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1.
A one year study from October 1972 to September 1973 in four freshwater fishponds of Bhagalpur (87° 02' E long, and 25° 15'N lat.), India, has shown that a high phytoplankton primary production occurred twice during the annual cycle. There were seasonal variations in the production rate with a great fluctuation in the maximum and minimum values (3 … 4 times). Amongst the ponds studied, the highest daily production recorded was 6.93 g C/m2/day in Pond I and the minimum was 0.82 g C/m2/day in Pond II. The highest annual gross production was estimated to be 1611.98 g C/m2/y in Pond I, next in the order was 1543 g C/m2/y in Pond IV and then 1155.7.5 g C/m2/y in Pond I and the minimum was 641.75 C/m2/y in Pond II. It has also been observed that in certain months the net:gross ratio recorded was zero, while the community respiration as percentage of the gross production value reached 100% in few months. A comparison has been made in the annual production of temperate and tropical freshwater systems and this indicates that tropical waters are more productive than the temperate waters. Various physico-chemical factors such as rainfall, light, temperature and alkalinity may regulate or limit production.  相似文献   

2.
The lake without any outlet (11 ha, 55000 m3, zmax 2,25 m) has a weak thermal stratification with maximum surface temperatures of 32.5 °C. The annual variation of temperature and depth of visibility is unimodal, with the maxima or minima in August. Phytoplankton consists mainly of Cyanophyceae. The primary production determined by the light-dark bottle technique (oxygen method) varies in the annual variation between 0.3… 0.5 g m?2 d?1 C (winter) and 3.4… 4.6 g m?2 d?1 C (summer); as the annual means of 1975 and 1976 there were found 1.9 and 2.4 g m?2 d?1 C, resp., gross production at a utilization of 0.42… 2.85% of the radiation energy. The chemism is a well-buffered hydrogen-carbonate water (pH 8.1… 9.0) with 74… 90 mg/1 Na and 20.5… 31.5 mg/1 K and with a good nutrient supply (20… 40 μg/1 PO4—P and 100… 240 μg/1 NO3—N) at the same time.  相似文献   

3.

The control of soil pollution in China has become an issue, and in this study, a compound contaminated site was selected and focus on the site and its nearby environment, organochlorine pesticides (OCPs) were investigated in both soil (top and deep soil) and air samples. The main pollutants in top soils at site are dichlorodiphenyltrichloroethane (DDTs, 0.05–104 mg/kg d.w., avg: 14.5 mg/kg d.w.) and hexachlorobenzene (HCB, 0.02–4.85 mg/kg d.w., avg: 0.72 mg/kg d.w.) which is in accordance with its production history. As for the deep soils, ΣOCPs at site were found concentrated at workshops especially the technical pesticide workshop (5.29–22.1 mg/kg d.w., avg: 9.15 mg/kg d.w.) and the history DDTs’ workshop (4.00–64.8 mg/kg d.w., avg: 20.4 mg/kg d.w). Around site, OCPs were mainly concentrated at layers of −20 cm and the −40 cm and decreased with distance being far away, at 5000 m, the ΣOCPs was comparable with normal agriculture soil (22.1−91.4 ng/g d.w., avg: 55.4 ng/g d.w.). ΣOCPs in the air samples ranged 64.6–823 ng/m3 (avg: 459 ng/m3) at site and 9.93–176 ng/m3 (avg: 50.8 ng/m3) around site which are all dominated with DDTs and HCHs. Soil–air exchange fugacity was calculated to judge the transportation of the OCPs and the results showed soils at the site and its nearby areas (within 5000 m) are releasing most of the OCPs into air, and accordingly through evaluation, inhalation was found to be the major source for human health risk, which is a great threat to the workers at site and the nearby residents.

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4.
The seasonal and interannual variability in the phytoplankton community in Liverpool Bay between 2003 and 2009 has been examined using results from high frequency, in situ measurements combined with discrete samples collected at one location in the bay. The spring phytoplankton bloom (up to 29.4 mg chlorophyll m−3) is an annual feature at the study site and its timing may vary by up to 50 days between years. The variability in the underwater light climate and turbulent mixing are identified as key factors controlling the timing of phytoplankton blooms. Modelled average annual gross and net production are estimated to be 223 and 56 g C m−2 year−1, respectively. Light microscope counts showed that the phytoplankton community is dominated by diatoms, with dinoflagellates appearing annually for short periods of time between July and October. The zooplankton community at the study site is dominated by copepods and use of a fine mesh (80 μm) resulted in higher abundances of copepods determined (up to 2.5 × 106 ind. m−2) than has previously reported for this location. There is a strong seasonal cycle in copepod biomass and copepods greater than 270 μm contribute less than 10% of the total biomass. Seasonal trends in copepod biomass lag those in the phytoplankton community with a delay of 3 to 4 months between the maximum phytoplankton biomass and the maximum copepod biomass. Grazing by copepods exceeds net primary production at the site and indicates that an additional advective supply of carbon is required to support the copepod community.  相似文献   

