于桥水库富营养化评价及空间分布特征研究

基于天津市于桥水库2000-2010年水质数据,结合卡尔森富营养化指数与3种GIS空间插值方法(反距离权重、径向基函数、普通克里金),评价水库富营养化状态并对其空间分布特征及成因进行分析。结果表明:①普通克里金插值方法下的指数半方差模型插值精度较高。②水库富营养化主要表现为氮污染超标,有机污染较轻,磷为限制因子,在降雨集中的汛期(7-9月)水质营养状态空间差异显著。③水库整体水质呈中营养-轻富营养状态,范围为45.87~54.58,水库北岸由于沿岸畜禽养殖污染已处于轻富营养状态,南岸由于农业产生的面源污染呈现向富营养化转变的趋势,反映了水库富营养化空间分布状况,为建立有效的水库环境保护措施提供了新思路。     

浙江省重要水库型饮用水水源地富营养化态势分析及对策

在分析浙江省重要水库型饮用水水源地富营养化变化态势的基础上,利用长系列水质监测资料,研究水库营养盐来源,提出保障水库型饮用水水源地安全的对策和建议。     

Spatial and seasonal variations in δ13C AND δ15N of particulate organic matter in a dam‐controlled subtropical river

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.     

Application of WASP model for assessment of water quality for eutrophication control for a reservoir in the Peruvian Andes

Water quality models are important tools for facilitating assessment of the main processes occurring in an aquatic system. To this end, a water quality analysis simulation programme (WASP8) was used to assess the eutrophication process in El Pañe Reservoir. The reservoir has a useful water volume of 99.6 hm³ and is connected to six other reservoirs located in the Chili Basin of the Arequipa Region. El Pañe Reservoir, which is the basin head, has exhibited eutrophication problems since 2014, causing water treatment problems for human consumption and a high probability of cyanotoxin releases from intensive algal blooms. Accordingly, the reservoir was divided into 11 segments, ammonia, nitrate, phosphate, total phosphate, dissolved oxygen, water temperature and chlorophyll‐a being the simulated water quality parameters. The simulations were set in a steady state condition for 3 years from October 2015 to October 2018, subsequently determining aquaculture activity and benthic flux as being meaningful nutrient sources impacting the phytoplankton community. The results of the present study provide necessary evidence of the need to exhaustively quantify both sources in future research, which will aid decision makers in identifying the best management option that can help guarantee the sustainable development of the involved human activities.     

Stable carbon and nitrogen isotope analysis of seston in a regulated Rocky Mountain river,USA

The δ¹³C and δ¹⁵N of seston, organic matter sources (riparian vegetation, algae, macrophytes, plankton) and an invertebrate detritivore were examined in a regulated Rocky Mountain river (fourth order). The isotopic composition of seston varied among sites and seasons for all size fractions; among-site variation was weakest for ultra-fine particulate organic matter (< 53 μm). Comminution of seston to ultra-fine size partially obscured isotopic differences among sites. Multiple isotope signatures of seston were distinct among sites at different distances from a dam (0.5, 5.3, 8.7 km) and between the river and a third order tributary. Seston (> 53 μm) from 0.5 km below the dam was relatively ¹³C-depleted (?30 to ?28°), reflecting the contribution of reservoir-derived plankton; seston from the site 8.7 km downstream was relatively ¹³C-enriched (?18 to ?23°), reflecting autochthonous inputs. Tributary seston had an intermediate δ¹³C value (?22 to ?26°), reflecting allochthonous inputs (conifer litter) and macrophyte (Elodea) detrital inputs. δ¹⁵N values of seston were generally similar among sites (4–8°) but were more depleted for the tributary (1–4°). Depleted δ¹⁵N values (0–2.5°) for seston from below the dam in late summer corresponded to a blue-green algae bloom in the reservoir. Isotopic shifts of organic matter incubated for 60–90 days in situ were small (< 2°) and varied in direction depending on isotope and litter type. The isotopic composition of stonefly larvae, Pteronarcys californica, varied among sites, and closely matched that of the local seston (especially FPOM), suggesting that with respect to detritus origin, larvae were opportunistic foragers. The origin of organic matter is influenced by flow regulation, resulting in compressed isotopic gradients.     

