Lake Phosphorus Research Articles

Forms and Mobility of Sediment Phosphorus in Shallow Eutrophic Lake Võrtsjärv (Estonia)

AbstractThe surficial sediment (0–10 cm) of shallow eutrophic Lake Võrtsjärv (Estonia) was characterized by an acid insoluble residue of 50% dry weight and low nutrient, Fe and Mn content. Among phosphorus (P) fractions (Hieltjes and Lijklema, 1980), NaOH‐NRP amounted on an average to 50%, HCl‐RP to 30%, NaOH‐RP to 16%, and NH4Cl‐RP to 4% of their sum. Seasonal changes in sediment P content were inconsistent with mass balance calculations and could be attributed to sediment redistribution caused by decreasing water level. High Fe/P ratio (26–30) and the aeration of surficial sediment by frequent resuspension kept phosphate adsorbed. Low pore‐water SRP (commonly <10 μg l−1) usually prevented phosphate release from surficial sediment. However, a storm in September 1996 (max. wind speed 16 m s−1) which coincided with the extremely low water level in the lake (mean depth 1.44 m), denuded deeper anoxic sediment layers and caused a SRP release of 193 mg P m−2 d−1.

Practical application of 25 years' research into the management of shallow lakes

The Norfolk Broads are a series of shallow, man-made lakes dug in medieval times for peat extraction, in Eastern England. Their eutrophic state has been well-documented and, since the early 1980s, their restoration has been attempted using a variety of techniques. The restoration began with the removal of point sources of phosphorus from sewage treatment works, which then revealed the role of sediment release when lake phosphorus levels failed to decline following inflow phosphorus levels. Small-scale removal of sediment layers in isolated broads demonstrated the feasibility, both technical and economic, of this technique, but experience then showed that sediment removal alone could not provide long-term restoration. Biomanipulation following sediment removal now offers the most reliable route to restoration, but the mechanisms by which a stable submerged plant community can be maintained after biomanipulation are still not clear.

Numerical Modeling of Wind-driven Current in Taihu Lake and Its Impact on TP's Distribution

A new up-winding finite element numerical model, which is two-dimensional and suitable for modeling lake current and the distribution of total phosphorus(TP) in shallow lakes, is derived. Moreover, it is used in the study of wind-driven current in Taihu Lake, and the impact of lake current field on the distribution of TP is also discussed.;A new up-winding finite element numerical model, which is two-dimensional and suitable for modeling lake current and the distribution of total phosphorus(TP) in shallow lakes, is derived. Moreover, it is used in the study of wind-driven current in Taihu Lake, and the impact of lake current field on the distribution of TP is also discussed.

Sedimentation and mineralisation of organic carbon, nitrogen and phosphorus in a large humic lake, northern Sweden

Lake Ortrasket is a large (7.3 km2) and deep (64 m) humic (DOC 10 mg-L-1) lake in northern Sweden. Sediment trap data (gross sedimentation) and sediment core data (net sedimentation) has been used ...

Fractionation and characterization of epilimnetic soluble organic phosphorus in an Amazon lake

Fractionation and characterization of epilimnetic soluble organic phosphorus in an Amazon lake

Metalimnetic gradients and the vertical distribution of phosphorus in a eutrophic lake

Analyses of the vertical distribution of phosphorus in a eutrophic lake showed constant accumulation of soluble reactive phosphorus and total P in the hypolimnion following spring diatom blooming. The downward flux of phosphorus was realised mostly in spring due to high rates of sedimentation and aerobic decomposition of algal biomass. Nearly two thirds of hypolimnetic phosphate-P accumulation had occurred before the hypolimnion became deoxygenated. An increase in soluble reactive P in the hypolimnion by a further 100 mg P m -3 took place during summer, most probably due to internal P loading from bottom sediments. Distinct gradients of phosphorus, chlorophyll, alkaline phosphatase activity and seston across the thermocline coupled with a low sedimentation rate in the summer presented evidence for the barrier role of the metalimnetic zone in vertical fluxes of matter in a lake. Possible consequences of this phenomenon for phosphorus cycling in a lake are discussed.

A Zero Degree of Freedom Total Phosphorus Model: 1. Development for Onondaga Lake, New York

ABSTRACT A seasonal, two-layer, variable volume, mass balance model for total phosphorus in a stratifying eutrophic lake is developed and tested for a single spring to fall interval. The model recognizes settling, sediment release, and vertical mass transport as key in-lake processes mediating phosphorus dynamics. The application presented is termed a “zero degree of freedom” model, as all inputs are determined independently through field and laboratory studies conducted on a test system. The model is considered validated for the test system because simulation results closely match field observations with no calibration (adjustment of model coefficients). Loading reductions at an adjoining wastewater treatment plant, the lake's major phosphorus source, provided an opportunity for model verification. The model framework has utility for other eutrophic stratifying lakes and the “zero degree of freedom” approach will find application where opportunities for both calibration and verification do not exist.

