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N. Wasmund 《洁净——土壤、空气、水》1984,12(3):255-272
For the determination of the contents of chlorophyll a and phaeopigment a in sediment samples the method according to LORENZEN with its principle and the error sources is discussed in detail. The acidification required for the determination of the phaeopigments should be carried out on a final concentration of 0.006 mol/l acid. As an extracting agent, such a quantity of acetone has to be added to the sediment sample that a final concentration of 90 % acetone will be obtained with the interstitial water being taken into account. By an extraction done twice 90 % of pigments are extracted. Methanol as an extracting agents is unsuitable for several reasons mentioned. Exposure to light at more than 1 W/m2 results in a high rate of chlorophyll degradation, the same effect being shown by increased temperatures. Between the trichromatic chlorophyll determination according to JEFFREY and HUMPHREY and the determination according to LORENZEN exists the linear relation chl. a (J. and H.)=chl. a (L.)+0.6. phaeo. a (L.). The procedure of the determination of chlorophyll a and phaeopigment a according to LORENZEN is described in a detailed representation. 相似文献
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Zhouli Liu Wei Chen Xingyuan He Lian Jia Yanqing Huang Yue Zhang Shuai Yu 《洁净——土壤、空气、水》2013,41(5):478-484
Phytoremediation of Cd‐contaminated soil using hyperaccumulators has become a new promising technique. Lonicera japonica Thunb. has been reported as a new Cd‐hyperaccumulator. In this study, the effect of Cd stress duration on growth, photosynthesis and mineral nutrition of L. japonica was investigated. At 30 days after Cd stress, there was not any visual leaf symptoms in L. japonica, and an obvious stimulating effect of 10 mg kg?1 Cd on net photosynthesis rate (PN) was well correlated to photosynthetic pigment contents and mineral nutrition (Mg and Fe) concentrations. With Cd stress time extended, no significant differences of shoots and total biomass and PN compared with the control was observed, indicating that L. japonica could develop effective tolerance mechanisms to avoid Cd‐induced damage to photosynthesis and growth. The photosynthetic performance remained functional through stomatal and non‐stomatal adjustments, and mineral nutrition responses. The improved growth based on shoots and total biomass and PN by 10 mg kg?1 Cd, as suggested by hormesis, may be beneficial to enhance the potential for phytoremediation, because it typically faced the low Cd concentrations in actual Cd‐contaminated soils. The study results indicated that L. japonica could be used for phytoremediation contaminated soils by Cd. 相似文献
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Human‐induced and natural interruptions with continuous streams of observational data necessitate the development of gap‐filling and prediction strategies towards better understanding, monitoring and management of aquatic systems. This study quantified the efficacy of multiple non‐linear regression (MNLR) versus artificial neural network (ANN) models as well as the temporal partitioning of diurnal versus nocturnal data for the predictions of chlorophyll‐a (chl‐a) and dissolved oxygen (DO) dynamics. The temporal partitioning increased the predictive performances of the best MNLR models of diurnal DO by 45% and nocturnal DO by 4%, relative to the best diel MNLR model of diel DO ($r_{{\rm adj}}^{2} = 68.8\%$ ). The ANN‐based predictions had a higher predictive power than the MNLR‐based predictions for both chl‐a and DO except for diurnal DO dynamics. The best ANNs based on independent validations were multilayer perceptron (MLP) for diel chl‐a, generalized feedforward (GFF) for diurnal and nocturnal chl‐a, MLP for diel DO, GFF for diurnal DO, and MLP for nocturnal DO. 相似文献
