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1.
Tanja Bergfeld Anja Scherwass Barbara Ackermann Hartmut Arndt Andreas Schöl 《河流研究与利用》2009,25(10):1232-1250
The dynamics of phyto‐, bacterio‐, proto‐ and metazooplankton were investigated for a period of 22 months fortnightly from March 1999 until December 2000 in the rivers Moselle, Saar and Rhine. Plankton abundances reached the lowest values in the Rhine and the highest in the Saar. Protozoa and not the much more studied metazoa clearly dominate the zooplankton not only by number but also by biomass by about 90%. We show that the plankton biomass in each of the rivers is the result of the interplay of the grazing by benthic predators and of the human induced factors such as river morphology, water residence time and nutrient load. Furthermore, we compare our study with the planktonic food web of three other large European rivers. The comparison between all studies revealed a general rise of the absolute mean biomass of all heterotrophic planktonic food web components (bacteria, protozoa, metazoa) parallel to an increase of the algal biomass of the river. For the rivers Rhine, Moselle and Saar, the average biomass of all investigated plankton groups was very low compared to the values obtained in the rivers Meuse, Loire and Elbe. The relative importance of organisms of the microbial food web increased with a decrease of the algal biomass or organic carbon content, respectively, in each of the rivers. We postulate that with a sinking nutrient level in the Rhine, the microbial food web components will become even more important within the plankton than they already are. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
2.
Tek Bahadur Gurung Jotaro Urabe Kentaro Nozaki Chikage Yoshimizu Masami Nakanishi 《Lakes & Reservoirs: Research and Management》2002,7(4):317-323
Seasonal production of bacterioplankton in a water column of Lake Biwa was examined based on cell‐specific growth rates at above (surface layer) and below the thermocline (deep layer). The growth rates were estimated by incubating bacterioplankton in situ with a dilution technique. The rates ranged from 0.05 per day in winter to 0.89 per day in summer, generally with much higher rates in the surface layer than in the deep layer. In an entire water column, bacterial production (in terms of carbon [C]) ranged from 0.217 to 0.811 gC/m2 per day with a mean of 0.451 gC/m2 per day, which, on average corresponded to 43% of primary production. However, no significant correlation was detected between bacterial production and primary production rates. Although the bacterial production rate correlated positively to water temperature, surface and deep layer rates were comparative for some dates because the deep layer shared a large fraction of the water column. These results suggest that, although specific bacterial activity was low in the deep layer due to the low temperature, bacteria in that layer play substantial roles in consumption of organic matter and material flows in Lake Biwa. 相似文献
3.
Different land uses directly affect the characteristics of a river basin and influence the aquatic biota and ecosystem processes. This study aimed to analyse the community structure and composition of aquatic invertebrates and the role of these organisms in the process of leaf litter breakdown in streams with different land uses. The study was conducted from September to December 2013 in five streams in the Neotropical region. At each stream, we placed 18 bags containing litter for colonization by aquatic invertebrates, and the bags were collected at different exposure times (5, 30, 45, 60, 75 and 90 days). We registered spatial differences in the aquatic invertebrate community structure and composition. There were no significant differences in the activity of invertebrates in the leaf litter breakdown process among streams with different land uses. However, the variability in mass decay rate was lower for the reference stream. This result may have been influenced by habitat quality, availability of organic matter and the structure and composition of benthic community present in the reference stream, which differs significantly among locations with different types of land use. The results of this study shows that human activities, particularly agriculture and urbanization, modify the structure and composition of the benthic community and acts on ecosystem processes, especially in the variability of the processing of allochthonous material invertebrates. However, we reject the hypothesis that land use negatively influences the decomposition of litter, measured by weight loss. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
4.
Damming of streams and rivers alters downstream ecosystem processes, and understanding its effects is essential in managing forested mountain streams. This study examined the effects of dams with a reservoir on organic matter decomposition and its seasonality in two neighbouring mountain streams over five seasons. The cotton‐strip assay and measurement of tensile strength loss were used to evaluate decomposition rates. In addition, the environmental factors, such as water level, water temperature, inorganic nitrogen concentrations and contribution of macro invertebrates were measured. The dams with a reservoir lowered decomposition rates downstream compared to upstream and unregulated sites, in all seasons. The decomposition rates also varied by season at all sites, with higher rates in summer and lowest in winter, and the seasonal variation was larger than the effects by the reservoirs in both streams. Seasonal variation in decomposition rates coincided with water temperature variation, suggesting strong influence of water temperature. However, the temperature differences did not explain the effects of reservoirs because water temperature was always higher at downstream sites. The downstream sites had lower nitrate concentrations and contribution of macroinvertebrates, and these factors may have greater effects than water temperature. Thus, damming of streams may lower the decomposition rates at downstream sites due to altered nutrient and biological effects. However, seasonal variation in water temperature may have more pronounced effects, resulting in greater seasonal variation than the difference among sites. 相似文献
5.
