三峡小江回水区真光层深度及其影响因素分析

为探讨三峡水库运行初期小江回水区水体的光学特性,2007年5月~2008年5月对回水区5个断面水下光合有效辐射(PAR)与常规水质指标进行监测,分析了真光层深度的时空特征及其影响因素.研究区域真光层深度空间差异不明显,但季节变化显著,冬季最高,夏季最低.回归分析表明光合有效辐射(PAR)衰减系数与透明度、总悬浮物浓度有显著的相关性(R2=0.861 9,R2=0.764),与叶绿素a相关性不明显(R2=0.011 3).进一步研究分析表明真光层深度、总悬浮物浓度、叶绿素a主要受小江河口流量、小江回水区水位的影响,复杂的水动力条件与独特的水文条件是影响三峡水库小江回水区真光层深度变化的主要因素.     

大气-水体系统中PAR传输模式及湖泊初级生产力

给出了一种大气-水体系统中PAR的传输模式,并利用太湖的气象和实测悬浮粒资料计算水体中PAR的时空变化.模式中考虑了大气的气溶胶、臭氧、水汽和CO₂的效应以及水面风浪、水中黄质、悬浮粒和浮游藻类的多次散射和吸收过程.最后,利用生物-光模式,计算了太湖的初级生产力.结果基本上能反映水中初级生产力随水深的变化趋势.     

太湖水体吸收系数与散射系数的特征研究

湖泊水体光学特性是进行湖泊水体光学及水体光学遥感研究的基础。计算了太湖冬、夏季水体的吸收系数和散射系数,并在分析水体吸收特性的基础上对水体的光学类型进行了分类。结果表明:冬季太湖水体的光学类型属PY型(悬浮粒和黄质共同作用型),即水体的吸收特性受悬浮质和黄质的共同作用,而夏季则属CPY型(浮游藻类、悬浮粒和黄质共同作用型),即水体的吸收特性受悬浮质、黄质和浮游藻类三者的共同作用;不论冬季还是夏季,非色素悬浮粒是影响太湖水体散射特性的主要因子。     

贵州阿哈湖物质循环过程中的铁同位素地球化学及其指示意义

使用AGMP-1氯化物型阴离子交换树脂(100--200目)对夏季贵州阿哈湖流域水体悬浮颗粒物等样品进行了化学分离,并在多接收电感耦合等离子体质谱仪(MC-ICP-MS)上进行了铁同位素分析.分析结果表明,夏季阿哈湖湖水分层期间湖水悬浮颗粒物及各端员环境样品的铁同位素组成变化较大:湖水悬浮颗粒物的δ56Fe为负值,分布范围为-1.36‰～-0.10‰之间;各支流河水悬浮颗粒物的铁同位素组成在-0.88‰～-0.16‰之间;大气颗粒物的平均铁同位素组成为 0.06‰±0.02‰;而未经化学清洗的浮游藻类的铁同位素组成为 0.08‰.对比研究表明,湖水悬浮颗粒物的铁同位素组成不仅受各输入端员的影响,湖泊内部复杂的生物地球化学过程也对颗粒物的铁同位素组成产生了重要影响.陆源输入的颗粒有机结合态铁使得湖泊表层悬浮颗粒物的铁同位素组成偏低,而大气沉降颗粒物和湖泊表层的浮游藻类整体上对铁同位素组成的影响并不显著."ferrous wheel"铁循环对于氧化还原界面附近水层中铁同位素的重分配起到了主要的控制和影响作用.δ56Fe值与Fe/A1呈现良好的负相关关系,也显示出活性铁的循环迁移是造成氧化还原界面附近水层中悬浮颗粒物的铁同位素组成变化的重要原因,表明铁同位素与Fe/A1可能可以作为表征水体生物地球化学环境的良好指标.     

