Xukou Bay Research Articles

Cyanobacteria-blooming water samples from Lake Taihu induce endoplasmic reticulum stress in liver and kidney of mice

To investigate whether endoplasmic reticulum (ER) stress was involved in apoptosis induced by cyanobacteria-blooming water, healthy male ICR mice were fed with water samples from cyanobacteria-blooming regions of Lake Taihu (China), including Meiliang Bay (M1 and M2), central lake region (H), macrophyte-dominated Xukou Bay (X), and tap water (control group) for three consecutive months. Hepatic and renal mRNA and protein expression of ER stress signaling molecules were measured with quantitative real-time PCR and western blotting. Compared to macrophyte-dominated and control water samples, cyanobacteria-blooming water changed hepatic ER stress signaling molecules. M1 water treatment increased the mRNA and protein levels of glucose regulation protein 78 (GRP78) and C/EBP homologous protein (CHOP), and decreased the mRNA levels of B-cell lymphoma 2 (Bcl-2). M2 water treatment up-regulated GRP78 mRNA and protein expression, whereas H water treatment up-regulated mRNA and protein expression of GRP78 and caspase-12. Cyanobacteria-blooming water exposure also changed mRNA and protein expression of ER stress signaling molecules in the kidneys. M1 water exposure up-regulated GRP78 mRNA and protein expression and CHOP mRNA expression, whereas M2 water treatment up-regulated caspase-12 and Bcl-2 mRNA expression. M1 and M2 cyanobacteria-blooming water exposure significantly increased relative liver weights, and induced hepatic cell apoptosis. However, cyanobacteria-blooming water treatment did not change kidney weights, and did not induce renal apoptosis compared to macrophyte-dominated and control water samples. Hence, cyanobacteria-blooming water induces hepatic apoptosis via ER stress, and ER stress may play an important role in the apparent anti-apoptotic effects on renal cells exposed to cyanobacteria-blooming water.

Screening level ecological risk assessment for synthetic musks in surface water of Lake Taihu, China

A total of thirty-three surface water samples were collected from Meiliang Bay, Gonghu Bay and Xukou Bay of Lake Taihu, and analyzed for synthetic musks, including 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-[γ]-2-benzopyrane (HHCB), 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN), 1-tert-butyl-3,5-dimethyl-2,5-dinitro-4-acetylbenzene (MK) and 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (MX). Ecological risks of these compounds were characterized by hazard quotient (HQ) method due to a lack of sufficient available toxicity data of synthetic musks. HHCB was the main synthetic musk detected in Lake Taihu, followed by AHTN, MK, and MX. The risk assessment results indicate that low ecological risks were posed by HHCB and total synthetic musks, and even lower risks posed by other synthetic musks in the worst case; much lower ecological risks were caused by both individual and total synthetic musks in the general case. The combined ecological risk from total synthetic musks calculation suggests that the combined ecological risk from all four synthetic musks was expected to be slightly higher than for the individual musks due to their joint action. The HQ spatial distribution maps show that several hot-spot areas were mainly around the river inlets to Lake Taihu, indicating that synthetic musks may be transported to Lake Taihu with municipal sewage and industrial wastewater from surrounding areas. However, the ecological risks in hot-spot areas posed by individual and total synthetic musks were still acceptable.

Chlorinated and brominated dibenzo-p-dioxins and dibenzofurans in surface sediment from Taihu Lake, China

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in surface sediment samples from Taihu Lake--an important water supply of the Yangtze River Delta, China--were investigated in the present study. Concentrations of PCDD/Fs ranged from 0.91 to 4.8 pg TEQ g(-1) dw (mean: 2.9 pg TEQ g(-1) dw, TEQ: Toxic Equivalent), which were all higher than the threshold effect level established by interim sediment quality guidelines in Canada (0.85 pg TEQ g(-1) dw). The levels of PBDD/Fs ranged from 0.16 to 1.6 pg TEQ g(-1) dw (mean: 0.52 pg TEQ g(-1) dw) and accounted for 5-33% (mean: 14%) of the total PCDD/Fs and PBDD/Fs TEQ. Comparatively, the abundance of sedimentary PCDD/Fs in the three regions (Meiliang Bay, Gonghu Bay, and Xukou Bay) showed a decreasing trend from the inflow region to the outflow region, while no significant difference was observed among their 2,3,7,8-PBDD/Fs levels, which suggested that the sources of PCDD/Fs and PBDD/Fs differed in this area. Principal component analysis suggested that the historical production/usage of pentachlorophenol and sodium pentachlorophenate was the dominant source of PCDD/Fs in the sediment of these regions. Although the specific sources of PBDD/Fs in the sediment of Taihu Lake were unclear, it was suspected to be due to atmospheric deposition; however, an additional study is needed to confirm this.

