Analysis on Aquatic Environment of an Artificial Lake and Control Measures to Its Pollution

[Objective] This study aimed to find out effective measures to solve land- scape water eutrophication. [Method] Based on an overview of the urban landscape water characteristics and pollution control situation, taking an example of the artificial lakes in a campus in Xi＇an, we comparatively analyzed the present pollution situation of Xiuyuan Lake and Mingyuan Lake, and provided controlling measures against eutrophication pollution, as well as restoration measures. [Result] All the indicators （TN, TP, Chl-a, NH3-N, CODMn） of the landscape water quality in both Xiuyuan Lake and Mingyuan Lake went severely beyond the Grade IV standards, presenting a state of heavy eutrophication. Nitrogen, phosphorus and other nutrient salts carried by atmospheric precipitation and its runoff, as well as domestic garbage generated by human activities were primary exogenous pollutants of the artificial lakes. And the release of sediment pollutants was endogenous substances causing deterioration of water quality. [Conclusion] This paper presents some measures to control the pollution of artificial lakes, and provides scientific references for the construction, operation and management of artificial lakes, as well as maintenance of aquatic environment.

Study on the Changes of Physiological Indexes of Water Spinach in Eutrophication Water

[Objective] Effect of hypoxic water culture on physiological characteristic of water spinach and its hypoxia tolerance were studied.[Method] Water spinach was planted in soil and eutrophication water by means of floating bed,respectively,and the change of physiological indexes including chlorophyll,proline（Pro）,malondialdehyde（MDA）,soluble sugar and soluble protein in water spinach leaves at mature stage was researched,while the hypoxia tolerance of water spinach and the effect of plant density on water spinach growth were discussed in our paper.[Result] In the hypoxic eutrophication water,the content of total chlorophyll,malondialdehyde,soluble sugar and soluble protein in water spinach leaves was lower than that of soil culture,with higher proline content,which showed that water spinach had better tolerance to hypoxic eutrophication water;the higher the plant density,the lower the chlorophyll content in water spinach leaves,and there was no significant effect of plant density on proline and malondialdehyde content,while soluble protein content was higher under high plant density.[Conclusion] The best plant density of water spinach was 66 plants per floating bed with the area of 2 m2,which could provide theoretical basis for the application of water spinach in floating bed.

Toxicity Effect of Hg^(2+) and Cr(VI) on Alga Growth in Eutrophic Water

[ Objective] The toxicity effect of Hg^2＋ and Cr（Ⅵ） on alga growth in eutrophic water was studied to provide reference for biomonitoring and bioremediation of eutrophic water. [ Method ] The mother liquid of alga, which was separated from the eutrophic water, were put into the solutions of Hg^2＋ and Cr（Ⅵ） with different concentrations and their mixture solution, respectively. And the toxicity effect of Hg^2＋ and Cr（Ⅵ） on the growth and propagation of alga in eutrophic water was observed. [ Result] The alga in eutrophic water performed rather sensitive to Cr（Ⅵ） and when its concentration was over 1 mg/L, threre was obvious effect on alga growth. The alga was not very sensitive to Hg^2＋ when its concentration was lower, but its toxicity became stronger and stronger when its concentration increased to some extent and the toxicity effect of Cr（Ⅵ） on alga growth was just on the contrary. When the ion concentration was lower than 10 mg/L, the toxicity of Hg^2＋ on alga was lower than that of Cr（Ⅵ）. When the concentration was over 10 mg/L, the toxicity of Hg^2＋ exceeded that of Cr（Ⅵ）. The toxicity of ion mixture solution of Hg^2＋ and Cr（Ⅵ） had synergism inhibition on alga, which could be performed only when the concentration was over 4 mg/L. [ Conclusion] The toxicity of heavy metal on alga not only related to the alga cell, but also related to the concentration of heavy metal ion.

A Study on Water Pollution and Bioremediation in Hedi Reservoir

Statistical work and analysis were made based on data of monitored wa- ter quality data in Hedi Reservoir during 2000-2010 and the results show that the content of nutritive salt was higher and water was moderate or light eutrophication. Based on status quo and practical survey research of the Reservoir, the causes for eutrophication deterioration were analyzed and countermeasures were proposed, providing scientific references for sustainable development of Hedi Reservoir.

