Characterization of the light attenuation by periphyton in lakes of different trophic state   总被引：1，自引：0，他引：1  

Uta Raeder  Johannes Ruzicka  Cornelia Goos 《Limnologica》2010,40(1):40-46

In order to measure the attenuation of light by periphyton a method has been developed which assures that natural periphyton architecture and therefore its optical characteristics remain preserved. This method has been applied to analyze the transmittance of periphyton of four lakes of different tropic states situated in the Osterseen Lake District (Upper Bavaria, Germany). The seasonal variation of the periphyton's transmittance has been studied using standard microscope glass slides exposed 1 m beneath the water surface within macrophyte beds. The study ran from February to November 1997 in two eutrophic lakes (Lake Waschsee, Lake Sengsee) and from May to November 1997 in the meso-oligotrophic Lake Eishaussee and in the oligotrophic Lake Herrensee.Generally the exposure-period, the seasonality, and the tropic state of the habitat affected the transmittance spectra of the periphyton. In all lakes the attenuation by periphyton increased with longer colonization times but at a different time scale. The periphyton of the nutrient-rich and the nutrient-poor lakes differed clearly in composition and architecture. The eutrophic lakes were characterized by a relatively thick but loosely attached, unstable periphyton community, which was translucent to a certain degree even at the end of the growth period. The transmittance of this periphyton fluctuated considerably and high percentages of filamentous green algae in this periphyton contributed to attenuation maxima within the range 400-500 nm and 650-700 nm due to photosynthetic pigments. By contrast, the periphyton of the meso-oligotrophic and of the oligotrophic lake was quite compact and nearly impervious to light.  相似文献   

Sources, loads and dispersion of dissolved inorganic nutrients in Paranaguá Bay     

Byanka Damian Mizerkowski  Karl-J. Hesse  Norbert Ladwig  Eunice da Costa Machado  Rodrigo Rosa  Taiana Araujo  Daniela Koch 《Ocean Dynamics》2012,62(10-12):1409-1424

The present study focuses on the nutrient sources and gradients in Paranaguá Bay (Southern Brazil), where nutrient inputs are related to losses from fertilizer loading in Paranaguá harbour and the discharge of untreated waste water. The input of dissolved inorganic nutrients to the bay from the harbour and city, as well as from river and atmospheric deposition, amounted to 642?t?year^?1 DIN-N and 92?t?year^?1 PO₄-P. Harbour losses accounted for 6?% of total DIN-N and 39?% of total PO₄-P loads to the bay, whereas sewage inputs from the city were responsible for 21?% and 22?%, respectively. River inputs made up 68?% of DIN-N, mainly in the form of nitrate, and 35?% of PO₄-P loads, while atmospheric wet deposition was estimated to be in the order of 5?% of DIN-N and 4?% of PO₄-P loads. Local maxima in nutrient levels deriving from highly concentrated sewage discharge were observed in front of the harbour and city of Paranaguá, but the plumes are diluted rapidly due to short residence times. DIN concentrations are negatively correlated with salinity, indicating the importance of freshwater input as a main factor controlling nitrogen distribution. Elevated phosphate levels in the stratified middle section of the bay may result both from harbour emissions and phosphate remobilization from sediments. Generally lower DIN and PO₄ concentrations during the warmer rainy season are supposed to be due to intensified assimilation rates especially in the middle section of the bay where dense phytoplankton blooms are observed. The bay as a whole cannot be classified as being seriously eutrophic, albeit eutrophication symptoms prevail in some restricted locations in front of Paranaguá harbour.  相似文献   

Sources,loads and dispersion of dissolved inorganic nutrients in Paranaguá Bay     

Mizerkowski  Byanka Damian  Hesse  Karl-J.  Ladwig  Norbert  da Costa Machado  Eunice  Rosa  Rodrigo  Araujo  Taiana  Koch  Daniela 《Ocean Dynamics》2012,62(10):1409-1424