5.
— Als Beitrag zur Erfassung des Stoffhaushalts phytoplanktonreicher Fließgewässer wurden am Beispiel der Unteren Havel bei Briest intensive Untersuchungen über den Sauerstoffhaushalt und die ihn beeinflussenden Faktoren durchgeführt. — Die nach der Odum -Methode errechnete Sauerstoffbruttoproduktion lag im Sommer zwischen 2,1 und 53,4 g O2/m2d und im Whiter zwischen 0,6 und 18.0 g O2/m2d. Die Respiration betrug im Sommer 0,6 … 26,4 g O2/m2d und im Winter 0,0 … 8,4 g O2/m2d. — Am nachhaltigsten wird der Sauerstoffhaushalt der Unteren Havel durch die Globalstrahlung beeinflußt. Nach einem extrem langen Winter kommt die verzögerte Phytoplanktonentwicklung explosionsartig zum Ausbruch, nach einem kurzen Winter entfaltet sich das Plankton allmählich. Davon abhängig gestaltet sich auch der Sauerstoffhaushalt des Gewässers im Frühjahr extrem unterschiedlich. — Der Gehalt an gelösten Nährstoffen zeigte eine sehr deutliche und starke Abhängigkeit von der Phytoplanktonentwicklung. — Die Fourieranalysen ergaben, daß vor allem bei den meteorologisch bedingten physikalischen Kriterien des Sauerstoffhaushaltes eindeutige Jahresperiodizitäten bestehen. — Für prognostische Zwecke wird die Bestimmung des Verhältnisses Globalstrahlung: Sichttiefe vorgeschlagen. Dieses Verhältnis zeigte bei Regressions- und Korrelationsberechnungen überwiegend signifikante Beziehungen zu den einzelnen Kriterien des Sauerstoffhaushaltes. Eine Überprüfung mittels Fourieranalyse ergab, daß eine eindeutige Jahresperiodizität vorhanden ist. Das Verhältnis Globalstrahlung: Sichttiefe eignet sich auch zur Kurz- und Langfristprognose der Wasserbeschaffenheit.  相似文献   

6.
In two test series, for which 10 and 2 … 4 g/1 wet matter of higher and lower aquatic plants from the lake Baikal and from the waters in the surroundings of Irkutsk were used, phenol solutions having concentrations of 10?3 … 10?5 M (1 … 5 mg/1) were applied. During the investigations the possible error clue to the presence of microorganisms was eliminated. The phenol decomposition by aquatic plants proceeds as a first-order reaction. The results of analyses are summarized in several tables and graphical representations.  相似文献   

7.
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8.
In twelve flowing water (Q 1.04… 30.4 m3/s, 0.5… 1.2 m/s) the self-purification efficiency in 110 river sections (L 1.3… 26.4 km) is determined as the load difference in kg · d?1 COD-Mn as well as in g · m?3 referred to the daily passage. In the economical comparison, the self-purification efficiency is valued as substitution for wastewater treatment plants of the same capacity. At a mean specific capacity of 8.6 g · m?3, the self-purification efficiency of the investigated waters is equivalent to economical values of 124 · 103… 534 · 103 M km?1 investment costs, 11 · 103… 80 · 103 M · a?1km?1 operating costs and 5… 81 MWh · a?1 km?1 expenditure of energy. The specific capacity in g · m?3 COD-Mn shows an exponential regression to the degree of saprobity (L = 0.015 · exp (1.7358 · S)). From this empirical model the limits of the self-purification capacity of aerobic waters by oxygen input can be detected: in respective examples more than 50% of the required oxygen input are due to weirs.  相似文献   

