香溪河库湾春季叶绿素a 浓度动态及其影响因子分析

2005年3月至4月,对三峡水库香溪河库湾的叶绿素a动态及其与TN、TP等环境因子的关系进行了研究。结果表明,从香溪河库湾下游到上游,叶绿素a存在明显的水平分布。在时间分布上,3月17日暴发一次大规模的水华,4月份水华的暴发有一个明显的平面推移的过程。叶绿素a浓度与TN、TP之间存在着一定的负相关关系,TN与叶绿素a浓度的相关性较显著。香溪河库湾极可能是N限制型水体,而不受P限制。叶绿素a与透明度存在反双曲线关系,与溶解氧呈显著正相关关系。     

三峡水库香溪河库湾夏季水华调查

以三峡水库支流香溪河为研究对象,以2011年夏季的采样数据为基础,比较分析了水华前后支流库湾营养盐和叶绿素a的时空分布规律及其相关性。结果表明,2011年6月21—29日,香溪河暴发了显著的藻类水华,叶绿素a峰值达到125.8 mg·m-3。相关分析表明,水华过程显著影响可溶性无机N、P的空间分布,营养盐空间分布从中游高、河口低,转变为从河口至上游递减,并且在水华区域锐减;长江干流较高的营养盐本底值增大了支流库湾水华的风险;高营养盐背景值的长江干流水体在香溪河库湾的潜出位置是水华最严重的区域;干流水体对库湾表层的营养盐补给作用是影响库湾水华生消的关键因素。     

香溪河库湾春季水华期间硝酸盐、磷酸盐的时空分布

在三峡水库香溪河库湾春季水华连续暴发期间(2005年2月26日—4月28日)对香溪河与长江汇合处(河口)至香溪河库湾上游库尾处总计14个采样点进行连续监测,结果表明硝酸盐和磷酸盐在库湾中存在明显的时空分布规律。在空间上,河口的硝酸盐浓度高,库尾浓度低,其变化趋势是随着与河口距离的增加而降低;磷酸盐的分布规律是库尾的浓度高,河口的浓度低,其变化趋势与硝酸盐恰好相反。各采样点硝酸盐和磷酸盐浓度在时间上也呈现出明显的规律。河口硝酸盐的浓度在不同时间变化幅度较小,库尾采样点的硝酸盐浓度的变化幅度较大,随着与河口距离的增加硝酸盐浓度在不同时间的变化幅度逐渐增大。各样点磷酸盐在时间上的变化趋势是样点S04-S08的变化幅度较大,位于香溪河库湾河口和库尾的变化幅度较小。     

三峡水库富营养化问题与对策研究

三峡水库蓄水后,大部分库湾已出现富营养化态势,并暴发了数次以甲藻(拟多甲藻)和硅藻(小环藻)为主的水华现象,特别是在春季。以香溪河库湾为例,分析两周年的营养状态变化,总体上说,除冬季外,大多数月份为富营养,在春季则为重富营养。对三峡水库22条入库支流库湾的营养状态进行综合评价,结果表明,有5条(22.7%)支流库湾为中营养,17条(77.3%)支流库湾为富营养(重富营养化支流库湾有10条,占45.5%);但三峡水库本身水质尚好,仍保持中营养状态。统计分析表明,入库支流流域的年均流量和流域面积与支流库湾叶绿素a存在显著负相关关系,说明支流库湾越小或年均流量越小,藻类叶绿素a浓度就越高,即越容易在春季形成水华。文中讨论了控制和减缓富营养化几项措施。     

香溪河库湾春季水华期间可溶性碳动力学研究

2005年2月23日—4月28日,对三峡水库香溪河库湾内一样点进行每天采样,监测水体中叶绿素a与可溶性碳(DOC)浓度的变化,研究在春季水华暴发期间DOC的动力学特性。监测结果表明,随着时间的推移,叶绿素a有逐渐升高的趋势。其间共暴发了两次水华,其中第一次历时较短,第二次历时较长。DOC的变化趋势与叶绿素a基本吻合。整个暴发过程中的叶绿素a与DOC的回归分析表明,二者具有较好的相关性(R2=0.62),但第一次暴发过程中的相关性很高(R2=0.72),而第二次暴发过程中的相关性较低(R2=0.30)。根据天然水体中DOC来源的主要途径,推测在第一次暴发过程中DOC的来源主要是水体中藻类的光合作用的代谢产物,而第二次暴发过程中DOC的来源主要是水体中藻类死亡腐烂而产生的有机物质。     

