太湖水华成因及控制途径初探

1990年8～12月对太湖水华9次调查表明,水华主要由漂浮性蓝藻—微囊藻组成,夏季SE风时其漂移集聚是西北湖区形成严重水华的主要原因。这种漂移使得藻类所含营养物逆吞吐流方向传输,形成了一种“生物营养滤器”,加速了太湖尤其是西北湖区的富营养化进程。太湖外源N、P负荷量分别为12.0和0.85g/(m~2·a),足以引起富营养化;表层5cm底泥中含丰富的N、P,其释放也成为湖水中部分营养的来源。因2～8月藻类总生物量的增长基本遵守Logistic方程dN/dt=N·r(1—N/K),故对藻类控制可从N、r入手,即通过收获藻类达到控制藻类总量和营养输出的双重功效;提高水位增加非光合层厚度,有效地降低水柱中藻类生产力;建立有水生植被的水质保护区也是一种局部藻类控制方法。     

Carbon and nutrients transfer from primary producers to lake sediments – A stoichiometric approach

We aimed to demonstrate different input of organic and inorganic carbon, nitrogen and phosphorus from three main groups of primary producers (phytoplankton, charophytes and vascular submerged macrophytes) to respective lake sediments. Studies were carried out in one eutrophic and two mesotrophic lakes. Samples of sediments were taken from profundal and from littoral zones, the latter divided into such overgrown by charophytes and others covered by vascular submerged macrophytes. We applied a stoichiometric approach to illustrate variable functional carbon to nutrients relationships. Among profundal sediments, the lowest organic to inorganic carbon ratio was found in sediments from the eutrophic lake due to precipitation of calcium carbonate during algal blooms. Extremely low inorganic carbon input to profundal sediment of one of the mesotrophic lakes may be explained by low phytoplankton production but also by dissolution of once deposited calcium carbonates. Charophyte-dominated littoral sediments contained significantly more inorganic carbon than other littoral and profundal sediments. Comparison of stoichiometric ratios between plant standing crop and underlying littoral sediments showed significant enrichment of sediments in nitrogen manifested by reduction of organic carbon to total nitrogen ratio during plant decomposition taking place both in charophyte and in vascular plant stands. We also attempted to divide phosphorus pool in sediments into organic P and calcium-bound P present in charophyte stands and in profundal sediments of eutrophic lake. In the former, calcium-bound P was estimated at 17–19 % of the total P pool while in profundal sediments it amounted 42 % of the total P. This difference suggests that calcium carbonate settling during algal blooms in a eutrophic lake may be more effective in P trapping than calcite encrustations covering charophyte plants in littoral sites. In conclusions, we underline the need of considering often neglected inorganic fractions of carbon and phosphorus to get better insight into carbon and nutrient burial in lake sediments.     

杭州西湖底泥磷分级分布

采用磷分级分离法对在杭州西湖采集的柱状泥样进行了磷分级提取,结果发现：HCl-rP即钙矿磷占据了西湖底泥总磷含量的30％－70％,其余依次为NaOH-rP(16%-40%)和NH4Cl-rP(0.6%-10%);活性磷由NoOH-rP和NH4Cl-rP构成,占总沉积磷的20％－40％,各磷分级组分和活性磷的垂直分布与总磷基本一致,含量随泥层深度的降低逐级增加,在10－30cm处形成峰值,但表层的蓄积量又出现逐层下降的趋势。     

Potential effect of sedimentary iron-phosphorus accumulation on frequent algal bloom in the Pearl River Estuary

Based on laboratory culture of harmful alga on iron and phosphorus uptake, and the study of accu-mulation of iron-phosphorus in cores and release of iron and phosphorus from surficial sediments collected in the Pearl River Estuary, the reasons of the high frequency of phytoplankton bloom therein are discussed. The results show that Fe starvation can make algal growth rate slow down and the peak of cell number decrease. Fe and P contents in algal cell bear a significant correlation and the molar ratio of P:Fe is ~356:1, suggesting that algal uptake of Fe and P is synergistic. Total Fe and total P in sediments are positively correlated and Fe-P is the main species of inorganic sedimentary P. Through continuous leaching with agitation, 34.26%―80.21% of exchangeable P and 4.04%―22.52% of ex-changeable Fe are released from surficial sediments, implying that the accumulation of Fe-P in sedi-ments is available for providing nutrients (P and essential Fe) for the demand of phytoplankton bloom. These factors might be responsible for a higher frequency of red tides than other marine regions.     