用三维荧光谱图分析原水输送过程中藻类和有机物的变化

采用新型分析技术三维荧光谱图方法对深圳东江水源工程水体中藻类进行了荧光分析。实验结果表明,水体中有较丰富的藻类,其中蓝藻、绿藻呈优势藻种,实验期间沿程水体叶绿素a浓度在1.71~16.43μg/L之间,藻密度在72.92万~1 375万个/L之间。三维荧光方法能较好表征水体中生长藻类种类和数量,三维荧光强度F(A.U)与叶绿素a浓度Chla(μg/L)、藻密度N(104个/L)呈较好的线性关系。三维荧光方法能较好的鉴别水体中可溶性有机物腐殖酸和蛋白质,并表征其含量多少。     

梅梁湾、大太湖夏季和冬季CDOM特征及可能来源分析

基于2004年夏季水华暴发期和冬季在梅梁湾及大太湖各2次采样,分析了夏季、冬季CDOM的特征及其可能的来源,发现夏季CDOM吸收系数、叶绿素a浓度均明显高于冬季,DOC浓度、CDOM吸收系数a(355)的变化范围分别为5.17～12.42 mg/L、2.57～6.77 m-1,最大值均出现在冬季(12月15日)的直湖港入湖口.CDOM吸收系数与DOC浓度、定标后的荧光值一般都存在显著正相关,但夏季由于受浮游植物降解的影响,与DOC浓度和荧光的相关性明显低于冬季.表征CDOM组成和来源的参数比吸收系数、M值、S值存在显著的季节差异,夏季吸收系数a*(355)值明显要大于冬季,而S值、M值则要小于冬季.夏季水华暴发时CDOM吸收系数与叶绿素a浓度空间分布较为一致,吸收系数与叶绿素a浓度存在正相关,浮游植物降解产物可能是水体中CDOM的重要来源;相反,冬季CDOM吸收系数呈现从梁溪河入湖口、湾内往湾口递减的趋势,其来源可能主要以陆源为主,受入湖河流的影响较大.     

物理及生物技术在密云水库富营养化防治中的应用

为防治密云水库富营养化问题,应用部分物理和生物技术进行现场试验。吸附性材料净水试验后,试验区内水中氮的浓度和磷的浓度比对照区都有所下降,这将对藻类生长所需的营养物质量起到一定的控制作用。水葫芦净化水体试验说明,试验区内水体的总磷和总氮浓度皆低于对照水体的,这将控制藻类生长所需的营养物质量,即控制藻类的生长速度。机械除藻试验后,水中的叶绿素含量比除藻前下降60%~100%。表底层水体交换试验后,试验区内表、中层水体的温度有所下降,温度降低将抑制表、中层水体中藻细胞的繁殖速率,对水华的发生将起到一定的抑制作用。     

城市路面径流重金属固液分配系数及其影响因素

以上海市中心城区为例,探讨路面径流重金属在颗粒物-水相间的分配特征及其影响因素.研究表明,路面径流Cr的25%分位数浓度值,以及Zn、Pb、Cd的90%分位数浓度值超出地表Ⅴ类水标准,Cu和Ni污染程度较轻.径流重金属Pb、Zn、Cu及Cd总量浓度与悬浮颗粒物(TSS)含量呈现较明显的正相关关系,Ni与TSS浓度相关性不显著.径流冲刷过程中Cu和Ni溶解态含量比例平均值为35%;Zn和Cr平均值为19%~22%;Cd和Pb溶解态比例最低,平均值为4%~8%.应用扣除残渣态后的颗粒物重金属含量计算固液分配系数依次为Pb>Cd>Zn>Ni>Cu>Cr.径流中悬浮颗粒物浓度与固液分配系数存在显著负相关关系,呈现明显的"颗粒物浓度效应",径流pH值在6.4~7.2区间时对固液分配系数影响相对较小.     