The present study focuses on the nutrient sources and gradients in Paranaguá Bay (Southern Brazil), where nutrient inputs are related to losses from fertilizer loading in Paranaguá harbour and the discharge of untreated waste water. The input of dissolved inorganic nutrients to the bay from the harbour and city, as well as from river and atmospheric deposition, amounted to 642 t year⁻¹ DIN-N and 92 t year⁻¹ PO₄-P. Harbour losses accounted for 6 % of total DIN-N and 39 % of total PO₄-P loads to the bay, whereas sewage inputs from the city were responsible for 21 % and 22 %, respectively. River inputs made up 68 % of DIN-N, mainly in the form of nitrate, and 35 % of PO₄-P loads, while atmospheric wet deposition was estimated to be in the order of 5 % of DIN-N and 4 % of PO₄-P loads. Local maxima in nutrient levels deriving from highly concentrated sewage discharge were observed in front of the harbour and city of Paranaguá, but the plumes are diluted rapidly due to short residence times. DIN concentrations are negatively correlated with salinity, indicating the importance of freshwater input as a main factor controlling nitrogen distribution. Elevated phosphate levels in the stratified middle section of the bay may result both from harbour emissions and phosphate remobilization from sediments. Generally lower DIN and PO₄ concentrations during the warmer rainy season are supposed to be due to intensified assimilation rates especially in the middle section of the bay where dense phytoplankton blooms are observed. The bay as a whole cannot be classified as being seriously eutrophic, albeit eutrophication symptoms prevail in some restricted locations in front of Paranaguá harbour.

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黄土古气候变化趋势与青藏高原隆升关系初探   总被引：8，自引：5，他引：3       下载免费PDF全文

刘秀铭  毛学刚  丁仲礼  吕镔  郭雪莲  陈渠  陈家胜  贾佳  杨善林  Hesse Paul  陈发虎 《第四纪研究》2009,29(5):988-999

粒度和磁化率是两个研究黄土古气候最常用的古环境变化指示参数,它们随着黄土古土壤地层变化而出现峰和谷的对应已经被证明是反映了天文轨道要素的周期变化。文章试图忽略这些受控于轨道要素的气候周期变化,而主要侧重考察黄土地层这两个参数的平均值(或背景值)所反映的长期变化趋势。对兰州九州台黄土进行了系统采样和测量,发现兰州九州台黄土剖面粒度和磁化率曲线显示出两个明显的趋势,粒度从剖面底部向上有明显逐渐变粗趋势,指示着冬季风增强,与此同时,磁化率自下而上却逐渐增大,指示着夏季风增强的趋势。与黄土高原其他黄土剖面磁化率和粒度曲线对比发现,这是两个普遍存在的趋势。地理位置靠近青藏高原的剖面,这两个增大的趋势更明显。冬、夏季风同时逐渐增强是海陆热力差异增大所引起,反映了青藏高原第四纪时期的逐渐不断的隆升过程。因此,根据粒度和磁化率曲线变化趋势线的变化特点可以帮助分析和反推第四纪以来青藏高原隆升的过程。兰州九州台以及黄土高原各剖面粒度和磁化率曲线的线性变化趋势则可能指示着第四纪以来青藏高原是逐渐均匀缓慢的变化过程。我们对22Ma以来风积地层记录的变化趋势也做了分析。前人过去普遍认识的第四纪以来跳跃式或间歇式剧烈隆升在我们的数据中没有得到反映。黄土高原西部西宁、兰州、靖远等剖面磁化率显著的增长趋势可能与青藏高原隆升到一定高度后高原季风加强所致。  相似文献   

Magnetic properties of the Tertiary red clay from Gansu Province, China and its paleoclimatic significance     

Liu Xiuming  AN Zhisheng  Tim Rolph  QIANG Xiaoke  Paul Hesse  Lu Huayu  ZHOU Jie  CAI Yanjun 《中国科学D辑(英文版)》2001,44(7)

