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1

Factors regulating the compositions and distributions of dissolved organic matter in the estuaries of Jiaozhou Bay in North China

Hu Jiaojie, Zou Li, Wang Jian, Ren Qianqian, Xia Bin, Yu Ge

Oceanologia

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2020

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No. 62 (1)

101--110

EN

Water samples collected from the Jiaozhou Bay every two months between April 2016 and February 2017 were analyzed for dissolved organic carbon (DOC), particulate organic carbon (POC), total dissolved carbohydrates (TCHO), total hydrolyzed amino acids (THAA), and chromophoric dissolved organic matter (CDOM) to explore the biogeochemical processes of dissolved organic matter (DOM) in anthropogenic estuarine and coastal environments. In addition, nutrients, chlorophyll a and COD (chemical oxygen demand) in these samples were also analyzed. All parameters exhibited temporal and spatial variations: POC 0.13-22.40 mg/L (average 1.75 mg/L), DOC 0.98-32.75 mg/L (average 5.04 mg/L), COD 0.23-7.58 mg/L (average 1.67 mg/L), TCHO 0.34-14.09 µM (average 3.18 µM), THAA 0.89-8.30 µM (average 4.04 µM), and the absorption coefficient a(355) of CDOM 0.23-16.35 m − 1 (average 3.09 m − 1). The temporal and spatial variations in the concentrations of TCHO, THAA, and DOC implied that the DOM in the study areas had a relatively higher biochemical activity. The canonical correspondence analysis (CCA) and maximal information coefficient (MIC) revealed that seasonal variations in temperature and the phosphate concentration were the dominant factors regulating the DOM distributions in Jiaozhou Bay, while riverine inputs and in situ reproduction mainly controlled the DOM compositions.

2

The Characteristics of Organic Compounds in Landfill Leachate Biologically Treated under Different Technological Conditions

Koc-Jurczyk Justyna, Jurczyk Łukasz

Journal of Ecological Engineering

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2020

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Vol. 21, nr 3

104--111

EN

In this work, the semi-synthetic wastewater made of the leachate derived from non-hazardous municipal waste landfill in Kozodrza (south-eastern Poland) and supplemented by ammonium, was treated in hybrid SBRs to assess the removal efficiency of organic compounds, including humic substances and dissolved fractions, depending on the technological conditions. The technological layout variants concerned both the volumetric proportions of aerated and anoxic zones (0.33 and 0.66) as well as the N/C ratio (0.1 and 0.2). It was found that the efficiency of organic compounds removal (expressed as COD, BOD5 and TOC) was influenced by the geometry of oxygen supply; in the SBRs operating with 0.33 ratio, it was significantly higher compared to that with 0.75 ratio. The analysis also revealed that the N/C ratio set at 0.1 resulted in higher treatment efficiency than that obtained for 0.2. The composition of dissolved organic fractions in outflows was also related both with the SBRs geometry and the N/C ratio. It was found that proportions of TOC and humic substances were significantly lower in the SBRs operating with aeration geometry of 0.33, compared to the ones working with 0.66. Moreover, the N/C ratio of 0.1 led to a higher content of dissolved humic substances and COD in outflows.

3

The influence of microfloc age on its strength and sorption capacity

Gumińska J.

Environment Protection Engineering

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2007

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Vol. 33, nr 1

5-14

EN

In the process of direct filtration, reagents are fed into the system before a filter or just above a filter bed. However, it is not clear which place is best. The results of many studies prove that a short time of the reaction of water with coagulant before the filter bed should allow only coagulant hydrolysis and the change of electrokinetic potential . Such a time of coagulant dosing just before filtration should unable agglomeration of flocs which are less susceptible to an attachment to filter media. The results of the research presented in this paper indicate that in the treatment of soft waters collected from mountainous streams, where dissolved organic matter is a prevailing contaminant, the time of the reaction of water with coagulant before the filer bed does not significantly influence the treatment effectiveness. Microflocs generated just after coagulant dosing are not only stable and effective in contaminant sorption, independently of their age and temp., but also susceptible to further separation during filtration.

PL

Podczas koagulacji wód w złożu filtracyjnym reagenty są dozowane bezpośrednio przed filtrem lub tuż nad powierzchnią złoża. Dotychczasowo nie stwierdzono jednoznacznie, jakie dozowanie jest lepsze. Prowadzone badania wskazują, iż krótki czas reakcji koagulantu z wodą ma jedynie zapewnić hydrolizę oraz zmianę potencjału elektrokinetycznego koagulantu, nie powinny natomiast wytworzyć się kłaczki. Przedstawione wyniki badań świadczą jednak, że w przypadku uzdatniania miękkich wód górskich, których podstawowym zanieczyszczeniem są rozpuszczone związki organiczne, czas reakcji koagulantu z surową wodą przed złożem filtracyjnym nie ma istotnego wpływu na skuteczność uzdatniania wody. Powstające mikrokłaczki są trwale niezależnie od wieku i temperatury, skutecznie sorbują zanieczyszczenia i są podatne na dalszą separację w procesie filtracji.

4

Surface microlayer in lakes of different trophic status : dissolved organic matter and microbial community

Kostrzewska-Szlakowska I.

Polish Journal of Ecology

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2005

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Vol. 53, nr 3

341-351

EN

The aim of this paper was to recognize the abundance and frequency of occurrence of neustonic organisms (i.e. bacteria and algae) and accumulation of organic matter in the surface microlayer of three lakes of various trophic status. Water samples of surface microlayer (0.5-0.6 mm) were taken (with Larsson plate) as well as from respective epilimnion layer (0.5 m deep). The samples were collected from shallow, humic (Sphagnum bog) lake (L. Flosek), shallow, eutrophic (L. Zełwążek) and deeper, mesotrophic lake (L. Kuc) in the period May-October during several years. The ratio of the organisms' density in the surface microlayer to that in deeper (0.5 m) layer was considered as the enrichment factor (Ef). Heterotrophic bacteria accumulation in the surface microlayer was more frequent in the humic lake (75% of samples), than in meso- and eutrophic lakes (64%). Mean Ef values for bacteria ranged from 1.3 to 1.4. Frequent, but not strong accumulation of dissolved organic matter measured as the absorbance A254 was noted in the surface microlayer. Dissolved organic carbon (DOC) measured in automatic analyzer showed much stronger accumulation in microlayer, particularly in humic lake. Concentration of chlorophyll a in the surface microlayer was found as the most fluctuating and the highest mean Ef value was found in the mesotrophic lake (Ef = 6.3). An attempt was undertaken to explain these differences between the lakes in terms of variable ratio between allochthonous and autochthonous production in humic, mesotrophic and eutrophic lakes.

5

The significance of dissolved organic matter photodegradation as a source of ammonium in natural waters

Grzybowski W.

Oceanologia

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2002

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No. 44 (3)

355-365

EN

Samples of sea, river and pond water of different absorbance were exposed to artificial radiation resembling sunlight in the UV range. A statistically significant increase in ammonium concentration was detected in pond water of the highest absorbance after 5 h of irradiation. In sea and river water a corresponding increase (< 0.5 žM) was recorded after an exposure time of 25 hours. The bulk characteristics of the analysed samples were insufficient to explain the observed differences.