Stratigraphy of Fossil Pigments as a Guide to the Environmental Changes of the Kortowskie Lake,Poland

A 294 cm long sediment core is divided into 1 cm disks at intervals of 7 cm. The disks are pollen-stratigraphically dated. At the same time, the pigment content is determined by two-dimensional thin-layer chromatography. The pigments were determined spectrophotometrically between 200 and 800 nm, six pigments having been identified, whereas in the chromatograms 13… 36 spots are found. Chlorophyll conversion products as well as epiphasic and hypophasic carotenoids were determined by liquid adsorption. The greatest variety was found with the pigments in the Atlantic period, the minimum of diversity lies in the Subboreal period. The concentration of the chlorophyll derivatives decreases with the age of sediments, whereas the carotenoids have maxima in the Atlantic and Subatlantic periods. On the basis of the ratio of chlorophyll derivatives to carotenoids and of the ratio of epiphasic carotenoids to hypophasic ones, the trophic state of the lake between oligotrophic and eutrophic as well as the relative share of autochthonous and allochthonous feed of matter to the sediment can be represented well.     

哈纳斯湖的水下地貌与表层沉积物的若干特征

测量表明,哈纳斯湖最大水深达188.5m,平均水深达120.1m,优质淡水容量达53.78×10~8m~3,均在我国湖泊中居突出地位。横断面为罕见的典型箱形,断陷作用仍在强烈进行之中。湖底表层沉积物粒度参数之分布主要受纵向搬运作用控制,局部受横向搬运作用影响。沉积物的矿物学特征与元素分布特征明显受沉积环境控制。沉积物中营养元素含量总体偏低。~(210)Pb法测得平均沉积速率为0.52mm/a,难以补偿断陷作用,湖盆将继续加深。     

太湖底泥表层越冬藻类群落动态的荧光分析法初步研究

为探索春季湖泊底泥表层不同藻类群落的复苏规律,本实验采集了太湖梅梁湾地区的底泥,应用荧光分析法测定藻蓝素,同时测定湖泊底泥中的叶绿素a和叶绿素b,确定春季梅梁湾底泥中不同藻类类群的色素含量变化,说明荧光分析法可以应用于底泥色素分析中,初步探讨了蓝藻群落和非蓝藻群落在春季温度上升期间恢复生长过程的差异。     

Analysis of the effect of copper-nickel works on the state of water resources in nearest features

The formation conditions of water exchange and quality in a lake used as a part of water disposal system of an operating copper-nickel metallurgical plant are considered. Water and material budget of the lake is calculated, including process water discharge, atmospheric precipitation, and snow melting. The quantitative and qualitative characteristics of bottom sediments and waters involved in lake water exchange are determined. The migration conditions of heavy metals from bottom sediments are evaluated and their dynamic layers are determined. Some measures are proposed for reducing the adverse impact of the coppernickel plant on water bodies.     

Plant pigments as indicators of water transformation in the upper Volga Chain of reservoirs

Results of studying spatial and temporal variability in plant pigments in the Volga River water from the upper sections of the Ivankovo Reservoir downstream to the Rybinsk Reservoir Main Reach, as well as the applicability of different groups of indices of the absolute and relative concentration of pigments (chlorophylls, phaeo-pigments, and carotenoids) are presented. To differentiate water masses, these pigments have been assessed using the standard spectrophotometric method. It has been found that waters of individual river sections, singled out according to their hydrological features, and waters of different reservoirs on the whole can be reliably distinguished according to the concentration of pigments in the plant suspension.     

The impact of faulting on the stability conditions of gas hydrates in Lake Baikal sediments

The phase transition problem of methane hydrate in porous sediments is solved. Based on the obtained solution, the impact of faulting on the stability conditions of gas hydrates is investigated by the numerical modeling of the filtration and thermal regimes in the sedimentary cover of the Central Basin of Lake Baikal within the segment of the anomalous behavior of the bottom simulating reflector (BSR). It is assumed that such behavior is caused by the tectonic action. The calculations testify to the plausibility of the proposed model of formation of the anomalous area with total decomposition of the contained hydrates. It is shown that dissociation of gas hydrates in sediments due to faulting and the subsequent uplift of the products of these transformations along the incipient channel toward the bottom of the lake can result in the extensive accumulation of gas hydrates on this surface. It is also shown that if the total amount of the free gas, which left the hydrate dissociation zone, reached the level of the lake surface at normal pressure and temperature, its volume could be equivalent to the resources of a medium-size gas field. The results of numerical modeling the violation of the gas-hydrate stability conditions in Lake Baikal sediments can also be valid for the other regions with hydrate-bearing sediments if the case specific conditions and regional tectonic activity are taken into account.     