南方水库季节性热分层消亡对沉积物铁和磷迁移的影响——以南宁市天雹水库为例

为了探究我国南方地区水库季节性热分层消亡前后沉积物铁和磷的迁移规律,于2019年11月-2020年1月对天雹水库多点位(浅水区和深水区)水体理化指标进行原位监测,并利用薄膜扩散梯度技术(DGT)高分辨率获取沉积物有效态铁和磷的浓度分布.结果 表明:(1)天雹水库沉积物有效态Fe和P浓度分别为4.67～18.72和0.0...     

典型风力条件及水力调度下太湖藻华高频时空动态监测

湖泊藻华问题已成为全球水生态环境领域面临的长期挑战,风力条件变化和引调水工程的水力调度能改变湖体水动力结构,对藻类的生长和聚集过程产生影响,进行该过程的精细化监测和机制分析对于湖泊藻华预报预警和应急处置具有重要意义。本研究基于Hiamwari-8/AHI卫星遥感高频监测数据,对比分析了归一化差异植被指数(NDVI)、增强植被指数(EVI)和浮游藻类指数(FAI) 3种不同指数对太湖藻华的反演效果,开展了典型风力条件下和水力调度下太湖藻华生消过程的持续监测分析。结果表明,FAI对藻华区域和非藻华区域的区分更加明显,其阈值提取的藻华面积与基于MODIS图像解译的藻华面积的相对误差最低,为-2.27%。当营养盐充足且水温持续保持在蓝藻大量生长增殖的阈值以上时,风力条件是导致太湖藻类迁移聚集的关键因子,风向主要影响藻类的水平迁移,使其进行方向性迁移并逐渐形成大面积藻华区域。风速主要影响藻类的垂向迁移并存在临界阈值,当风速低于约2.5 m/s的临界风速时,藻华面积随风速增加而增加;当风速高于临界风速时,藻华面积随风速增加而降低。水力调度对距离较近的贡湖湾区域具有显著影响,主要通过水动力扰动来影响...     

太湖、巢湖、滇池水华与相关气象、水质因子及其响应的比较(1981-2015年)

比较了太湖、巢湖、滇池（"三湖"）1981-2010年间的气象要素,1987-2015年间的水质要素,2000-2013年间的年内水华起始日期与持续时间,以及与水华相关的已有研究情况.其中,气象要素包括气温、日温差、风速、风向、气压、降水、相对湿度等;水质要素包括水温、总氮浓度、总磷浓度、水体综合营养指数等.对比结果表明,云贵高原湖泊滇池因其冬、春季节气温较高且日温差较大等气象特征,以及总磷浓度较高等水质特征,相比于东部平原湖泊太湖、巢湖而言更易发生水华,且在"三湖"中水华年内起始日期最早,持续时间最长.然而,目前有关滇池水华的研究相对于"三湖"中的太湖却远远不足.鉴于滇池所处湖区的独特气象、水质特征,平原水华湖泊的研究结果难以有针对性地指导其水华控制,亟需提高滇池水华研究的系统性与深度.只有因地制宜,方有希望逐步有效控制、减轻、乃至消除滇池水华.     