Characterizing ecological risk for polycyclic aromatic hydrocarbons in water from Lake Taihu, China

Lake Taihu provides vital ecological services for humans in China; it receives a great deal of attention regarding its ecological and environmental conditions. In this study, the ecological risks of eight individual polycyclic aromatic hydrocarbons (PAHs) in water were assessed using probabilistic distributions of the hazard quotient based on Monte Carlo simulation. The results show that the 95th percentile of the hazard quotients ranged from 0.00074 to 2.831, and the ecological risk of Flua was highest, followed by, in descending order of risk, B[a]P > Pyr > Ant > Phe > Flu > Ace > Chr. The probabilities of hazard quotients exceeding a decision criteria of 0.3 were 18.09%, 6.51%, 3.76%, and 2.85% for Flua, B[a]P, Pyr, and Ant, respectively, indicating their potential ecological risks to aquatic organisms. The spatial distribution of hazard quotients for these four individual PAHs with potential ecological risk were obtained using Geographic Information System (GIS), and similar spatial distribution patterns were also observed in the lake. The highest ecological risks of these four individual PAHs to aquatic organisms were found in Meiliang Bay, followed by Gonghu Bay and Xukou Bay. The uncertainty within the ecological risk assessment was also discussed.

Assessing the toxicity of ingested Taihu Lake water on mice via hepatic histopathology and matrix metalloproteinase expression

Water from Taihu Lake (China) is used as a drinking source. The frequency of contamination in Taihu Lake has increased over the past decade and the bloom-forming cyanobacteria are the dominant species during eutrophication. Cyanobacteria can produce various harmful secondary substances including microcystins capable of endangering human health and ecological safety. This study investigated toxicity of ingested Taihu Lake water on mice via hepatic histopathology and matrix metalloproteinase (MMP) expression. Water was sampled from four Taihu Lake locations, Meiliang Bay 2 group (M2), Meiliang Bay 1 group (M1), Lake Center (H) and Xukou Bay (X), along a gradient of decreasing degree of eutrophication. The experimental design consists of five groups of male mice (Mus musculus, ICR): one control and four groups ingesting water from the four sampling sites for 90 days. Compared to control, M1 and M2 mice showed hepatic histopathological changes including swollen, vacuolar degeneration or inflammatory. Immunohistochemical staining demonstrated a higher expression of MMP-2 proteins in M2 group and a lower expression of MMP-9 in M1. Enzyme-linked immunosorbent assay indicated that MMP-9 concentration was significantly reduced from 0.55 to 0.28 ng/g liver weight in M2 (p < 0.05). Real time PCR revealed a down-regulation of MMP-9 mRNA by 2.2 fold in M1 and an up-regulation of MMP-2 mRNA by 1.73 fold in H. Using this mouse model as a gauge of water toxicity, our results revealed that potential health risks induced by Taihu Lake water might arise from the use of this source water by local resident.

Uptake of various forms of nitrogen by phytoplankton community in spring in Lake Taihu

