scholarly journals Effects of extreme water levels on water quality in a large shallow eutrophic lake (Changhu Lake, China)

Author(s):  
Haiyan Wang ◽  
Jun Yang ◽  
Tao Li ◽  
Jianqiang Zhu ◽  
Zhangyong Liu

Abstract Changhu Lake, a large shallow eutrophic lake in central China, experienced an extreme low water level event from November 2015 to January 2016 followed by an extreme high water level event in July 2016. In this study, we examined the effects of two extreme water levels on the nutrient status of Changhu Lake over five years. The nutrient concentrations in Changhu Lake showed significant interannual variations and the water quality of sites in the western part of Changhu Lake was better compared to sites at the outlet of the lake. In late 2015, the effect of low water levels led to a significant increase in nutrient concentrations. After July 2016, however, the high water level occurred leading to a marked decrease in nutrient concentrations. These changes in nutrient parameters were strongly related to the water level fluctuations. The dilution effect was the key process that determined the variations of nutrient parameters in Changhu Lake. As extreme water levels are likely to become more frequent during the twenty-first century, this work may provide some insights into the conservation and management of lake ecosystems in the face of climate change and human activity.

2014 ◽  
Vol 1010-1012 ◽  
pp. 821-825
Author(s):  
Song Mei Wang ◽  
Chun Du Wu ◽  
Jin Yu Chu ◽  
Qing Jie Xie

We perform a study of the waste water from overflow in the Zhenjiang Neijiang . Determine content of COD、NH3-N、TP which changing along the distance at different water levels . Based on the SPSS14.0 correlation analysis , single factor pollution index and the comprehensive pollution index we study water movement rule and quality assessment. The results showed that : At low water level COD、NH3-N、TP decrease alleviation, the whole datum are high; at high water level COD、NH3-N、TP decrease greatly between 0~7m,but decrease alleviation between 7~200m. (2) Only the content of NH3-N (0~7m ) has significant differences (p<0.05),the other content all has not significant differences (p>0.05), the waste water from overflow was seriously polluted so that the wetland can not purify it adequately. (3)Based on the Vwater quality grade standard, at low water level the content of COD、NH3-N、TP(0~200m ) are all beyond standard; at high water level the content of COD、NH3-N、TP(80~200m ) are all beyond standard; the order of the potential ecological rick is: NH3-N>TP>COD. The study on the datum could offer a favorable plan for purifying the waste water from overflow in the Zhenjiang Neijiang. Keyword: overflow; water movement rule; correlation analysis; water quality assessment


Author(s):  

Reasons of the extremely high water level in Lake Khanka (it was 0.5 m higher the historical maximum over the past years) have been revealed within the frameworks of the carried out exploration. The lake capacity characteristics alteration due to the natural and anthropogenic factors’ impact has been assessed. We have considered the factors that form the Lake Khanka level regime, i.e. natural: atmosphere circulation, atmospheric perspiration, river inflow to the lake, evaporation from the lake surface, and outflow; anthropogenic: economic activities on the catchment on Russian and Chinese territories (hydro/melioration and the runoff transfer). The passage capacity of the Sungachi River, the only outflow from the lake, has been analyzed in details at different water levels in Lake Khanka. The paper is based on summing up and analysis of information on the lake hydro/meteorological regime and economic activities on its catchment, as well as reference literature. As a result of the study the authors for the first time has identified the main reason of the abnormal rise of the Kanka level. It was found that the significant transformation of the lake level regime occurred due to the Mulinkhe Rivers runoff transfer to Lake Malaya Khanka from the People’s Republic of China. A forecast of the lake level for 2016 taking into consideration different scenarios of the basin moistening has been given. In connection with the forecasted rise of the water level in Lake Khanka in the nearest future we propose a number of measures aimed to minimize inevitable damage to the Russian party.