Impact of environmental variables on spatial and seasonal internal phosphorus loading in a mesoeutrophic lake

Strzeszynskie Lake was formerly a slightly eutrophic (meso-eutrophic) water body. The aim of the current research was to define variables on both spatial and seasonal internal phosphorus loading from bottom sediments at five stations located in zones varying in depth, oxygenation, macrophyte presence, and uses of the neighboring catchment area. Ex situ experiments done with the use of intact bottom sediment cores have shown that the highest phosphorus release occurred in the deepest part of the lake and reached 3.6?mg?P/m²d under anoxic conditions during summer thermal stratification. In turn, the internal loading from littoral sediments, which were well aerated all year round, was clearly lower. Furthermore, phosphorus accumulation in the bottom sediment was observed to reach a maximum of 1.45?mg?P/m² d in autumn. A comparison of the internal loading intensity in lake zones with different land uses of the neighboring catchment area has shown slightly higher values at stations adjacent to the forest catchment area than those used for recreation. Changes in the land use of the catchment area of Strzeszynskie Lake, especially the increase in impermeable surfaces, have led to an increased inflow of external loads after heavy rains, resulting in deterioration in water quality and a delayed increase in internal loading.     

太湖：过去、现在和将来

The presence of roads, farm house foundations, wells and Liangzhu period cultural relics in the bottom of Lake Taihu attest to the fact that this shallow depression was probably dry between 4 and 5 thousand years ago. This interpretation is corroborated by the sudden disappearance of algal pigments at sediment depths carbon-14 dated at 4-5 thousand years before present.In winter, the stronger winds are predominantly from the northeast. These winds result in a powerful counterclockwise current that transports lake sediments and has altered the very shape of the lake over the last 300 years. Winds produce a complex mixing pattern in Lake Taihu with storm induced sediment deposition occurring near the lake''s center.During approximately 240 days of the year, the wind blows across Lake Taihu with sufficient force to mix it to its bottom. As a result, this polymictic lake rarely becomes anoxic and dissolved oxygen at the mud water interface is maintained at or above 4 mg·l^-1. The consequences of this high dissolved oxygen are quite impressive as high organic loading to the lake would otherwise render its bottom waters anaerobic killing many of its natural inhabitants.Because suspended solids reduce (attenuate) light penetration, the major primary production takes place in the top metre of the lake (mean Secchi Transparency-0.25 m). Suspended clays are slow to settle and wind mixing keeps fine-grained suspended solids in suspension in all but the most quiet backwaters of the lake.In the recent past about 23 000 metric tonnes of phytoplankton were produced in Lake Taihu. This large production represents only about 5% of the total influx of organic material entering the lake. In summer and fall, cyanobacteria such as Microcystis spp. and Anabaena spp. dominate most of the lake. Recently, however, mixotrophic flagellates displaced cyanobacteria as the dominant algae in parts of Lake Taihu with high bacteria and high suspended solids (e.g. Wuli and Meiliang Bay). In the future, facultative heterotrophs may come to dominate an ever larger portion of the lake waterc column.     

Distribution of Heavy Metals in Lake Seliger Bottom Deposits

The distribution of some microelements in the surface and stratified layers of bottom sediments in Lake Seliger is studied. Data on the bottom deposit pollution by heavy metals is used to determine the anthropogenic load on the lake ecosystem. Cd, Zn, and Pb are shown to rapidly accumulate in thick (>1 m) bottom deposits that have formed during the period of lake existence. The concentrations of Cd and Zn are shown to correlate with the organic matter in thick bottom deposits.     

The discovery of annually laminated sediments (varves) from shallow Sugan Lake in inland arid China and their paleoclimatic significance

Detailed examination of sedimentary cores retrieved from Sugan Lake in the northern Qaidam Basin of northwest China’s Tibetan Plateau reveal that fine laminated beddings form in the sediments where water depth exceeds 3 m. Seasonal surface sediments trapped at the bottom of the lake suggest that sediments deposited during summer and autumn are mainly light colored monohydrocalcites, while those deposited in winter are dark organic matter, indicating that varve layers form under modern limnological conditions. Continuous varve sediments comprising four types have accumulated in the upper 5.5 m of Core SG03I from the center of the lake. All types exhibit clear seasonality indicative of annual deposition. Varve counts correspondence with 210Pb dates on recent sediments in the upper core suggest the continuous varves of the upper 5.5 m of the core formed in the late Holocene (2670 a BP). The Sugan Lake varve sequence is the first demonstration of annually laminated sediments re-ported in arid western China.     

