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Liu, C.; Chen, D.; Zheng, X., and Zheng, A., 2019. The content and distribution of nitrogen in nature colloids from Jiulongjiang River. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 70–76. Coconut Creek (Florida), ISSN 0749-0208. The content, distribution and seasonal variations of nitrogen in nature colloids were examined in surface waters of south Xiamen Bay, Jiulongjiang River estuary and Jiulongjiang River of China. Water samples were fractionated into total dissolved (< 0.2 µm), colloidal (10 kDa-0.2 µm) and truly dissolved (< 10 kDa) phases with the cross-flow ultrafiltration system. Results showed that average concentrations of different nitrogen species in truly dissolved phase were evidently higher than those in colloidal phase, and concentrations of NO2-, NO3-, NH4+, TN, TIN, and ON were 52, 238, 18, 9, 39 and 3 times higher respectively. In addition, NO3- was the most abundant inorganic species and was 11-28 times as high as NH4+ and NO2- in truly dissolved phase, but 2-15 times as high as NH4+ and NO2- in colloidal phase. NO2-, NO3-, NH4+, TN, and TIN in truly dissolved phase make up 77.2%-100.0% of that in total dissolver phase while those of colloidal phase make up only 0-19.0%; ON contents in truly dissolved phase made up 42.2%-69.3% of that in total dissolved phase while those of the colloidal phase made up 30.7%-57.9% of them. This indicated that IN species were distributed mainly in truly dissolved phase (< 10 kDa) in natural aquatic environments, and ON was distributed mainly in colloidal phase (10 kDa-0.22 µm). It was also found that the seasonal variations of all N species in truly dissolved phase was similar to that of total dissolved phase in all waters from different sources. There was slight variation of NO2- and NH4+ with season. The NO3- was highest in April and March and lowest in August and November. The seasonal variation of ON was related to the water sources. The contents of all N species in both dissolved phase and truly dissolved phase decreased from river to sea. [ABSTRACT FROM AUTHOR]

Liu, C.; Chen, D.; Zheng, X., and Zheng, A., 2019. The content and distribution of nitrogen in nature colloids from Jiulongjiang River. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 70–76. Coconut Creek (Florida), ISSN 0749-0208. The content, distribution and seasonal variations of nitrogen in nature colloids were examined in surface waters of south Xiamen Bay, Jiulongjiang River estuary and Jiulongjiang River of China. Water samples were fractionated into total dissolved (< 0.2 µm), colloidal (10 kDa-0.2 µm) and truly dissolved (< 10 kDa) phases with the cross-flow ultrafiltration system. Results showed that average concentrations of different nitrogen species in truly dissolved phase were evidently higher than those in colloidal phase, and concentrations of NO2-, NO3-, NH4+, TN, TIN, and ON were 52, 238, 18, 9, 39 and 3 times higher respectively. In addition, NO3- was the most abundant inorganic species and was 11-28 times as high as NH4+ and NO2- in truly dissolved phase, but 2-15 times as high as NH4+ and NO2- in colloidal phase. NO2-, NO3-, NH4+, TN, and TIN in truly dissolved phase make up 77.2%-100.0% of that in total dissolver phase while those of colloidal phase make up only 0-19.0%; ON contents in truly dissolved phase made up 42.2%-69.3% of that in total dissolved phase while those of the colloidal phase made up 30.7%-57.9% of them. This indicated that IN species were distributed mainly in truly dissolved phase (< 10 kDa) in natural aquatic environments, and ON was distributed mainly in colloidal phase (10 kDa-0.22 µm). It was also found that the seasonal variations of all N species in truly dissolved phase was similar to that of total dissolved phase in all waters from different sources. There was slight variation of NO2- and NH4+ with season. The NO3- was highest in April and March and lowest in August and November. The seasonal variation of ON was related to the water sources. The contents of all N species in both dissolved phase and truly dissolved phase decreased from river to sea. [ABSTRACT FROM AUTHOR]

Ge, H.; Chen, D.; Li, S.; Zheng, A.; Zhu, Z., and Zheng, X., 2019. Determination of Fe, Ti in seawater using a flow-injection pretreatment system with ICP-MS. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 77–82. Coconut Creek (Florida), ISSN 0749-0208. In order to solve the interference caused by low metal concentration and salts matrix of seawater samples, this paper present a handy flow- injection system with solid-phase extraction to automate pretreatment procedures for offline Fe and Ti analysis in seawater by ICP-MS. By combining 8-position, 3-way and 6-way valves in the pipeline, the flow-injection system enhance the sample treatment efficiency by simultaneously loading two reagents online for: sample loading, buffering, and preconcentration. Each sample treatment spends about 16 min and consumes 12 mL of seawater sample and 8 mL of buffer solution. The chelation of Toyopearl-AF-Chelate-650M for Fe and Ti occurs in pH5.5 at an injection rate of 1.0 mL·min-1. The eluent (0.8 mol·L-1 HNO3) is able to elute Fe and Ti in 90 s at an elution rate of 1.0 mL·min-1. Seawater sample needs 90 min of 120 W UV-oxidation to dissociate metal-organic complexes. The precision and availability of this method are tested by measuring Jiulongjiang Estuary seawater samples. [ABSTRACT FROM AUTHOR]

Ge, H.; Chen, D.; Li, S.; Zheng, A.; Zhu, Z., and Zheng, X., 2019. Determination of Fe, Ti in seawater using a flow-injection pretreatment system with ICP-MS. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 77–82. Coconut Creek (Florida), ISSN 0749-0208. In order to solve the interference caused by low metal concentration and salts matrix of seawater samples, this paper present a handy flow- injection system with solid-phase extraction to automate pretreatment procedures for offline Fe and Ti analysis in seawater by ICP-MS. By combining 8-position, 3-way and 6-way valves in the pipeline, the flow-injection system enhance the sample treatment efficiency by simultaneously loading two reagents online for: sample loading, buffering, and preconcentration. Each sample treatment spends about 16 min and consumes 12 mL of seawater sample and 8 mL of buffer solution. The chelation of Toyopearl-AF-Chelate-650M for Fe and Ti occurs in pH5.5 at an injection rate of 1.0 mL·min-1. The eluent (0.8 mol·L-1 HNO3) is able to elute Fe and Ti in 90 s at an elution rate of 1.0 mL·min-1. Seawater sample needs 90 min of 120 W UV-oxidation to dissociate metal-organic complexes. The precision and availability of this method are tested by measuring Jiulongjiang Estuary seawater samples. [ABSTRACT FROM AUTHOR]