2019 ◽  
Vol 37 (2) ◽  
pp. 133-137
Author(s):  
Carla D Tedesco ◽  
Claudia Petry ◽  
Edson C Bortoluzzi ◽  
Alfredo Castamann

ABSTRACT White Star (Nymphoides humboldtiana), an aquatic-environmental native species of Brazilian flora, was selected in order to be used as ornamental plant in lakes. White Star plants were submitted to two water levels (high water level, up to 30 cm water depth and, low water level until substrate saturation) and two light intensities (full sun and 50% shading) to evaluate vegetative and flowering development. The experimental design was completely randomized, in a subplot scheme, being the water level the main plot and luminosity the subplot. Seven replicates were performed, and the sample unit consisted of one plant. Data related to number of leaves and flowers, length and diameter of petioles and leaf area were submitted to analyze of variance and regression. We observed an increase in number of leaves and flowers in the treatment of high water level in full sun, and an increase of petiole length in high water level with shading. No difference between leaf area of plants grown under full sun and with shading (p<0.05) was observed. At low water level, plants presented lower vegetative development than those grown at high water level, besides the flowering inhibition in shaded condition. These results demonstrated that White Star can be used in ornamental lakes with a water depth of at least 20 cm above the rhizome and exposed to full sun.


1951 ◽  
Vol 41 (3) ◽  
pp. 191-202 ◽  
Author(s):  
A. Eden ◽  
G. Alderman ◽  
C. J. L. Baker ◽  
H. H. Nicholson ◽  
D. H. Firth

1. Studies were made of the effects of varying ground water-levels upon the productivity and composition of Italian Ryegrass grown on a calcareous light peat in the Fenland area. Six cuts were taken throughout the season at 3 to 4-weekly intervals.2. High ground water-level (approximately 15in. below ground surface) had a very deleterious effect on the total yield of fresh grass and of dry matter. Yields were little more than half of those obtained at medium and low water-levels (24 and 38 in. below ground surface, respectively).3. High water-level apparently interfered with nitrogen metabolism in the soil, and considerably lower percentages of crude protein were found in the grass growing on the high water-level plots than at the other levels. On the other hand, the percentage of crude fibre remained fairly constant for all levels of ground water.4. High water-level also had a depressing effect on the percentage of potassium, magnesium and chlorine in the grass. It had no obvious effect upon the calcium and phosphorus levels in the plants. The silica content of the grass rose steadily as the season advanced, this being most marked on the high water-level plots.5. Physical examination of typical plants showed the effect of the various ground water-levels upon the development of the root systems, with consequent effect upon the chemical composition of the grass.6. The composition of hay and aftermath showed similar changes to those reported for the green herbage.7. The findings are discussed in relation to grassdrying policies in Fenland areas.


2010 ◽  
Vol 10 (1) ◽  
pp. 29-36
Author(s):  
Agnieszka Ławniczak ◽  
Janina Zbierska ◽  
Sylwia Machula ◽  
Adam Choiński

Fluvial lakes affect on phosphorus and potassium concentrations in the Samica Stęszewska River The aim of the study was to evaluate the effect of shallow lakes on reactive, total phosphorus and potassium concentrations in the river water and analyse the effect of changes in water retention in lake on nutrient concentrations in river waters. The study was carried out in the Samica Steszewska River. This is lowland river, which flows through two polymictic lakes. The study site is located in the Wielkopolska Lowland, Central-west Poland. Water samples were collected at depths of 0.5 m below the water surface. Reactive, total phosphorus and potassium were analysed monthly by standard methods. The study was carried out from January to December 1999-2002 (period with high water retention), 2005-2008 (period with low water retention), at four control points. Sites were located at the inflow and outflow of the Samica Stęszewska River into and out of Niepruszewskie and Tomickie Lakes. From 1974 to 2002, Lake Niepruszewskie was regulated at its outlet by a weir. In 2002, the water level was reduced. Changes of water retention in Niepruszewskie Lake influenced water discharge of the Samica Stęszewska River. The results indicate that changes in water retention have significantly influenced water quality in the river, particularly total and reactive phosphorus concentrations; however, this influence was not observed in respect to potassium concentrations. Nutrient concentrations in river strongly depend on water quality of the lake ecosystem and their buffering capacity. Additionally, by improving water quality, increased oxygen concentrations, and decreasing dissolved nutrient concentrations, as well as increased amplitude of water level fluctuations in lakes may increase P-fixation rates in outlet streams.


