Purifying Effects of Nitrogen in Wangyu River Water through Natural Wetlands

In order to study the purifying effects and influences on nitrogen caused by natural riparian wetlands in the river course, Cao Lake and Ezhen Lake in Wangyu River were selected as the main research regions. Samplings in the transfer period with a large flow in May, 2010 were taken in the sites over the whole wetland area and along the main river course, respectively. Observations on the physicochemical indexes such as water temperature, pH, dissolved oxygen(DO), turbidity, suspended solid(SS), total nitrogen (TN), total dissolved nitrogen(DTN), ammonia, nitrate and nitrite were performed to analyze the concentration and chemical forms variations, regional difference of nitrogen nutrient in the river water column. Results are showed as follows: (1) As the water flowed through Cao Lake and Ezhen Lake, the TN、DTN and nitrate showed a trend of descending (descending proportion: 10.45%, 17.85%, 7.62% in Ehen Lake, 9.09%, 7.17%, 7.60% in Cao Lake). The overall removal effects of nitrogen in Ezhen Lake was better than that in Cao Lake, but the retaining effect of ammonia in Cao Lake was better than that in Ezhen Lake. (2) The nitrogen existed in the water mainly in the forms of DTN and the rates on TN were 88.0% and 91.4%, respectively, higher than that of particle nitrogen, but the rates would decrease for the sedimentation of particle nitrogen in the vertical distribution.(3) Water temperature, pH and DO were the dominant factors that affected the purifying effects of nitrogen in the riparian areas. The research showed the obvious retaining effects of nitrogen and evident influences on the nutrients forms variations in the river water column. The results could provide theoretical foundation and technical support for nitrogen purification in the river course.

Download Full-text

STUDY ON CHANGING IN RIVER WATER TEMPERATURE IN KYUSYU REGION

Journal of Japan Society of Civil Engineers Ser B1 (Hydraulic Engineering) ◽

10.2208/jscejhe.74.5_i_79 ◽

2018 ◽

Vol 74 (5) ◽

pp. I_79-I_84

Author(s):

Yoji NODA ◽

Tomoko MINAGAWA ◽

Hidetaka ICHIYANAGI ◽

Akihiko KOYAMA

Keyword(s):

Water Temperature ◽

River Water ◽

River Water Temperature

Download Full-text

Effects of Temperature and Salinity on Vibrio vulnificus Population Dynamics as Assessed by Quantitative PCR

Applied and Environmental Microbiology ◽

10.1128/aem.70.9.5469-5476.2004 ◽

2004 ◽

Vol 70 (9) ◽

pp. 5469-5476 ◽

Cited By ~ 115

Author(s):

Mark A. Randa ◽

Martin F. Polz ◽

Eelin Lim

Keyword(s):

Population Dynamics ◽

Water Temperature ◽

Water Column ◽

Quantitative Pcr ◽

Vibrio Vulnificus ◽

Most Probable Number ◽

Salinity Regime ◽

Optimal Salinity ◽

Probable Number ◽

Barnegat Bay

ABSTRACT The abundance of Vibrio vulnificus in coastal environments has been linked to water temperature, while its relationship to salinity is less clear. We have developed a culture-independent, most-probable-number quantitative PCR approach to examine V. vulnificus population dynamics in Barnegat Bay, N.J. Based on the combined analysis of our results from Barnegat Bay and from the literature, the present data show that (i) V. vulnificus population dynamics are strongly correlated to water temperature and (ii) although the general trend is for V. vulnificus abundance to be inversely correlated with salinity, this relationship depends on salinity levels. Irrespective of temperature, high abundances of V. vulnificus are observed at 5 to 10 ppt, which thus appears to be the optimal salinity regime for their survival. At 20 to 25 ppt, V. vulnificus abundances show a positive correlation to salinity. Unsuccessful attempts to resuscitate V. vulnificus, combined with our inability to detect cells during the winter despite an assay adapted to detect viable but nonculturable (VBNC) cells, suggest that the decline and eventual disappearance of V. vulnificus from the water column during the winter months is due primarily to a significant reduction in population size and is not only the consequence of cells entering the VBNC state. These findings are in line with the hypothesis that the sediment serves as a refuge for a subpopulation of V. vulnificus over the winter and weather-driven mixing events during the spring initiate a summer bloom in the water column.

Download Full-text

Nitrogen and oxygen availabilities control water column nitrous oxide production during seasonal anoxia in the Chesapeake Bay

Biogeosciences ◽

10.5194/bg-15-6127-2018 ◽

2018 ◽

Vol 15 (20) ◽

pp. 6127-6138 ◽

Cited By ~ 3

Author(s):

Qixing Ji ◽

Claudia Frey ◽

Xin Sun ◽

Melanie Jackson ◽

Yea-Shine Lee ◽

...