引江济太对太湖水体碱性磷酸酶动力学参数的影响

采用野外定点采样、室内同步分析水体碱性磷酸酶活性及水化学指标的方法,研究引江济太调水对太湖各湖区水体碱性磷酸酶最大反应速率(v_max)、米氏常数(Km_m)值的影响。结果表明:在引江济太调水试验期间,各湖区水体中v_max及Km_m值时空分布存在差异性。调水稀释了各湖区蓝藻浓度,抑制了水体碱性磷酸酶v_max;贡湖区、西岸河口区及湖心区水体中Km_m值与入湖累积水量之间有显著的二次函数关系(p=0.007)。梅梁湖、竺山湖、贡湖及西岸河口区水体碱性磷酸酶v_max/Km_m随着总磷浓度升高而增加,但竺山湖、贡湖、草型湖、湖心及西岸河口区水体v_max/K随生物可利用磷(PO₃--P)浓度增加而下降。除草型湖区外,其它湖区水体v/K随叶绿素a浓度升高而增加。     

淄博市区大气颗粒物重金属元素分布特征及其来源分析

为科学认识淄博市区大气颗粒物污染状况,探讨颗粒物的污染水平和元素在颗粒物中的分布与分配特征,对颗粒物中元素的来源进行分析。于2015年冬季和夏季期间分别布设45个和16个采样点采集悬浮颗粒物（TSP）、PM₁₀及PM_2.5样品,分析了颗粒物和18种元素（或化合物）的质量浓度。结果表明：1）大气颗粒物中冬季TSP、PM₁₀及PM_2.5的质量浓度均值高于夏季;PM₁₀和PM_2.5质量浓度均超过国家标准,其中冬季PM_2.5质量浓度是标准限值的1.96倍。2）不同粒径的颗粒物中元素质量分数差别显著,As、Cd、Cr、Cu、Ni、Pb、Zn等多数重金属元素主要富集在PM_2.5中,且PM_2.5约占PM₁₀的65%（冬季）和73%（夏季）。3）颗粒物PM_2.5中Al₂O₃、CaO、Fe₂O₃、K₂O、MgO等氧化物主要受土壤扬尘控制;As、Cd、Hg、Pb、Se、Zn等元素主要源于人为污染;Se的富集因子最高,反映了PM_2.5污染主要来源于燃煤;Co、Cu、Ni、Na₂O受土壤扬尘和人类活动的共同作用,而Cr具有混合污染的特点。     

Calibration of a Bio-optical Model in the North River, North Carolina (Albemarle–Pamlico Sound): A Tool to Evaluate Water Quality Impacts on Seagrasses

Seagrasses are typically light limited in many turbid estuarine systems. Light attenuation is due to water and three optically active constituents (OACs): nonalgal particulates, phytoplankton, and colored dissolved organic matter (CDOM). Using radiative transfer modeling, the inherent optical properties (IOPs) of these three OACs were linked to the light attenuation coefficient, K _PAR, which was measured in North River, North Carolina, by profiles of photosynthetically active radiation (PAR). Seagrasses in the southern portion of Albemarle-Pamlico Estuarine System (APES), the second largest estuary in the USA, were found to be light limited at depths ranging from 0.87 to 2 m. This corresponds to a range of K _PAR from 0.54 to 2.76 m^?1 measured during a 24-month monitoring program. Turbidity ranged from 2.20 to 35.55 NTU, chlorophyll a from 1.56 to 15.35 mg m^?3, and CDOM absorption at 440 nm from 0.319 to 3.554 m^?1. The IOP and water quality data were used to calibrate an existing bio-optical model, which predicted a maximum depth for seagrasses of 1.7 m using annual mean water quality values and a minimum light requirement of 22% surface PAR. The utility of this modeling approach for the management of seagrasses in the APES lies in the identification of which water quality component is most important in driving light attenuation and limiting seagrass depth distribution. The calibrated bio-optical model now enables researchers and managers alike to set water quality targets to achieve desired water column light requirement goals that can be used to set criteria for seagrass habitat protection in North Carolina.     

