二龙山水库水体变色原因初探

在对2005年7月至2006年5月二龙山水库相关水质指标进行监测分析的基础上,评价了水库的总体水质,鉴定和检测了水库的藻类和藻毒素,探讨了水库水体变色的原因。研究结果表明,二龙山水库总体水质为V类和劣V类,为中度污染和重度污染,主要污染物为总氮和总磷,已呈现富营养化状态,可能诱发水库水华的发生。水体的富营养化和铜绿微囊藻等藻类的大量繁殖是水库水体变色的主要原因。     

风浪扰动对太湖水体重金属形态的影响

对不同风浪条件下水体中的悬浮颗粒物,采用ICP-AES测定其中Co,Cr,Cu,Ni,Pb,Zn,Al,Fe和Mn不同形态的含量.研究表明,水体中Al,Fe,Co,Cr,Pb和Ni可提取态含量随风浪扰动程度的增强其含量均有不同程度的增大. Mn,Zn和Cu在7m·s-1风浪下含量最高,11m·s-1风浪次之,2m·s-1风浪最小.7m·s-1风浪与2m·s-1风浪相比,水体中Mn, Co, Cr, Zn, Cu和Ni的B1, B2, B3态含量增加3-20倍.11m·s-1风浪与7m·s-1风浪相比,Co, Cr和Ni的B1态含量分别增加31.1%-76.8%,Mn, Zn和Cu分别减少22.1%-38.6%; Cr,Zn和Ni的B2态含量增加12.1%-50.2%, Mn减少65.6%, Co和Cu的含量相当; Co和Ni的B3态含量增加15.4%-10.3%,Cr,Mn,Zn和Cu略微减少.水体中的金属主要以Fe-Mn氧化物结合态存在,且金属的三态比例随风浪的变化不明显. Mn的生物有效性最高,Zn,Cu和Ni次之,毒性较大的Pb和Cr的生物有效性较低.Al, Fe和Pb的Fe-Mn氧化物结合态比例非常高,约有74.56%-100%. Co,Cr和Ni的有机结合态比例较高,且Co和 Ni的三态比例比较均一,Cu的B3态较低.     

The Influence of Chironomus plumosus Larvae on Nutrient Fluxes and Phosphorus Fractions in Aluminum Treated Lake Sediment

One of the methods to diminish the internal phosphorus (P) loading is inactivation of P by aluminum (Al). After addition of Al to lake water an Al(OH)₃ floc is formed, which settles to the bottom and initially form a lid on the sediment surface. The effects of Chironomus plumosus larvae on sediment nutrient fluxes and P binding-sites in the sediment after addition of Al were tested. C. plumosus larvae were added to sediment cores in which sediment–water fluxes of nutrients were measured four times. After one month, the sediment was sectioned with depth and P fractions were measured by sequential chemical extraction. The chironomids created burrows through the Al layer which caused a significantly increased efflux of P from the Al treated sediment, because the P had only limited contact to the added Al. The chironomids also affected the P fractions in the sediment by their bioturbating activity. Thus, they caused increased Al concentrations in the upper part of the Al treated sediment. This created an enhanced contact between Al and P in the upper 7 cm of the sediment and, as a result, an increased binding of P to Al and a lowered porewater P. The DIP efflux is therefore expected to be lowered after the initial phase. Al had no effects on the nitrogen fluxes, but the chironomids enhanced the release, and decreased the release or increased the uptake by the sediments.     

Changes in soil characteristics and plant species composition along a moisture gradient in a Mediterranean pasture

Soil physicochemical characteristics, total aboveground biomass, number of species and relative abundance of groups and individual species were measured along a moisture gradient in a pasture, flooded in part during winter through early summer, adjacent to Pamvotis lake in Ioannina, Greece. Soil and vegetation measurements were conducted in 39 quadrats arranged in four zones perpendicular to the moisture gradient. The zone closest to the lake, recently separated from the lake, became part of the pasture and its soil texture was quite different from that of the other zones with a substrate containing 91% sand. Except for pH, this zone had the lowest values in the other five soil physicochemical characteristics measured (organic matter, total and extracted inorganic nitrogen, Olsen extracted phosphorus and extractable potassium); in the other zones organic matter, total nitrogen, phosphorus and potassium tended to increase from the driest to the wettest zone. Total aboveground biomass, ranging from 280 to 840 gm-2, is high for herbaceous pastures in the conditions of Mediterranean climate and it was not related to distance from the lake's shoreline, although the highest values were measured at intermediate distances, or to any of the various soil characteristics measured. Also, the number of species/0.25 m2 was not related to any of the various soil characteristics, but it was highest at the intermediate distances from the lake's shoreline. Species composition varied along the moisture gradient. Forbs as well as annual grasses and legumes declined in abundance from the driest to the wettest places; the reverse was the case for sedges and perennial grasses and legumes. These results indicate that the soil moisture gradient was the principal factor affecting soil characteristics and plant species composition. Since most species were recorded in all the four zones of the pasture, indicating that these can tolerate all variations in abiotic conditions of pasture, the vegetation zonation seems to be influenced by competition. Each functional group of species tends to dominate in a particular range of the soil moisture gradient where it is better suited and tends to exclude competitively other species. Management practices (mowing and grazing) affect the kinds of processes which maintain the observed community structure either by preventing the establishment of later successional species, like reeds and woody species, or by moderating the shoot competition, especially in the wetter zones, and thus permitting the creeping species to grow successfully.     