Mesocosm tracer studies. 1. Zooplankton as sources and sinks in the pelagic phosphorus cycle of a mesotrophic lake

The impact of various zooplankton groups on the cycling and retention of phosphorus in a mesotrophic lake in late summer was estimated in a 10‐d mesocosm experiment with addition of 33P. Specific assimilation rates for various dissolved and particulate fractions and individual zooplankton species were estimated by application of tracer models. By means of mathematical inverse methods, these estimates were used to construct a balanced P budget that included the different zooplankton groups.Altogether, the consumers (including the mixotrophic Dinobryon) were responsible for >60% of the estimated P sedimentation (∼1% d−1). The microconsumers had the largest specific P assimilation (0.28 d−1) and regenerated 45% of assimilated P; Daphnia had an intermediate P assimilation (0.17 d−1), but regenerated <20%, whereas Cyclops assimilated P quite slowly (0.07 d−1) and regenerated 230% of its assimilation of algal P <20 µm, due to its feeding on microconsumers.The microconsumers, and the daphnids in particular, thus act mainly as sinks for P, whereas the cyclopoids act mainly as sources of P by assimilating and regenerating P otherwise trapped in the microconsumers. The mechanisms responsible for these different roles seem related to growth rate and P content of the consumers relative to that of their diet.

Reconstruction of Lake Phosphorus Loading and Dynamics Using the Sedimentary Record

Reconstruction of Lake Phosphorus Loading and Dynamics Using the Sedimentary Record

Development and Testing of a Total Phosphorus Model for Onondaga Lake

ABSTRACT Adynamic two-layer mass balance model for total phosphorus (TP) is developed for culturally eutrophic Onondaga Lake, NY, and tested for the May 1987 through 1990 period. The model accommodates key processes in the lake's phosphorus cycle, including settling of the particulate fraction of TP, sediment release, and vertical mass transport Model development and testing were supported by a comprehensive program of field and laboratory measurements and experiments, to determine model coefficients and external loads, and to establish temporal and vertical distributions of lake TP concentrations. The model performs well in tracking documented interannual, seasonal, and vertical distributions of TP in the lake, and thus is appropriate as a management tool to evaluate management scenarios aimed at abating the lake's cultural eutrophication problem.

Resuspension and Diffusive Flux of Nitrogen and Phosphorus in a Hypereutrophic Lake

AbstractBottom sediments in shallow lakes can play a major role in releasing nutrients to the overlying water column during wind induced sediment resuspension or by constant flux due to diffusion. Internal nutrient loads due to these processes may be equal to or higher than external loads. Laboratory and field experiments were conducted on Lake Apopka, a shallow, hypereutrophic subtropical lake located in central Florida. Ammonium (NH+4) and soluble reactive P (SRP) flux during sediment resuspension were measured under laboratory conditions using intact sediment cores. Ammonium N and SRP flux due soley to diffusion were assessed using in situ porewater concentrations. Average diffusive flux from sediment to the overlying water was estimated to be 25 mg NH4‐N m−2 d−1 and 1 mg P m−1 d−2. Resuspension fluxes of NH+4 and SRP were higher than diffusive flux. Soluble reactive P profiles of porewater showed distinct profile differentiation, with the surface 0 to 8 cm sediment depth acting as a P‐depletion zone, and the underlying sediment displaying steep gradients in porewater SRP. These results suggest that dissolved NH+4 and SRP transport from the surface 8 cm of sediment was due to sediment resuspension, while below this depth, upward mobility of NH+4 and SRP was regulated by diffusion. Although dissolved N and P flux is upwards (from sediment to water column), during extended periods (annual cycle) the lake is functioning as a net sink for N and P by transforming inorganic pools of nutrients into organic forms and depositing them on the sediment surface.

Prediction on the dynamic change of total phosphorus in West Lake, Hangzhou

Prediction on the dynamic change of total phosphorus in West Lake, Hangzhou

Estimator Bias in a Lake Phosphorus Model with Observation Error

We investigated observation‐error‐induced parameter bias using least squares and Stein‐corrected least squares estimators in a model for predicting lake phosphorus. The Stein‐corrected estimator performed better than the uncorrected estimator from bias and “closeness” perspectives, though the corrected estimator was still biased. Examination of the model structure revealed that parameter bias is strongly related to both the parameter space and sample space. Additionally, the model is robust to parameter bias over a large portion of the sample and parameter space, indicating that this model may be particularly useful for estimation and prediction. Analogous structure in other models could be an important consideration for model selection.

Sequential extraction of phosphorus in freshwater wetland and lake sediment: Significance of humic acids