悬浮物浓度对水下光照和初级生产力的影响

采用太湖湖泊生态系统研究站生态实验室的模拟生态槽进行水动力模拟实验研究(1999年5月8日～6月24日),探讨了水动力的扰动引起悬浮物的增加、改变水下光强的分布,并由此造成了初级生产力的变化.结果表明,无论是静止还是小水流、大水流状态,水下光强随深度都是按指数规律衰减;在静止状态下,槽水清澈见底,光衰减系数为1m-1左右,到小水流和大水流时,由于动力的扰动、悬浮物浓度的增加,光学衰减系数增加到2m-1和4m-1左右,真光层深度也由最初的4m降到2m、1m;对光学衰减系数、真光层深度与悬浮物浓度进行线性和幂函数回归,发现他们之间的相关性很好,反映了风浪扰动引起水中悬浮物增加是改变水下光照分布的主要原因;在静止状态下,由于槽水清澈,强光作用下表面存在光抑制现象,最大初级生产力出现在04～06m,其他情形光抑制很弱或基本上不存在,最大初级生产力出现在0～02m.     

Suspended Matter,Chl-a,CDOM, Grain Sizes,and Optical Properties in the Arctic Fjord-Type Estuary,Kangerlussuaq, West Greenland During Summer

Optical constituents as suspended particulate matter (SPM), chlorophyll (Chl-a), colored dissolved organic matter (CDOM), and grain sizes were obtained on a transect in the arctic fjord-type estuary Kangerlussuaq (66°) in August 2007 along with optical properties. These comprised diffuse attenuation coefficient of downwelling PAR (K _d(PAR)), upwelling PAR (K _u(PAR)), particle beam attenuation coefficient (c _p), and irradiance reflectance R(−0, PAR). PAR is white light between 400 and 700 nm. The estuary receives melt water from the Greenland Inland Ice and stations covered a transect from the very high turbid melt water outlet to clear marine waters. Results showed a strong spatial variation with high values as for suspended matter concentrations, CDOM, diffuse attenuation coefficient K _d(PAR), particle beam attenuation coefficients (c _p), and reflectance R(−0, PAR) at the melt water outlet. Values of optical constituents and properties decreased with distance from the melt water outlet to a more or less constant level in central and outer part of the estuary. There was a strong correlation between inorganic suspended matter (SPMI) and diffuse attenuation coefficient K _d(PAR) (r ² = 0.92) and also for particle beam attenuation coefficient (c _p; r ² = 0.93). The obtained SPMI specific attenuation—K _d^*(PAR) = 0.13 m² g⁻¹ SPMI—and the SPMI specific particle beam attenuation—c _p^* = 0.72 m² g⁻¹—coefficients were about two times higher than average literature values. Irradiance reflectance R(−0, PAR) was comparatively high (0.09−0.20) and showed a high (r ² = 0.80) correlation with K _u(PAR). Scattering dominated relative to absorption—b(PAR)/a(PAR) = 12.3. Results strongly indicated that the high values in the optical properties were related to the very fine particle sizes (mean = 2–6 μm) of the suspended sediment. Data and results are discussed and compared to similar studies from both temperate and tropical estuaries.     

Quantifying Contributions to Light Attenuation in Estuaries and Coastal Embayments: Application to Narragansett Bay,Rhode Island

In Narragansett Bay, light attenuation by total suspended sediments (TSS), colored dissolved organic matter (CDOM), and phytoplankton chlorophyll-a (chl-a) pigment is 129, 97, and 70%, respectively, of that by pure seawater. Spatial distribution of light attenuation indicates higher values in the upper Bay, where rivers with sediment and nutrient-rich waters enter and elevate TSS, CDOM, and chl-a concentrations. The temporal trends of light attenuation during the summer months (July–August) differed at various locations in the Bay, having the highest values in July. For the same period, spectral methods overestimated attenuation throughout the Bay. These findings quantify the behavior of light attenuation in space and time, providing information that can guide decisions related to improving water clarity and help understanding the effects of various environmental and management scenarios on it.     