三峡水库香溪河库湾夏季藻类水华的时空动态及其影响因素

2008年6-8月,三峡水库香溪河库湾相继暴发蓝藻和绿藻水华.依据香溪河库湾夏季的每周监测,对研究区2次水华分别进行聚类和判别分析,研究了2次水华的时空动态及其影响因素.结果表明：研究区2次水华过程均可划分为无水华组、过渡组和水华组;2次水华的暴发对可溶性硅(DSi)、硝态氮与亚硝态氮(NO₃--N+NO₂^--N)和磷酸盐(PO₄^3--P)3种营养盐的吸收程度不同;蓝藻水华暴发期间的DSi、总氮/总磷(TN/TP)、DSi/TN和DSi/TP值均低于绿藻水华;判别蓝藻水华暴发的参数为叶绿素a(Chl a)、TN和PO₄^3--P,而Chl a和DSi则是绿藻水华暴发的判别因子,将2次水华过程划分为水华组和无水华组的判别效果更好;判断蓝藻和绿藻水华暴发的叶绿素a临界浓度分别为40和20 μg·L^-1.     

香溪河库湾轮虫现状及水质评价初探

香溪河是长江三峡水库湖北省最大的支流。通过对香溪河库湾(下游河段)一周年的调查,发现轮虫80种,其中占优势的有13种。轮虫密度在不同样点差异显著,样点Ⅸ最低(仅为68.96 ind./L),样点Ⅵ最高(为1505.83ind./L);对9个样点进行聚类分析,可分为4组,第1组为样点Ⅰ至Ⅴ,第2组为样点Ⅵ,第3组为样点Ⅶ、Ⅷ,第4组为样点Ⅸ;除样点Ⅸ外,沿着水流方向,轮虫密度逐渐降低;在时间上差异也显著(P<0.01),9月份最高(2664.17ind./L),12月份最低(85.00ind./L)。水质评价表明香溪河库湾属于中污染。     

香溪河库湾水体异养细菌及无机磷细菌分布特征

2003 年三峡水库蓄水后, 香溪河入库区段形成典型的水库型库湾, 磷污染严重, 导致水华频发。异养细菌是水体物质循环的重要参与者, 其中无机磷细菌释放结合态磷加重了水体富营养化。为了研究异养细菌和无机磷细菌对水体富营养化的影响, 在库湾设置7 个采样点, 2015 年 4 月、6 月、9 月和12 月分别采集水样, 测定样品总氮(TN)、总磷(TP)、磷酸盐(PO₄-P)及表层(水面下方0.5 m)水体叶绿素a(Chl.a)浓度, 实验室培养异养细菌及无机磷细菌。利用SPSS 17.0 对水体可培养异养细菌和无机磷细菌的时空变化进行单因素方差分析, 并用SPSS 软件分析细菌含量与总氮浓度、总磷浓度、磷酸盐浓度和叶绿素 a 浓度的相关性。结果显示: 异养细菌和无机磷细菌含量与叶绿素 a 浓度无显著相关性; 无机磷细菌与氮磷相关性均高于异养细菌, 说明香溪河库湾无机磷细菌与水体氮磷关联性大于异养细菌。     

香溪河库湾枝角类的种类组成及垂直分布

枝角类在水库生态系统的物质循环和能量流动过程中具有重要的作用,有关水库枝角类的研究在水库水生生物研究中历来备受重视[1,2]。枝角类在深水水体中具有垂直分布的特性,生物和非生物因素影响着包括枝角类在内的浮游动物垂直分布及垂直分布的时空变化[3,4]。香溪河河口至兴山峡口段在2003年6月三峡水库蓄水后被淹没,形成香溪河库湾。因受干流库区的水体顶托,库湾水体流速缓,更新时间长,容易产生富营养化现象,香溪河库湾2004年春季就有藻类异常繁殖现象发生[5]。滤食性的枝角类与藻类具有捕食和被捕食关系,枝角类的垂直分布及其在垂直方向上…     