Epiphyte loads on seagrasses and microphytobenthos abundance are not reliable indicators of nutrient availability in oligotrophic coastal ecosystems

Despite marked gradients in nutrient availability that control the abundance and species composition of seagrasses in south Florida, and the importance of nutrient availability in controlling abundance and composition of epiphytes on seagrasses in other locations, we did not find that epiphyte load on the dominant seagrass, Thalassia testudinum, or that the relative contribution of algal epiphytes to the epiphyte community, was positively correlated with nutrient availability in the water column or the sediment in oligotrophic seagrass beds. Further, the abundance of microphytobenthos, as indicated by Chlorophyll-a concentration in the sediments, was not directly correlated with concentrations of nutrients in the sediments. Our results suggest that epiphyte and microphytobenthos abundance are not unambiguous indicators of nutrient availability in relatively pristine seagrass environments, and therefore would make poor candidates for indicators of the status and trends of seagrass ecosystems in relatively low-nutrient environments like the Florida Keys.     

226Ra behavior in the Pee Dee River-Winyah Bay estuary

Concentrations of dissolved²²⁶Ra in Winyah Bay, South Carolina, and in the adjacent Atlantic Ocean are augmented by the desorption of radium from sediments in the low-salinity area of the estuary and diffusion from bottom sediments. Desorption of²²⁶Ra is reflected by lower concentrations in suspended sediments from higher-salinity regions of the estuary. Bottom sediments from the high-salinity region have lower²²⁶Ra/²³⁰Th activity ratios than those from the low-salinity end.The shape of the dissolved²²⁶Ra vs. salinity profile is influenced by the river discharge. During average-discharge conditions, desorption of²²⁶Ra from suspended and bottom sediments increases the dissolved²²⁶Ra concentrations by a factor of 3.5 as the water passes through Winyah Bay. High river discharge produces an initial increase of dissolved²²⁶Ra by a factor of 2 to 3 and apparently reflects only desorption from suspended sediments. By driving the salt wedge down the estuary and reducing the zone of contact of salt water with bottom sediments, the high-flow conditions sharply reduce the flux of²²⁶Ra from bottom sediments.     

Subaqueous geothermal activity revealed by lacustrine sediments of the acidic Nakadake crater lake, Aso Volcano, Japan

Lacustrine sediments were sampled from the inaccessible acidic (pH = 0.43) Nakadake crater lake of Aso Volcano, Japan by a simple method. The sediments contain an extremely high content (74 wt.%) of sulfur, which exits as elemental sulfur, gypsum and anhydrite. The abundant elemental sulfur is likely formed by the reaction of SO₂ and H₂S gases and by the SO₂ disproportionation reaction in magmatic hydrothermal system below the crater lake. Based on the sulfur content of sediments and measurements of elevation change of the crater bottom, the sulfur accumulation rate at the Nakadake crater lake was calculated as 250 tonne/day, which is comparable with the SO₂ emission rate (200–600 tonne/day) from the Nakadake crater. The sediments include a small amount (9%) of clear glass shards that are apparently not altered in spite of the high reactivity of hyperacid lake water. This finding suggests that the clear glass shards are fragments of recently emitted magmas from fumaroles on the bottom of the crater lake and the magma emissions continuously occur even in quiescent periods.     

Groundwater recharge from an oxbow lake-wetland system in the Mississippi Alluvial Plain

The Mississippi River Valley Alluvial Aquifer ranks among the most overdrafted aquifers in the United States due to intensive irrigation. Concern over declining water levels has increased focus on understanding the sources of recharge. Numerous oxbow lakes overlie the aquifer that are often considered hydraulically disconnected from the groundwater system due to fine-grained bottom sediments. In the current study, groundwater levels in and around a 445-ha oxbow lake-wetland in Mississippi were monitored for a 2-year period that included an unusually long low-water condition in the lake (>17 months), followed by a high-water event lasting over 4 months before returning to earlier low-water levels. The high-water pulse (>4 m rise) provided a unique opportunity to track the impact in the underlying alluvial aquifer. During low-water conditions, groundwater flowed westward beneath the lake. Following the lake rise, groundwater beneath and near the perimeter responded as quickly as the same day, with more delayed responses moving away from the lake. Within 2 months, a groundwater mound formed near the centre of the oxbow (>3 m increase), with a reversal in the local hydraulic gradient towards the east. Flow returned to a westward gradient when the lake level dropped back below 0.3 m. Analysis of precipitation and nearby river stage could not account for the observed behavior. Recharge to the aquifer is attributed to rising water levels spreading over point bar deposits and into the surrounding forested wetlands where preferential flow pathways are likely to exist due to buried and decomposing tree remains. An earlier study in the wetland demonstrated an increasing redox potential in isolated zones, consistent with the existence of preferential flow pathways through the bottom sediments (Lahiri & Davidson, 2020). Retaining high-water levels in oxbow lakes could be a relatively low-cost water management practice for enhancing aquifer recharge.     