Harmful algal blooms and eutrophication: "strategies" for nutrient uptake and growth outside the Redfield comfort zone

While many harmful algal blooms have been associated with increasing eutrophication, not all species respond similarly and the increasing challenge, especially for resource managers, is to determine which blooms are related to eutrophication and to understand why particular species proliferate under specific nutrient conditions. The overall goal of this brief review is to describe why nutrient loads are not changing in stoichiometric proportion to the "Redfield ratio", and why this has important consequences for algal growth. Many types of harmful algae appear to be able to thrive, and/or increase their production of toxins, when nutrient loads are not in proportion classically identified as Redfield ratios. Here we also describe some of the physiological mechanisms of different species to take up nutrients and to thrive under conditions of nutrient imbalance.

De-eutrophication of effluent wastewater from fish aquaculture by using marine green alga Ulva pertusa

The de-eutrophication abilities and characteristics of Ulva pertusa, a marine green alga, were investigated in Qingdao Yihai Hatchery Center from spring to summer in 2005 by analyzing the dynamic changes in NH4-, NO3-, NO2- as well as the total dissolved inorganic nitrogen （DIN）. The results show that the effluent wastewater produced by fish aquaculture had typical eutrophication levels with an average of 34.3 ~mol L-1 DIN. This level far exceeded the level IV quality of the national seawater standard and could easily lead to phytoplankton blooms in nature if discarded with no treatment. The de-eutrophication abilities of U. pertusa varied greatly and depended mainly on the original eutrophic level the U. pertusa material was derived from. U. pertusa used to living in low DIN conditions had poor DIN removal abilities, while materials cultured in DIN-enriched seawater showed strong de-eutrophication abilities. In other words, the de-eutrophication ability of U. pertusa was evidently induced by high DIN levels. The de-eutrophication capacity of U. pertusa seemed to also be light dependent, because it was weaker in darkness than under illumination. However, no further improvement in the de-eutrophication capacity of U. pertusa was observed once the light intensity exceeded 300 pmolM2 S1. Results of semi-continuous wastewater replacement experiments showed that U. pertusa permanently absorbed nutrients from eutrophicated wastewater at a mean rate of 299 mg/kg fresh weight per day （126 mg/kg DIN during the night, 173 mg/kg in daytime）. Based on the above results, engineered de-eutrophication of wastewater by using a U. pertusa filter system seems feasible. The algal quantity required to purify all the eutrophicated outflow wastewater from the Qingdao Yihai Hatchery Center into oligotrophic level I dean seawater was also estimated using the daily discharged wastewater, the average DIN concentration released and the de-eutrophication capacity of U. pertusa.

Nutrient and chlorophyll a anomaly in red-tide periods of 2003-2008 in Sishili Bay, China

Sishili Bay is the most important aquiculture and tourism area for the city of Yantai, China; however, red tides occurred frequently and have caused huge economic losses in this bay in recent years. To gain a better understanding of the local ecological environments in the bay, we conducted this research between 2003 and 2008 to analyze variations in nutrients and chlorophyll （chl-a） during high frequency red tide period （May to September）. The results show that the chl-a concentration increased from 2.70 in 2003 to 7.26 mg/m3 in 2008, while the concentration of total inorganic nitrogen （TIN） and silicate （SiO3-Si） increased lineally from 5.18 and 1.45 pmol/L in 2003 to 18.57 and 9.52 pmol/L in 2008, respectively, and the annual phosphate （PO4-P） varied between 0.15 and 0.46 μmol/L. Special attention was given to a red tide in August 2007 occurred when water temperature was high and nutrient concentrations increased sharply because of a heavy rainfall. Overall, the results show the P limitation in Sishili Bay, and reveal that red tides were caused by eutrophication from terrestrial inputs and local warm weather, particularly during rainy periods. Therefore, to control red tide, greater efforts should be made to reduce sewage discharges into Sishili Bay, particularly during rainfall seasons.