三峡水库香溪河库湾春季水华期间悬浮物动态

在三峡水库香溪河库湾春季藻类水华期间开展了水体悬浮物动态研究.调查结果表明：总悬浮物浓度的中位数是6.80 mg·L^-1, 波动范围是0.66～134.92 mg·L^-1,从河口到库尾入库点呈现逐渐递增的趋势;无机悬浮物空间格局与总悬浮物基本相似,而有机悬浮物空间格局与总悬浮物差异较大,与叶绿素a较为相似.回归分析表明：库湾中部水域叶绿素a与总悬浮物、有机悬浮物均有显著的线性关系,分别解释了总悬浮物、有机悬浮物总变异的66.7%～96.7% 和 58.9%～85.5%;在库湾两端（河口与库尾）叶绿素a与悬浮物参数均没有显著的线性关系.在库湾中部水域,有机悬浮物比无机悬浮物更能解释总悬浮物的变异;在库湾两端,无机悬浮物比有机悬浮物更能解释总悬浮物的变异.这意味着库湾中间水域总悬浮物的动态主要受有机悬浮物内源性生产的影响,而河口或库尾总悬浮物的动态主要受外源性的无机悬浮颗粒物输入的影响.     

Role of dissolved organic carbon in the attenuation of photosynthetically active and ultraviolet radiation in Adirondack lakes

1. We surveyed eighty-five lakes located in the Adirondack Mountain Region of New York State, U.S.A., to characterize the attenuation of photosynthetically active (PAR) and ultraviolet radiation (UVR) in relation to dissolved organic carbon (DOC) concentrations and pH. Attenuation of PAR was quantified in situ . Attenuation was also inferred by measuring the light absorption of filtered lake water samples at wavelengths (300, 340 and 440 nm) representing UV-B, UV-A and PAR.
2. Substantial variation in transparency was observed among lakes in this region. Attenuation depths ( z _1%) for PAR ranged from 0.5 to greater than 20 m, while inferred values for UV-B and UV-A ranged from a few centimetres to > 5 m. Median values of UV-A penetration (0.75 m) and UV-B penetration (0.45 m) corresponded to 11% (UV-A) and 6% (UV-B) of lake maximum depth.
3. Much of the variation in PAR and UVR attenuation was explained by differences in lake DOC. Univariate power models based solely on DOC accounted for 85% (PAR), 90% (UV-A) and 91% (UV-B) of the variation in absorption.
4. Attenuation and absorption coefficients were generally lower for recently acidified lakes compared to acidic and circumneutral lakes which have not undergone recent acidification. However, differences among these three groups of lakes were not statistically significant. Our results suggest that the effects of acidification on the optical properties of a regional population of lakes, even in an area experiencing widespread acidification, are relatively subtle in comparison with other factors contributing to inter-lake variability.
5. The presence of near-shore wetlands is probably a key factor influencing regional variability in DOC and light climate among Adirondack lakes. Temporal variability in climatic factors influencing wetland DOC production and export may mask more subtle influences on lake DOC associated with anthropogenic acidification.     