为研究太湖春季浮游植物群落氮吸收特征及其与浮游植物群落结构和环境因子的关系, 于2010年5月中旬采集太湖6个点位水样, 利用15N稳定同位素示踪技术, 测定太湖浮游植物群落对硝态氮, 铵态氮和尿素的吸收, 结果表明:太湖浮游植物群落对铵态氮的吸收速率均值最高, 占几种氮总吸收量ρ(DN)的62.8%, 各点位值在0.181-1.575μmol/(L·h)之间.各点位浮游植物群落对硝态氮和尿素态氮的吸收速率范围分别为0.004-0.118μmol/(L·h)和0.043-1.116μmol/(L·h).梅梁湾, 湖心以及五里湖三个湖区浮游植物群落均优先吸收铵态氮、其次为尿素, 对三种氮的吸收速率都是ρ(NH₄) >ρ(UREA) >ρ(NO<sb>3</sub>), 而胥口浮游植物群落优先吸收尿素, 且对尿素的绝对吸收速率最大, 其次为铵态氮, 硝态氮最低.在可利用氮含量较高的情况下, 浮游植物丰度、组成结构等因子可能是影响太湖浮游植物群落氮吸收空间差异的最重要因素。;To characterize the nitrogen uptake by phytoplankton and its relationships with phytoplankton community structure and enviromental factors,we measureed the uptake of ammonium,nitrate and urea by phytoplankton community from different areas of Lake Taihu in mid-May, 2010,using the ¹⁵N-tracer technology.The results showed that:Uptake rate of ammonium was highest for all lake areas,accounting for 62.8% of the total nitrogen uptake.The uptake rates were 0.181-1.575, 0.004-0.118 and 0.043-1.116μmol/(L·h) for ammonium,nitrate and urea,respectively.Phytoplankton communities preferred uptaking ammonium in Meiliang Bay,Lake Center and Wuli Bay and the uptake rates of the three forms of nitrogen were arranged as follows:ρ(NH₄) >ρ(UREA) >ρ(NO₃).However, phytoplankton community in Xukou Bay preferred urea to ammonium and the uptake rate of urea was the highest,the uptake rate of nitrate was the lowest.When concentrations of nitrogen are high,phytoplankton abundance and com-munity structure are likely important factors determining the nitrogen uptake by phytoplankton community in Lake Taihu.

Sedimentary record of hydrophobic organic compounds in relation to regional economic development: A study of Taihu Lake, East China

Sediment cores taken from Taihu Lake, East China were analyzed for polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polybrominated biphenyl ethers (PBDEs). The results showed a general sharp increase of HCH, DDT, PAH and PBDE concentrations in the surface layers, corresponding to a sedimentation time of 1980 and 1990 onward in the Meiliang Bay and Xukou Bay, respectively. The source of PAHs has largely transferred from petrogenic to pyrogenic origin, and good relationships were observed between sediment PAH concentrations and the regional gross domestic product. The sharp increase of DDTs in recent years may be related to the mobilization and migration of these chemicals from surface soil to lake sediment, as a result of enhanced soil run-off due to large scale land transform, as well as the contribution of current usage of dicofol and DDT-containing anti-fouling paints.

Calculation and retrieval of euphotic depth of Lake Taihu by remote sensing

The euphotic zone is defined as the layer where net phytoplankton production is positive. Therefore, determination of the euphotic depth is useful for estimating primary production. The TM data on 2007-01-07 and 2006-08-01, accompanied by real-time water quality parameters including concentrations of tripton and chlorophyll-a (Chl.a) in Lake Taihu, were used to develop quantitative retrieval models of tripton and Chl.a. Euphotic depth was calculated using the model developed in Lake Taihu based on the concentrations of tripton and Chl.a. The euphotic depth ranged from 0.27 to 2.28m (mean 0.56±0.22m) in winter depth from 0.21 to 2.03m (mean 0.98±0.24m) in the summer. In the winter, the euphotic depths showed spatial distributions which were ordered as : the south of Lake Taihu the west coast of Lake Taihu the lake center Xukou Bay Gonghu Bay Meiliang Bay East Lake Taihu Zhushan Bay. In summer, the order changed as follows: the west coast of Lake Taihu Meiliang Bay East Lake Taihu the lake center Gonghu Bay Zhushan Bay the south of Lake Taihu. Seasonally, the euphotic depth was significantly shallower in summer than in winter; however, seasonal variation differed among areas of the lake. Euphotic depths in Meiliang Bay, Gonghu Bay, the west coast of Lake Taihu, the lake center, Xukou Bay and the south of Lake Taihu were higher in the summer than in the winter, but no marked seasonal variations were found in Zhushan Bay and East Lake Taihu.

