Nutrient dynamics in shallow lakes of northern greece

GOAL, SCOPE, BACKGROUND: Shallow lakes display a number of features that set them apart from the more frequently studied deeper systems. The majority of lakes in Northern Greece are small to moderate in size with a relatively low depth and are considered as sites of high value of the wetland habitat. However, the water quality of these lakes has only been evaluated segmentally and occasionally. OBJECTIVE: The objectives of this study were to thoroughly investigate nitrogen and phosphorus speciation in lakes of a high ecological significance located in N. Greece, in order to evaluate their eutrophication status and possible nutrient limitation factors, and to investigate the main factors/sources that affect the water quality of these systems. METHODS: An extensive survey was carried out during the period from 1998-1999. Water samples were collected on a monthly basis from lakes Koronia, Volvi, Doirani, Mikri Prespa and Megali Prespa located in N. Greece. Water quality parameters (temperature, dissolved oxygen, pH and conductivity), organic indices (COD, BOD5), and N- and P-species (NO3(-), NO2(-), NH4(+), and PO4(3-), Kieldahl nitrogen and acid-hydrolysable phosphorus) were determined according to standard methods for surface water. Statistical treatment of the data was employed. RESULTS AND CONCLUSIONS: The physicochemical parameters determined in the lakes studied revealed a high temporal variation. The trophic state of the lakes ranged from meso- to hypertrophic. The nutrient limiting factor varied among lakes suggesting either P-limitation conditions or mixed conditions changing from P- to N-limitation throughout the year. Urban/industrial activities and agricultural runoff are the major factors affecting all lakes, although with a varying contribution. RECOMMENDATION AND OUTLOOK: This lake-specific research offers valuable information about water quality and nutrient dynamics in lakes of significant ecological value located in N. Greece that can be useful for an effective pollution control/management of these systems. Due to the large intra-annual variability of certain physicochemical parameters, a properly designed monitoring program of lake water is recommended.     

Impact of Hazardous Exposure to Metals in the Nile and Delta Lakes on the Catfish, Clarias lazera

The impact of metal pollution in the Nile and Delta lakes was studied in Clarias lazera. Lake Edku is grouped as the site highest in metal concentrations. Compared to Lakes Maryût and Edku, the Nile stations displayed lower levels of metal contamination signifying their selection as reference sites. Metals were accumulated most by the liver, less by muscles and least by serum. Iron showed the highest bioconcentration factors (BCF) in liver, muscles or serum compared to other metals. Even after the refinement of the surrounding water, fish seem to uphold the metals that have been previously ingested. Mercury, in particular, seems to eventually reside in muscles rather than in liver. The positive relationship between total serum protein and metal contents may indicate the formation of specific metal-binding proteins. Meanwhile, serum hyperalbuminemia in polluted fish is probably a shock response towards the high stress index induced by metals. The hypothesis that most of serum copper is bound to ceruloplasmin is documented also in C. lazera. Moderate, but not extennsive, exposure to metals was quite stimulatory to liver alkaline phosphatase (AP) biosynthesis. AP could, thus, be considered as a promising bioindicator for assessing sublethal water intoxicosis.     

Reduced Metals Concentrations of Water, Sediment and Hyalella Azteca from Lakes in the Vicinity of the Sudbury Metal Smelters, Ontario, Canada

Hyalella azteca (Crustacea: Amphipoda), water and sediments from 12 circum-neutral lakes between Sudbury and North Bay in Ontario, Canada were sampled in August 1998 and analyzed for 10 metals including Cu, Zn, Cd, Ni, Pb, Co, Mo, V, Ba and Ti. Statistical analyses showed that concentrations of the metals in H. azteca, water and sediment differed significantly (ANOVA, P<0.05) among lakes (except for Zn and Pb in H. azteca and Mo in water). There was a trend of declining metal concentration, especially for Cu, Ni and Co (in water, Hyalella and sediment), with distance from the smelters indicating the reduced impact of atmospheric pollution. Metal concentrations of lakes (water) in the Sudbury area were found to be lower compared to data from the 1970s and 1980s indicating an improvement in water quality. Metal concentrations in field-collected amphipods compared favorably with those measured in the laboratory in animals exposed to deep-water sediments, provided metal concentrations were not extremely low (e.g., Pb) and that water chemistry differences (e.g., pH) were taken into account for some metals (especially Cd). In general bioaccumulation of metals in H. azteca was predicted better from surface water than from sediment total metal.     