Spatial and temporal patterns of light attenuation among lakes of the Mackenzie Delta

SUMMARY 1. The seasonal dynamics of light attenuation, and the relative roles of total suspended solids (TSS), dissolved organic carbon (DOC) and chlorophyll as light attenuators among two sets of lakes in the Mackenzie Delta, were assessed during the open‐water periods of 1998 and 1999. 2. The first set consisted of 40 spatially discrete lakes where the frequency of flooding with river water was controlled by sill height (‘sill‐set lakes’). The second set consisted of a chain of six lakes connected to a main river channel (frequently flooded, all with same frequency), but where riverine influence was controlled by the distance from the channel connection point (‘chain‐set lakes’). 3. As the flooding frequency of lakes decreased (sill‐set), and as the distance from the channel connection point increased (chain‐set), lake water became increasingly transparent and the stability (decreasing temporal variability) of underwater light increased. 4. The effect of flooding on transparency was greater in years with a high minimum summer water level. However, the effect of river flooding on lake water transparency was damped more by an increase in the frequency and duration of flooding than by an increase in distance from the channel connection point. 5. The index of scattering was linearly related to TSS over the common range of concentrations in both sets of lakes. The specific attenuation coefficient for TSS (and scattering) increased substantially from the most turbid to the most transparent waters. 6. During the summer, DOC provided an approximate index of water colour in the sill‐set lakes but not in the chain‐set lakes, where the gradient of DOC ran counter to the gradient of water colour. The specific attenuation coefficient for water colour was roughly constant among both sets of lakes. 7. Calculations of partial attenuation show that, during the spring flood peak, TSS is the dominant attenuator among most lakes, other than those with high sills or positioned far from channel connection points. During the lengthy summer period of open water, however, water colour appeared to be the most important light attenuator among almost all of the lakes in the central delta, with chlorophyll a of only minor importance. 8. Lakes of the Mackenzie Delta may be quite sensitive to changes in climate and ultraviolet‐b (UV‐b) radiation in the circumpolar arctic because of the role of DOC as an attenuator of photosynthetically active radiation and UV‐b irradiance and as an energy source for microbial foodwebs in this system.     

Effects of seston on ultraviolet attenuation in Lake Biwa

We examined the attenuation of underwater ultraviolet (UV) radiation and photosynthetically available radiation (PAR) in Lake Biwa, Japan, at offshore and inshore sites and under contrasting stratification and mixing regimes. There were large spatial differences in the water column transparency to both wavebands, despite little change in concentrations of dissolved organic carbon (DOC). The 1% of surface irradiance depth varied from 0.3 to 2.7 m at 305 nm, from 0.8 to 6.3 m at 380 nm, and from 2.3 to 12.8 m for PAR. Both PAR and UV transparency declined abruptly in the South Basin of the lake when a typhoon caused the resuspension of sediments. The water column ratio of UV to PAR increased by 30% at all stations over the course of a 3-week sampling period associated with the general increase in phytoplankton concentrations. At several sites, the diffuse attenuation coefficient for UV radiation deviated substantially from that predicted from UV-DOC models. A significantly positive linear relationship was found between UV attenuation (K _d determined with a profiling UV radiometer) and the beam attenuation coefficient at 660 nm as measured by transmissometer. These results indicate that scattering and absorption by particulate matter can reduce UV transparency to below that inferred from DOC concentrations, and that current UV-exposure models should be modified to incorporate this effect. Received: March 21, 2001 / Accepted: August 17, 2001     

Temporal Coherence of Chlorophyll a during a Spring Phytoplankton Bloom in Xiangxi Bay of Three‐Gorges Reservoir,China

Algal bloom phenomenon was defined as “the rapid growth of one or more phytoplankton species which leads to a rapid increase in the biomass of phytoplankton”, yet most estimates of temporal coherence are based on yearly or monthly sampling frequencies and little is known of how synchrony varies among phytoplankton or of the causes of temporal coherence during spring algal bloom. In this study, data of chlorophyll a and related environmental parameters were weekly gathered at 15 sampling sites in Xiangxi Bay of Three‐Gorges Reservoir (TGR, China) to evaluate patterns of temporal coherence for phytoplankton during spring bloom and test if spatial heterogeneity of nutrient and inorganic suspended particles within a single ecosystem influences synchrony of spring phytoplankton dynamics. There is a clear spatial and temporal variation in chlorophyll a across Xiangxi Bay. The degree of temporal coherence for chlorophyll a between pairs of sites located in Xiangxi Bay ranged from –0.367 to 0.952 with mean and median values of 0.349 and 0.321, respectively. Low levels of temporal coherence were often detected among the three stretches of the bay (Down reach, middle reach and upper reach), while high levels of temporal coherence were often found within the same reach of the bay. The relative difference of DIN between pair sites was the strong predictor of temporal coherence for chlorophyll a in down and middle reach of the bay, while the relative difference in Anorganic Suspended Solids was the important factor regulating temporal coherence in middle and upper reach. Contrary to many studies, these results illustrate that, in a small geographic area (a single reservoir bay of approximately 25 km), spatial heterogeneity influence synchrony of phytoplankton dynamics during spring bloom and local processes may override the effects of regional processes or dispersal. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Penetration of solar ultraviolet radiation into New Zealand lakes: influence of dissolved organic carbon and catchment vegetation