Keyword(s):

Nitrous Oxide ◽

Chesapeake Bay ◽

Water Column ◽

N2o Emissions ◽

N2o Production ◽

Isotope Tracer ◽

Relative Contribution ◽

Environmental Controls ◽

Long Run ◽

Nitrate And Nitrite

Abstract. Nitrous oxide (N2O) is a greenhouse gas and an ozone depletion agent. Estuaries that are subject to seasonal anoxia are generally regarded as N2O sources. However, insufficient understanding of the environmental controls on N2O production results in large uncertainty about the estuarine contribution to the global N2O budget. Incubation experiments with nitrogen stable isotope tracer were used to investigate the geochemical factors controlling N2O production from denitrification in the Chesapeake Bay, the largest estuary in North America. The highest potential rates of water column N2O production via denitrification (7.5±1.2 nmol-N L−1 h−1) were detected during summer anoxia, during which oxidized nitrogen species (nitrate and nitrite) were absent from the water column. At the top of the anoxic layer, N2O production from denitrification was stimulated by addition of nitrate and nitrite. The relative contribution of nitrate and nitrite to N2O production was positively correlated with the ratio of nitrate to nitrite concentrations. Increased oxygen availability, up to 7 µmol L−1 oxygen, inhibited both N2O production and the reduction of nitrate to nitrite. In spring, high oxygen and low abundance of denitrifying microbes resulted in undetectable N2O production from denitrification. Thus, decreasing the nitrogen input into the Chesapeake Bay has two potential impacts on the N2O production: a lower availability of nitrogen substrates may mitigate short-term N2O emissions during summer anoxia; and, in the long-run (timescale of years), eutrophication will be alleviated and subsequent reoxygenation of the bay will further inhibit N2O production.

Download Full-text

Exploring and Quantifying River Thermal Response to Heatwaves

Water ◽

10.3390/w10081098 ◽

2018 ◽

Vol 10 (8) ◽

pp. 1098 ◽

Cited By ~ 7

Author(s):

Sebastiano Piccolroaz ◽

Marco Toffolon ◽

Christopher Robinson ◽

Annunziato Siviglia

Keyword(s):

Water Temperature ◽

River Water ◽

Thermal Response ◽

Hydrological Regime ◽

Management Policy ◽

Extreme Weather Events ◽

Thermal Dynamics ◽

Depth Analysis ◽

River Water Temperature

Most of the existing literature on river water temperature focuseds on river thermal sensitivity to long-term trends of climate variables, whereas how river water temperature responds to extreme weather events, such as heatwaves, still requires in-depth analysis. Research in this direction is particularly relevant in that heatwaves are expected to increase in intensity, frequency, and duration in the coming decades, with likely consequences on river thermal regimes and ecology. In this study we analyzed the long-term temperature and streamflow series of 19 Swiss rivers with different hydrological regime (regulated, low-land, and snow-fed), and characterized how concurrent changes in air temperature and streamflow concurred to affect their thermal dynamics. We focused on quantifying the thermal response to the three most significant heatwave events that occurred in Central Europe since 1950 (July–August 2003, July 2006, and July 2015). We found that the thermal response of the analyzed rivers contrasted strongly depending on the river hydrological regime, confirming the behavior observed under typical weather conditions. Low-land rivers were extremely sensitive to heatwaves. In sharp contrast, high-altitude snow-fed rivers and regulated rivers receiving cold water from higher altitude hydropower reservoirs or diversions showed a damped thermal response. The results presented in this study suggest that water resource managers should be aware of the multiple consequences of heatwave events on river water temperature and incorporate expected thermal responses in adaptive management policy. In this respect, additional efforts and dedicated studies are required to deepen our knowledge on how extreme heatwave events can affect river ecosystems.