云南省九大高原湖泊水污染现状调查与分析

从云南九大高原湖泊水污染综合防治"十一五"规划编制入手,对九湖水污染情况进行系统汇编和整理,分析九湖存在的主要环境问题,为水污染综合防治工作提供参考和借鉴.     

PERCEPTION OF WATER QUALITY BY SELECT RESPONDENT GROUPINGS IN INLAND WATER-BASED RECREATIONAL ENVIRONMENTS1

ABSTRACT: This paper examines four lake environments which are paired by lake size and by trophic state, where trophic state is employed as an identifier of water quality. Two large lakes and two intermediate-sized lakes, with each pair having one oligotrophic lake and one eutrophic lake are selected for cross-sectional survey-oriented questionnaire research. This paper focuses upon one aspect of the research, namely, the perception of water quality by three user groups. The user groups examined are recreationists, cottage and homeowners, and fishermen. The groups are compared utilizing percentage response profiles and cluster level groupings. It appears from a preliminary analysis of the data that the lakes selected are viable trophic state endpoints for questionnaire analysis of respondents. Each user group surveyed does appear sensitive to select water quality parameters; where shifts in sensitivity appear within and between user groups with changes in ecological settings, as well as with factors independent of ecological settings.     

THE RESTON (VIRGINIA) LAKE-USE SURVEY: PUBLIC PERCEPTIONS AND MANAGEMENT IMPLICATIONS1

ABSTRACT: A public attitude survey was developed by a citizen committee and mailed to all residences (14,747) in the planned, suburban community of Reston, Virginia, which is responsible for maintaining four small, recreational impoundments. Over 18 percent of survey forms were returned, and characteristics of the survey sample suggest that the suite of respondents was representative of the Reston community as a whole. Of those respondents indicating a preferred lake use, 48 percent chose walking or looking as most important; boating as second at 27 percent; and fishing was third, favored by only 8 percent. Citizens feel strongly (94 percent) that the lakes are valuable community assets. Appearance was the characteristic most valued by 62 percent of respondents, and 58 percent considered degradation of water quality either the first or second most important ecological issue affecting local lakes. These findings provide a decisive public mandate for lake management activities related to visual quality. In response to this survey, the Reston Association, a homeowners' organization responsible for the lakes, increased public access of visual enjoyment, intensified litter control, expanded activities in public education on lake management and ecology, and continued a long-term program of water quality monitoring.     

CHANGES IN STRATIFICATION IN ONONDAGA LAJKE,NEW YORK1

ABSTRACT: The calibration of a mixed-layer stratification model to the complex stratification region of Onondaga Lake is documented. The short- and long-term impacts of the closure of an adjoining alkali plant on the stratification regime of Onondaga Lake are evaluated with this model from the perspective of natural variations associated with meteorological variability. Chemical stratification prevailed in the lake during the operation of the facility as a result of its discharge of ionic waste. A predicted likely short-term impact of the closure, that was subsequently observed, was the failure of the lake to turn over in the spring immediately following the closure. Spring turnover did not occur regularly during the operation of the facility; but turnover can be expected to occur regularly in the future. Other projected changes in average stratification conditions include: 1) a 45% shorter period of stratification, 2) a 3m deeper upper mixed layer, and 3) a 30% lower maximum density gradient. Substantial variability in the stratification is predicted as a result of meteorological variability, indicating that comparison of characteristics for individual years during and after the operation of the facility could be misleading. The changes in the stratification regime are expected to affect water quality. In particular, certain features of the oxygen resources of the hypolimnioa are expected to improve (e.g., delayed onset of anoxia).     