Distribution of colloidal enzymatically hydrolysable phosphorus in natural waters

分别在太湖草型湖区胥口湾及藻型湖区梅梁湾采集水样,采用常规过滤与切向流超滤相结合的方法,将水体中的颗粒/胶体依据粒径大小分离,通过测定计算得到64-1μm,1-0.5μm,0.5-0.1μm,0.1μm-1nm,<1nm五个粒级的可酶解磷含量.同时采集太湖引江济太工程长江调水口—望虞河口水样、千岛湖水样及千岛湖下游河流型水库富春江段水样进行分析.结果显示,5种典型水体中颗粒相的可酶解磷含量占总可酶解磷含量的比重较高,胶体相的可酶解磷也占了相当的比重,是生物必需磷不可忽视的重要储库.望虞河口河水总磷0.216mg/L,可酶解磷含量达0.174mg/L,其输入可能对太湖水体生物有效磷浓度的增加起到重要的贡献,引江济太调水时具有一定生态风险.对于胶体范围的可酶解磷,胥口湾、望虞河的胶体态可酶解磷主要分布在较大、中胶体范围,梅梁湾和千岛湖的胶体态可酶解磷主要分布在中、微胶体范围,富春江水库的胶体态可酶解磷分布的相对比较均匀.;Contents of enzymatically hydrolysable phosphorus (EHP) in particle and colloidal phases in Lake Taihu were analyzed. Colloid in lake water was separated by tangential flow ultrafiltration, which included the component with diameters from 1nm to 1000nm. The EHPs from Wangyu River, a large water channel connected Lake Taihu with Yangtze River, and from Lake Qiandao and Fuchun River were also studied. Mean of particle EHP (particle size larger than 1000nm) accounted 58% of total EHP, which was the main contributor in the water. Mean of colloidal EHP accounted 35% of total, which also shows a high ratio compared to the true dissolved phosphorus. During the investigation period, total phosphorus and EHP in Wangyu River were 0.216mg/L and 0.174mg/L, respectively, suggesting that there is a high ecological risk to pump too much Yangtze River water to Lake Taihu. In Lake Taihu, percentage of micro-size colloid in marcophyte dominated zone (Xukou Bay) was much higher than that in cyanobacteria dominated zone (Meiliang Bay).

Spatial pattern of euphotic depth and estimation of phytoplankton primary production in Lake Taihu in autumn 2004

基于2004年10月对全湖67个采样点水下光合有效辐射(photosynthetically active radiation:PAR)和各光学活性物质浓度的测定,分析了真光层深度的空间分布及其影响因素.利用实测的叶绿素a浓度,真光层深度,PAR强度,由水温计算得到的最佳固碳速率以及由经纬度计算的日照周期等,在垂向归纳模型(vertically generalized production model:VGPM)的支持下估算了全湖秋季浮游植物初级生产力.真光层深度的变化范围为0.37-5.27m(均值为1.52±1.06m),高值出现在东太湖、胥口湾、东西山之间等水生植物分布茂盛的草型湖区,而在梅梁湾、湖心区以及西南面的开阔湖区真光层深度均较小.回归分析显示,真光层深度主要受制于非色素颗粒物浓度,浮游植物和溶解性有机物的贡献相对要小得多.叶绿素a浓度和VGPM模型估算的浮游植物初级生产力变化范围分别1.21-53.59μg/L、77.4-2484.9mg/(m²·d),其时空分布基本一致,高值出现在富营养化的藻型湖区梅梁湾,低值出现在胥口湾和西南开阔湖区.VGPM模型和经验模式对比结果显示两者值比较接近并存在显著相关(r²=0.79,p<0.0001),两类模型全湖的均值分别为694.5±492.0、719.8±315.4mg/(m²·d),但由于VGPM模型考虑到真光层深度、温度、PAR强度以及日照周期对初级生产力的影响,其变化范围明显大于经验模型,也更能反映初级生产力的空间变化.;Based on the underwater photosynthetically active radiation (PAR) profile measurement and the concentrations of the optically active substances, the spatial patter and affecting factors of euphotic depth in Lake Taihu are discussed. Phytoplankton primary production (PP_eu) of all the lakes in autumn 2004 is estimated using the vertically generalized production model (VGPM) based on measured surface chlorophyll-a (Chl.a) concentration, euphotic depth, water temperature, PAR at the water surface, photoperiod and water depth. Euphotic depth ranges from 0.37 to 5.27m with a mean value of 1.52±1.06 m. The higher euphotic depth appears in the macrophyte-dominated lake regions such as East Lake Taihu, Xukou Bay and water area between Xishan and Dongshan Islands. In contrast, the lower euphotic depth is found in algal-dominated lake region such as Meiliang Bay and the southwestern open water. The regression analyses show that euphotic depth is mainly controlled by nonpigment particle matter, next to phytoplankton and chromophoric dissolved organic matter (CDOM). Nonpigment particle matter can explain 96.7% variation of euphotic depth. The ranges of Chl.a concentration and estimated PP_eu are 1.21-53.59μg/L, 77.4-2484.9mg/(m²·d), respectively. The estimated daily mean PP_eu distribution coincides closely with that of Chl.a concentration. Higher Chl.a and PP_eu values are recorded in Meiliang Bay and lower values are found in Xukou Bay or southwestern open water. There is a good correlation between VGPM PP_eu and primary production from the empirical model (PP_em)(r² = 0.79, p<0.0001). Daily mean_eu and PP_em of all the lakes are 694.5±492.0, 719.8±315.4mg/(m²·d), respectively. Although the ranges of the two methods differ, the mean values are very close. PP_eu more accurately captures spatial variation by considering the effect of euphotic depth, water temperature, surface PAR and photoperiod on PP.