Eleven lakes in the South Island of New Zealand were sampled in summer 1996. Water column profiles of ultraviolet radiation (UVR) at four wavelengths and photosynthetically available radiation (PAR) were obtained, along with analyses of dissolved organic carbon (DOC) concentration, total suspended solids (TSS), and catchment vegetation, including forest and natural grassland. Downward attenuation coefficients (K _d) and lake water transparency (1/K _d) for UVR were examined in relation to these variables. Consistent with other regions of the world, DOC concentration and variables related to DOC were the best predictors of UVR penetration. With our data set, we calculated ratios of water column integrals (RI) of UVR/PAR irradiance, using equations from the literature. At DOC concentrations below 4 g m⁻³, a progressive increase in RI shows that lakes become increasingly transparent to UVR. We also normalized chromophoric dissolved organic matter (CDOM) absorption of UVR at 380 nm (a ₃₈₀) to DOC concentration and found that the UVR-absorbing capacity per unit DOC increases with increasing percentage of forest in the catchment area. This indicates that not only DOC concentration but also DOC type or composition is important in determining the transparency of lake water to UVR, and that qualitative differences in DOC are dictated by the type and amount of vegetation present in the lake's catchment area. Received: September 18, 2000 / Accepted: December 14, 2000     

不同风浪条件下太湖梅梁湾光合有效辐射的衰减

基于2003年7月12～17日在太湖梅梁湾进行的连续6 d原位水下光场观测资料,分析了不同风浪条件下光合有效辐射（PAR）的衰减和真光层深度,探讨了影响水下光合有效辐射的主导因子.结果表明,整个观测期间向下PAR衰减系数为2.63～4.71·m^-1（均值为3.63±0.47·m^-1）,对应的真光层深度为0.98～1.75 m（均值为1.29±0.18 m）,显示1.5 m以下深度浮游植物、沉水植物基本上无法获取足够的太阳光能进行光合作用.从小风浪到中风浪、大风浪向下PAR衰减系数分别是2.63、3.72和4.37·m^-1,衰减系数分别增加了41%、66%.透明度、PAR衰减系数、真光层深度与悬浮物浓度存在显著性线性相关,并且与悬浮物中无机颗粒物相关性最好,而与叶绿素a、脱镁叶绿素及溶解性有机碳相关性很低.多元逐步线性回归表明,叶绿素a和溶解性有机碳最先被剔除方程,说明在梅梁湾由于风浪扰动引起悬浮物浓度的改变是影响水下光场的主导因素.     

Effects of a Prorocentrum minimum bloom on light availability for and potential impacts on submersed aquatic vegetation in upper Chesapeake Bay