云南阳宗海表层沉积物有机质组成结构对磷赋存形态特征的影响

利用连续提取分级的方法定量分析阳宗海表层沉积物磷赋存形态,阐明了沉积物C、N、H和O组成及溶解有机质(DOM)紫外-可见光谱特征,探讨沉积物元素组成及DOM组成结构对不同形态磷含量的影响.结果表明:(1)沉积物潜在可移动磷含量在68.67~124.70 mg/kg之间变化,平均占总磷含量的9.81%,表现为BD-PNa OH-nr PNH_4Cl-P;沉积物稳定磷含量在496.73~908.28 mg/kg之间变化,平均占总磷含量的60.86%.(2)沉积物C、N含量和疏水性DOM光谱参数A_(240-400)表现出北部高、南部低的变化趋势,但H/C、O/C和(N+O)/C摩尔比和亲水性DOM光谱参数A_(240-400)变化趋势则与之恰好相反.(3)沉积物NH4Cl-P含量与C、N和H含量之间呈显著正相关,但与H/C、O/C、(N+O)/C摩尔比和亲水性DOM光谱参数E_2/E_3值之间呈显著负相关;NaOH-rP和BD-P+NaOH-rP含量均与O含量及O/H摩尔比呈显著负相关;NaOH-rP、BD-P+NaOH-rP和HCl-P均与疏水性DOM光谱参数A_(240-400)值之间呈显著正相关.因此,天然有机质元素组成及官能团结构是影响沉积物磷赋存形态的重要因素.     

卫星遥感解译湖泊蓝藻水华的几个关键问题探讨

蓝藻水华是全球性的水环境健康问题,对水华暴发过程信息的快速准确获取是制定有效防治措施的关键.卫星遥感因具有大范围、周期性观测的特点,被广泛地用于湖泊蓝藻水华的时空动态监测.本文指出在利用遥感对湖泊蓝藻水华进行研究时,需要注意的4个问题:(1)湖泊水体中泥沙等信号对藻华存在干扰;(2)大气程辐射及水陆边界影响藻华特征提取...     

武汉东湖主要湖区的藻类与营养型评价

对东湖９个湖区藻类的群落结构、生长潜力、初级生产力和营养状况进行了比较研究。结果表明,９个湖区藻类的种类组成无明显差异,绿藻为主,蓝藻和硅藻次之;藻类的生长潜力和初级生产力各湖区差异较大,均以茶港湾重污染区最高和牛巢湖最低。根据各项指标综合分析,９个湖区水质优劣的顺序是：牛巢湖、汤林湖、后湖、郭郑湖、菱角湖、筲箕湖、庙湖、喻家湖和茶港湾重污染区。对东湖的大水面郭郑湖４０年来藻类的有关参数进行比较发     

Phosphorus Buildup and Release Risk Associated with Agricultural Intensification in the Estuarine Sediments of Chaohu Lake Valley,Eastern China

Phosphorus (P) accumulation and the risk of P release were studied in the estuarine sediments of the Chaohu Lake Valley in Eastern China. Rapid agricultural intensification has occurred in this area since the 1980s, resulting in the extensive use of phosphate fertilizers. This extensive use of phosphate has affected P processes throughout the valley and resulted in the total phosphorus (TP) contents in the substrates and surface sediments increasing from 374 to 537 mg/kg, on average. Of all the forms of P evaluated in this study, residual P (Res‐P) was present at the highest levels and accounted for 19.8–74.0% of the TP. Conversely, the lowest contents were observed for KCl‐extracted P (KCl‐P), which accounted for only 0.602% of the TP. Additionally, aluminum/iron‐bound P (NaOH‐Pi), which accounted for 16.0–53.1% of the TP, was an important factor that caused the TP to increase due to long‐term P fertilization. However, calcium‐bound P (Ca‐P) was maintained at a relatively stable level. Furthermore, the degree of P saturation (DPS) and the P‐induced lake eutrophication risk index (ERI) were investigated to determine the risk of release of P from the sediments. The average DPS and ERI values were found to range from 3.92–21.4% and from 12.6–33.6%, respectively. These results suggest that almost half of the estuarine sediments posed a potential risk of eutrophication. Moreover, these findings indicate that estuarine sediments that have been enriched with P are likely the sources of P that lead to the formation of algal blooms in Chaohu Lake.     

Distribution and partitioning of polycyclic aromatic hydrocarbons (PAHs) in different size fractions in sediments from Boston Harbor, United States.