黄河三角洲湿地柽柳灌丛周围有机质富集及水分运动研究

为研究滨海湿地柽柳灌丛水分推动下的土壤养分富集作用,对黄河三角洲单株柽柳个体周围不同位点、不同土层土壤有机质含量及土壤水、地表水和黄河水同位素进行分析。结果表明:(1)土壤有机质在灌木主干周围出现富集现象,形成深度为20cm,半径为1.5m的富集圈层,有机质含量空间分布呈现冠幅下明显高于冠幅边缘和株间空地,且随土层深度增加而降低,表现出非常明显的肥岛效应。(2)不同土壤剖面水分同位素值出现差异:0~5cm表层土δD、δ18 O同位素值表现为冠幅下冠幅边缘株间空地,而5~10cm土层δD、δ18 O同位素值为冠幅下冠幅边缘株间空地。0~5cm表层土同位素值大于5~10cm土层同位素值。(3)水分运动对柽柳灌丛周围有机质含量产生影响,沿灌木主干流下的雨水冲刷和黄河水侧渗作用是影响灌丛下土壤有机质含量冠幅下冠幅边缘株间空地的原因之一。有机质等土壤养分在肥岛效应及水分运动影响下向柽柳主干周围聚集,这种土壤养分的小尺度空间异质性促进了柽柳自身及附近其他植物的生长,改变了土壤的理化性质。本研究结果同时可以作为黄河三角洲盐碱地土壤改良和植被恢复的参考依据。     

Chemical and Isotopic Tracer Evaluation of Water Mixing and Evaporation in a Dammed Texas River During Drought

The interaction between drought and river regulation is monitored to better understand river flow mixing, evaporation and surface‐groundwater exchange in changing regional climates and in increasingly regulated waterways. This study compared Brazos River stable isotope (δ¹⁸O and δD) and electrical conductivity values with reservoir, creek and aquifer samples in the Brazos watershed, the largest watershed in Texas. The combination of tributaries, rainfall and the Brazos River Alluvium Aquifer, on the one hand, and the Lake Whitney reservoir, on the other hand, represent endmembers of dilute run‐off water and evaporated saline water, respectively. A simple isotope mixing model that uses monthly river discharge, Lake Whitney discharge, historical monthly precipitation δ¹⁸O and pan evaporation accurately reconstructs river δ¹⁸O (±0.5‰ on average). Data and isotope balance modelling support continued evaporation of ¹⁸O‐enriched Lake Whitney water as it flows downstream, although the most evaporation took place in Lake Whitney. The difference between river and precipitation δ¹⁸O, or Δ¹⁸O_RIV‐_PPT, here a measurement of degree of evaporation, ranged from ?0.1‰ for a small creek, to 1.7‰ for the Brazos River, to at least 2.7‰ in Lake Whitney. This study indicates that drought in regulated rivers may enhance reservoir discharge dominance in river flows during peak drought conditions when combined run‐off and baseflow dominance would be expected in a similar undammed river. Copyright © 2016 John Wiley & Sons, Ltd.     

Sources of nitrogen to stream food webs in tributaries of the Red River Valley,Manitoba

Lake Winnipeg has undergone rapid eutrophication over the last several decades with a large portion of the associated nutrient loads delivered via the Red River. Consequently, subcatchments of the Red River Valley (RRV) are priorities for nutrient management, an aim that requires identification of key nutrient sources to stream food webs. We identified the primary sources of nitrogen to food webs of rural streams of the RRV, as well as variation in nitrogen input between spring and summer. We measured δ¹⁵N of particulate organic matter (POM) and collector-gatherer invertebrates collected in spring and summer from 20 subcatchments, which exhibited a range of agricultural intensity and size of municipal wastewater lagoons. δ¹⁵N values of POM and collector-gatherer invertebrates were best predicted by the presence of wastewater treatment lagoons, with δ¹⁵N values increasing with the number of people served by lagoons in spring and summer. When present, wastewater contributed a greater proportion of nitrogen to stream food webs than agricultural sources. Waste sources also had a greater relative contribution to food webs in summer than spring. Despite wastewater lagoons releasing nitrogen in short-term, pulsed discharges, the influence of wastewater on food web nitrogen persisted from the summer release into the following spring. Based on the observed importance of wastewater as a source of nitrogen to stream food webs, we recommend management agencies consider additional actions to reduce nutrient losses from wastewater treatment facilities as well as agricultural lands to more effectively protect aquatic ecosystems.     

Patterns of fish diversity in a mainstem Missouri River reservoir and associated delta in South Dakota and Nebraska,USA

There is an expansive and expanding delta at the confluence of the Niobrara and Missouri Rivers in the Lewis and Clark Reservoir. The delta provides diverse aquatic habitat that is somewhat similar to the historic Missouri River and to remnant river habitats. As such, the delta may have relatively high fish species diversity compared to lentic reservoir habitats. To compare patterns of fish diversity between the delta and reservoir habitats, we collected fish in several nursery habitats in both areas using four gear types (seine, gill net, electrofisher and fyke net) on three occasions (July, August and September) in 2005. Species richness was higher in the delta ( n = 34) than the reservoir ( n = 22). Thirteen species composed more than 1% of delta collections while only four species composed more than 1% of reservoir collections. Species diversity (Fisher's α) was also significantly higher in the delta. Higher species diversity in the delta may be explained by higher habitat diversity. These results suggest that newly forming deltas have the potential to protect and restore fish species diversity, because they retain natural river functions such as sediment transport and habitat formation. Copyright © 2007 John Wiley & Sons, Ltd.     