Download Full-text

To the problem of uncertainty in interpolation of annual runoff

Hydrology Research ◽

10.2166/nh.2012.073 ◽

2012 ◽

Vol 43 (6) ◽

pp. 833-850 ◽

Cited By ~ 5

Author(s):

Ziqi Yan ◽

Lars Gottschalk ◽

Irina Krasovskaia ◽

Jun Xia

Keyword(s):

Cross Validation ◽

Drainage Basin ◽

Annual Runoff ◽

Mean Value ◽

Regular Grid ◽

Main River ◽

Average Annual Runoff ◽

The One ◽

Better Than

The long-term mean value of runoff is the basic descriptor of available water resources. This paper focuses on the accuracy that can be achieved when mapping this variable across space and along main rivers for a given stream gauging network. Three stochastic interpolation schemes for estimating average annual runoff across space are evaluated and compared. Two of the schemes firstly interpolate runoff to a regular grid net and then integrate the grid values along rivers. One of these schemes includes a constraint to account for the lateral water balance along the rivers. The third scheme interpolates runoff directly to points along rivers. A drainage basin in China with 20 gauging sites is used as a test area. In general, all three approaches reproduce the sample discharges along rivers with postdiction errors along main river branches around 10%. Using more objective cross-validation results, it was found that the two schemes based on basin integration, and especially the one with a constraint, performed significantly better than the one with direct interpolation to points along rivers. The analysis did not allow identification of possible influence of surface water use.

Download Full-text

Assessment of the water pollution level and the environmental status of rivers in the Siverskyi Donets basin by BOD5

Ukrainian hydrometeorological journal ◽

10.31481/uhmj.26.2020.08 ◽

2020 ◽

pp. 91-101

Author(s):

N. S. Loboda ◽

І. V. Katynska ◽

О. V. Smalii

Keyword(s):

Water Quality ◽

River Water ◽

Catchment Area ◽

Donets Basin ◽

Pollution Level ◽

Early 21St Century ◽

Main River ◽

Environmental Status ◽

The City ◽

Hydrochemical Index

The paper topicality consists in the necessity for determination of the environmental status of the rivers in the Siverskyi Donets Basin and assessment of the possibilities for them to achieve ‘good environmental status’ under the modern climatic conditions and the anthropogenic load. Siverskyi Donets is the main river in the Eastern Ukraine. There are large industrial zones at the water catchment area. Among them, there are the Donetsk Coal Basin and the industrial complexes within the City of Kharkiv, which have exerted influence on surface water quality for decades. A method for assessment of the pollution level and the environmental status of waters by the hydrochemical index of BOD5 (biochemical oxygen demand for 5 days) is used in the paper. The paper is aimed at identification of the main trends in water quality changes by hydrochemical index of BOD5. The object of research is a pollution of the rivers at the Siverskyi Donets Basin by industrial, municipal and mine wastewaters. The subject of research is an assessment of water qualitative status by BOD5. The hydrochemical observation data for 7 gauges at the main river and 7 tributaries for the period of 1990-2015 were used in the paper. The major attention is focused on the most polluted rivers in the Eastern Ukraine: the Udy and the Kryvyi Torets. The quality of the Udy River water is largely determined by the municipal wastewater from Kharkiv. The Kryvyi Torets River belongs to the Donbas rivers, where pollution by mine water and wastewater from industrial enterprises is significant. Pollution levels, environmental status and saprobity were determined by the average annual indices of BOD5. Empirical probabilities for occurrence of a certain pollution parameter at various gauges were calculated for comparative analysis. It is found that a BOD5 downward trend has been prevalent on the rivers at the Siverskyi Donets catchment area in the early 21st century. The highest BOD5 values were observed on the Donbas tributaries and the Udy River (downstream from the City of Kharkiv), as well as upstream and downstream from Lysychansk, and the lowest ones were observed on the Oskil River. It is also revealed that in the early 21st century, the main river water has a ‘threshold’ environmental status (β-mesosaprobic zone), except for the Lysychansk gauge, where the status is ‘irreversibly altered’ owing to the inflow of polluted water from Donbas rivers into the Siverskyi Donets. Research into the Udy River water quality upstream and downstream from the industrial city of Kharkiv has shown that the water in the upper reaches of this river is classified as ‘clean’ and ‘moderately polluted’, and the environmental status may become ‘good’ in the future. Downstream from the city, the water is mostly ‘dirty’, and the environmental status is ‘irreversibly altered’, which corresponds to the α-mesosaprobic zone. For the Kryvyi Torets River (the Donbas Region), owing to the impact of organic pollution, the environmental status is defined as ‘threshold’, ‘irreversibly altered’ and it has begun to deteriorate in recent years. To improve the environmental status of the Donbas rivers, the reduction in discharges of untreated municipal and industrial wastewater into surface watercourses, as well as the construction of state-of-the-art sewage treatment plants are necessary.