Extraordinary spring blooms of the dinoflagellate Prorocentrum minimum have been a recurring feature of upper Chesapeake Bay for many years. Though not thought to be toxic in Chesapeake Bay, these blooms produce extraordinarily high concentrations of chlorophyll, thereby increasing light attenuation. A particularly large event occurred in the spring of 2000. Here, we assess the impact of the spring 2000 P. minimum bloom on habitat quality for submerged aquatic vegetation (SAV) in the mesohaline region of Chesapeake Bay and its tributaries. We determined the light absorption and scattering spectrum of P. minimum on a per cell basis by analyzing inherent optical properties of natural samples from the Rhode River, Maryland, which were overwhelmingly dominated by P. minimum. Using these per cell properties, we constructed a model of light penetration incorporating observed cell counts of P. minimum to predict the impact of the bloom on other tributaries and main stem locations that experienced the bloom. Model estimates of diffuse attenuation coefficients agreed well with the limited measurements that were available. Impacts of the mahogany tide on diffuse attenuation coefficient ranged from negligible (10–30% increase above the seasonal median in the Patapsco and Magothy rivers), to a greater than six-fold increase (Potomac River). Attenuation coefficients in tributaries to the north and south of the bloom region either decreased or were unchanged relative to seasonal medians. Segments with SAV losses in 2000 were mostly the same as those that experienced the P. minimum bloom. Segments north and south of the bloom area mostly had SAV increases in 2000. Though all of the segments that experienced a decline in SAV area after the spring 2000 bloom showed an increase in 2002, the 2000 setback interrupted what otherwise has been a slow recovery in mid-Bay SAV, demonstrating the adverse impact of P. minimum blooms on SAV populations in Chesapeake Bay.     

Longitudinal Differences of Phytoplankton Community during a Period of Small Water Level Fluctuations in a Subtropical Reservoir Bay (Xiangxi Bay,Three Gorges Reservoir,China)

The Three Gorges Reservoir (TGR) had a great inflow discharge with small water level fluctuations in the flood season of the year 2008, when a large‐scale cyanobacterial bloom broke out in Xiangxi Bay (a tributary bay behaving like a lake) for the first time after the construction of the TGR impoundment. To compare spatiotemporal longitudinal differences of phytoplankton community structure during this period, weekly surveys were performed in Xiangxi Bay. The cyanobacterial bloom lasted from June 6 to July 18, 2008, with Microcystis aeruginosa as the dominant species. During this bloom the species diversity, evenness and community change rate was relatively low. The probable causes for the interruption of the bloom were precipitation and water temperature. In the non‐cyanobacterial bloom period (July 25 to September 26, 2008) many other species dominated the community including Stephanodiscus hantzschii and Cryptomonas ovata, with higher values of species diversity, evenness and community change rate. As for the longitudinal differences, the community structure in the riverine zone was different from that in other zones, indicating the important effect of inflow from the upstream of Xiangxi Bay. The management actions in Xiangxi Bay should prevent blooms in the mainstream, lacustrine and transitional zone. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Photoproduction of dissolved inorganic carbon in temperate and tropical lakes – dependence on wavelength band and dissolved organic carbon concentration

We have evaluated photoeffects of UV-B, UV-A and PAR radiation on dissolved organic matter (DOM). Photochemical production of dissolved inorganic carbon (DIC) was measured in sterile lake water from Sweden and Brazil after 6 hours of sun exposure. Tubes were exposed to four solar radiation regimes: Full-radiation, Full-radiation minus UV-B, Full-radiation minus UV-B and UV-A (PAR) and darkness.In both areas, lakes with most DOC (varying between 3 and 40 mg C l^-1) were highly humic, resulting in high UV-B attenuation coefficients (K_d = 5–466 m^-1). Under Full-radiation, photooxidative DIC-production varied from 0.09 to 1.7 mg C l^-1per 6 h, without UV-B from 0.07 to 1.4 mg C l^-1 and with PAR only from 0.02 to 0.7 mg C l^-1. UV-B radiation explains a minor part (17%) of the photoooxidative DIC-production, while UV-A and PAR have larger effects (39% and 44%, respectively). Photooxidation was proportional to DOC-content and DIC-production was positively related to decrease in DOC and to loss of absorbance at 250 nm. There was no significant difference in DOC and radiation normalized DIC-production between Swedish and Brazilian lakes. The UV-B dose during incubations was approximately 3 times higher in Brazil compared to Sweden, while UV-A and PAR doses were similar. We conclude that DOC from tropical and temperate freshwaters do not seem to differ with respect to sensitivity to photooxidation.     

Role of terrestrial carbon in aquatic UV exposure and photoprotective pigmentation of meiofauna in subarctic lakes

相似文献