Assessing the Effects of Alternative Setback Channel Constraint Scenarios Employing a River Meander Migration Model

River channel migration and cutoff events within large river riparian corridors create heterogeneous and biologically diverse landscapes. However, channel stabilization (riprap and levees) impede the formation and maintenance of riparian areas. These impacts can be mitigated by setting channel constraints away from the channel. Using a meander migration model to measure land affected, we examined the relationship between setback distance and riparian and off-channel aquatic habitat formation on a 28-km reach of the Sacramento River, California, USA. We simulated 100 years of channel migration and cutoff events using 11 setback scenarios: 1 with existing riprap and 10 assuming setback constraints from about 0.5 to 4 bankfull channel widths (bankfull width: 235 m) from the channel. The percentage of land reworked by the river in 100 years relative to current (riprap) conditions ranged from 172% for the 100-m constraint setback scenario to 790% for the 800-m scenario. Three basic patterns occur as the setback distance increases due to different migration and cutoff dynamics: complete restriction of cutoffs, partial restriction of cutoffs, and no restriction of cutoffs. Complete cutoff restriction occurred at distances less than about one bankfull channel width (235 m), and no cutoff restriction occurred at distances greater than about three bankfull widths (∼700 m). Managing for point bars alone allows the setbacks to be narrower than managing for cutoffs and aquatic habitat. Results suggest that site-specific “restriction of cutoff” thresholds can be identified to optimize habitat benefits versus cost of acquired land along rivers affected by migration processes.     

滇池流域磷循环系统的物质流分析

研究营养元素在社会经济系统中的物质代谢结构及特征,是有效预防和控制地表水体富营养化的关键性分析技术之一.以滇池流域磷循环为研究案例,运用物质流分析方法建立了2000年流域静态物质流模型(PHOSFAD),并在此基础上识别出流域磷循环系统的总体结构特征,以及资源开采、化工生产、农业种植、畜禽养殖、居民生活等生产和消费部门的物质利用效率特征,为科学防治滇池水体富营养化提供了重要决策依据和参考.     

水源水中摇蚊幼虫的孳生与生态控制

摇蚊幼虫(红虫)在城市供水系统中的出现,成为困扰水厂正常生产运行的又一水处理难题.首先对其生理特性与环境因子之间的关系进行了论述,然后从生态学角度出发,利用生态群落中的食物链关系,分析了富营养化水体中摇蚊幼虫大量孳生的原因.在此基础上提出了利用合理的生物操纵技术,通过鱼类与水生生物间的"下行效应",以达到恢复生态平衡并控制摇蚊幼虫孳生为目的的生态治理方案.     

河湖水环境问题及管理和治理模式

本文首先介绍了我国当前的河湖水环境现状,分析了我国水资源存在的一系列问题,主要问题包括水体污染和富营养化;河湖面积严重萎缩,河湖水的功能逐渐退化;难以降解的有机污染物污染量加大。有针对性地提出了改善我国河湖水环境的管理以及治理模式,进一步落实了保护河湖水环境工作,加强水资源周围生态环境的文明建设,实现河湖水环境的可持续发展。     

三峡水库浮游植物群落特征及水体富营养化评价

基于2003—2017年三峡水库浮游植物群落结构、优势种群的变化和2017年水库干支流水质数据,全面分析浮游植物群落结构和演替特征,并运用综合营养状态指数法对水体富营养化程度进行评价。结果表明,三峡水库浮游植物种类丰富,监测期间共鉴定出浮游植物7门62属,细胞密度在7.5×10~4~2.8×10~7cell/L之间变化,Shannon-Wiener多样性指数为1.0~3.0,在α-中污带和β-中污带之间,说明三峡水库水生态环境健康状况相对较好;三峡水库浮游植物季节性演替特征呈硅藻和甲藻向蓝藻和绿藻演替的趋势,年际变化特征分析发现浮游植物密度在2008年175 m实验蓄水后大量增长,且优势藻类由河道型藻类向湖泊型藻类转化。通过监测数据分析,得出三峡水库干流处于中营养状态,支流在春季主要处于轻度富营养状态,秋季支流比春季支流的富营养化程度低,主要处于中营养状态,总氮(total nitrogen,TN)、总磷(total phosphorus,TP)和透明度(transparency,SD)为水质主要影响因子。     

Characterisation of Selected Lentic Habitats of Dharwad, Haveri and Uttar Kannada Districts of Karnataka State, India

Water quality survey was undertaken to study the current status of water quality of some lentic habitats of Dharwad, Haveri and Uttar Kannada districts, to provide a baseline data, comprising study of their main physical and chemical characteristics and also to evaluate the recent limnological changes those have occurred over a time period in some lentic habitats. Trophic status was also analysed. Present study reveals that Unkal lake, and B.K. Shigigatti tank of Dharwad district, Timmapur, Hosalli, and Krishnapur tanks of Haveri district are fast progressing towards hypereutrophication. Of the other tanks, Galgi tank of Dharwad district, Gudgur, Hanamapur, Medleri, and Kadkol tanks of Haveri district have reached the eutrophic stage. The anthropogenic activities, sewage and fertilizers used in agricultural fields appear to be the major causes of the eutrophication in these tanks. If the habitats have to be preserved for their intended use, sustainable and holistic management measures for the remediation of the tanks are an immediate necessity.