Download Full-text

Fleshy Red Algae Mats Influence Their Environment in the Mediterranean Sea

Frontiers in Marine Science ◽

10.3389/fmars.2021.721626 ◽

2021 ◽

Vol 8 ◽

Author(s):

Neele Schmidt ◽

Yusuf C. El-Khaled ◽

Felix I. Roßbach ◽

Christian Wild

Keyword(s):

Environmental Factors ◽

Light Intensity ◽

Water Temperature ◽

Mediterranean Sea ◽

Water Column ◽

Red Algae ◽

Water Movement ◽

Ecosystem Engineer ◽

Overlying Water ◽

The Mediterranean

In the Mediterranean Sea, the fleshy red alga Phyllophora crispa forms dense mats of up to 15 cm thickness, mainly located on rocky substrates in water depths below 20 m. Because of the observed density of these mats and some first observations, we hypothesize that P. crispa is a yet undescribed ecosystem engineer that provides a multitude of ecological niches for associated organisms along small-scale environmental gradients. Therefore, we conducted an in-situ pilot study in the Western Mediterranean Sea to assess potential influence of the algae mats on the key environmental factors water movement, temperature and light intensity. We comparatively and simultaneously measured in P. crispa mats, in neighboring Posidonia oceanica seagrass meadows, on neighboring bare rocky substrates without algae mats, and in the directly overlying water column. We used several underwater logging sensors and gypsum clod cards. Findings revealed that P. crispa significantly reduced water movement by 41% compared to the overlying water column, whereas water movement was not affected by P. oceanica meadows and bare rocky substrates. Surprisingly, P. crispa increased the water temperature by 0.3°C relative to the water column, while the water temperature in P. oceanica and on bare rocky substrates was reduced by 0.5°C. Light intensity inside the red algae mats was reduced significantly by 69% compared to the water column. This was similar to measured light reduction of 77% by P. oceanica. These findings highlight the strong influence of the dense red algae mats on some key environmental factors. Their influence is obviously similar or even higher than for the well-known seagrass ecosystem engineer. This may be a factor that facilitates associated biodiversity similarly as described for P. oceanica.

Download Full-text

Study of the thermal regime of a reservoir on the Qinghai-Tibetan Plateau, China

PLoS ONE ◽

10.1371/journal.pone.0243198 ◽

2020 ◽

Vol 15 (12) ◽

pp. e0243198

Author(s):

Yanjing Yang ◽

Yun Deng ◽

Youcai Tuo ◽

Jia Li ◽

Tianfu He ◽

...

Keyword(s):

Tibetan Plateau ◽

Diurnal Variation ◽

Water Temperature ◽

Water Column ◽

Temperature Structure ◽

Observation Data ◽

The Mean ◽

Low Altitude ◽

Mean Variance ◽

Whole Water

The Qinghai-Tibetan Plateau region has unique meteorological characteristics, with low air temperature, low air pressure, low humidity, little precipitation, and strong diurnal variation. A two-dimensional hydrodynamic CE-QUAL-W2 model was configured for the Pangduo Reservoir to better understand the thermal structure and diurnal variation inside the reservoir under the local climate and hydrological conditions on the Qinghai-Tibetan Plateau. Observation data were used to verify the model, and the results showed that the average error of the 6 profile measured monthly from August to December 2016 was 0.1°C, and the root-mean-square error (RMSE) was 0.173°C. The water temperature from August 2016 to September 2017 was simulated by inputting measured data as model inputs. The results revealed that the reservoir of the Qinghai-Tibetan Plateau was a typical dimictic reservoir and the water mixed vertically at the end of March and the end of October. During the heating period, thermal stratification occurred, with strong diurnal variation in the epilimnion. The mean variance of the diurnal water temperature was 0.10 within a 5 m water depth but 0.04 in the whole water column. The mixing mode of inflow changed from undercurrent, horizontal-invaded flow and surface layer flow in one day. In winter, the diurnal variation was weak due to the thermal protection of the ice cover, while the mean variance of diurnal water temperature was 0.00 within both 5 m and the whole water column. Compared to reservoirs in areas with low altitude but the same latitude, significant differences occurred between the temperature structure of the low-altitude reservoir and the Pangduo Reservoir (P<0.01). The Pangduo Reservoir presented a shorter stratification period and weaker stratification stability, and the annual average SI value was 26.4 kg/m2, which was only 7.5% that of the low-altitude reservoir. The seasonal changes in the net heat flux received by the surface layers determined the seasonal cycle of stratification and mixing in reservoirs. This study provided a scientific understanding of the thermal changes in stratified reservoirs under the special geographical and meteorological conditions on the Qinghai-Tibetan Plateau. Moreover, this model can serve as a reference for adaptive management of similar dimictic reservoirs in cold and high-altitude areas.

Download Full-text