9.
The two eutrophicated reservoirs Husinec (2.6 km3, 35 ha, zmax 18 m, MQ 1.87 m3/s) and ?ímov (34.5 hm3, 216 ha, zmax 44 m, MQ 4.14 m3/s) show concentrations of total phosphorus of 10… 50 mg/m3 and chlorophyll contents of 7… 36 mg/m3 in the summer season. For both reservoirs a good correlation exists between the chlorophyll concentration and the density of the phytoplankton (20 · 103… 13 · 106 ind./l). With average concentrations of 10… 20 mg/m3 chlorophyll a in summer, the water can be treated for producing drinking water only at a higher expenditure. The water quality will be improved by a reduction of the phosphorus load.  相似文献   

10.
Danube river water samples were saturated with mineral oil, and then the primary production (gross) was determined by means of the light-dark bottle method (oxygen) in situ at depths of 0.1… 1.5 m in comparison with untreated samples. Samples were exposed for half a solar day alternately during the first and second half-days. Investigations carried out between March and October for periods of 14 days showed a mean production of 2.56 g · m?2d?1 O2, which was reduced by 36% due to 12.6 mg/l hydrocarbons. Production decreases with the water depth from 6.2 to 0.9 mg · l?1d?1 02, whereas the inhibition by hydrocarbons increases from 31 to 41%.  相似文献   

11.
The Rihand reservoir having a surface area of 46,588 ha, a capacity of 10.6 km3 and a shore line length of 561 km is used for hydroelectricity generation. With an annual-cylcic behaviour in the same direction, measurements of the chemism generally yield higher values of mineralization in the littoral region than in the pelagial one. Especially the hydrogencarbonate content and the concentration of alkaline earths are clearly higher in the littoral zone. By investigations using the light-and-dark-bottle method the following average and extreme data of the primary production were obtained in mg C/m3 · d: littoral zone, gross 431 (200 … 1386), net 269 (11 … 1016): pelagial zone, gross 268 (83 … 562), net 122 (0 … 286). Measurements were carried out only immediately below the water surface, not in depth series. Nevertheless, they demonstrate the considerable share of shallow water zones in the total production of the storage reservoir.  相似文献   

12.
Sediment traps were deployed in the Gulf of Papua in June–July 1997, to determine fluxes of organic matter and inorganic elements from the photic zone to deeper waters at the base of the continental slope and in the northern Coral Sea. Three stations, ranging from 900 to 1500 m depth, had “shallow” traps at 300 m below the water surface and “deep” traps set 100 m above the bottom. Infiltrex II water samplers collected particulate and dissolved organic matter from the Fly, Purari and Kikori rivers, and near-surface water from the shelf of the Gulf of Papua. Samples were analysed for molecular organic biomarkers to estimate the sources of organic carbon and its cycling processes.Dry weight fluxes from the shallow traps ranged from 115 to 181 mg m−2 day−1 and particulate organic carbon (POC) fluxes ranged from 1.2 to 1.9 mM OC m−2 d−1 with molar organic carbon to particulate nitrogen ratios (C/N) ranging from 6.0 to 6.5. Fluxes in deep traps were likely influenced by both early diagenesis and entrapment of resuspended shelf sediments. Dry weight fluxes in deep traps ranged from 106 to 574 mg m−2 day−1 and POC fluxes ranged from 0.6 to 1.5 mM OC m−2 d−1, with C/N ratios ranging from 8.5 to 10.8. 13C/12C ratios were −20.2‰ to −21.7‰ in all trap samples, indicating that most of the settling POC was “marine-derived”. Shallow traps had δ15N values of 6.3‰ to 7.2‰ while the values in deep traps were 4.9–5.0‰, indicating the N-rich near-surface OC was less degraded than that in the deep traps. The biogenic lipids consisted of hydrocarbon, sterol and fatty acid biomarkers indicative of marine zooplankton, phytoplankton and bacteria. Sterol markers for diatoms and dinoflagellates were abundant in the water samples. Highly branched isoprenoid alkenes, usually attributable to diatoms, were also detected in both water and shallow traps. Traces of C26–C34 n-alcohols indicative of land–plant biomarkers, were found in river water samples and in the shallow sediment traps. A large unresolved complex mixture (UCM) of hydrocarbons, and a uniform distribution of n-alkanes, indicative of petroleum hydrocarbons, were also detected in the traps. Hopane and sterane biomarkers detected in the trap oil were characteristic of a marine carbonate source, and the aromatic hydrocarbon composition distinguished at least two different oil signatures.We concluded that mass and POC fluxes were similar to those reported for other continental shelves and marginal oceans in tropical and subtropical regions. There was a dramatic decrease in POC as particles sank, due to zooplankton repackaging and photochemical and bacterial decomposition. Carbon isotopic and biomarker patterns showed most of the POC in the sediment traps was marine-sourced with only traces of terrestrial input. There was a significant flux of petroleum, which may signal the existence of natural petroleum seeps in this region.  相似文献   