Phosphorus Speciation in Wetland Sediments of Zhujiang (Pearl) River Estuary,China

Phosphorus fractions and adsorption-release characteristics of sediments in the Zhujiang （Pearl） River estuary wetland were investigated. Results showed that the total phosphorus （TP） content in surface sediments ranged from 648.9 mg/kg to 1064.0 mg/kg; inorganic phosphorus （IP） was the major fraction of TP and ranged from 422.5 mg/kg to 643.9 mg/kg. Among the inorganic phosphorus, the main fractions were phosphorus bound to A1 and Fe （Fe/A1-P）, and calcium-bound phosphorus （Ca-P）, accounting for 23%-42% and 21%-67% of IP, respectively. The vertical distribution of TP contents were significantly positive correlated with organic phosphorus （Org-P） and Fe/A1-P contents. The bio-available phosphorus contents in vertical sediments varied from 128.6 mg/kg to 442.9 mg/kg, mainly existed in Fe-AI/P fraction, and increased from the bottom to top sediments. The transport of phosphorus in sediment-water in- terface was controlled by the soil characteristics. The active Fe and A1 content was considered as the main factor that determines adsorp- tion capacity in vegetated marsh wetland. The P buffering capacity of the sediments in vegetated marsh wetland was greater than that in mudflat wetland. The potential risk of eutrophication in the study area is high. Reducing terrestrial phosphorus discharge and preventing the sediment Fe/A1-P release to the interstitial water are the possible solutions to reduce the risk of eutrophication in estuary wetlands, and planting vegetation in estuary wetland can also reduce the release of phosphorus in surface sediment.

Relationship between environmental factors and plankton in the Bayuquan Port, Liaodong Bay,China：a five-year study

To understand the relationship between the plankton community and environmental factor and water quality in the Bayuquan Port of Liaodong Bay, China, and investigations were carried ou during six dif ferent periods(April 2009, April 2010, October 2011, April 2012, October 2012, and Apri 2013). This area was characterized by high levels of nutrient and suspended solids(SPS) during surve periods, and eutrophication led to the occurrence of red tides in April and October 2012 and April 2013 Our analyses revealed that the plankton communities of Bayuquan Port lacked stability and were af fecte seriously by external disturbance(e.g., oceanographic engineering and river runof f). Our data indicate tha oil, dissolved inorganic nitrogen(DIN), SPS, and chlorophyll a(Chl- a) were key factors that regulated th phytoplankton and zooplankton communities. The partial redundancy analysis(partial RDA) suggested tha oil and SPS were the most important environmental variables af fecting the phytoplankton community i April 2010 and 2012, whereas DIN concentration played a governing role in zooplankton dynamics. Oi and Chl-a concentrations af fected signifi cantly the zooplankton community in October 2012. Therefore, th plankton communities could refl ect both dynamic changes in coastal environmental factors and the ongoin eutrophication process caused by anthropogenic activities in this area.

Application of an integrated methodology for eutrophication assessment:a case study in the Bohai Sea

An integrated methodology for eutrophication assessment,which integrates both water quality indicators(causative factors) and ecological response indicators(effect factors),is described.It is then applied to rank the eutrophication status of the years 2007 and 2008 in the southwest Bohai Sea.The assessment model identified that north Bohai Bay and west Laizhou Bay were the two areas with the most serious eutrophication problems in the southwest Bohai Sea.In addition,compared to that in the west Laizhou Bay,the eutrophication conditions in the north Bohai Bay was more serious in both years.Eutrophication problems such as harmful algal blooms(HABs) and low dissolved oxygen(DO) events in north Bohai Bay were frequent.The integrated method outmatched the currently used Chinese nutrient index method by definitely identifying areas with the most serious eutrophication problems,while the nutrient index method gave ambiguous results between the two years.Inclusion of both causative factors and effect factors,combining concentration,spatial coverage and frequency of indicators,as well as use of multi-season monitoring datasets in the methodology result in a more accurate,representative and useful assessment.

