Lake Water Color Research Articles

Seasonal Mixing and Genesis of Endogenic Meromixis in Small Lakes in Southeast Norway

The inland region of Southeast Norway contains many lakes with endogenic meromixis. A synoptic study of seasonal mixing was conducted in 27 oligo- and mesotrophic lakes with surface area 0.0013 – 7.4 km2 and water colour 2-146 Hazen units. The scope was to identify properties of morphometric, optical and chemical nature that lead to development of endogenic meromixis. The summer mixing depths were found to depend on lake area and water colour. Small lakes (< 0.3 km2) were incompletely aerated during the spring circulation and had hypolimnetic temperatures near the temperature of maximum density throughout the summer stagnation. Insubstantial autumn mixing is considered the primary reason lakes in this area develop meromixis. Iron and manganese concentrations in anoxic deep waters depend on concentrations in the sediments and on accumulation of dissolved inorganic carbon in the deep waters. Development of endogenic meromixis is favoured by iron concentration in the sediment more than 5% of dry weight and manganese more than 0.5% of dry weight.

Orthogonal variance structures in lake water quality data and their use for geo-chemical classification of dimictic, glacial/boreal lakes

The accumulating volumes of data collected within environmental monitoring programs facilitate the use of exploratory statistical methods of data analysis as a supplement to traditional methods of characterizing lake water quality. When principal component analysis and multidimensional scaling are applied to a matrix containing approximately 24000 samples of lake water quality variables pH, alkalinity, conductivity, hardness, color, Secchi depth and total phosphorus concentration, it is found that the total matrix variance can be approximately reproduced in an orthogonal two-dimensional base with transformations of hardness and color as best principal component representatives. This base is suggested as an empirical lake classification standard where the variance structure of subset lake populations (such as single lakes) can be referenced to the water quality standard of the generic population. Since the principal axes of the base exclusively contain inorganic and organic related variables respectively, the combined inorganic/organic characteristics of the lake can be expressed with the hardness and color variables alone. With the data matrix being large enough to produce high significance levels, and with variable ranges wide enough to represent a majority of dimictic, glacial/boreal lakes, the analysis results should be valid in many lakes throughout the world.

Photochemical mineralization of synthetic lignin in lake water indicates enhanced turnover of aromatic organic matter under solar radiation

The degradation of 14C-[ring]-labelled synthetic lignin (14C-DHP) and dissolved organic carbon (DOC) from lake water were studied simultaneously. 14C-DHP was incubated in humic lake water (colour 173 mg Pt 1(-1)) for 7 d in the dark or under solar radiation. In the dark <0.4% of the introduced 14C-DHP label and 4% of the indigenous DOC were mineralized, indicating that the 14C-labelled aromatic rings of DHP and the humic DOC were microbiologically recalcitrant. Under solar radiation (116 MJ m(-2)), 17-21% of the 14C-labelled carbons in DHP and 18-23% of the indigenous DOC were mineralized in 7 d. Simultaneously the water solubility of 14C-DHP increased. Solar radiation converted the aromatic cores of synthetic lignin to CO2 and soluble organic photoproducts. The results suggest that solar radiation plays a key role in the decomposition of natural polyaromatic matter.

Predicting chlorophyll vertical distribution in response to epilimnetic nutrient enrichment in small stratified lakes

Light-limited metalimnetic phytoplankton communities are thought to be negatively impacted by epilimnetic nutrient enrichment because of shading by increased epilimnetic phytoplankton biomass. We tested this expectation with a dynamic simulation model that was calibrated to three lakes undergoing whole-lake nutrient and food web manipulations. Total areal chlorophyll increased due to nutrient enrichment in each lake, but the magnitude of the response varied between lakes. Modeling experiments, which allowed analysis of separate components of each lake's response to nutrient enrichment, indicated that the response to enrichment depended on lake water color and food web structure. In weakly stained lakes (˜10 mg Pt 1−1, k4 = 0.4 m−1), metalimnetic chlorophyll was stimulated by nutrient enrichment up to moderate levels (1 μg Pt1−1 day−1). In more strongly colored lakes (25 mg Pt 1−1, k4 = 1.0), metalimnetic chlorophyll responded negatively to nutrient enrichment at all P loading rates. Food web structure, as expressed by rates of zooplanktivory, interacted with water color in two ways. One impact was through direct grazing losses on metalimnetic chlorophyll. The other process involved was indirect impact from grazing on epilimnetic phytoplankton, which reduced shading on metalimnetic chlorophyll. Vertical redistribution of chlorophyll between the epilimnion and the metalimnion led to little accumulation of areal chlorophyll with increased P loading over limited ranges of water color and nutrient input rates. Model predictions may be most effectively tested with whole-lake experiments contrasting food web structure, water color and nutrient loading.