13.
The meliorated Oberes Rhinluch fen is used by agriculture as grassland with maize-cultivation on about 30 % of its area. In the ditch system of this area with water levels of 30 to 150 there were observed 67 taxa of aquatic plants and marsh plants, of which about 15 achieve covering degrees of more than 3 % and form 80 … 90 % of the biomass. Biomasses of between 20 … 184 g/m2 dry weight (Lemna) and 504 … 1612 g/m2 (Phragmites) are obtained in pure populations. In mixed populations the biomasses amount to between 304 and 916 g/m2 dry weight. According to their density and orientation, riparian copses and trees cause a more or less intense overshadowing of ditches, resulting in a considerable reduction of the biomass of macrophytes. By copses and trees on the south side of the waters the light available may be reduced to 30 %, from which a reduction of the biomass to 10 … 30 % results. By means of such planting it is possible to control the growth of plants in order to reduce the necessary and very expensive weed-removal and bottom-clearing actions.  相似文献   

14.
The Gru?a Reservoir (located at 238…269 m a. s. l., volume 64.6 · 106 m3, surface 934 ha, drainage area 318 km2, max. depth 31 m, mean theoretical retention time 22 months) was investigated during the years 1996 to 2001. The obtained values of trophic state parameters (9…200 μg L?1 total phosphorus, 3…99 μg L?1 chlorophyll‐a, and 0.5…2 m transparency) indicate that water of the Gru?a Reservoir is eutrophic according to three types of classification: Carlson, OECD, and Jones and Lee. It was noticed that values of average biomass abundance are large in the Gru?a Reservoir, and they could indicate a richer trophic state. When these indices are cited in connection with parameters of the trophic state, it is apparent that the Gru?a Reservoir can be classified as a eutrophic water on the basis of total phosphorus content of chlorophyll‐a and hypertrophic water with respect to transparency.  相似文献   

15.
The Chinese Continental Scientific Drilling (CCSD) project is located at the Sulu ultrahigh-pressure metamorphic (UHPM) belt. It offers a unique opportunity for studying the radiogenic heat production of both shallower and deeper rocks. Based on the concentrations of radiogenic elements U, Th and K on 349 samples from main hole of CCSD (CCSD MH), pilot holes and exposures, we determined radiogenic heat productions of all major rock types in the Sulu UHPM belt. Results show the mean values of orthogneiss and paragneiss are respectively 1.65 ± 0.81 and 1.24 ± 0.61 µW m? 3. Due to different composition and grade of retrogressive metamorphism, the eclogites display significant scatter in radiogenic heat production, ranging from 0.01 to 2.85 µW m? 3, with a mean of 0.44 ± 0.55 µW m? 3. The radiogenic heat production in ultramafic rocks also varies within a large range of 0.02 to 1.76 µW m? 3, and the average turns out to be 0.18 ± 0.31 µW m? 3. Based on the measurements and crustal petrologic model, the vertical distribution model of heat production in Sulu crust is established. The resulting mean heat production (0.76 µW m? 3) contributes 24 mW m? 2 to the surface heat flow. 1-D thermal model indicates that the temperature at the Moho reaches above 750 °C, and the thermal thickness of the lithosphere is ~ 75 km, in good agreement with the geophysical results. The high teat flow (~ 75 mW m? 2) together with thin lithosphere presents strong support for the extension events during the late Cretaceous and Cenozoic.  相似文献   

16.
The objective of this case study was to calibrate and verify detailed transport model of sediment in a 4‐kilometre stretch of the middle Elbe floodplains in Germany. The hydraulic RMA‐2 model and the SED2d‐WES sediment transport model were used. These models were calibrated and validated by detailed measurement of the surface water elevations, the velocities at six profiles, and the suspended sediment concentration and deposition (by means of 10 sediment traps). The flow was modelled for three steady‐state discharges. The surface water elevations were calculated to an accuracy of less than 5 cm compared to measurements. The differences between the calculated and measured velocities were with one exception smaller than 0.2 m/s (measured range 0.1…?1.0 m/s). An average sediment input of 35 g/(m2 d) was calculated for the flood event studied. The highest calculated sedimentation rates of 700 g/(m2 d) (dry density 90 kg/m3) occurred in quiescent zones and abandoned channels. Twenty‐five percent of the deposited sediment settled in the quiescent zones (which only account for 13% of the area). The most sensitive parameters of the sediment transport model were the settling velocity and critical shear stress. The modelling techniques used allowed sediment deposition on the floodplains of the Elbe to be realistically depicted.  相似文献   