A simple empirical optical model for simulating light attenuation variability in a partially mixed estuary

Representation of the subsurface light field is a crucial component of pelagic ecosystem and water quality models. Modeling the light field in estuaries is a particularly complicated problem due to the significant influence of high concentrations of dissolved and particulate matter that are derived from both terrestrial and estuarine sources. The goal of this study was to develop a relatively simple but effective way to model light attenuation variability in a turbuid estuary (Chesapeake Bay, United States) in a coupled physical-biological model. We adopted a simple, nonspectral empirical approach. Surface water quality data (salinity was used as a proxy of chromophoric dissolved organic matter [CDOM]) and light measurements from the Chesapeake Bay Program were used to determine the absorption coefficients in a linear attenuation model using regression methods. This model predicts K_c (specific attenuation due to phytoplankton/chlorophylla [chla]), K_t (specific attenuation due to total suspended solids), and K_s (a function of specific attenuation coefficients of CDOM in relation to salinity). The Bay-wide fitted relation between the light attenuation coefficient and water quality concentrations gives generally good estimates of total light attenuation, K_d. The direct inclusion of salinity in the relationship has one disadvantage: it can yield negative values for K_d at high salinities. We developed two separate models for two different salinity regimes. This approach, in addition to solving the negative K_d problem, also accounts for some changes in specific light absorption by chla, seston (nonphytoplankton particulate matter), and CDOM that apparently occur in different salinity regimes in Chesapeake Bay. The resulting model predicts the statistical characteristics (i.e., the mean and variance) of K_d quite accurately in most regions of Chesapeake Bay. We also discuss in this paper the feasibility and caveats of using K_d converted from Secchi depth in the empirical method.     

增强的UV-B对湖泊生态系统的影响研究

近20多年来，由于平流层臭氧层减薄引起紫外辐射（UV-B）增强而导致严重的生态学后果，已受到各国广泛的重视，并对此进行了深入研究，尤其集中在海洋浮游植物初级生产者及淡水食物网上。综述了国外在UV-B对湖泊生态系统影响的研究现状与动态，增强的UV-B在湖泊中呈指数衰减，不同湖泊衰减系数变化很大；光衰减系数与溶解性有机碳（DOC）、有色可溶性有机物（CDOM）一般呈显著性正相关；增强的UV-B对浮游植物、浮游细菌、浮游动物及鱼类均有不同程度的影响；由于不同生物具有不同适应UV-B伤害的机制，湖泊生态系统的结构和功能也势必会发生变化。最后提出了未来在太湖等富营养化湖泊UV-B的研究设想。     

Refining habitat requirements of submersed aquatic vegetation: Role of optical models

A model of the spectral diffuse attenuation coefficient of downwelling irradiance was constructed for Chincoteague Bay, Maryland, and the Rhode River, Maryland. The model is written in terms of absorption spectra of dissolved yellow substance, the chlorophyll-specific absorption of phytoplankton, and absorption and scattering by particulate matter (expressed as turbidity). Based on published light requirements for submersed aquatic vegetation (SAV) in Chesapeake Bay, the model is used to calculate the range of water-quality conditions that permit survival of SAV at various depths. Because the model is spectrally based, it can be used to calculate the attenuation of either photosynthetically active radiation (PAR, equally weighted quanta from 400 nm to 700 nm) or photosyntheticallyusable radiation (PUR, the integral of the quantum spectrum weighted by the pigment absorption spectrum of SAV). PUR is a more accurate measurement of light that can be absorbed by SAV and it is more strongly affected by phytoplankton chlorophyll in the water column than is PAR. For estuaries in which light attenuation is dominated by turbidity and chlorophyll, the model delimits regions in which turbidity alone (chlorophyll <10 μg 1^?1), chlorophyll alone (turbidity <1 NTU) or both factors (chlorophyll >10 μg 1^?1, turbidity >1 NTU) must be reduced to improve survival depths for SAV.     

