5 ppm of NO 2 -N was oxidized within 1.5 h in all concentrations of ozone treatments at a rate of 4.5 mg NO 2 -N/L per h. One of 5 ppm NO 3 -N was oxidized by all concentration of ozone treatment after 24 h. In addition, ozone also oxidized dissolved organic carbon and maintained the concentration at about 2.9 ± 0.77 ppm from the 15 ppm of initial concentration by 12 h. DO was increased from 5.9 to 9.4 ppm within 30 min in all ozone treatment and stabilized thereafter. Bromate concentrations increased sharply within the first 6 h of ozonation at the rate of 7.3 ± 2.4 mg/L per h in almost all ozone treatments; the rate decreased to 2.5 ± 0.15 mg/L per h thereafter. However, bromate concentration was not increased in the ammonia experiment until all ammonia was oxidized. Therefore, further studies are needed to determine the relationship between NH 4 -N concentration and bromate formation in seawater.
Grateloupia elliptica
(Holmes, 1896) is a red alga belonging to the order Halymeniales and phylum Rhodophyta. In this study, the complete mitochondrial DNA (mtDNA) of
G. elliptica
has been described. The complete circular mtDNA of
G. elliptica
was 28,503 bp in length, with an A + T content of 68.78%; it encoded a total of 49 genes, including 20 tRNA, three rRNA, and 26 protein-coding (
CDS
) genes. Phylogenetic analysis based on complete mitochondrial genomes revealed that
G. elliptica
was most closely related to
G. angusta
. The complete mitochondrial sequence of
G. elliptica
will enrich the mitochondrial genome database and provide useful resources for population genetics and evolution analyses.
Polyopes affinis
((Harvey) Kawaguchi & Wang, 2002) is a red alga in the order Halymeniales of the phylum Rhodophyta. The entire mitogenome of
P. affinis
was sequenced and compared to related Halymeniales species. The entire circular-mitogenome is 25,988 bp long, has 27.59% GC content, and comprises 25 protein-coding genes (CDS), 23 transfer RNA (tRNA) genes, and three ribosomal RNA (rRNA) genes. In terms of gene synteny and tRNA composition, the
P. affinis
mitogenome differs significantly from that of
P. lancifolius
. Phylogenetic analysis shows
P. affinis
mitogenome in a branch sister to
P. lancifolius
, indicating a close relationship with other Halymeniales species.
The potential of wetland plants as an onsite biosorbent and a biomonitor for combined pollution of arsenic and four heavy metals from non‐point sources was investigated in this study. Ceratophyllum demersum, Hydrilla verticillata, Hydrocharis dubia, and Salvinia natans were exposed to a water containing mixture of As, Cr, Cu, Pb, and Zn. Growth inhibition and biosorption potential of the wetland plants in artificially contaminated conditions were studied. These contaminants significantly reduced the growth of the plants. The tested wetland plants accumulated appreciable amounts of the contaminants in the following order: Pb>Cr>Cu>Zn>As. H. verticillata showed distinct visual change and a high biosorption factor (BSF) rank for As and heavy metals among the plants used in the study. As an unspecific collector of contaminants, it might be useful as a biomonitor and biosorbent in the As and heavy metal‐contaminated aquatic system.
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