Inorganic Carbon Parameters Responding to Summer Hypoxia Outside the Changjiang Estuary and the Related Implications

The eutrophication, hypoxia and coastal acidification are attracting more and more attention. In this study, inorganic carbon parameters, including dissolved inorganic carbon （DIC）, total alkalinity （TA） and calculated partial pressure of CO2 （pCO2）, obtained from a summer cruise in August, 2009, were used to investigate their integrated response to biological processes accompanying the oxygen depletion in the areas off the Changjiang Estuary. According to the observations, the typical hypoxia occurred in the bottom water just outside the Changjiang Estuary with Dissolved Oxygen （DO） lower than 2.00 mg L^-1. The biological uptake in the surface water and the decomposition of organic matter in the bottom water were fully coupled with each other. The high concentration of Chl_a （Chl_a = 10.9μgL^-1） and DO （9.25 mgL^-1）, profoundly decreased DIC concentration 0828 μmolkg^-1） and elevated pH （8.42） was observed in the surface water. The correspondingly increased DIC and depletion of oxygen were observed in the bottom water. The semi-quantitative analysis proved that the locally-produced phytoplankton, determined by primary productivity, was deposited to the bottom and contributed about 76% of total amount of the organic carbon decomposition in the bottom. However, in the bottom hypoxia （DO = 2.05 mgL^-1） area observed in the Southern Zhejiang coastal water, the responding patterns of inorganic carbon parameters deviated from the previous one. The expanding of Changjiang Diluted Water （CDW）, the adding of Hangzhou Bay water （with high DIC concentration） and Coastal Current together modify the DIC background value in this area, and the local degeneration and upwelling process may also help to offset the local DIC removed by net biological uptake in surface water. In addition when the mixing occurring in autumn, which may break the summer stratification, the excess release of high DIC in the bottom water to the subsurface water could have an important influence on coastal acidification and the CO2 uptake capacity in this area.

Source and composition of sedimentary organic matter in the head of Three Gorges Reservoir: a multiproxy approach using δ^(13)C,lignin phenols, and lipid biomarker analyses

A multiproxy approach including bulk organic carbon, δ^(13) C, lignin phenols, and lipid biomarker analyses were applied to characterize the source and composition of sedimentary organic matter in the head part of Three Gorges Reservoir. OM consisted of both natural(autochthonous and allochthonous) and anthropogenic inputs.The natural OM included input from vascular plants,especially non-woody angiosperms. The allochthonous input included plankton and microbial production, likely due to localized eutrophication. Anthropogenic inputs likely derived from petroleum input and/or urban activities.Other anthropogenic inputs were untreated sewage waste.These influences were concluded to be regionally specific point sources of pollution based on relative distributions and on the fact that molecular characteristics of sedimentary OM were not distributed smoothly along a gradient.

Spatially Different Nutrient Histories Recorded by Multiple Cores and Implications for Management in Taihu Lake, Eastern China

The Taihu Lake,a large shallow lake in the floodplain of the Changjiang(Yangtze) River in the eastern China,is faced with challenging ecological problems resulting from eutrophication,which has affected the regional freshwater supply of a large population.Although efforts have been made to assess the nutrient evolution histories in the northern bays,little is known regarding nutrient histories in different parts across the entire lake basin.In this paper,we present nutrient histories for different parts of the lake based on chironomid transfer functions applied to four short cores obtained from the northern,western and eastern regions of the lake.The chironomid-inferred total phosphorus(CI-TP) concentrations were compared with the phosphorus concentrations obtained by using instrumental and sedimentary data.The results suggest that trophic evolution histories were asynchronous throughout the lake during the past decades in response to different ecological regimes controlled by the nutrient input,wind direction and shoreline topography.The restoration of aquatic plants may be an effective option for the management of lake rehabilitation to ′natural′ conditions.Given the multiple factors controlling the biotic communities in such a large and complex lake,combined analyses among the multi-proxies encountered in the sediments are necessary for comprehensive insight into paleolimnological studies.The spatial heterogeneity in the ecological trajectories within this complicated ecosystem suggests that different management practices should be undertaken for specific lake zones in the Taihu Lake.