Wetland effects on lake water quality in the Minneapolis/St. Paul metropolitan area

A method developed to evaluate the cumulative effect of wetland mosaics on water quality was applied to 33 lake watersheds in the seven-county region surrounding Minneapolis-St. Paul, Minnesota. A geographic information system (GIS) was used to record and measure landscape variables derived from aerial photos. Twenty-seven watershed land-use and land-cover variables were reduced to eight principal components which described 85% of the variance among watersheds. Relationships between lake water quality variables and the first six principal components plus an index of lake mixis were analyzed through stepwise multiple regression analysis. A combination of three landscape components (wetland/watershed area, agriculture/wetlands, and forest/soils components) explained 49% of the variance in a trophic state index, even though most of the lakes examined were already highly eutrophic, and thus were influenced by internal loading. The regression equations explained a range of 14 to 76% of the variation in individual water quality variables. Forested land-use was associated with lower lake trophic state, chloride, and lead. High lake trophic state was associated with agricultural land-use and with wetland distance from the lake of interest. The extent of wetlands was associated with low total lead and high color in lakes downstream. Wet meadows or herbaceous, seasonally-flooded wetlands contributed more to lake water color than did cattail marshes.

A Model to Predict Lake Water Colour

AbstractThis study is an attempt to quantitatively determine variables of significance for predicting colour in small glacial lakes. Lake colour is an important variable in many lake ecological contexts. The data emanate from two extensive data‐sets from Sweden, one of which concerns 1456 lakes, and the other 91 more well‐suited lakes. Four year average values of lake colour were compared to catchment and morphometric parameters to help identify the processes which influence variability in colour between lakes. Various hypotheses concerning the factors regulating colour in lakes were formulated and tested. Various statistical tests were used to separate random influences from causal influences. Those “map parameters” with the most significant influence on colour were the theoretical lake water retention time, the percent of rocks, lakes and mires of the drainage area, the ratio between lake area and drainage area and the lake mean depth. Each model parameter provides only a limited explanation (statistical) of the variability in colour between lakes. The predictability of colour by these models can not be markedly improved by accounting for the distribution of the characteristics in the drainage area. The stability of the final model, which gives an r2‐value of 0.74, has been tested with positive results. The model allows lake colour to be estimated from knowledge of “geological” characteristics of the lake and its drainage area. The variability between lakes from other factors, such as temperature, precipitation and/or contamination of acidifying substances and nutrients, may then be quantitatively differentiated from the impact of these “geological” factors.

Landsat Views of Sudbury (Canada) Area Acidic and Nonacidic Lakes

Multivariate statistical procedures are used to establish empirical associations between acidity, visual lake water colour, dissolved organic carbon (DOC) concentrations, and Landsat-5 Thematic Mapper (TM) radiance data. Acidic lakes in an area northeast of Sudbury (Canada) are characterized by their clear, blue colours and very low DOC. With a subjective, three-class water colour grouping, 92% of the study lakes were correctly classified using TM data. Further, it is shown that DOC, the major component of water colour in this area, can be predicted within 1 mg/L of observed concentrations using TM data (multiple r = 0.93, P &lt; 0.01). By deriving interrelationships between pH levels, water colour, and DOC, Landsat data provide a means to discriminate and map the acidic and nonacidic lakes of the study area. Examination of the reflectance characteristics of a single acidic lake (Bowland Lake) that has undergone neutralization suggests that Landsat data may be used to detect optical changes over time. However, the capability for monitoring the temporal dimension of lake acidification using satellite data has yet to be established.

Relationships between mercury in lake water, water colour and mercury in fish

Relationships between mercury in lake water, water colour and mercury in fish

The humic content of lake water and its relationship to watershed and lake morphometry

The relationship of lake water color (mg liter−1 Pt) to watershed and lake morphometry, derived from topographical, hydrological, and bathymetric maps, was examined by log‐linear multiple regression on a data set obtained from 337 lakes from the northern United States and Canada. Color was positively related to the drainage ratio, and negatively related to watershed slope, mean lake depth, and lake area. Lakes that receive significant indirect drainage from other lakes were less colored than headwater lakes. The best regression model explained 60% of the variance in lake water color. Regression models were calculated separately for four geographic regions (the Laurentians of Quebec, eastern Quebec‐Maine, northeastern Wisconsin, and the Experimental Lakes Area of western Ontario). The regression coefficients for the most significant variables, drainage ratio, watershed slope, and lake area were similar over these four areas, but the regional models still had significantly smaller standard errors than the general model based on the whole data set.

Attempts to reconstruct lake water pH and colour from sedimentary diatoms and Cladocera

(1988). Attempts to reconstruct lake water pH and colour from sedimentary diatoms and Cladocera. SIL Proceedings, 1922-2010: Vol. 23, No. 2, pp. 870-873.