The concentrations of 16 US EPA priority pollutant polycyclic aromatic hydrocarbons (PAHs) were analyzed in four size fractions (< 62, 62-125, 125-250, and > 250 microm) in three contaminated Boston Harbor sediments. Total PAH concentrations ranged from 7.3 to 358 microg/g dry wt. and varied largely among the different size fractions in these sediments. For all three sites, the highest PAH concentrations were associated with the large size (> 250 microm) fractions while the fine silt and clay fractions (< 62 microm) contained relatively low PAHs. Despite the great concentration differences, the composition of PAHs in the four size fractions of these sediments showed similar patterns dominated by PAHs with three or more rings. By examining the distribution patterns of selected alkyl homologs to parent compounds, the results indicate that the major PAHs contributing to the high contamination in the inner harbor sediments were from pyrogenic sources. A positive correlation between PAHs and sedimentary organic carbon exists for all size fractions in the sediments. Calculated organic carbon normalized partition coefficients (log K(oc)) for selected major PAHs indicate near-equilibrium partitioning of PAHs among the different size fractions despite their large concentration variations. Sedimentary organic matter associated with different size fractions was the controlling factor for the observed distribution differences of PAHs among the size fractions. Our results also suggest that sedimentary organic matter with different origins and maturities may have somewhat different PAH sorption characteristics. Particulate organic matter of charcoal, plant detritus and Capitella fecal pellets in the sediments appear to sorb PAHs more strongly than organic matter associated with clay minerals. The strong association of PAHs with these organic particles in sediments will have a great influence not only on their distribution but also on long-term environmental impact.     

长江中下游浅水湖泊沉积物腐殖质组分赋存特征

应用化学方法,对长江中下游浅水湖泊表层沉积物有机质含量、腐殖质组成及结合形态进行了研究.结果表明:①长江中下游浅水湖泊11个沉积物的有机质含量变化较大.在0.98%-11.0%之问波动.污染程度重的沉积物中有机质含量均较污染程度轻的高.其有机质的分布特征与沉积物污染程度和湖泊周边的人类活动有关.②腐殖质组成中,胡敏酸(...     

底泥和藻体对太湖湖泛的诱发及水体致黑物的供应潜力

为确定底泥和藻体在太湖湖泛形成过程中对致黑物形成的贡献,采用室内模拟系统,研究底泥、蓝藻以及底泥+蓝藻3种处理,模拟湖水在不同厌氧程度下湖泛特征参数(黑度、铁及硫形态)的变化,分析不同处理以及受不同聚藻程度影响区(八房港、焦山)底泥对湖泛的诱发作用及致黑物供给潜力.结果表明,各处理组诱发太湖湖泛发生的难易顺序为:底泥+蓝藻处理组底泥处理组蓝藻处理组.底泥+蓝藻处理组中Fe2+浓度为蓝藻处理组的11~94倍,其平均浓度为后者的33倍,而底泥+蓝藻处理组中还原性硫浓度为其他处理组的2~56倍.研究还发现,聚藻区底泥较非聚藻区更易发生湖泛,这是由于聚藻区底泥富集了更高浓度的铁、硫等还原性物质,但厌氧处理与非厌氧处理在诱发湖泛发生的风险差异不明显.以上结果证实,厌氧环境下低价铁硫供应潜力的差异是决定湖泛发生的主要物质来源,加强对聚藻区底泥及蓝藻的控制是有效防控太湖湖泛发生的主要措施之一.     

Speciation of organic carbon,Cu and Mn in the River Marne (France): the role of colloids