Nutrient and eutrophication characteristics of the Dongshan Bay, South China

We recorded NO3-N, NOz-N, NH4-N, PO4-P, SiO3-Si, salinity, and temperature data at 10 stations in the Dongshan Bay in May, June, July, August, October, and November 2008, analyzing nutrient and eutrophication characteristics. The mean concentration of dissolved inorganic nitrogen （DIN） was 0.304）.40 mg/dm3; generally, NO3-N was the main form in most areas. The mean concentrations of PO4-P and SiO3-Si were 0.0404）.060 mg/dm3 and 1.00-1.50 mg/dm3, respectively. We proved that the majority of the SiO3-Si in the Dongshan Bay came from the Zhangjiang River, with some coming from the Bachimen Strait. DIN originated from both the Zhangjiang River and the Bachimen Strait. Most PO4-P originated from the Bachimen Strait, and some came from the Zhangjiang River. We found that P was an overall limiting factor to the phytoplankton community in most of the Dongshan Bay, and that Si and N were in surplus. However, near the Bachimen Strait Si became a limiting factor, especially for diatoms, while P and N were in comparative surplus. We used a potential eutrophication assessment method to analyze eutrophication, and showed that the most serious eutrophication occurred near the Zhangjiang River estuary and near the Bachimen Strait. In 2008, DIN levels were four times higher than that in 1988; PO4-P levels were three- fold higher, while SiO3-Si was approximately double. Dissolved nutrients increased between 1988 and 2008. DIN increased at the greatest rate comparing to PO4-P and SiO3-Si, thus the N/P and N/Si mol ratios increased. Further studies on the effects of high DIN concentrations on the phytoplankton communities and marine ecosystems of the Dongshan Bay are needed.

Marine ciliate community in relation to eutrophication of coastal waters in the Yellow Sea

We assessed the potential of marine ciliate community as an indicator to coastal water quality using water samples collected from four stations in thc Yellow Sea in the summer 2000. The four stations were characterized by different levels of pollution. The ciliate communities consisted primarily of tintinnids and aloricate ciliates that were 〈30 um. A total of 78 species were classified： 55 species at Station 2, 51 species each at Stations l and 4, and 47 species at Station 3. The mean number of species at each site was 29.2±2.0 （Station 1）, 28.5±2.9 （Station 2）, 27.8±1.7 （Station 3）, and 24.5±2.3 （Station 4）. The abundance was highly variable： 19 331±11 187 ind./L at Station 1, 7 960±5 639 ind./L at Station 2, 29 015±12 999 ind./L at Station 3, and 8 190±4 658 ind./L at Station 4. Our results suggest that neither the simple chemical analysis （e.g. chemical oxygen demand, dissolved inorganic nitrogen, and phosphate） nor the eutrophication/pollution index adequately described the water quality at the four stations. The same was true of the number of species and their abundance, both of which had no correlation with the chemical indices. In contrast, Margalef＇s diversity index values （3.12 at Station 2, 2.89 at Station 1, and 2.64 at Stations 3 and 4） generally discriminated the water quality status of the four stations. The difference in water quality among the stations was strongly supported by the pattern of species richness （i.e. the total number of species） of ciliates at each station. Our evaluation was consistent with the results of long-term water quality monitoring at the four stations. With increasing eutrophication, we observed also a compositional and functional shift in the ciliate assemblages from algivorous oligotrich/choreotrich to nonselective-omnivorous gymnostomatids to bacterivorous-detrivorous scuticociliatids. Thus, eiliates may be used to indicate the coastal water quality status of a given site.

Changes in the small-jellyfish community in recent decades in Jiaozhou Bay, China

We used long term monitoring data to evaluate changes in abundance and species dominance of small-jellyfish (collected with zooplankton net whose bell diameter was less than 5 cm) between 1991 and 2009 in the Jiaozhou Bay, China. Zooplankton samples were vertically towed with conical plankton net from near-bottom to surface, identified microscopically, and mapped in time-space using Grapher 7.0 and Surfer 8.0. Results show that the abundance of small-jellyfish throughout the bay had been increasing during 2001-2009 on average of 15.2 ind./m 3 , almost 5 times higher than that between 1991 and 2000. The occurrence of peak abundance shifted from spring to summer after 2000, and two peaks appeared in spring and summer, respectively, after 2005. Both the abundance and the frequency of blooms of small-jellyfish increased after 2000 in the bay. In addition, the biodiversity of jellyfish has increased significantly in recent years with a change in dominant species. Several new dominant species appeared after 2000, including Rathkae octopunctata in winter, Phialidium hemisphaericum in spring, summer, and autumn, Phialucium carolinae in spring, and Pleurobrachia globosa in summer and autumn, while some previous dominant species throughout the 1990s (Eirene ceylonensis, Zanclea costata, Lovenella assimilis, and Muggiaea atlantica) were no longer dominant after 2000. The abundance of small-jellyfish was positively correlated with the density of dinoflagellates, and the abundance of zooplankton. We believe that the changes in smalljellyfish abundance and species composition were the result of eutrophication, aquaculture and coastal construction activities around the bay. Concurrently, seawater warming and salinity decrease in recent decades promoted the growth and reproduction of small-jellyfish in the bay.