The study on magnetic properties of the red clay indicates that the red clay and loess- paleosol sequence have a common magnetic mineralogy, with magnetite, maghemite, hematite (and possibly goethite) contributing to the magnetic behavior. The red clay magnetic susceptibility is also found to have a positive relation with extrafine superparamagnetic grains. This suggests that, like the Quaternary loess-paleosols, an ultrafine ferrimagnetic component produced during pe-dogenesis in the red clay under humid conditions also plays an important role in susceptibility enhancement in the soil units. This is supported by the correlation between Rb/Sr ratio and magnetic susceptibility. This signifies that, like the above loess-paleosol sequence, the magnetic susceptibility of the red clay can be used as a general proxy paleoclimatic indicator, although whether its susceptibility in the red clay is comparable to pedogenesis intensity and requires further investigation. Magnetic susceptibility variation in the red clay thus also provides an eo-lian/pedogenic record of paleoclimatic evolution. Study of the background susceptibility indicates that, on average, the absolute scale of the paleoclimatic shift from red clay development to Quaternary loess deposition is similar to the climatic shift from stage 5 (S1) to stage 2-4 (L1). This may suggest that during the Quaternary there is an evident strengthening of the absolute wind intensity to bring more (about double) coarser and less weathered (non-SP fraction) eolian magnetic input from the source regions to the Loess Plateau than during the Pliocene. The presence of eolian red clay since 7.5 Ma BP in central-northern China implies an important envi-ronmental change from the underlying Cretaceous red sandstone. The red clay development was closely related to global drying and climate cooling since the Cretaceous and closely associated with the abrupt uplift of the Qinghai-Xizang Plateau at about that time. This uplift of the plateau intensified the East Asia monsoon system and started red clay deposition.  相似文献   

Der Wasserhaushalt von Kulturpflanzen     

Prof. Dr. habil. W. Hesse 《Pure and Applied Geophysics》1956,34(1):253-259

Zusammenfassung Der Wasserhaushalt von Kulturpflanzen ist sehr kompliziert und wird durch zahlreiche Umweltfaktoren beeinflu\t. Von meteorologischer Seite her sind schon mehrere Methoden entwickelt worden, um die Verdunstung zu erfassen. In den Vegetationsperioden 1950, 1953, 1954 und 1955 benutzten wir in Leipzig ein neu entwickeltes Klein-Lysimeter aus Glas und ab 1954 eine aus sechs verschiedenen Klein-Lysimetern (Gazelysimetern) sowie einem Transpirographen bestehende Me\anordnung. Mit der Lysimeteranlage ist es möglich, alle Komponenten der Wasserhaushaltsgleichung zu bestimmen und auf den gesamten Wasserhaushalt der Pflanzen zu schlie\en. Zahlreiche Messungen mit jeweils 6 Wiederholungen brachten wertvolle Ergebnisse, die für die Landwirtschaft, die angewandte Botanik etc. gro\e Bedeutung haben.

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Summary The water budget of cultural plants is very complicated and liable to the influence of numerous environmental factors. Many methods have already been developed by meteorologists for the study of the evaporation. During the growing periods of 1950, 1953, 1954 and 1955 we in Leipzig applied a newly developed small-lysimeter (of glas) and from 1954 on a measuring arrangement containing 6 small-lysimeters (gauze lysimeters) of different kind as well as a transpirograph. By means of the lysimeter installation it is possible to determine all components of the equation of the water balance and to draw conclusions upon the complete water budget of the plants. Numerous measurements with six repetitions for each of them showed valuable results which are of great importance for agriculture, applied botany etc.