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We examined the effects of freshwater flow and light availability on phytoplankton biomass and production along the Louisiana continental shelf in the region characterized by persistent spring–summer stratification and widespread summer hypoxia. Data were collected on 7 cruises from 2005 to 2007, and spatially-averaged estimates of phytoplankton and light variables were calculated for the study area using Voronoi polygon normalization. Shelf-wide phytoplankton production ranged from 0.47 to 1.75 mg C m−2 d−1 across the 7 cruises. Shelf-wide average light attenuation (kd) ranged from 0.19–1.01 m−1 and strongly covaried with freshwater discharge from the Mississippi and Atchafalaya Rivers (R2=0.67). Interestingly, we observed that the euphotic zone (as defined by the 1% light depth) extended well below the pycnocline and to the bottom across much of the shelf. Shelf-wide average chlorophyll a (chl a) concentrations ranged from 1.4 to 5.9 mg m−3 and, similar to kd, covaried with river discharge (R2=0.83). Also, chl a concentrations were significantly higher in plume versus non-plume regions of the shelf. When integrated through the water-column, shelf-wide average chl a ranged from 26.3 to 47.6 mg m−2, but did not covary with river discharge, nor were plume versus non-plume averages statistically different. The high integrated chl a in the non-plume waters resulted from frequent sub-pycnocline chl a maxima. Phytoplankton production rates were highest in the vicinity of the Mississippi River bird's foot delta, but as with integrated chl a were not statistically different in plume versus non-plume waters across the rest of the shelf. Based on the vertical distribution of light and chl a, a substantial fraction of phytoplankton production occurred below the pycnocline, averaging from 25% to 50% among cruises. These results suggest that freshwater and nutrient inputs regulate shelf-wide kd and, consequently, the vertical distribution of primary production. The substantial below-pycnocline primary production we observed has not been previously quantified for this region, but has important implications about the formation and persistence of hypoxia on the Louisiana continental shelf. 相似文献
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David P. Hamilton Katherine R. O’Brien Michele A. Burford Justin D. Brookes Chris G. McBride 《Aquatic Sciences - Research Across Boundaries》2010,72(3):295-307
The factors affecting vertical distributions of chlorophyll fluorescence were examined in four temperate, warm monomictic
lakes. Each of the lakes (maximum depth >80 m) was sampled over 2 years at intervals from monthly to seasonal. Profiles were
taken of chlorophyll fluorescence (as a proxy for algal biomass), temperature and irradiance, as well as integrated samples
from the surface mixed layer for chlorophyll a (chl a) and nutrient concentrations in each lake. Depth profiles of chlorophyll fluorescence were also made along transects of the
longest axis of each lake. Chlorophyll fluorescence maxima occurred at depths closely correlated with euphotic depth (r
2 = 0.67, P < 0.01), which varied with nutrient status of the lakes. While seasonal thermal density stratification is a prerequisite
for the existence of a deep chlorophyll maximum (DCM), our study provides evidence that the depth of light penetration largely
dictates the DCM depth during stratification. Reduction in water clarity through eutrophication can cause a shift in phytoplankton
distributions from a DCM in spring or summer to a surface chlorophyll maximum within the surface mixed layer when the depth
of the euphotic zone (z
eu) is consistently shallower than the depth of the surface mixed layer (z
SML). Trophic status has a key role in determining vertical distributions of chlorophyll in the four lakes, but does not appear
to disrupt the annual cycle of maximum chlorophyll in winter. 相似文献
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Masayuki Sakakibara Yuko Ohmori Nguyen Thi Hoang Ha Sakae Sano Koichiro Sera 《洁净——土壤、空气、水》2011,39(8):735-741
Phytoremediation is an environmental remediation technique that takes advantage of plant physiology and metabolism. The unique property of heavy metal hyperaccumulation by the macrophyte Eleocharis acicularis is of great significance in the phytoremediation of water and sediments contaminated by heavy metals at mine sites. In this study, a field cultivation experiment was performed to examine the applicability of E. acicularis to the remediation of water contaminated by heavy metals. The highest concentrations of heavy metals in the shoots of E. acicularis were 20 200 mg Cu/kg, 14 200 mg Zn/kg, 1740 mg As/kg, 894 mg Pb/kg, and 239 mg Cd/kg. The concentrations of Cu, Zn, As, Cd, and Pb in the shoots correlate with their concentrations in the soil in a log‐linear fashion. The bioconcentration factor for these elements decreases log‐linearly with increasing concentration in the soil. The results indicate the ability of E. acicularis to hyperaccumulate Cu, Zn, As, and Cd under natural conditions, making it a good candidate species for the phytoremediation of water contaminated by heavy metals. 相似文献