Lacustrine sediments and lichen transplants: two contrasting and complimentary environmental archives of natural and anthropogenic lead in the South Urals, Russia

Lead (Pb) concentrations and isotope ratios of two different geochemical archives are compared; lake sediment cores and lichens (Hypogymnia physodes, naturally growing and transplanted) from a ca. 80 km-long transect centred on the Cu smelter and former mining town of Karabash, Ural Mountains, Russia. Lead concentrations in sediment cores from 10 lakes were generally low near their base and show an abrupt increase in their upper portions interpreted to coincide with the onset of large-scale smelting operations in 1910. Lead isotope ratios derived from ²⁰⁴Pb, ²⁰⁶Pb, ²⁰⁷Pb, ²⁰⁸Pb of the bottom layers differed significantly from those of the top. The top sediments have isotope ratios that show distinct end members, one of which was the stack dust from the Karabash smelter, which is similar to the Pb derived from ores from Sibay, a major mine in the Urals. The composition of the bottom sediment layers generally fall slightly off a mixing line between the top sediments and average Earth’s upper crust. Lichens transplanted from a reference site, as well as naturally growing lichens, sampled from southwest of the smelter have isotope ratios similar to those of the stack dust. Lichens to the northeast contained Pb from the smelter, but are increasingly influenced by other sources probably leaded petrol and local soils, and a signature derived from a source enriched in ²⁰⁷Pb. Vegetables collected from local kitchen gardens contained Pb from an additional atmospheric source, possibly coal. Our work confirms that: (1) Pb isotopes in lake sediments provide a long-term record of inputs and allows the characterisation of natural and anthropogenic sources; (2) Pb isotopes in lichens provide a short-term record of local and long-range atmospheric deposition at high spatial resolution and short time scales as they replace their Pb content within a few months; (3) determination of all four stable Pb isotopes is necessary for the identification of the sources of Pb and is extremely sensitive for discerning minor source signatures, even in an area with a dominant source such as a smelter. Particularly significant for the Karabash area is that ore-smelter-derived airborne Pb is a major component in the lake sediments and lichens but its contribution reaches insignificant levels ca. 40 km from the smelter.     

The Oxygen Cycle in Lake Baikal

The oxygen cycle and the balance of free oxygen and oxygen bound in CO₂in Lake Baikal are discussed based on new data on the gas exchange between the lake and atmosphere, O₂consumption in bottom sediments, and the rate of aerobic decomposition in the abyssal zone of the lake.     

近1800年来云南洱海流域气候变化与人类活动的湖泊沉积记录

对云南洱海湖泊岩芯沉积物进行了多环境指标（年代学、色素、硅藻、有机碳稳定同位素、磁化率、化学元素）的分析,建立了近１８００年来云南洱海流域气候与环境变化的序列,气候演化具有暖干、冷湿交替的组合呈些特征气候阶段如中世纪温暖期、小冰期气候特征在洱海源泊沉积记录中均有反映,洱海湖泊上沉积记录的气候暖干－冷湿交替变化规律,反映了西南委风影响下的气候演化特征,湖泊沉积记录中包含丰富的人类以的信息,磁化率,元     

Dispersion Potential of Selected Iowa Lake Sediments as Influenced by Dissolved and Solid‐phase Constituents

Critics charge that agricultural managers routinely overdose their fields with chemical N and P to levels that exceed the soil's capacity to adsorb these materials, creating a situation that promotes hypoxia in Iowa lakes. Soil colloidal particles, capable of forming complexes with inorganic and organic N and P, control the equilibrium concentration of dissolved nutrients in lake waters. However, it should be realized that adsorbed nutrients also exhibit strong influences on the potential of sediments to undergo dispersion, a condition that may directly impact nutrient bioavailability. Thus, direct links may exist between adsorbed nutrient compositions and flocculation/dispersion properties of lake colloidal material. This paper presents work involving four Iowa lakes undertaken to determine relationships between ion composition and the dispersion potential of sediments. Surface waters and lake‐bottom grab samples were collected at three separate collection times from August to October. Samples were characterized for dissolved and adsorbed cations. Dispersion potential of each water sample was characterized by relating the total suspended solids concentration to the absorbance at 560 nm. It was found that sediment dispersion was easily predictable by a simple yet significant linear correlation with the concentration ratio of Na (CR_Na = [Na]/[Ca]^–1/2) in solution. This correlation was further improved by including Na concentration, CR_K, electrical conductivity, temperature, and solution P concentrations into the model. Nonlinear inter‐dependences were found between TSS and cation exchange capacity (CEC), and adsorbed Na, K, P, and heavy metals. Our analysis suggests that solution/solid phase constituents influenced the dispersion behavior of sediments through subtle manipulations of the excess surface charge.     

Chloropigments a in the Gulf of Gdańsk (Baltic Sea) as markers of the state of this environment

The Gulf of Gdańsk receives the waters of the Wis?a (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.