Effect of deep freezing of lakes on food supply in habitats of waterbirds

The phenomenon of bottom substrate exposure in deeply freezing lakes during the melting of ice in spring is described. It leads to the formation in the lake of a large temporary biotope—a combination of shoals and exposed portions of the silty bed—with a high trophic capacity for ducks, shorebirds, gulls, etc. The lake in such a state is a rich foraging area for nesting and migrating bird populations. This phenomenon, which is widespread in the Central Yakutian plain, is an ecological manifestation of cryoarid conditions developing in the plains due to extreme climate continentality.     

Temporal Trends in Mercury Accumulation in Lake Sediments in Sweden

Lake sediment cores were analyzedto study the history of mercury (Hg) pollution andparticularly to determine whether recent sedimentconcentrations have declined in response todeclining atmospheric deposition of Hg. Sedimentcores from 6 forest lakes distributed fromsouthern to northern Sweden and 3 northernmountain lakes were analyzed for Hg using CVAAS. A400 cm sediment profile from Måkevatten insouthwest Sweden indicates that the onset of Hgpollution occurred in the 18th century. Anindisputable increase in Hg concentrationsoccurred concurrent with the appearance ofspheroidal carbonaceous flyash particles (SCP)derived from fossil-fuel combustion, in themid-19th century. There is a strong correlationbetween Hg and SCP concentrations in the sedimentcores (r=0.67 to 0.91), which suggests a strongrelationship between historical Hg pollution andfossil fuel burning. In contrast to sediment corestaken in 1979, maximum Hg concentrations are nowobserved below the sediment surface and declinetowards the sediment surface. This study confirmsthat reductions in atmospheric deposition of Hgover Sweden have resulted in a decreased transferof total Hg to aquatic environments as reflectedby lake sediments, and that lake sediment profilesof Hg concentrations reflect relative trends inthe atmospheric deposition of Hg rather thanpost-depositional diagenetic processes.     

Nutrient Sources and Transport in the Missouri River Basin,with Emphasis on the Effects of Irrigation and Reservoirs1

Brown, Juliane B., Lori A. Sprague, and Jean A. Dupree, 2011. Nutrient Sources and Transport in the Missouri River Basin, With Emphasis on the Effects of Irrigation and Reservoirs. Journal of the American Water Resources Association (JAWRA) 47(5):1034‐1060. DOI: 10.1111/j.1752‐1688.2011.00584.x Abstract: SPAtially Referenced Regressions On Watershed attributes (SPARROW) models were used to relate instream nutrient loads to sources and factors influencing the transport of nutrients in the Missouri River Basin. Agricultural inputs from fertilizer and manure were the largest nutrient sources throughout a large part of the basin, although atmospheric and urban inputs were important sources in some areas. Sediment mobilized from stream channels was a source of phosphorus in medium and larger streams. Irrigation on agricultural land was estimated to decrease the nitrogen load reaching the Mississippi River by as much as 17%, likely as a result of increased anoxia and denitrification in the soil zone. Approximately 16% of the nitrogen load and 33% of the phosphorus load that would have otherwise reached the Mississippi River was retained in reservoirs and lakes throughout the basin. Nearly half of the total attenuation occurred in the eight largest water bodies. Unlike the other major tributary basins, nearly the entire instream nutrient load leaving the outlet of the Platte and Kansas River subbasins reached the Mississippi River. Most of the larger reservoirs and lakes in the Platte River subbasin are upstream of the major sources, whereas in the Kansas River subbasin, most of the source inputs are in the southeast part of the subbasin where characteristics of the area and proximity to the Missouri River facilitate delivery of nutrients to the Mississippi River.