Seasonal variations of dissolved organic carbon and total nitrogen concentrations in Nam Co and inflowing rivers, Tibet Plateau

The study presents the results of the analysis of development stages of Luronium natans (L.) Raf. depending on water conditions (pH, light, total nitrogen, total phosphorus, organic carbon) in 21 populations in north-western Poland. The fractions of seedlings, juvenile, mature and generative stems, as well as the course of phenological phenomena were determined. Seedlings are sparse and can be found from May to July. Most of them occur in waters ranging from slightly acid to neutral (pH 6.0-7.0) with TP concentrations of 10-20 µg dm-3, TN concentrations < 1.0 mg dm-3 and DOC concentrations of 3.5-5.0 mg dm-3, on a mineral (5-10% OC) and fairly well lit (31-40% PAR) substrate. The generative phase lasts from May to October. The flowering period is between August and mid-September. Only 35.2±9.4% of flowering stems produce fruits. The plant flowers abundantly in waters with total nitrogen concentrations > 1.2 mg dm-3, that is above the level of TN concentrations most favourable to seedlings and both juvenile and mature individuals. TP and DOC concentrations, and light intensity (PAR) do not influence the size of the generative stems fraction in populations. However, sediment structure is of importance in this respect: about 62.9% of stems flower and fruit on a mineral substrate (< 1% OC), whereas only 17.4% do so on an organic one. The results of this study may be useful in the conservation of this endangered European endemic species.

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Trophic complexity in aqueous systems: bacterial species richness and protistan predation regulate dissolved organic carbon and dissolved total nitrogen removal

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.2724 ◽

2016 ◽

Vol 283 (1825) ◽

pp. 20152724 ◽

Cited By ~ 27

Author(s):

Muhammad Saleem ◽

Ingo Fetzer ◽

Hauke Harms ◽

Antonis Chatzinotas

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Total Nitrogen ◽

Nutrient Removal ◽

Bacterial Species ◽

Nutrient Balance ◽

Vital Role ◽

Microbial Interactions ◽

Ecosystem Functions ◽

Nutrient Loads

Loading of water bodies with dissolved organic carbon (DOC) and dissolved total nitrogen (DTN) affects their integrity and functioning. Microbial interactions mitigate the negative effects of high nutrient loads in these ecosystems. Despite numerous studies on how biodiversity mediates ecosystem functions, whether and how diversity and complexity of microbial food webs (horizontal, vertical) and the underlying ecological mechanisms influence nutrient removal has barely been investigated. Using microbial microcosms accommodating systematic combinations of prey (bacteria) and predator (protists) species, we showed that increasing bacterial richness improved the extent and reliability of DOC and DTN removal. Bacterial diversity drove nutrient removal either due to species foraging physiology or functional redundancy, whereas protistan diversity affected nutrient removal through bacterial prey resource partitioning and changing nutrient balance in the system. Our results demonstrate that prey–predator diversity and trophic interactions interactively determine nutrient contents, thus implying the vital role of microbial trophic complexity as a biological buffer against DOC and DTN.

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Seasonal variations in concentration and lability of dissolved organic carbon in Tokyo Bay

Biogeosciences ◽

10.5194/bg-12-269-2015 ◽

2015 ◽

Vol 12 (1) ◽

pp. 269-279 ◽

Cited By ~ 17

Author(s):

A. Kubo ◽

M. Yamamoto-Kawai ◽

J. Kanda

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

River Water ◽

Seasonal Variations ◽

Relative Concentration ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Tokyo Bay ◽