天然有机物对纳滤膜污染的研究进展 总被引：1，自引：0，他引：1
介绍了纳滤膜的性质、纳滤膜技术的特点以及纳滤膜的分离机理,对天然有机物污染纳滤膜的影响因素,如pH值、离子浓度、操作条件和磁场等作了详细的阐述,并对纳滤技术的应用前景进行了展望。 相似文献
6.
Kenneth A. Krieger 《Journal of Great Lakes research》1984,10(2):197-209
The benthic macroinvertebrates of the central basin of Lake Erie were sampled with a Ponar grab in the summers of 1978 and 1979 along a 155-km reach of the nearshore zone (≤ 12 km offshore) in Ohio, U.S.A., at depths of less than 20 m. The major groups and their most abundant species were, in order of overall abundance, Oligochaeta (Limnodrilus hoffmeisteri, L. cervix-L. claparedeianus group, L. maumeensis), Sphaeriidae (Pisidium casertanum, P. henslowanum, Sphaerium corneum, Musculium transversum), and Chironomidae (Procladius sp., Chironomus spp.). The average abundance of oligochaetes in the harbors was 21,000 individuals m?2 in 1978 and 12,700 m?2 in 1979, compared with 1,500 m?2 and 1,200 m?2, respectively, in the areas outside of harbors. Comparison of the macrobenthic assemblages with those in other regions of the Great Lakes, using several numerical indices as well as indicator species distributions, indicated that the general area of the nearshore zone outside of harbors possesses a moderate degree of organic enrichment, with a gradient of decreasing pollution in an offshore direction. The harbors appeared to be severely degraded, as reflected by the high densities of oligochaetes and the almost complete absence of all but the most pollution-tolerant species. The documentation of species distributions will enable future assessments of changes in the nearshore benthic communities. 相似文献
7.
生态修复是改善生态环境的重要手段,对于土壤、水文、植被等多方面具有影响。介绍了植被恢复对土壤水分、土壤密度、土壤有机质、土壤氮等4个方面的影响。结果表明：①植被恢复对土壤的影响有利有弊,大多数情况下植被恢复降低土壤水分,提高养分含量,降低土壤密度;②从不同的指标来看,植被恢复改善土壤性状所需时间不同,从3年至20年以上;有些立地条件下,人工造林土壤性状长期低于天然林;③对于改善土壤性状没有明显作用的植物种,在进行合理配置后,有可能产生很好的改良土壤作用。在此基础上提出植被恢复需进一步明确的各类指标目标阈值及措施。 相似文献
8.
Job Mwamburi 《Lakes & Reservoirs: Research and Management》2016,21(2):94-113
No detailed studies have been conducted on the spatial distribution of sediment characteristics within Nyanza Gulf of Lake Victoria, especially after the invasion of water hyacinth. Accordingly, a rapid, inexpensive method was used to determine the spatial sediment organic matter variations, expressed as loss on ignition (LOI). Surficial sediments were collected during different survey periods from about thirty‐two sampling sites between 1994 and 2012, in order to characterize the sediments. Although the deeper (>40 m) depositional areas are located in the open lake, visual observations indicate that most of the offshore sediments consist of muddy deposits, plus significant shell remains, with a more sandy type of sediments located in some areas off the inflowing river mouths. The surficial sediments were characterized by a relatively high water content, with over 89% of the samples containing water contents greater than 75%. The sediment organic matter contents from the 2012 survey were more variable, ranging from 1.90% to 33.47%. The sediment organic carbon contents varied spatially, although there were no significant variations between the different sampling periods. Evaluating the SOM at different heating durations at a constant temperature (550 °C) and a very high temperatures (950 °C) did not identify any significant differences. High primary production and greater settling in the deeper areas contribute to the nature of sediments deposited, also being reflected in the relatively high OC contents. Spatially, it is thought that detritus from water hyacinth and terrestrial external loads are important sources of organic matter deposited on the lake bottom within the gulf and may support its growth because of enrichment of nutrient elements. The importance of sediments in adsorption of contaminant substances and influencing geochemical processes within the lake is also emphasized. 相似文献
9.