Sedimentation and sediment core profile of heavy metals in the Owabi reservoir in Ghana

Tropical reservoirs are important for numerous socioeconomic and ecological reasons, including water supply, fishing and flood control. These functions are easily compromised, however, when reservoirs undergo accelerated sedimentation with increased inputs of chemical contaminants. The present study applied the concept of sediment core analysis to evaluate the sedimentation rate in Owabi Reservoir, which has served as a source of drinking water supply in Kumasi, Ghana, for nearly a century. The temporal variation of contamination from heavy metals was also assessed over this period. The sedimentation rate for Owabi Reservoir was estimated to be 6.82 mm/year, suggesting a relatively low rate of sedimentation, which is ecologically healthy in preventing a rapid loss of reservoir water volume. Heavy metal concentrations in the sediment cores taken from the reservoir reflected varying degree of contamination from the 1930s to 2010s. The concentration of iron (Fe) (1,560–1,770 mg/kg) was found to be the highest among the metals in the sediment core, while mercury (Hg) concentration (0.01–0.04 mg/kg) was the lowest. Lead (Pb) contamination peaked in the 1980s. Arsenic (As) and mercury (Hg) contamination exhibited more recent peaks in the 2000s, coinciding with recent widespread issues of artisanal and small‐scale gold mining (ASGM) in Ghana. Thus, even though ASGM activities are known to occur in remote districts, releases from such activities might eventually contaminate reservoirs designated as urban drinking water supplies.     

南方某水源水库富营养化水质主控因子识别与评价研究

淡水湖泊与水库富营养化使其农业灌溉、防洪、发电以及生活用水水源的功能日趋受损。本文以南方某水源水库富营养化动态监测的10个指标(UV254、CODMn、TOC、可溶性硅、总氮、硝酸盐氮、氨氮、亚硝酸盐氮、总磷和磷酸盐)为自变量,叶绿素a为因变量。通过主成分分析(PCA)与多元线性回归(MLR)对变量进行分析,最后得到了以TOC、总氮(总磷)、亚硝酸盐氮为自变量,叶绿素a为因变量的拟合曲线。统计分析表明模型的F值为18.670,Sig.值为0,证明曲线相关性很高;通过回代检验得到模型的符合率为86.1%,表明该评价模型对富营养化具有一定预报能力;模型分析结果进一步表明叶绿素a、总氮(总磷)是该水库富营养的水质主控因子,其中总氮与总磷对该水源水库富营养化水平的影响程度相近。     

Stable carbon and nitrogen isotopic signatures of organic matter sources in near-shore areas of Lake Victoria,East Africa

Stable isotope ratios of organic carbon and nitrogen (δ¹³C and δ¹⁵N) were measured in suspended particulate matter (SPM) and sediment in the near-shore areas of Tanzanian waters of Lake Victoria (LV) to identify the various sources of organic matter in different areas of the lake. Spatial variations in δ¹³C, δ¹⁵N, and C/N ratios in SPM and sediments in inshore areas were due to differences in the proportions and sources of autochthonous or allochthonous matter. Watershed characteristics, such as urbanization, and lake characteristics, such as algal blooms, also immensely influenced the stable isotope signal of the organic matter in sediments. Stable C and N ratios showed that inshore areas in bays without pronounced fluvial input were dominated by autochthonous planktonic organic matter; conversely, for bays receiving significant fluvial inflows, the composition of organic matter depended on the extent of preservation of shoreline vegetation. Signals resulting from input of anthropogenic organic waste as a result of urbanization were distinguishable from natural sources. This work demonstrates the potential to discriminate between input sources of organic material into lakes using stable isotope signals in sediment and suspended particulate matter.     

Temporal and spatial patterns based on sediment and sediment–water interface characteristics along a cascade of reservoirs (Paranapanema River, south-east Brazil)

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.     

Spatial heterogeneity of physical and chemical conditions in a tropical reservoir wetland

Abiotic data, such as physical and chemical variables and inorganic nitrogen status were obtained from substrate compartments in four environments in the Lobo reservoir wetlands. The sampling sites were selected by‘in-situ’observation of the hydrological features, the degree of‘openness’to the flow-through of water and macrophyte communities. For each site, three compartments were considered: the sediment, the interstitial water and the overlaying water at the sediment water interface. The pH, electrical conductivity, dissolved oxygen, nitrate, nitrite and ammonium nitrogen, organic matter and moisture content were analyzed in the substrate. The spatial distribution of these properties was associated with the hydrological and nutritional flooding conditions. Lobo wetland sediment may be an efficient buffer system due to its high interstitial and exchangeable ammonium concentrations.     