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The ability of seven hyperaccumulator macrophytes which grow naturally in the heavy metal contaminated channels of three different industries (Hindustan Aeronautical Ltd., Eveready Ltd., and Scooter India Ltd.) to accumulate heavy metals was recorded. All these industries use electroplating processes in their manufacturing and are located in the inner area of Lucknow City, U.P., India. Of the three industries monitored, effluent released from Eveready Ltd. contained the highest concentration of heavy metals. In general, accumulations of heavy metals depend upon the plant species and the metal concentration in the media. All plant samples showed heterogeneous metal accumulations, except for Fe or Cd. It was observed that some plant species accumulated high level of metals, e. g., Eichhornnia crassipes for Fe (4052.44 μg/g), Mn (788.42 μg/g), and Cu (315.50 μg/g), and Spirodela polyrhiza for Cd (12.75 μg/g), Pb (20.25 μg/g), and Cr (128.27 μg/g), even when the metal concentrations were not high in the effluent. In summary, these two plants were found to be the best accumulators at each contaminated site. The results will be helpful in the selection of plant species which can be used as bioaccumulators or bioindicators. 相似文献
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《Continental Shelf Research》2005,25(9):1081-1095
The mesoscale distribution and seasonal variation of the size structure of phytoplankton biomass, as measured by chlorophyll a (chl a), was studied in the Ebro shelf area (NW Mediterranean) during three different seasons: autumn, winter and summer. In autumn and summer, when the water column was, respectively, slightly or strongly stratified and nutrient concentrations were low at surface, average total chl a values were 0.31 and 0.29 mg m−3, respectively. In winter, the intrusion of nutrients into the photic zone by intense vertical mixing and strong riverine inputs, produced an increase of the total autotrophic biomass (0.76 mg m−3). In the three seasons, the main contributor to total chl a was the picoplanktonic (<2 μm) size fraction (42% in winter and around 60% in autumn and summer). The nanophytoplankton (2–20 μm) contribution to total chl a showed the lowest variability amongst seasons (between 29% and 39%). The microplanktonic (>20 μm) chl a size fraction was higher in winter (27%) than in the other seasons (less than 13%). The maximum total chl a concentrations were found at surface in winter, at depths of 40 m in autumn and between 50 and 80 m in summer. The relative contribution of the <2 μm size fraction at these levels of the water column tended to be higher than at other depths in autumn and winter and lower in summer. In autumn and winter, nutrient inputs from Ebro river discharge and mixing processes resulted in an increase on the >2 μm contribution to total chl a in the coastal zone near the Ebro Delta area. In summer, the contribution of the <2 and >2 μm chl a size fractions was homogeneously distributed through the sampling area. In autumn and summer, when deep chl a maxima were observed, the total amount of the autotrophic biomass in the superficial waters (down to 10 m) of most offshore stations was less than 10% of the whole integrated chl a (down to 100 m or to the bottom). In winter, this percentage increased until 20% or 40%. The >2 μm chl a increased linearly with total chl a values. However, the <2 μm chl a showed a similar linear relationship only at total chl a values lower than 1 mg m−3 (in autumn and summer) or 2 mg m−3 (winter). At higher values of total chl a, the contribution of the <2 μm size fraction remained below an upper limit of roughly 0.5 mg m−3. Our results indicate that the picoplankton fraction of phytoplankton may show higher seasonal and mesoscale variability than is usually acknowledged. 相似文献
10.