The lower Colorado River from Laughlin, Nevada, to the border with Mexico is one of the most regulated rivers in North America. An analysis of particulate organic matter (POM) transport through the system was made to determine POM concentrations, composition and point of origin, as well as to determine the effect dams had on this transport. Particulate organic matter concentrations generally increased from upstream to downstream, and were dominated by very fine organic detritus (< 25μm size fraction). Reservoirs released more POM than they received during spring and summer, but less during autumn and winter. Reservoirs recycled POM, taking in organic detritus and discharging small limnoplankton. Backwater complexes functioned as filters during storm events, trapping coarse material and releasing fine material. Agricultural drains made only minor contributions of POM, but provided important nutrients for in-channel production of POM. Water diversions forced POM off-channel, whereas sluicing operations reduced inorganic loads in the canals. Despite the presence of six mainstem dams, the lower reaches support a diverse assemblage of detritivorous fishes, similar to that found in the lowermost reaches of natural, unregulated rivers. The food base for this fishery stems from autochthonous production of POM. 相似文献
10.
Studies during the last two decades have revealed the importance of planktonic micro‐organisms in the aquatic matter flux. However, studies on the planktonic food web structure have mostly concentrated on lentic waters. In the present study the biomass partitioning of the major plankton groups (bacteria, algae, heterotrophic flagellates (HF), ciliates and metazoans) in a large river (Lower River Rhine) has been analysed for a complete annual cycle and calculations on potential carbon flow within the planktonic food web were conducted for the four seasons. The plankton biomass was dominated by phytoplankton followed by bacterioplankton. The zooplankton was dominated by HF, contributing more than 65% of the total zooplankton biomass in all seasons. A significant part of the HF biomass was contributed by large flagellates (> 20 µm). In accordance with the dominance of the HF and their high growth rates, this group contributed the largest part of the planktonic matter turnover within the zooplankton. The calculations suggest that the HF were able to consume between 11 and 65% of the seasonal mean bacterial production and that the HF consumed a larger amount of phytoplankton than both ciliates and metazoans. According to these calculations, only a small part of the total potential production of the phytoplankton as well as that of the total zooplankton was consumed by planktonic predators. Since the plankton abundance did not generally increase during the downstream passage, the present data suggest that a large part of the plankton production is lost by other means. The role of benthic predators has been discussed in this context. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
11.
Physical and chemical characteristics of the sediments in a cascade of eight reservoirs located in the Paranapanema River (south‐east Brazil) were analysed during two consecutive years during summer (January), autumn (April), winter (July) and spring (October) of 2000 and 2001, respectively. The granulometric texture, organic matter content and nutrient concentration (total nitrogen and phosphorus) were determined in the superficial sediment of 19 sampling stations, as well as the temperature, dissolved oxygen, pH, conductivity and redox potential in the bottom layer of the water column. Seasonal and spatial changes were observed for both years, especially for organic matter and nutrient concentrations. Three different areas could be identified along the river, which corresponded to the upper, middle and lower Paranapanema basin. The first area was characterized by an increase of nutrients and organic matter in the sediments and a decrease of temperature and dissolved oxygen in the downstream direction. The second one represented a region where fluctuations in nutrient and organic matter concentrations and a reduction in dissolved oxygen were observed. In the third area, there was an increase in nutrient and organic matter in the sediments and also an increase in temperature and dissolved oxygen towards the river mouth. The results of the principal components analysis, using water and sediments variables, showed the ordination of sampling stations by periods: wet (January–April) and dry (July–October) during 2000. This pattern was also verified during 2001, but with slight changes, probably due to the increase in the rains which would have produced certain homogenization effects along the river. 相似文献
12.
13.
Dissolved organic matter (DOM) in aquatic systems originates from a range of sources. Some is allochthonous, transported from the surrounding landscape to the water body, and is derived from and influenced by the geology, land use and hydrology of its origin. Some is created in situ through microbial activity, which may provide an independent source of organic matter, or a recycling mechanism for that which has been transported into the water body. The relative contribution of each source depends upon the location and environmental conditions within and without the water body. Human activity is also a source of DOM, much of which is believed to be labile, which can enter the aquatic system through direct point discharges, diffuse leaching and aerial dispersal. Fluorescence spectroscopy can provide an excellent tool to source DOM fractions, and to monitor and understand DOM transformations in aquatic systems, as much DOM has an intrinsic fluorescence. In particular, recent advances in optical technology, enabling rapid investigation of shorter wavelengths, have enabled more detailed characterization of organic material and its reactions in water. In this article, we review the use of fluorescence spectroscopic techniques to measure the intrinsic fluorescence of organic matter and the application of fluorescent DOM analysis in marine waters, freshwaters and wastewaters. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
14.