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Vortrag, gehalten auf der Vierten Allgem. Versammlung derSocietà Italiana di Geofisica e Meteorologia (Genova, 5.–8. April 1956).  相似文献   

Stabilisation of soil organic matter by interactions with minerals as revealed by mineral dissolution and oxidative degradation   总被引：4，自引：0，他引：4  

Karin Eusterhues  Cornelia Rumpel  Markus Kleber  Ingrid Kgel-Knabner 《Organic Geochemistry》2003,34(12):1591-1600

Soil organic matter is known to contain a stable fraction with an old radiocarbon age. Size and stabilisation processes leading to the formation of this old soil carbon pool are still unclear. Our study aims to differentiate old organic matter from young and labile carbon compounds in two acid forest soils (dystric cambisol, haplic podzol). To identify such fractions soil samples were exposed to oxidation with Na₂S₂O₈ and to dissolution by hydrofluoric acid (HF). A negative correlation between ¹⁴C activity and carbon release after dissolution of the mineral matrix by HF indicates a strong association of stabilised carbon compounds with the mineral phase. A negative correlation between the ¹⁴C activity and the relative proportion of carbon resistant to oxidation by Na₂S₂O₈ shows that young carbon is removed preferentially by this treatment. The fraction remaining after oxidation represents a certain stabilised, long residence time carbon pool. This old fraction comprises between 1 and 30% of the total soil organic carbon in the surface horizons, but reaches up to 80% in the sub-surface horizons. Old OC is mainly stabilised by organo-mineral associations with clay minerals and/or iron oxides, whereas intercalation in clay minerals was not found to be important.  相似文献   

Geochemistry of Peruvian near-surface sediments   总被引：6，自引：0，他引：6  

Philipp Böning  Michael E. Böttcher  Cornelia Kriete  Sven Lars Borchers 《Geochimica et cosmochimica acta》2004,68(21):4429-4451

Sixteen short sediment cores were recovered from the upper edge (UEO), within (WO) and below (BO) the oxygen minimum zone (OMZ) off Peru during cruise 147 of R/V Sonne. Solids were analyzed for major/trace elements, total organic carbon, total inorganic carbon, total sulfur, the stable sulfur isotope composition (δ³⁴S) of pyrite, and sulfate reduction rates (SRR). Pore waters were analyzed for dissolved sulfate/sulfide and δ³⁴S of sulfate. In all cores highest SRR were observed in the top 5 cm where pore water sulfate concentrations varied little due to resupply of sulfate by sulfide oxidation and/or diffusion of sulfate from bottom water. δ³⁴S of dissolved sulfate showed only minor downcore increases. Strong ³²S enrichments in sedimentary pyrite (to −48‰ vs. V-CDT) are due to processes in the oxidative part of the sulfur cycle in addition to sulfate reduction. Manganese and Co are significantly depleted in Peruvian upwelling sediments most likely due to mobilization from particles settling through the OMZ, whereas release of both elements from reducing sediments only seems to occur in near-coastal sites. Cadmium, Mo and Re are exceptionally enriched in WO sediments (<600 m water depth). High Re and moderate Cd and Mo enrichments are seen in BO sediments (>600 m water depth). Re/Mo ratios indicate anoxic and suboxic conditions for WO and BO sediments, respectively. Cadmium and Mo downcore profiles suggest considerable contribution to UEO/WO sediments by a biodetrital phase, whereas Re presumably accumulates via diffusion across the sediment-water interface to precipitation depth. Uranium is distinctly enriched in WO sediments (due to sulfidic conditions) and in some BO sediments (due to phosphorites). Silver transfer to suboxic BO sediments is likely governed by diatomaceous matter input, whereas in anoxic WO sediments Ag is presumably trapped due to sulfide precipitation. Cadmium, Cu, Zn, Ni, Cr, Ag, and T1 predominantly accumulate via biogenic pre-concentration in plankton remains. Rhenium, Sb, As, V, U and Mo are enriched in accordance with seawater TE availability. Lead and Bi enrichment in UEO surface sediments is likely contributed by anthropogenic activity (mining). Accumulation rates of TOC, Cd, Mo, U, and V from Peruvian and Namibian sediments exceed those from the Oman Margin and Gulf of California due to enhanced preservation off Peru and Namibia.  相似文献   

Physical and chemical growth conditions of Ordovician organogenic deep-water dolomite concretions: implications for the δ¹⁸O of Early Palaeozoic sea water     