1953 ◽  
Vol 43 (3) ◽  
pp. 265-274 ◽  
Author(s):  
H. H. Nicholson ◽  
D. H. Firth ◽  
A. Eden ◽  
G. Alderman ◽  
C. J. L. Baker ◽  
...  

1. Further studies were carried out during 1950 on the effects of different ground water-levels upon the productivity and composition of Italian ryegrass grown on a calcareous light peat soil. The season was an unusually wet one, in contrast with the dry season experienced in 1949.2. Seven successive cuts were taken during the season from each of two crops of ryegrass, one following a crop of marrow-stem kale, and the other a crop of celery. Different amounts of a general compound fertilizer had been applied.3. Generally, the findings confirmed those of the previous year's investigation. High ground waterlevel (approximately 18 in. below ground surface) had a deleterious effect upon the yield and quality of ryegrass as reflected by its protein content, compared with the medium and low water-levels (23 and 30 in. below ground surface, respectively).4. The high water-level also had a depressing effect upon the percentage of potassium and magnesium in the grass, but had no consistent effect upon calcium and phosphorus. The silica content rose steadily in all cases as the season advanced, as occurred in the previous year.5. Residual manuring effects were well marked in the crop following celery. The total yields of dry matter from the medium and low water-levels considerably exceeded those of similar plots following kale, and the protein contents were also appreciably higher. This demonstrates the advantages of a high soil nutrient status, under conditions of suitable water-levels, for a crop of fenland grass.6. A high water-level inhibited growth and quality, irrespective of the nutrient status of the soil.


Author(s):  
Katherine A. Serafin ◽  
Peter Ruggiero ◽  
Kai A. Parker ◽  
David F. Hill

Abstract. Extreme water levels driving flooding in estuarine and coastal environments are often compound events, generated by many individual processes like waves, storm surge, streamflow, and tides. Despite this, extreme water levels are typically modeled in isolated open coast or estuarine environments, potentially mischaracterizing the true risk to flooding facing coastal communities. We explore the variability of extreme water levels near the tribal community of La Push, within the Quileute Indian Reservation on the Washington state coast where a river signal is apparent in tide gauge measurements during high discharge events. To estimate the influence of multivariate forcing on high water levels, we first develop a methodology for statistically simulating discharge and river-influenced water levels in the tide gauge. Next, we merge probabilistic simulations of joint still water level and discharge occurrences with a hydraulic model that simulates along-river water levels. This methodology produces water levels from thousands of combinations of events not necessarily captured in the observational record. We show that the 100-yr ocean or 100-yr streamflow event does not always produce the 100-yr along-river water level. Along specific sections of river, both still water level and streamflow are necessary for producing the 100-yr water level. Understanding the relative forcing of extreme water levels along an ocean-to-river gradient will better prepare communities within inlets and estuaries for the compounding impacts of various environmental forcing, especially when a combination of extreme or non-extreme forcing can result in an extreme event with significant impacts.


1999 ◽  
Vol 1999 (1) ◽  
pp. 489-495 ◽  
Author(s):  
Jaydeep A. Purandare ◽  
Tiehong Huang ◽  
Makram T. Suidan ◽  
Ben Johnston ◽  
Albert D. Venosa ◽  
...  