为了解潘家口水库网箱清理活动对水环境改善具体情况,摸清潘家口水库现存主要污染物种类及特征,针对研究区域不同时间和空间表层水体样品开展了分析研究。利用全二维气相色谱飞行时间质谱联用的高通量筛查技术方法,对潘家口水库2017、2018年水体样品进行检测,检测结果经匹配度、检出率等条件进一步筛选确认,对确认结果进行化合物属性及用途分类,将最终结果用于污染物种类变化趋势分析。与2017年结果相比,2018年减少化合物244种(包括38种酮类、27种烷烃类、26种酚类、21种酯类和15种有机酸类化合物及其他),其中包含用于工业中间体的25种化合物,用于香料香精的14种化合物,用于食品添加剂的12种化合物,用于工业生产的8种化合物,用于医药的6种化合物以及用于增塑剂的14种化合物等。与2017年结果相比,2018年增加化合物22种(包括10种酯类、3种酮类、2种醚类、1种苯类、1种醇类、1种醛类、1种有机酸类化合物及其他),其中包括用于香料香精的5种化合物,用于增塑剂的4种化合物,用于中间体的2种化合物以及用于阻燃剂的1种化合物等。研究结果表明该区域水体中有机化合物数量在2017年后大幅减少,可能由该区域开展的养殖网箱清理活动导致。 相似文献
15.
基于钱塘江河口段上、中、下游3个站点连续5天高频次的流速、潮位、水深、含氯度等实测资料,采用通量机制分解法计算每个潮周期的含氯度输运通量,分析了含氯度输运通量与潮差的相关性、水盐输运分离现象、强潮作用下盐水入侵的动力机制及其对抗咸的启示。结果表明:河口段下游的含氯度输运主要受斯托克斯效应控制,而上游则受平流输运和潮泵输运共同主导,垂直切变作用对含氯度输运的影响非常有限;在河口段的上游存在水体向下游输运,而含氯度向上游输运的现象,该现象会加剧上游河段的盐水上溯;向陆的含氯度输运通量与潮差存在较强的正相关关系,可将潮差作为盐水入侵程度及抗咸调度的重要指标。 相似文献
16.
Alteration of stream flow by artificial dams has been observed to be a significant factor for river water environmental changes. Therefore, understanding the biogeochemical processes occurring in the dam‐controlled rivers is important for water resource management. In this paper, δ13C and δ15N signatures of particulate organic matter (POM) in a dam‐controlled subtropical river, Beijiang River, in south China are reported for their spatial and seasonal distributions. POM affected by reservoirs is lighter in δ13C and heavier in δ15N relative to unaffected POM. In April, POM δ13C and δ15N values show less spatial variation in the mainstem, and suggest relatively greater contributions of terrestrial organic matter (OM) to POM. This could be related to the onset of summer monsoon that caused an abrupt increase in terrestrial input to the river by the monsoon‐induced enhancement of rainfall and runoff. In August and December, however, POM isotopic values for the sites affected by the Feilaixia dam reservoir in the middle of the river show marked changes, suggesting aquatic plankton proliferation in the reservoir during the times. Upstream from the reservoirs, POM isotopes are seasonally less varied and suggest mainly terrestrial origin. However, the isotopic signals of aquatic plankton proliferation in the reservoir in August and December is imprinted on the POM isotopic compositions downstream the reservoir, indicating far‐reaching influences of the reservoir on the downstream water environment. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
17.
Nephelometric turbidity is an optical index for the side scattering of light caused by fine particles suspended in water. When a mixed composition of suspended inorganic and organic materials, including dissolved organic material, is present, turbidity measurements can be affected by the different optical properties of the organic and inorganic materials present, and different turbidimeters are more or less sensitive to these influences. Two different methods of nephelometric turbidity measurement were assessed (using instruments confirming to two different turbidity standard methods: EPA 180.1 and ISO 7027). We investigated the influence of particulate organic matter and coloured dissolved organic matter on relationships between turbidity and suspended sediment concentration for rivers in diverse Otago catchments, in the South Island of New Zealand. The presence of organic matter and dissolved colour affected turbidity measurement owing to light absorption; however, turbidity measurement following the ISO 7027 standard, which specifies near infrared radiation at wavelengths where organic absorption is very weak, was less affected by organics. As a result, rating equations between suspended sediment and turbidity may be significantly different with ISO 7027 compared with EPA 180.1 methods. 相似文献
18.
