Chen Kaining

Discussion on possible error for pbytoplankton chlorophyll-a concentration analysis using hot-ethanol extraction method

Hot-ethanol extraction method is a widely used method in the world to determine phytoplankton chloro- phyll-a concentration.This paper aims to introduce the hot-ethanol extraction method in detail to all the scientists dealing with aquatic environment research in China.By experience from the authors,possible error during the oper- ation of the analysis was discussed.Hot-ethanol extraction method is a widely used method in the world to determine phytoplankton chloro- phyll-a concentration.This paper aims to introduce the hot-ethanol extraction method in detail to all the scientists dealing with aquatic environment research in China.By experience from the authors,possible error during the oper- ation of the analysis was discussed.

Ecological restoration engineering in Lake Wuli, Lake Taihu:a large enclosure experiment

Lake Wuli is a hyper-eutrophic, shallow lake in China, situated near the Wuxi city in Jiangsu Province. It is a northern bay of Lake Taihu, which has a mean depth of 1. 6 m, a maximum depth of 2. 6 m and a surface area of 6.4 km2 . For improving water quality, from January 2004 a large-scale ecological restoration experiment( 10 ×104m) has been carried out in southwestern Lake Wuli. Main measures applied include setting-up a large enclosure for facilitating growth of submerged macrophytes, sediment dredging, fish removal, rehabilitating sediment, stocking piscivorous fish, planting aquatic macrophytes, stocking benthic animals and so on. The results showed that 23 aquatic macrophyte association had been set up, including 15 family, 22 genus and 32 species. The coverage of aquatic macrophytes increased from 0 to 40% -55%. Water quality has been markedly improved inside enclosure. The mean concentrations of TN , TP, NH4 - N , NO3 - N , NO2 - N and PO4 - P from August 2004 to July 2005 inside enclosure were 20. 7% ,23. 8% ,35. 2% ,21. 1% ,45. 6% and 54. 0% lower than those of outside enclosure. The mean concentrations of TN and TP were lower than 2. 50 mg/L and 0. 080 mg/L, respectively. Secchi depth was increased significantly from 0. 39m to 0. 70m. According to the results of this study, it is important and a first step to rehabilitate ecological structure and function in littoral of lakes, and to improve water quality gradual- ly , and to establish submerged macrophytes at length. Biomanipulation could be applied to increasing secchi depth, reducing algal biomass and improving water quality in open area for whole lake restoration.

Status of submerged macrophytes and its relationship with environmental factors in Lake Chaohu,2010

Based on the investigation of submerged macrophytes and its relational environmental factors in June,2010,Lake Chaohu,this paper analyzed the characteristics of submerged macrophyte community and distribution,discussed the relationship between submerged macrophytes and environmental factors with redundancy analysis.The results showed that there were 6 submerged macrophyte species in 5 families,4 genera.Total biomass of submerged macrophytes was about 8077.8t and their total distribution area was just 1.54% of the whole lake area.Potamogeton malaianus was the dominant species,which occupied 90.7% of the total distribution area of submerged macrophytes.Ceratophyllum demersum Linn.,Myriophyllum spicatum Linn.and Hydrilla verticillata(Linn.f.) Royle appeared rarely and had been at the verge of extinction.Monte Carlo test results showed that the correlation between TP,PO3-4-P,COD,SD,depth of water and the distribution of submerged macrophyte community was significant,however,TN had no significant effect,which suggesting that the distribution of submerged macrophyte community was more limited by P than N.The results also showed that the correlation between TN and TP of sediment and the distribution of submerged macrophyte community were not significant,while the influence of sediment TOC on the distribution of submerged macrophyte community was significant.Based on the investigation of submerged macrophytes and its relational environmental factors in June,2010,Lake Chaohu,this paper analyzed the characteristics of submerged macrophyte community and distribution,discussed the relationship between submerged macrophytes and environmental factors with redundancy analysis.The results showed that there were 6 submerged macrophyte species in 5 families,4 genera.Total biomass of submerged macrophytes was about 8077.8t and their total distribution area was just 1.54% of the whole lake area.Potamogeton malaianus was the dominant species,which occupied 90.7% of the total distribution area of submerged macrophytes.Ceratophyllum demersum Linn.,Myriophyllum spicatum Linn.and Hydrilla verticillata(Linn.f.) Royle appeared rarely and had been at the verge of extinction.Monte Carlo test results showed that the correlation between TP,PO3-4-P,COD,SD,depth of water and the distribution of submerged macrophyte community was significant,however,TN had no significant effect,which suggesting that the distribution of submerged macrophyte community was more limited by P than N.The results also showed that the correlation between TN and TP of sediment and the distribution of submerged macrophyte community were not significant,while the influence of sediment TOC on the distribution of submerged macrophyte community was significant.