Spatiotemporal pattern of bacterioplankton in Donghu Lake

Bacterioplankton play key roles in the biogeochemical cycle and in organic contaminant degradation. The species richness and abundance of bacterial subgroups are generally distinct from each other, and this is attributed to their different functions in aquatic ecosystems. The spatiotemporal variations of eight phylogenetic subgroups （Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, Planctomycetes, alpha-, beta-, and gamma-Proteobacteria） derived from Donghu Lake were investigated using PCR-DGGE fingerprinting, to explore their responses to environmental factors. Results indicate that Actinobacteria and beta-Proteobacteria were the two largest bacterial subgroups detected. These two groups and Bacteroidetes showed clear seasonal patterns in composition of the operational taxonomic unit. Results also suggest that the bacterioplankton subgroups in Donghu Lake were significantly correlated with different environmental factors. In brief, the total nitrogen was one of the major factors regulating all the bacterioplankton except for Actinobacteria. However, total phosphorus, another important eutrophication factor, contributed to the two largest bacterial groups （Actinobacteria and beta-Proteobacteria）, as well as to the Cyanobacteria and Firmicutes. Therefore, the responses of bacterioplankton subgroups to environmental factors were different, and this should be attributed to the differences in the fimctions of different groups.

Seasonal Community Structure of Mesozooplankton in the Daya Bay,South China Sea

Mesozooplankton are key components of coastal ecosystems,linking the microbial food web to the classic food chain.In this study,species composition and abundance of mesozooplankton is studied for the Daya Bay in April(spring) and October(fall),2006.A total of 27 species of mesozooplankton were identified in spring and 58 species in fall.Dominant species were Oithona tenuis,Flaccisagitta enflata,Penilia avirostris and Centropages tenuiremis in spring,shifting to Microsetella norvegica,Oithona tenuis and Parvocalanus crassirostris in fall.Higher mesozooplankton abundance was found at Aotou Cove and Dapeng'ao Cove compared to other stations,indicating the influence of eutrophication on mesozooplankton community in the Daya Bay.The outbreak of Noctiluca scintillans bloom in spring reduced the species diversity and abundance of mesozooplankton.

Molecular characterization of cyanobacterial diversity in Lake Gregory, Sri Lanka

Eutrophication or the process of nutrient enrichment of stagnant waters due to excessive use of fertilizer is becoming a critical issue worldwide. Lake Gregory, an artificial lake situated in Nuwara Eliya, Sri Lanka was once a very attractive landscape feature and recreational area attracting a large number of visitors. Rapid urbanization in surrounding areas and the consequent intensification of agricultural and industrial activities led to eutrophication and siltation in the lake. Present study was conducted to detect cyanobacterial diversity and their ability to produce hepatotoxic microcystins using polymerase chain reaction (PCR)-based techniques. Twenty five water samples (surface and bottom) were collected from the lake and total nitrogen and total carbon were estimated. Cyanobacterial cultures were grown in appropriate media and microscopic observations were used to determine the morphological diversity of cyanobacteria isolated from different sites. Genomic DNA was isolated and purified from cyanobacteria using Boom's method. DNA samples were analyzed by PCR with oligonucleotide primers for 16S rRNA gene and mcyA gene of the operon that encodes a microcystin synthetase. The 16S rRNA gene sequences revealed the presences of cyanobacteria belong to Synechococcus sp., Microcystis aeruginosa, Calothrix sp., Leptolyngbya sp., Limnothrix sp., order Oscillatoriales and order Chroococcales. The sequences obtained from this study were deposited in the database under the accession numbers (GenBank: GU368104-GU368116). PCR amplification of mcyA primers indicated the potential for toxin formation of isolated M. aeruginosa from Lake Gregory. This preliminary study shows that the Lake Gregory is under the potential risk of cyanobacterial toxicity. Clearly more work is needed to extend this finding and clarify if other cyanobacterial isolates have genetic potential to produce microcystin since this lake is utilized for recreational activities.