Chl A

Abstract. Concentrations of recalcitrant and bioavailable dissolved organic carbon (DOC) and their seasonal variations were investigated at three stations in Tokyo Bay, Japan, and in two freshwater sources flowing into the bay. On average, recalcitrant DOC (RDOC), as a remnant of DOC after 150 days of bottle incubation, accounted for 78% of the total DOC in Shibaura sewage treatment plant (STP) effluent, 67% in the upper Arakawa River water, 66% in the lower Arakawa River water, and 78% in surface bay water. Bioavailable DOC (BDOC) concentrations, defined as DOC minus RDOC, were lower than RDOC at all stations. In freshwater environments, RDOC concentrations were almost constant throughout the year. In the bay, RDOC was higher during spring and summer than in autumn and winter because of freshwater input and biological production. The relative concentration of RDOC in the bay derived from phytoplankton, terrestrial, and open-oceanic waters was estimated to be 8–10, 21–32, and 59–69%, respectively, based on multiple regression analysis of RDOC, salinity, and chl a. In addition, comparison with previous data from 1972 revealed that concentrations of RDOC and BDOC have decreased by 33 and 74% at freshwater sites and 39 and 76% in Tokyo Bay, while the ratio of RDOC to DOC has increased. The change in DOC concentration and composition was probably due to increased amounts of STP effluent entering the system. Tokyo Bay exported mostly RDOC to the open ocean because of the remineralization of BDOC.

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Spatial heterogeneity of soil organic carbon and total nitrogen concentrations in aLithocarpus glaber-Cyclobalanopsis glaucaevergreen broadleaved forest

Acta Ecologica Sinica ◽

10.5846/stxb201401230170 ◽

2014 ◽

Vol 34 (12) ◽

Author(s):

杨丹 YANG Dan ◽

项文化 XIANG Wenhua ◽

方晰 FANG Xi ◽

樊纲惟 FAN Gangwei ◽

许玉庆 XU Yuqing ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Spatial Heterogeneity ◽

Total Nitrogen ◽

Nitrogen Concentrations

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Enhanced Coagulation with Mn(III) Pre-Oxidation for Treatment of Micro-Polluted Raw Water

Water ◽

10.3390/w11112302 ◽

2019 ◽

Vol 11 (11) ◽

pp. 2302 ◽

Cited By ~ 2

Author(s):

Yan ◽

Sun ◽

Wang ◽

Pan ◽

...

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Total Nitrogen ◽

Transformation Products ◽

Ammonia Nitrogen ◽

Emerging Pollutants ◽

Toxicity Tests ◽

Raw Water ◽

Bisphenol S ◽

Oxidation Technology

Mn(III) oxidation technology has attracted increasing interest in recent years because of its fast decontamination kinetics and second-pollution-free characteristic. Whether it can be used as a pre-oxidation step to enhance conventional coagulation process remains to be evaluated. Herein, an Fe-coagulation/sedimentation process combined with Mn(III) pre-oxidation (Mn(III)+C/S), hypochlorite pre-oxidation (Cl2+C/S), and permanganate pre-oxidation (PM+C/S) was applied to treat simulated micro-polluted raw water. The removal performance of routine water quality indices (turbidity, dissolved organic carbon, total nitrogen, nitrate-nitrogen, ammonia-nitrogen, Pb(II), and Cr(VI)) and the emerging pollutants (acesulfame, carbamazepine, bisphenol S, and nano-ZnO) created by these three processes were researched. The mechanism of how Mn(III) pre-oxidation influences C/S was explored by identifying the transformation products of Mn(III), measuring the timely variation of flocs’ zeta potential and size, and scanning flocs’ micromorphology. Compared to Cl2+C/S and PM+C/S, Mn(III)+C/S exhibited its superiority in removing dissolved organic carbon (72.9%), total nitrogen (31.74%), and emerging pollutants (21.78%–93.49%). The enhanced removal of these contaminants by Mn(III)+C/S found its explanation in the strong oxidation power of Mn(III) and the multiple roles of in-situ formed MnO2 (e.g., flocculation core, adsorption co-precipitant, and densification agent). The acute toxicity tests confirmed that water treated by Mn(III)+C/S did not show a significant change in the associated toxicity. The findings of the present study indicate that Mn(III) oxidation technology shows great potential as an alternative to pre-oxidation technology of waterworks.

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