Reinhard Hesse  Jehangir Shah†  Shafiul Islam‡ 《Sedimentology》2004,51(3):601-625

The estimated depth of formation of authigenic dolomite concretions in the Middle Ordovician Cloridorme Formation, Quebec, ranges from < 1 m to 150–200 m below sea floor (mbsf) (mostly between < 1 and 25 mbsf), based on centre‐to‐margin variations in minus‐cement porosity (80–90% to 45–75%). Formation depths are > 350 mbsf (25–17% porosity) in the Lower Ordovician Levis Formation. Outward‐decreasing δ¹³C_VPDB values (10·2–0·8‰) suggest precipitation in the methane generation zone with an increasing contribution of light carbonate derived by advection from thermocatalytic reactions at depth. Anomalously low δ¹⁸O_VPDB values (centre‐to‐margin variations of ?0·4 to ?7·5‰) give reasonable temperatures for the concretion centres only if the δ¹⁸O of Ordovician sea water was negative (?6‰) and the bottom water was warm (> 15 °C). The 3–5‰ lower values for the concretion margins compared with the centres can be explained if, in addition, volcanic‐ash alteration, organic‐matter decomposition and/or advection of ¹⁸O‐depleted water lowered the δ¹⁸O of the pore water further by 2·0–4·0‰ during the first 25–200 m of burial. Reasonable growth temperatures for the margins of 17–20 °C are compatible with a lowering of the isotopic ratios by 1 to < 1·3‰ as a temperature effect. The systematic concentric isotope zonation of the concretions suggests that the well‐ordered near‐stoichiometric dolomite is a primary feature and not the result of recrystallization. Diagenetic dolomite beds of the Cloridorme Formation appear to have formed by coalescence of concretions, as shown by randomly sampled traverses that indicate formation at different subsurface depths. Growth of the Cloridorme dolomites was probably limited by calcium availability, at least 50% of which was derived from connate water, and the remainder by diffusion from sea water. Dolomite precipitation was favoured over calcite by very high sedimentation rates, the abundance of marine organic matter in the host sediment and a correspondingly thin sulphate reduction zone. Deep‐seated concretion growth in the Levis Formation required either internal sources for the participating ions (carbonate dissolution event) or porewater advection along faults.  相似文献   

Hydrochemistry,origin and evolution of sedimentary subsurface fluids: I. Early diagenetic pore-water evolution in low-sedimentation rate offshore basins     

Reinhard Hesse 《中国地球化学学报》1986,5(4):297-319

Pore water studies enable (1) the detection of diagenetic reactions actively occurring in the sediment at the time of sampling,(2) the distinction between principal modes of solute transport, i.e., between advection (convection) and diffusion, and (3) the assessment of mineral-solution equilibria, Pore waters are, therefore, preferred diagnostic objects in the study of diagenesis, particularly early diagenesis. The single most important factor for pore-fluid evolution in modern offshore basins is sedimentation rate which is closely correlated with organtic matter content of the sediment. Organic matter represents the most reactive sediment constituent which, through bacterial decomposition, provides some of the main solutes involved in early diagenetic mineralization reactions. On the basis of sedimentation rate and organic matter content, it is convenient to distinguish two end-members of basins (environments) with respect to early diagenesis: I. Low to intermediate-sedimentation rate basins with convection or diffusion-controlled pore-water profiles and II. high-sedimentation rate basins with reaction-controlled pore-water profiles. The first group of basins or environments, which is the subject of this paper, is typically represented by pelagic sediments. Three principally different trends of pore-water evolution occur: 1. convection-controlled profiles with no pronounced vertical gradients for the dissolved species; 2. diffusion-controlled profiles with vertical gradients but linear correlations between major ions, especially Ca and Mg, and 3. profiles with gradients but no linear correlation between the major ions. The later are transitional to the trends seen in high-sedimentation rate basins. With respect to redox-potentials, the diagenetic environments of low-sedimentation rate basins are generally oxic to suboxic.  相似文献