ABSTRACT Use and transport of petroleum products can result in serious contamination of freshwater habitats via leakage, spills, aerosols, and runoff. Little development of bioremediation strategies has occurred for enhancing degradation of petroleum products in situations involving contamination of freshwater wetland ecosystems. The objective of this study was to investigate different inorganic mineral nutrients for their ability to enhance biodegradation of crude oil in contaminated wetlands on a microcosm scale. Aquaria of 10-gallon capacity, filled with wetland soil and planted with species of emergent wetland plants, were used to simulate natural wetlands. Two levels of water coverage were studied: (1) water level even with soil surface, and (2) water level 10 cm above the soil surface. Six treatments were evaluated in duplicate for each water level: unoiled, no-nutrient control; oiled + no nutrient control; oiled + nitrate addition; oiled + nitrate + phosphate addition; oiled + ammonia addition; and oiled + ammonia + phosphate addition. Thus, 24 aquaria were set up for each sampling event (0, 2, 4, 8, 16, and 32 weeks) totaling 144 aquaria. Nutrients were applied once each week. Nitrate, ammonia, dissolved oxygen, pH, temperature, and conductivity were measured before and after nutrient addition. Biodegradation was tracked by GC/MS analysis of hopane-normalized crude oil components from the sacrificed aquaria over the 32-week experimental period. Results indicated that: (1) the rates of biodegradation of the alkanes and PAHs (polycyclic aromatic hydrocarbons) were higher for all treatments in the high-water level microcosms compared with the low-water level microcosms; (2) the highest rates of alkane and PAH degradation were measured in the high-water level microcosms receiving nitrate and phosphate; (3) the treatments with nitrate and phosphate showed nearly a 90% reduction of alkanes and a 50% reduction of PAHs as compared to nearly a 50% reduction of alkanes and 40% reduction of PAHs by the oil with no nutrients control for the high-water level; (4) the nitrate and phosphate addition treatments, for both water levels, showed good plant growth and the highest plant and root densities as compared to the other treatments. This information is being used in the design of a mesoscale experiment as part of the second phase of this study.


2021 ◽  
Author(s):  
Huazu Liu ◽  
Qiu Jin ◽  
Ruijie Shi ◽  
Chengxu Lv ◽  
Junxiao Luo ◽  
...  

Abstract. Hydrological conditions drive the distribution of plant communities in wetlands to form vegetation zones where the material cycling varies with plant species. This mediation effect caused by the distribution of vegetation under hydrological conditions will affect the emission of N2O during the nitrogen migration in wetlands. In this study, five vegetation zones in the second largest wetland of China were investigated in situ during high and low water levels to elucidate the effect mediated by vegetation. With the increase in the rate of change of water levels, the zones of the mud flat, nymphoides, phalaris, carex, and reeds were distributed in sequence in the wetland, and the densities of carbon and nitrogen sequestrated by plants also increased. The carbon and nitrogen densities in each zone during low water level was significantly higher than that during high water level, while the organic carbon and the total nitrogen of sediments during high water level was higher. Sediments converted between source and sink for both carbon and nitrogen, during the annual fluctuation in water level. The flux in N2O emissions showed significant differences between the vegetation zones during each water level period. The emission flux decreased with the increasing C : N ratio in sediments, approximating the threshold at 0.23 μg m−2 h−1 when the C : N ratio > 25. The phylum abundance of Firmicutes, Proteobacteria, and Chloroflexi in sediments increased with flooding. The denitrifying nirS and nirK genes and anammox hzsB gene were significantly affected by water level fluctuation, with the maximal variations of these genes occurring in the mud flat and nymphoides zone. The results indicate that the distribution of plants under hydrological conditions modified the stoichiometric ratio of sediments, resulting in the variations of N2O emission fluxes and microbial communities in vegetation zones. Therefore, hydraulic regulation rather than direct planting would be an effective strategy to reduce greenhouse gas emissions in freshwater wetlands.


2020 ◽  
Vol 6 ◽  
pp. 11-32
Author(s):  
Anna Yu. Bessudova ◽  
Larisa M. Sorokovikova ◽  
Valery N. Sinyukovich ◽  
Alena D. Firsova ◽  
Irina V. Tomberg ◽  
...  

Large tributaries of Lake Baikal considered as a “hotspot” for silica-scaled chrysophytes diversity. Here we presented the updated species composition of silica-scaled chrysophytes and ecological parameters of their habitat in the Barguzin and Selenga River tributaries and delta in a high water level period. The number of registered taxa was significantly lower compared to the low water conditions (23 versus 66 species) and included the following genera with a given number of species: Chrysosphaerella – 1; Paraphysomonas – 2; Clathromonas – 1; Spiniferomonas – 3; Mallomonas – 9; Synura – 7. Mallomonas guttata and Synura borealis were identified in Russian waters for the first time. Thus, the corrected total list of silica-scaled chrysophytes in the Baikal Region includes 79 taxa. Though, the high water level reduced the total number of silica-scaled chrysophyte taxa, it made the water ecosystem more dynamic by enriching it with the entirely new species for this region.


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