The distribution of organic carbon (OC) and of some metals (Cu, Mn) amongst the particulate (>0·2 μm), colloidal (10 kDa–0·2 μm) and the truly dissolved (<10 kDa) fractions of the River Marne was investigated during the phytoplankton spring bloom. A tangential ultrafiltration (UF) device was utilized to separate the colloidal fraction. On average, 22% of the OC, 31% of the Cu and 53% of the Mn, usually assigned to the so‐called dissolved fraction, were found in the colloidal fraction. The colloidal fraction exhibited a behaviour different from that of the particulate and truly dissolved fractions. Autochthonous production led to enrichment in the colloidal and particulate OC pools: up to 47% of the total dissolved OC was in the colloidal fraction. An increase in the colloidal metal fraction, concomitant with a fall in the truly dissolved fraction, coincided with peaks in phytoplankton during the bloom. These phenomena might be related either to an increase in pH associated with photosynthetic activity, resulting in the precipitation of truly dissolved forms into the colloidal fraction, or to scavenging of the truly dissolved metals by the algal species of colloidal size. The interaction between the colloidal and the truly dissolved phases was very important. The partition coefficients of the Cu and Mn between the colloidal and truly dissolved fractions were higher than between the particulate and the truly dissolved fractions. This pattern is consistent with a greater specific surface area of colloids than macroparticles. Consequently, the adsorption and complexation capacities are enhanced in the colloidal fraction of the particulate matter. The extraction of hydrophobic complexes with Cu using C₁₈ Sep‐Pak columns, showed that the Cu occurring in colloidal, total dissolved or truly dissolved forms was significantly complexed by the organic matter. The truly dissolved fraction might be complexed up to 100% during a phytoplankton bloom. Copyright © 1999 John Wiley & Sons, Ltd.     

太湖藻类水平漂移特征及其影响因素

采用原位观测平台,研究分析了太湖竺山湾风速、湖流流速、波高以及藻类水平漂移特征及其影响因素,结果表明日间藻类水平漂移速率呈锯齿式交替特征,日内藻类水平漂移速率变化幅度大;藻类水平漂移速率与风速之间呈显著线性正相关;当0.02 m < 有效波高 < 0.1 m时,藻类水平漂移速率与有效波高呈显著线性负相关,当有效波高 > 0.1 m时,波浪会显著改变藻类运动方式,破坏藻类表层聚集形态;湖流对藻类水平漂移速率无显著性影响;藻类水平漂移方向受湖流流向和风向的共同作用;藻类水平漂移速率与风速、波高、湖流流速间关系可用多元线性方程表达,且拟合度良好,可为藻类水华预测模型构建提供依据.     

东洞庭湖沉积物覆水后磷形态变化及其释放量

研究干燥覆水后低流速条件下东洞庭湖沉积物中磷的形态变化及释放量,可以为轻度富营养化湖泊中磷的生物地球化学循环提供基础数据,为季节性湖泊內源营养盐的迁移转化规律研究、內源营养盐的释放风险评价提供理论依据.本文采集处于干湿交替状态的东洞庭湖表层沉积物,利用室内模拟装置,研究风干沉积物低流速条件下覆水后沉积物及上覆水中磷的形态变化.结果表明,低流速覆水后东洞庭湖沉积物中的磷向上覆水及大气中迁移释放,上覆水中磷的释放量随覆水时长增大,释放速率随覆水时长减小,上覆水流速和磷释放量相关性显著.上覆水循环过程中释放到上覆水中的溶解态有机磷比溶解态活性磷更容易吸附于颗粒物而转化为颗粒态磷.覆水后沉积物中各形态有机磷、无机磷及磷的生物有效性均发生转变,覆水初期沉积物中无机磷向有机磷转化,磷的生物可利用性增大;上覆水循环过程中有机磷向无机磷转化,磷的生物可利用性减小;覆水后沉积物的无机磷的主要组分由铝磷转变为铁磷,有机磷的主要组分有从中活性有机磷向活性有机磷转变的趋势.     

Nutrient sources and composition of recent algal blooms and eutrophication in the northern Jiulong River,Southeast China

The natural process of eutrophication is accelerated by human activities worldwide that interrupt nutrient biogeochemical cycles. Three algal bloom events have been monitored in the northern tributary of the Jiulong River since 2009. The inflection points in a robust locally-weighted regression analysis (LOESS) of the relationship between TN and TP concentrations in the river water, and a TN:TP comparison with nutrient source loadings, suggested that both external loading and internal nutrient cycling contributed to these algal blooms. Nutrient release from the sediments may have played an important role in regulating the nutrients in the overlying water column. In particular, excessive nutrient inputs from various sources and ubiquitous river damming caused further accumulation of the nutrient loading. In-situ autochthonous primary production was enhanced in this relatively stable “river” to “lake” water body. Thus, attention must be paid to the effects of river damming and the consequent internal nutrient release.