Effects on nitrogen and phosphorus distribution in interstitial water and sediment-water nitrogen and phosphorus release with growing of submerged macrophytes

Effect with growing of submerged maerophytes on NH_4~+ -N and PO_4~(3-)-P concentration in the interstitial water was studied by using undisturbed core samples in Lake Talhu,and analyzed the relationship between biomas- ses of submerged macrophytes and amount of nitrogen and phosphorus release.The results showed that concentration of NH_4~+ -N from 0-5 cm in interstitial water was gradually reduced by the biomasses increase of submerged macro- phytes,and amount of nitrogen release is distinctly negative correlated with biomasses of submerged macrophytes; The PO_4~(3-) -P concentration in interstitial water change was me peak tendency by the growing of submerged macro- phytes,indicating that there was no distinct corlationships between amount of phosphorus release and biomasses of submerged macrophytes.There mingt exisf different biogeochemcal mechanism of the absorption of nitrogen and phosphorus by submerged macrophytes.

Influences of water depth gradient on photosynthetic fluorescence characteristics of Vallisneria natans

In order to study the influences of water depth gradients on photosynthetic fluorescence characteristics of Vallisneria natans,three water depths of 0. 6,1. 3 and 2. 0 m were set,and Chlorophyll fluorescence characters and rapid light curves( RLCs)of V. natans grew in three water depth treatments were measured by a submersible,pulse-amplitude modulated fluorescence: Diving-PAM. The results suggested that,with water depth increasing,the number of ramets and leaves,total root length,root surface area decreased significantly,while the maximum leaf length,average leaf length,maximum leaf width did not change significantly.The growth of V. natans under 2. 0 m were restricted. With the increase of water depth from 0. 6 m to 2. 0 m,the difference of minimum fluorescence( F0) and maximum fluorescence( Fm) were not significant,while maximum quantum yield of photosystemⅡ( PSⅡ) and fluorescence parameter Fv/ F0 increased significantly,which indicated that photochemical efficiency of PSⅡ of V.natans grew under the condition of 2. 0 m was improved remarkably. The photosynthetic efficiency in leaf of V. natans grew in water depth of 2. 0 m with lower light intensity was higher than that grew in water depth of 0. 6 m with higher light intensity,and V.natans grew in water depth of 0. 6 m had better light protection mechanisms via fluorescence quenching assay. Compared to the leaf of V. natans grew under the condition of 0. 6 m,the leaf grew in water depth of 2. 0 mgot higher relative electron transport rate,and the initial slope of RLCs,light suppression parameter,maximum electron transport rate and minimum saturating irradiance were significantly different. The contents of chlorophyll-a( Chl. a),chlorophyll-b( Chl. b),carotenoid( Car) of the leaf of V.natans grew in water depth of 2. 0 m were significantly higher than those grew in water depth of 0. 6 m,but the ratio of Chl. a and Chl. b,the ratio of Car and Chl. a were not significantly different. The experimental results above reveal that with the increase of the water depth from 0. 6 m to 2. 0 m,the photosynthetic capability of V. natans became weaker,however,the light protection mechanisms of the V. natans showed the reverse,indicating that V. natans was likely to adapt to different environment caused by water depths by adjusting itself photosynthetic physiology.