沉水植物附植生物膜藻类组成及重金属累积特征 总被引：2，自引：1，他引：1
沉水植物表面常富集水体中有机质、泥沙、菌胶团、藻类、微生物等形成附植生物膜,在湖泊生物地球化学循环过程中具有重要作用.在草海选取金鱼藻（Ceratophyllum demersum）、微齿眼子菜（Potamogeton maackianus）和光叶眼子菜（Potamogeton lucens L.）3种不同叶形的沉水植物,研究附植生物膜的形貌结构、理化特征、藻类及其重金属镉（Cd）、铅（Pb）累积特征.结果表明：3种沉水植物附植生物膜上共鉴定出藻类6门8纲17目29科65属81种,主要为蓝藻、绿藻和硅藻,不同附植生物膜藻类功能群组成不同,冗余分析表明,水环境因子能解释藻类功能群变化的88.3%;3种沉水植物附植生物膜铁（Fe）、锰（Mn）、总氮（TN）、总磷（TP）含量变化规律一致,均为：金鱼藻 > 微齿眼子菜 > 光叶眼子菜;附植生物膜中重金属的累积具有选择性,Pb大量累积（11.41~41.31 mg/kg）,Cd累积含量较低（0.59~5.76 mg/kg）且与植物相当（0.44~5.56 mg/kg）,附植生物膜中Pb累积含量与生物膜中隐藻门、硅藻门藻类生物量、Fe、Mn及TN含量呈显著相关,但Cd累积与生物膜各指标均无显著相关性.附植生物膜在草型湖泊污染物归趋转化中的作用值得关注. 相似文献
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Effect of varying normal stress on stability and dynamic motion of a spring-slider system with rate- and state-dependent friction 
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下载免费PDF全文 Incorporating rate and state friction laws, stability of linearly stable (i.e., with stiffness greater than the critical value) spring-slider systems subjected to triggering perturbations was analyzed under variable normal stress condition, and comparison was made between our results and that of fixed normal stress cases revealed in previous studies. For systems associated with the slip law, the critical magnitude of rate steps for triggering unstable slips are found to have a similar pattern to the fixed normal stress case, and the critical velocity steps scale with a/(b - a) when k = kcr for both cases. The rate-step boundaries for the variable normal stress cases are revealed to be lower than the fixed normal stress case by 7 %–16 % for a relatively large α = 0.56 with (b - a)/a ranging from 0.25 to 1, indicating easier triggering under the variable normal stress condition with rate steps. The difference between fixed and variable normal stress cases decreases when the α value is smaller. In the same slip-law-type systems, critical displacements to trigger instability are revealed to be little affected by the variable normal stress condition. When k ≥ kcr(V*), a spring-slider system with the slowness law is much more stable than with the slip law, suggesting that the slowness law fits experimental data better when a single state variable is adopted. In stick-slip motions, the variable normal stress case has larger stress drops than the constant normal stress case. The variable normal stress has little effect on the range of slip velocity in systems associated with the slowness law, whereas systems associated with the slip law have a slowest slip velocity immensely smaller than the fixed normal stress case, by ~10 orders of magnitude. 相似文献
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This in situ study used photosynthetic activity (measured as chlorophyll a fluorescence) and photosynthetic pigment concentrations to assess the effect of copper, cadmium, lead and zinc on the seagrass Zostera capricorni. Custom-made portable in situ exposure (PIE) chambers were developed so seagrasses could be dosed within the meadow. Z. capricorni was exposed to 0.1 and 1 mg l−1 of metal solutions for 10 h. During this time and for the subsequent four-day recovery period, the effective quantum yield of photosystem II (PS II) (ΔF/Fm′) was measured. While the results were variable, copper and zinc exposed samples had a depressed ΔF/Fm′ during the exposure period. Samples exposed to zinc recovered to pre-exposure levels but those exposed to copper did not. Cadmium and lead did not impact on the chlorophyll a fluorescence and the chlorophyll pigment data supported these findings. This study presents an innovative new application of chlorophyll a fluorescence stress assessment. 相似文献
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During a summer period we studied the vertical variation of in vivo and chlorophyll a specific phytoplankton absorption spectra in relation to the underwater light climate of ten deep North Patagonian Andean lakes of Argentina. The lakes were thermally stratified, and the underwater light climate was characterized by extended euphotic zones which included highly illuminated epilimnetic layers (both UVR and PAR) and metalimnia exposed to dim blue-green light. Most of the lakes presented the development of Deep Chlorophyll Maxima (DCM) at the metalimnetic layers, near 1% of surface PAR irradiance. Analyzing the fourth-derivative plots of in vivo phytoplankton absorption spectra [dIVaph(λ)], we were able to identify several maxima absorption values attributed to different pigments. Considering lakes with