Compositional differences of chromophoric dissolved organic matter derived from phytoplankton and macrophytes

Chromophoric dissolved organic matter (CDOM) is an important component in the aquatic environment and plays a key role in light attenuation and in carbon biogeochemical cycles. We examined CDOM production in each of two laboratory experiments in which phytoplankton and macrophyte degradation were monitored using absorption and excitation–emission matrix fluorescence spectroscopy (EEMs). During the incubation period, CDOM was produced from phytoplankton and macrophytes, and partly decomposed by microorganisms. The absorption spectra of the phytoplankton derived and the macrophyte derived CDOM were distinct and characterized by peaks and shoulders in the UV bands. Production of CDOM absorption at 350 nm, a(350), was 0.0125 m²/g per unit of chlorophyll a from phytoplankton CDOM from 0–3 d. Meanwhile a(350) production was 2.708 × 10⁻⁴ m²/g per unit of wet biomass from macrophytes CDOM from 1–7 d. Despite the high production of CDOM by phytoplankton and macrophytes, extrapolation of these values to the field indicated that about 15% of total CDOM was produced from phytoplankton during algal blooms in Meiliang Bay in summer and about 8% of total CDOM was produced from macrophytes in the macrophyte dominated littorals. The mean value of the spectral slope (S) describing the exponential decrease of the absorption spectrum, which was strongly correlated to an optical index of molecular size, for the phytoplankton derived CDOM was 10.26 ± 2.05 μm⁻¹, which was significantly lower than the mean S of 14.47 ± 2.88 μm⁻¹ for the macrophyte derived CDOM (t-test, p < 0.001). The mean value of the spectral slope ratio (S_R) for the phytoplankton derived CDOM was 1.79 ± 0.52, which was significantly higher than that of 0.35 ± 0.58 for the macrophyte derived CDOM (t-test, p < 0.001). Three fluorescent components were validated in parallel factor analysis (PARAFAC) models calculated separately for phytoplankton derived and macrophyte derived CDOM, each CDOM source resulting in distinct excitation and emission maxima for each component. The significant differences in CDOM absorption spectra, S, S_R and PARAFAC fluorescence component characteristics, all showed that phytoplankton derived CDOM was compositionally distinct from macrophyte derived CDOM. Overall both sources were important to the CDOM pool in the shallow temperate lake.     

Temporal and Spatial Distribution Characteristics of Colored Dissolved Organic Matter in Coastal Waters of Jiangsu Province

Colored Dissolved Organic Matter (CDOM) is one of important ocean color factors. In the background of “Jiangsu Coastal Development”, it is important to monitor the water quality and pollution status of coastal waters by analyzing its spatial and temporal distribution characteristics with remote sensing data. This paper was based on the high temporal resolution of Geostationary Ocean Color Imager (GOCI) image downloaded from Korea Ocean Satellite Center. The temporal-spatial distribution of CDOM in Jiangsu coastal waters was analyzed on daily, weekly and monthly time scales from April, 2011 to May, 2016. CDOM in Jiangsu coastal waters are mainly terrigenous, and higher inshore than that of offshore. The monthly average concentration of CDOM in the western coast of the South Yellow Sea was 0.167~0.201 m^-1, and those of central and southern regions were 0.086~0.187m^-1. The maximum values were outside the maximum turbidity zone of the Yangtze River Estuary, which was 0.180~0.206 m^-1 (absorption coefficient at 440 nm). The diurnal variation of CDOM in near shore waters was found to coincide with the change of tide, which decreased at first and then increased in the sea area. By fitting the monthly mean using cosine function, significantly cyclical variation of mean CDOM was found in the South Yellow Sea. The central region of the South Yellow Sea waters fitting coefficient was 0.823. Affected by the Yellow Sea cold water mass, the sub-regions of the South Yellow Sea changed seasonally, whose CDOM concentration in winter and spring was higher than that in summer and autumn. Because of Changjiang Diluted Water and other water masses, seasonal variation of the Yangtze River Estuary was contrary to that of the South Yellow Sea. On monthly scale, CDOM concentration was positively correlated with total suspended matter, with correlation coefficient r being 0.72. The trend of the central and southern region was more significant.