Physiological response of Phragmites communis seedling to two types of sediment under submergence and its recovering growth

Its important to study the response of wetland plants to submergence and its recovery growth status for lacustrine wetland restoration.In this study,we revealed the varieties of relative chlorophyll content(rChlc),malondi-aldehyde content(MDA) and chlorophyll fluorescence characteristics of Phragmites communis in submergence every 5 d during one month in two types of sediment(one from Lake Chaohu(LS),and the other from farmland(AS)),and its recovery status in 10 d,20 d and 30 d after submergence.Results showed that,compared to AS,P.communis growing in LS had higher rChlc and chlorophyll fluorescence characteristics during the rejuvenate period.rChlc decreased after submergence and obviously after 20 d,and further decreased by 40.82% and 39.49% in 30 d in LS and AS,respectively.However,MDA increased,and it was higher in AS than in LS.Chlorophyll fluorescence parameters Fv/Fm and Y both decreased,with significant correlation with rChlc varieties as a whole.The rapid light curves(RLCs) of P.communis growing in LS decreased slowly in 25 d,comparing to an obvious decrease in 15 d in AS.After submergence,rChlc and chlorophyll fluorescence characteristics of P.communis in two sediments all increased,with a greater range of the plant in AS than that in LS;however,they were both higher in LS than those in AS,and MDA had a same decreasing trend.It took longer time for P.communis to recover to the normal growth status with the extension of submergence,the leaves withered after 30 d submergence and sprouted new leaves and plant.At the same time,the recovery time was shorter of the plant grown in LS than that in AS.Consequently,submergence inhibits the growth of P.communis,and the inhibited effect is greater with the extension of submergence.It takes a short time for plant to recover to the normal growth status when in short submergence,and it needs to sprout new leaves and plants to adapt when in long submergence.Simultaneously,its meaningful for P.communis to increase its submergence tolerance and recover growth after submergence when growing in sediment with relative better nutritional status.

Growth and photosynthesis characteristics of the Nymphoides peltata under different temperatures

Roots of Nymphoides peltata collected from Lake Taihu were cultured under three different temperatures(28,30,32℃).The biomass under such different temperature conditions were 0.0019±0.0002,0.0021±0.0003 and 0.0020±0.0003g(DW)/cm2,respectively.Meanwhile,the dry weight of stem and root was maximum under 30℃ than other treatments thathad significant difference;the order of the dry weight and biomass per unit area of leave was 30℃28℃32℃.Light response curves and ACI curves were determined by a Li-6400 portable photosynthesis analysis system,and the non-rectangularhyperbolic method was used to fit the curve to obtain relevant photosynthetic parameters.The results showed that the influences of temperature on order of N.peltata photosynthetic capacity was 30℃32℃28℃,the order of carboxylation efficiency was 32℃30℃28℃,transpiration efficiency and stomatal conductance showed the same trend,30℃28℃32℃.The photosynthetic capacity of N.peltata increased significantly with the increasing temperature,and the growth of N.peltata was promoted;however,the photosynthetic efficiency reduced when the temperature exceeded 30℃ with the suppression of N.peltata.In the appropriate temperature range(30℃),small amplitude warming(2℃) produced a significant effect of accumulated temperature(200℃·d),which promote the growth of N.peltata.It is deduced that the phenomenon that the average temperature of Lake Taihu increased about 1℃ during 1998-2006 may promote the expansion of N.peltata in Lake Taihu in recent years.

Spatial distribution characteristics of soil nitrogen of four types of plant community in Zhucao river mouth wetland into the lake

Spatial distribution of nitrogen in the soil,biomass and nitrogen contents of Typha latifolia community,Polygonum hydropiper community,Juncus effuses community and Phragmites communis community in the Zhucao river mouth wetland into Daxi Reservoir in Liyang City,Jiangsu Province were studied.Significant differences of aboveground biomass,belowground biomass and nitrogen contents of four plants were found.Soil loss on ignition(LOI),total nitrogen(TN) and nitrate nitrogen(NO-3-N) concentrations showed decreasing trend on the vertical distribution with increasing depth.Ammonium nitrogen(NH+4-N) concentrations in soil profiles decreased first,and then increased.Soil nitrogen concentrations of the four plant communities were different,but most of them were higher than the control,and organic nitrogen was the main form,indicating that the wetland had a certain nitrogen storage capacity and different plant communities affected the distribution of nitrogen.The correlations between LOI and total nitrogen,ammonium nitrogen,nitrate nitrogen were significant.Inorganic nitrogen constituted only a small proportion(1.41%),which indicated that the nitrogen mainly presented in the organic form.However,there was nearly no correlation between biomass,nitrogen contents of four types of plant and nitrogen concentrations of each soil layer.This indicated that soil nitrogen contents were affected not only by the form of plant growth,but also by the plant root zone environment,the number and activity of microorganisms.