DCM, a significant positive linear relationship was found between dIVaph (495–500 nm) normalized by chlorophyll a and downward irradiance. Indeed, a negative significant relationship was found between dIVaph (495–500 nm) normalized by chlorophyll a and diffuse PAR attenuation coefficients. These results point out an increase in the relative concentration of different carotenoids at surface layers indicating the role of photoprotection of these pigments. On the other hand, significant negative linear relationships were found between fourth-derivative spectra normalized by chlorophyll a at 650, 590–595, 560–565 and 520–525 nm and downward irradiance. These results indicated an increase in the relative concentration of photosynthetic accessory pigments at deep layers of the euphotic zone. Furthermore, we found a decrease in depth of specific absorption spectra at 440, 670 nm and in the ratio aph* (440 nm) to aph* (670 nm). This pattern was associated with the package effect concept. The increase in relative photosynthetic accessory pigment concentrations and the decrease in values of specific absorption spectra at the bottom of the euphotic zone were attributed to changes in phytoplankton communities between surface and deep layers. These outcomes pointed out that the underwater light climate and temperature water structure are, like in marine systems, very important factors governing the distribution of phytoplanktonic organisms. In addition, the possession of specific photosynthetic accessory pigments suggests that dominant species in the DCM are well adapted to these dim blue-green light scenarios. 相似文献
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The Gulf of Gdańsk receives the waters of the Wisła (Vistula), the largest Polish river and the second largest river flowing into the Baltic Sea. Chloropigments a (chlorophyll a and its derivatives) were determined in water and sediments from the Gulf. Samples were collected during cruises of R.V. ‘Oceania’ at 19 stations located at different water depths and distances from the shore, in May (2003) and October (2004), i.e., at the beginning and at the end of the growing season, respectively. Seawater was also sampled on the beach at Sopot in June, July and August 2004, i.e., during the height of the growing season. All water samples were collected with a bathometer and passed through Whatman GF/F filters. Recent sediments (0–10 cm) were collected with a core sampler and divided into sub-samples (0–1, 1–5 and 5–10 cm). The pigments were determined using HPLC-DAD. The results were first correlated with a set of parameters measured in situ during sample collection (salinity, temperature, oxygen content of seawater) and determined in the same material (organic carbon content, granulometry), then worked up statistically. Although this investigation shows that particular chloropigments a in recent sediments are indicative of the prevailing environmental conditions in the study area and the trends in their variations, they should be treated as a relative and not an absolute measure, since this is the first such study based on a large and coherent set containing both chloropigment a and environmental data. In addition, a chlorophyll a budget is estimated for the Gulf of Gdańsk on the basis of the literature and the authors’ own data. Only c. 10% of the chlorophyll a produced annually in the Gulf of Gdańsk is transferred to sediments in the form of chloropigments a; 2.8% is in the form of undecomposed chlorophyll a and 7.2% in the form of chlorophyll a derivatives. About 90% of chlorophyll a is decomposed to colourless products. 相似文献
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B. Jesus V. Brotas L. Ribeiro C.R. Mendes P. Cartaxana D.M. Paterson 《Continental Shelf Research》2009
Tagus intertidal microphytobenthos (MPB) assemblages were characterized over a wide range of sediment type and tidal height and the possible effects of these variables on MPB spatial distribution and photo-adaptation mechanisms were investigated. Two transects with six different sediment type and different tidal height sites were sampled once every two months from 2002 to 2004. Upper shore and sandy sites showed higher chlorophyll a (chl a) content, with sandy sediments showing a biomass peak in late winter–early spring, and muddy sites showing no obvious seasonal pattern. Stepwise multiple linear regressions showed that only SiO2, tidal height and sediment particle size <63 μm were significant variables (p<0.05), explaining 