Christopher T. Filstrup J. Thad Scott Joseph D. White Owen T. Lind 《Lakes & Reservoirs: Research and Management》2010,15(1):25-39
Paleolimnological studies are rarely performed on reservoirs because of concern that sediments might not accurately chronicle reservoir history. Eutrophication indicators might behave differently in polymictic reservoirs and stratified natural lakes because of system and/or mixing regime differences. Particulate organic carbon (POC), particulate organic nitrogen (PON), and total phosphorus (TP) concentrations, carbon:nitrogen (C:N) and nitrogen:phosphorus (N:P) ratios, and carbon (δ13C) and nitrogen (δ15N) stable isotopes from a sediment core were measured to demonstrate that sufficient information can be derived from sediments to permit a historical reconstruction. The scattered POC data were likely biased by seasonal/annual variability in allochthonous organic matter (OM) loading. The upwardly increasing PON in the sediment core supported historic primary productivity (PP) data, suggesting PON could be a better PP indicator than POC. The upwardly increasing TP documented historic P enrichment. The upwardly decreasing C:N ratio identified an OM source shift from allochthonous to increasingly autochthonous sources with reservoir age. The upwardly increasing N:P ratio implied that N‐fixation rates have increased with reservoir age, to compensate for increasing N limitation as the P loading increased. The δ13C decreased as the PP increased with reservoir age producing an atypical relationship compared to stratified natural lakes. The OM source shifts likely biased the δ13C–PP relationship, and might weaken δ13C‐inferred PP reconstructions in similar reservoirs. The δ15N increased with reservoir age, likely resulting from dissolved inorganic N (DIN) source changes, rather than nitrate utilization. Watershed urban growth and dairy operation intensification potentially contributed greater loads of isotopically heavy DIN. This study demonstrated that paleolimnology has great potential to assist eutrophication assessment and management efforts in reservoirs. 相似文献
19.
为了得出给水厂沉淀池排泥水中二氯乙酰胺(dichoro-acetamide,DCAc Am)主要前体物特性,研究排泥水中二氯乙酰胺生成势(DCAc Am FP)与不同组分特征ρ(DON)、ρ(DON)/ρ(DOC)值之间的关系。结果表明:沉淀池排泥水的ρ(DON)值为0.3~0.6 mg/L高于原水中的值(0.2~0.4 mg/L),且亲水性小分子量占大部分;DCAc Am FP达到5~8μg/L。DCAc Am FP与不同组分DON之间存在一定的相关关系(R2=0.623),DCAc Am FP与ρ(DON)/ρ(DOC)值之间存在很强的线性相关性(R2=0.868),表明DCAc Am的主要前体物为氨基酸、蛋白质类亲水性小分量含氮有机物。 相似文献
20.
Spectral slope (S), describing the exponential decrease of the absorption spectrum over a given wavelength range, is an important parameter in the study of of chromophoric dissolved organic matter (CDOM) dynamics, and also an essential input parameter in remote sensing models. Furthermore, S is often used as a proxy for CDOM composition, including the ratio of fulvic to humic acids and molecular weight. The relative broad range in S values reported in the literature can be explained by the different spectral ranges and fitting methods used. A single exponential model is used to fit the S values for 17 investigations involving 458 samples in Lake Taihu from January to October in 2004. The average S value was 15.18 ± 1.39 μm−1 for the range of 280–500 nm, which fell within the range reported in the literature. The frequency distribution of S value basically obeyed a normal distribution. Significant differences in S values between summer and other seasons showed that phytoplankton degradation was one of the important sources of CDOM in summer, whereas CDOM mainly came from the river input in other seasons. Furthermore, the estimated S value decreased with increasing wavelength range used in regression. The maximum and minimum values derived from the regression were 17.89 ± 1.25 μm−1 and 13.62 ± 2.11 μm−1 for the wavelength ranges of 280–380 nm and 400–500 nm, respectively, a decrease of 23.9%. S values significantly decreased with the increase of CDOM absorption coefficients. CDOM absorption coefficients could be more appropriately estimated from exponential model introducing the variation of S with absorption coefficients, making them useful for a remote sensing bio-optical model of Lake Taihu. DOC-specific absorption coefficient a*(λ) and the parameter M describing molecular size of the humic molecules could also be used as a proxy for the sources and types of CDOM. A general relationship was found between S and a*(λ), and M values. S increased with the decrease of DOC-specific absorption coefficient and the increase of M corresponding to the decrease of molecular weight. 相似文献