Response of phytoplankton to ecological restoration in eutrophic lakes:an experimental large enclosure in Wuli Lake,Lake Taihu

Response of phytoplankton to ecological restoration was evaluated based on the results of an experimental large enclosure in eutrophic Wuli Lake of Lake Taihu,China.The results indicated that in the first year of restora- tion,algal biomass significantly increased,and cyanobacteria blooms broke out although the coverage of aquatic plant was up to 55%;TN and TP were significantly decreased,and secehi depth was enhanced by 100% or so.in the next year,algal growth,including cyanobacteria and Microcystis,was inhibited in certain extent with improve- ment of environment in enclosure compared with that in the lake area(outside enclosure,a control area).The re- sult showed that response of phytoplankton to ecological restoration was a slow process.Higher TN and TP were not decisive factors for the breakout of cyanobacteria biomass though the increase of total algal biomass was caused by higher nutrition(TP).Bottom-up effort was weaker than top-down effort.The lower TN to TP ratio possibly facili- tated cyanobacteria growth,which was the cause and the result of cyanobacteria growth.In addition,the algal di- versity index(Shannon index)was not totally indicating aquatic environment improvement status.It was suggested that it needed to integrate many factors for evaluating the trend of ecosystem.

A Study on the environmental effect in the zone of restoration of aquatic plants at the northeastern Dianchi Lake: II. the effect on removing the pollutants

The effects of removing the pollutants by aquatic plants in the restoration zone in the northeastern of Di-anchi Lake were investigated in this paper. The volume of the pollutants removed from the lake by the aquatic plant harvesting and the sedimention had also been estimated. The result showed that the restoration zone had a remarkable accelerative effect on silting-up of the restoration. In the whole restoration zone, the average sedimentation flux was 118.9 kg/(m2·a). There fore it means about 120g/(m2·a) TN , 70g/(m2·a) TP and 1080g/(m2·a) TOC can be removed from lake. The situation of the sedimention in the zone has been improved a lot, as the concentration of TN and TOC in the surface sediment was 4 times as high as before. The amount of harvested aquatic plants was about 113000 kg in 2002 , which means that 30. 0 g/( m2·a) TN and 4. 8 g/( m2·a) TP were removed from lake. Therefore, it can be concluded that the restoration of aquatic plants in the littoral may be used as an effective engineering measure for lakes pollution control especially the algae bloom control at the northeastern Dianchi Lake, and in other severely polluted water bodies.The effects of removing the pollutants by aquatic plants in the restoration zone in the northeastern of Di-anchi Lake were investigated in this paper. The volume of the pollutants removed from the lake by the aquatic plant harvesting and the sedimention had also been estimated. The result showed that the restoration zone had a remarkable accelerative effect on silting-up of the restoration. In the whole restoration zone, the average sedimentation flux was 118.9 kg/(m2·a). There fore it means about 120g/(m2·a) TN , 70g/(m2·a) TP and 1080g/(m2·a) TOC can be removed from lake. The situation of the sedimention in the zone has been improved a lot, as the concentration of TN and TOC in the surface sediment was 4 times as high as before. The amount of harvested aquatic plants was about 113000 kg in 2002 , which means that 30. 0 g/( m2·a) TN and 4. 8 g/( m2·a) TP were removed from lake. Therefore, it can be concluded that the restoration of aquatic plants in the littoral may be used as an effective engineering measure for lakes pollution control especially the algae bloom control at the northeastern Dianchi Lake, and in other severely polluted water bodies.