50% of MPB biomass spatial–temporal variability. However, when data were separated by transect, only tidal height remained significant at both transects. Sandier sediments exhibited higher zeaxanthin/chl a and lower fucoxanthin/chl a ratios characteristic of a mixed cyanobacteria/diatom assemblages, showing an alternate seasonality with cyanobacteria increasing in summer and diatoms dominating in spring. Diatom biofilms showed contrasting features depending on the sediment type. Epipsammic diatoms were small with an average length of around 10 μm, while epipelic diatoms showed a wider size range with size distribution peaks at 10–15 μm, 25–35 μm and >60 μm. Epipelic biofilms showed evidence of being low light-acclimated (high fucoxanthin/chl a) and of photo-regulating by vertical migration movements (presence of endogenous vertical rhythms and lower diatoxanthin/diadinoxanthin). Epipsammic biofilms showed higher diatoxanthin/diadinoxanthin ratios and no vertical migration rhythms. Thus, the two diatom biofilm types had distinct strategies to photo-regulate: epipelic diatoms using vertical migration to position themselves at the sediment depth of optimum light conditions, and epipsammic diatoms using the xanthophyll cycle to photo-regulate. Further studies comparing epipsammic and epipelic assemblages are necessary to better understand MPB photo-regulation mechanisms. 相似文献
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Cambrollé J Redondo-Gómez S Mateos-Naranjo E Figueroa ME 《Marine pollution bulletin》2008,56(12):2037-2042
In the joint estuary of the Odiel and Tinto rivers (SW Spain), the invasive Spartina densiflora Brongn. and the native Spartina maritima (Curtis) Fernald are growing over sediments with extreme concentrations of heavy metals. The contents of As, Cu, Fe, Mn, Pb and Zn were determined in sediments, rhizosediments and different tissues of both species, from Odiel and Tinto marshes. S. densiflora showed a higher capability to retain metals around their roots and to control the uptake or transport of metals, mediated by a higher formation of plaques of Fe/Mn (hydro) oxides on the roots. At the Tinto marsh, there were no differences between the metal concentrations of the sediment and those of the rhizosediment, a fact that could be explained by the extremely high concentrations of metals which can pass over a threshold value, altering the properties of root cells and preventing roots from acting as a ‘barrier’ to the uptake or transport of metals. 相似文献
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A total of 1503 events for a 2-month period associated with am
N 2.6 rockburst is investigated for possible space-time correlations between low magnitude (–1.1 to –0.4)b values and several estimates of stress (static stress drop, apparent stress, and dynamic stress). Spatial variations of decreasingb values were found to be well correlated with increasing stress release estimates for time intervals prior to the rockburst and following the aftershock sequence. The strongest correlation tob value was with the dynamic stress drop, having correlation coefficients of 0.87 and 0.79 for the two intervals, respectively. The rockburst was found to actually occur at the intersection of the spatial coordinates corresponding to the largest gradient inb value. Based on these correlations, we conclude that the low magnitude seismicity is an indicator of the stress state within the rock mass, and can be used to study and forecast stress patterns in the vicinity of an impending major event. Time variations, however, did not show the same clear correlations and these are discussed in terms of departure from steady state conditions. Regardless, our results favour the use ofb values in a spatial, context rather than in a time analysis approach, and we consider thatb values provide valuable information regarding the changing stress conditions within the seismogenic volume. 相似文献
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白洋淀沉积物-沉水植物-水系统重金属污染分布特征 总被引：6，自引：1，他引：5
通过对白洋淀沉水植物及对应沉积物和水中Cd、Pb、As含量测定,以期揭示白洋淀沉积物-沉水植物-水系统中重金属污染状况及分布规律,明确不同沉水植物对重金属的富集能力.结果表明,地表水Cd、Pb、As浓度均符合我国地表水I类水质标准,不同采样区重金属浓度差异不显著.上覆水Pb浓度显著高于地表水和间隙水,间隙水As浓度显著高于地表水和上覆水;地积累指数法和潜在生态危害指数法评价结果表明,沉积物中重金属污染程度表现为Cd > Pb > As,Cd污染最严重,达到"轻度-偏重度"污染程度,"中等-极强"生态危害级别,As为清洁水平,不同采样区重金属污染程度表现为生活水产养殖区 > 纳污区 > 淀边缘区;沉水植物重金属富集能力表现为金鱼藻（Ceratophyllum demersum L.） > 菹草（Potamogeton crispus L.）和穗状狐尾藻（Myriophyllum spicatum L.） > 篦齿眼子菜（Potamogeton pectinatus L.）.植物体内重金属含量与体内氮、磷含量呈显著正相关,氮、磷营养盐影响沉水植物对重金属的富集. 相似文献