17.
于2014年1月(枯水期)、7月(丰水期)对鄱阳湖湖水进行采集,测定相应的理化参数、叶绿素a浓度和光合有效辐射,结合初级生产力垂向归纳模型估算浮游植物初级生产力,分析湖区初级生产力特征及与环境因子的相关性.结果表明,鄱阳湖枯水期浮游植物初级生产力波动范围为83.50~355.43 mg C/(m~3·d),平均值为193.33 mg C/(m~3·d),初级生产力空间分布特征主要受水体类型的影响,枯水期初级生产力与氮、磷营养盐浓度呈负相关,其中与铵态氮浓度呈显著负相关,枯水期不会出现营养盐限制现象;丰水期浮游植物初级生产力波动范围为113.80~1134.06 mg C/(m~3·d),平均值为412.12 mg C/(m~3·d),初级生产力空间分布主要受河流注入的影响,丰水期浮游植物初级生产力与总磷及悬浮物浓度呈显著正相关,由于悬浮物对浮游植物生长的促进作用大于抑制作用,鄱阳湖丰水期会出现磷营养盐的限制;鄱阳湖整体平均流速约为0.28 m/s,易于浮游植物的生长,南鄱阳湖平均流速约为0.21 m/s,而北鄱阳湖平均流速约为0.35 m/s,所以南鄱阳湖比北鄱阳湖更容易发生水体富营养化并暴发水华.  相似文献   

18.
The method is based on the determination of the number of the nonmotile sperms and/or the lethally damaged sperms with the aid of the fluorescent dye primuline. Incubation takes place at a suspension density of 10.000/mm3… 38.000/mm3, at 40°C or 46 °C for 15… 60 min. During the test with sublimate the loss of motility amounts to 55% at 4 mg/l Hg2+, the LC50 is 7.3 mg/l Hg2+. Phenyl-mercuric acetate causes the total loss of motility with 20 mg/l, the LC50 is above 168 mg/l (equivalent to 100 mg/l Hg2+). The LC50 of sodiumpentadecylmonosulphonate and dodecylpyridinchloride are 11.6 and 15.8 mg/l, resp. Filtrates of blooming of cyanophyceae on Baltic, having been digested by repeated freezing and thawing, with 1.5… 6.4 g/l dry matter showed motility losses of 30… 100 % for Nodularia spumigena, whereas no significant effect was produced by a filtrate of Microcystis aeruginosa with 28.2 g/l dry matter as well as water-blooming of Nodularia spumigena from the Small Jasmund Bodden.  相似文献   

19.
The role of the benthic ciliofauna of the Tsibulnik bay of the Kremenchug reservoir in the comsumption of the primary production of phytomicrobenthos and the destruction of organic Substances is shown. In July all over the buy ciliates had consumed 41 % of the benthic primary production. During the process, consumption rates had reached 1.34 kJ/m2 d on seperate sections of the bottom. Sufficiently high is the role of these protists in the destruction of organic substances. They had destroyed 1.4… 1.5% of the whole mineralised organic substances in summer and 10… 11% in autumn. The authors made a conclusion on the importance of the benthic ciliofauna in the transformation of organic substances in an eutrophic bay.  相似文献   

20.
The difficulties arisen in an assimilation pond, as it is called, after 17 years of operation were solved by a stabilization system for the purification of effluents and utilization for fish breeding. It consists of two basins (0.56 and 1.04 ha) and a fish pond (15.58 ha) to which water can flow from a brook by-passing the system. When the stabilization system had worked for 6 years, it was proved that in the case of the average daily intake of milk of 93,846…118,134 litres, effluents flowing out of the dairy plant amounted to 205.28…228.53 m3, on average. The BOD5 of effluents ranged from 201.33 to 261.73 kg/d and the total solids ranged from 95.5 to 139.3 kg/d on average. The average daily outflow from the pond amounted to 394.7…1567.0 m3 of water with 4.1…23.8 kg of BOD5 and with 29.3…112.4 kg of total solids. The average decrease of the main nutrients and extractable substances ranged from 62.8% (Ca2+) to 100% (NO?3). Only the BOD5 value at the end of the growing season in 1984 (8.4…10.3 mg/l) exceeded three times the standards for the admissible pollution of the receiving stream.  相似文献   

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