The scattering characteristics of Lake Taihu waters

利用Wetlabs公司研制的AC-S和BB9于2006年10月24日至11月2日对太湖水体的散射系数和后向散射系数进行了测量,在此基础上建立了太湖水体散射系数与后向散射系数之间的关系模型.用2种曲线函数模拟,即在蓝光波段使用S形曲线模型,在绿光和红光波段使用逆函数模型,各模型的MAPE和RMSE变化范围分别为0.027-0.156m^-1、0.005-0.050m^-1,模型整体预测精度都较高.研究发现后向散射系数与散射系数的空间分异现象明显,北部梅梁湾、湖心区、西部及西南部水域散射较强,而东太湖、胥口湾等东部水域的散射相对较弱.;Based on water inherent optical properties using AC-S and BB9, which were developed by WETlabs Inc, the backscattering and scattering coefficients of Lake Taihu waters had been obtained from Oct. 24th to Nov. 2rd, 2006. Based on data analysis, the models between backscattering coefficients and scattering coefficients had been established. Two kinds of curve functions had been used to simulate, i.e. S curve at blue waveband and inverse function at green and red wavebands. And the change ranges of MAPE and RMSE are 0.027-0.156 m^-1 and 0.005-0.050m^-1, which indicated higher accuracy. Meanwhile, marked spatial distribution differences of the backscattering and scattering coefficients were found in Lake Taihu. As far as the entire lake was concerned, the scattering and backscattering coefficients in wester lake regions were higher than those in eastern lake regions. Strong scattering and backscattering were found in Meiliang Bay, center region of lake, western and southwestern lake region, while weak values were in East Lake Taihu and Xukou Bay.

Optically active substances and their contributions to the underwater light climate in Lake Taihu, a large shallow lake in China

There are few data sets on optically active substances and optical conditions to partition the relative contribution of every substance on light attenuation in a lake. To address this need, underwater photosynthetically active radiation (PAR), optical parameters and concentrations of three optically active substances, tripton (non- phytoplankton particulate matter), chlorophyll-a (Chl-a), chromophoric dissolved organic matter (CDOM) were measured at 67 sites in Lake Taihu, a large shallow lake in China in October 2004. The spatial variation of optically active substances and their relative contributions to the underwater light climate were determined. The PAR diffuse attenuation coeffi cient Kd(PAR) at different sites varied between 0.87 and 12.43 m -1 , with a mean of 4.42 m -1 . Sig- nifi cant spatial differences were found for optically active substances and PAR attenuation, with low concentrations and weak light attenuation in macrophyte-dominated bays such as East Lake Taihu, Xukou Bay and Gongshan Bay, and high concentrations and strong light attenuation in the open water and algae-dominated areas such as the center of the lake, southwestern region, and Meiliang Bay. The mean relative contributions of tripton, Chl-a, and CDOM to light attenuation were 82.6 %, 9.7 %, and 6.8 % of Kd(PAR), respectively. Tripton was the dominant constituent of Kd(PAR), and mean of 97.5 % of the variation in Kd(PAR) could be explained by tripton. In autumn, the relative contribution of CDOM to light attenuation was lower than that of phytoplankton. We conclude that suspended par- ticulate matter, rather than dissolved organic matter, is the dominant factor for PAR attenuation in Lake Taihu.