The effects of impoundment and non‐native species on a river food web in Mexico's central plateau

Habitat modifications, non‐native species and other anthropogenic impacts have restructured fish communities in lotic ecosystems of central Mexico. Conservation of native fishes requires understanding of food web changes resulting from the introduction of non‐native species, flow alteration and other human impacts. Using δ¹³C and δ¹⁵N analysis of fishes and invertebrates we investigated the effects of non‐native species, and reservoirs on food webs of the Laja river ecosystem (Guanajuato, central Mexico). We estimated trophic position (TP), relative trophic niche and food web dispersion at 11 reservoir, river and tailwater sites. Reservoirs and non‐native fishes modified food webs in the Laja. Food web dispersion was greater in reservoir than in tailwater and river sites. Reservoir food webs had the greatest range of δ¹³C values, indicating a more diverse resource base compared to rivers. δ¹³C values increased with distance downstream from reservoirs, suggesting declining subsidies of river food webs by reservoir productivity. Stable isotopes revealed potential effects of non‐native fishes on native fishes via predation or competition. Non‐native Micropterus salmoides were top predators in the system. Non‐natives Cyprinus carpio, Oreochromis mossambicus and Carassius auratus exhibited lowest TP in the Laja but overlapped significantly with most native species, indicating potential for resource competition. Native Chirostoma jordani was the only species with a significantly different trophic niche from all other fish. Many rivers in central Mexico share similar anthropogenic impacts and similar biotas, such that food web patterns described here are likely indicative of other river systems in central Mexico. Copyright © 2008 John Wiley & Sons, Ltd.     

三门峡水库水沙运动的若干规律——兼论水库溯源冲刷对黄河下游河道的影响

小浪底水库的合理运用对于延长水库寿命,确保黄河下游防洪减淤、长治久安,至关重要。本文基于与小浪底水库河谷地貌、水沙运动基本相似的三门峡水库潼关以下库段和下游河道数十年的基本资料,分析了水库造床及冲淤形态、水库拦粗排细和水库泄空、溯源冲刷的特点,以及溯源冲刷本身对黄河下游河道冲淤的影响。这些对于深化认识和科学制定小浪底水库拦沙后期的运用方式是非常重要的。     

桉树人工林区水库底泥氮、磷和有机质时空分布特征

为探究桉树种植对其林区水库底泥理化特性的影响及水库内部营养盐和有机质的运移转化机制,针对广西南宁市桉树人工林区那降水库,测定了底泥的含水率、总氮、总磷、总有机碳和有机质,分析探讨了底泥氮、磷和有机质的分布特征及氮、磷与有机质之间的相关关系,并评价了底泥的肥力状况。研究结果表明:那降水库底泥氮、磷和有机质的含量随其深度的增加而降低; 8月底泥氮、磷平均质量比分别为2 199 mg/kg和256 mg/kg,均略高于12月的平均质量比(1 994 mg/kg和230 mg/kg),主要在于夏季水库形成水温分层,延缓了底泥营养盐释放;桉树培育期施用的肥料是底泥氮、磷的重要来源,农药及砍伐后的残枝落叶是底泥有机质的主要成分;底泥有机指数远大于0. 05,属于Ⅲ级肥污染状态;桉树对林区水体的氮、磷及有机质的贡献较其他树种更为显著,是林区水库底泥肥污染的重要原因之一。     

Comparisons between the chemical compositions of lake water,inflowing river water,and lake sediment in Nam Co,central Tibetan Plateau,China and their controlling mechanisms

The chemical composition of lake water and inflowing river water was investigated in Nam Co (lake), Tibetan Plateau, in September 2005. Lake water samples (n = 76) were collected at different depths along a south–north transect of the eastern part of the lake while water samples were collected from 69 rivers flowing into the lake; a sediment core was collected at 64 m midway along the water survey transect to investigate salt precipitation. Na⁺ and Ca²⁺ were the dominant cations, accounting for 76.2% and 60.6% of the lake and river water cations, respectively while HCO₃⁻ was the dominant anion accounting for 70.8% and 93.4% of lake and river anions, respectively. CaCO₃ precipitation from the water column decreased Ca²⁺ in the lake water, with the relative proportion of other ions increasing significantly. Evaporation–crystallization processes largely control Nam Co lake-water chemistry, while rock weathering is the dominant processes influencing the chemistry of river water; carbonate and silicate weathering are the major sources of ions in these rivers.