We modified a five-step sequential extraction scheme originally developed for phosphorus (P) in lake and marine sediments for use in a Danish freshwater wetland rich in organic matter. In contrast to the original scheme, the modification suggests isolation of P associated with aluminum (Al) and iron (Fe) in humic acid complexes. As in the original scheme, discrimination also was obtained between inorganic P associated with reducible forms of Fe and inorganic P associated with Al oxides. This is important because only iron-bound P is likely to be mobilized when wetland sediments become anoxic. Extraction of ironbound P was performed by use of bicarbonate-buffered dithionite and was followed by a NaOH treatment that extracted most organic bound P together with P adsorbed onto clays and Al oxides. The NaOH extract was dark brown, but upon acidification (pH≈1), we produced a precipitate of presumeably humic acids (HA) and a clear supernatant. The precipitate contained up to 30% of the total sediment P and significant fractions of sediment Al and Fe. Ratios of ∼ 12 between HA-Al and HA-P and of ∼ 2.5 between HA-Fe and HA-P suggest that most HA-P was associated with Al in the humic acid complexes. Comparison with sediment from an acid-bog lake suggests that the HA-P fraction might also be important in other freshwater sediments. A similar Al:P and Fe:P ratio was found in the humic acid precipitate from the lake sediment, indicating that the same mechanism was responsible for binding inorganic P in the humic acid complex as in the wetland sediment. When wet sediments were sieved through a 2-mm mesh and handled under N2, the method was highly reproducible, and no further precision could be obtained by grinding the wet sediment prior to extraction.

Long‐term effect of tourism on the recent upward trend of phosphorus in a shallow alpine lake, Japan

AbstractThe trend of total phosphorus (TP) concentrations in May‐October of the tourist season was analyzed to examine the effect of more than 30 years of tourism on a shallow oligo‐mesotrophic lake, Lake Oze‐Numa. Annual mean TP concentrations increased rapidly at the rate of 11.6%/yr, from 7.5mg/m3 to 14.4 mg/m3 in 1982‐90, and a mesotrophic condition of 23.1 mg/m3 is predicted for the year 2000. TP concentrations at the end of the tourist season were higher than at the beginning due to autumn circulation of the bottom sediment, and correlated with the current year TP loadings from tourists. TP concentrations in May were the lowest for the season, and showed good correlation with previous year concentrations. The recent upward trend of phosphorus concentration was mainly brought about by long‐term tourism because 10% of the TP loading by tourists was estimated to accumulate annually in the water column. Phosphorus reduction measures should be taken urgently in such a shallow lake which now shows an accelerated rate of eutrophication.

Regional Patterns of Total Phosphorus in Lakes of the Northeastern United States

ABSTRACT A map of total phosphorus regions has been compiled for lakes in the glaciated portion of the northeastern United States. Total phosphorus data from over 2,600 of the approximately 22,000 lakes larger than 1 hectare in the study area were used for the analysis. Many of the lake regions delineated include lakes with widely differing phosphorus levels. The distinguishing feature of each region is the distribution, or mosaic, of lake phosphorus values. The pattern of values is determined by, or associated with, the particular landscape characteristics of that region and differs in comparison to patterns of lake phosphorus values in adjacent regions. Characteristics examined included: physiography, land cover/land use, vegetation (both potential and existing), soil type, and bedrock and surficial geology. For some regions, where summer lake phosphorus data were sparse, increased emphasis was placed on using combinations of landscape characteristics to refine boundaries. This method comprised using those characteristics most strongly associated with patterns of summer phosphorus data elsewhere in the region and/or patterns developed and qualitatively adjusted from lakes sampled during other seasons. Accompanying the map are descriptions of the distinctive attributes of each region, the reliability of the data used for analysis, and frequency distributions of known and estimated summer total phosphorus concentrations in lakes. The predictive power of similar regionalizations (Omernik 1987, Omernik et al. 1988) has been evaluated using independent data sets (Larsen et al. 1986, Omernik et al. 1991) and the regionalizations have proven useful for managing lakes in the Midwest (Heiskary et al. 1987, Heiskary and Walker 1988, Fulmer and Cooke 1990, Omernik et al. 1991, Lillie et al. 1993). This regionalization is offered as a framework for further verification and application to lake management decisions and the setting of regionally appropriate goals for attainable water quality in lakes of the northeastern United States.

Empirical relationships between oligochaete communities and phosphorus in lakes before and after the abatement of eutrophication mssub: 1994-03-02

In oligochaete communities of lakes, mean relative abundance (OS) of oligotrophic species (mostly Stylodrilus heringianus and Peloscolex velutinus) was negatively correlated with total phosphorus (TP) concentrations in the water. This empirical relationship, previously computed from nine lakes in which eutrophication was increasing, was extended in the present study to Lakes Geneva and Neuchâtel (Switzerland) in which eutrophication was decreasing. Even in this situation, OS can be predicted from TP.

Determination of phosphorus in turbid waters using alkaline potassium peroxodisulphate digestion

The evaluation of the use of alkaline peroxodisulphate digestion with autoclaving or microwave heating for the determination of total phosphorus in turbid lake and river water is described. Procedures were evaluated by the analysis of suspensions (20, 50 and 100 μg P/l) of two standard reference materials, National Institute of Environmental Science, Japan No. 3 Chlorella and No. 2 Pond Sediment. Suspensions were prepared by adding these materials to distilled deionized water (pH 6) and homogenisation using shaking, sonification and stirring. Best recoveries of phosphorus were found when the final solution was 0.045 M in potassium peroxodisulphate and 0.04 M in sodium hydroxide and solutions digested in an autoclave at 120 °C for 60 min. or heated in a microwave oven at 450 W for 10 min. Complete recoveries of phosphorus (99–103%) from 20, 50 and 100 μg P/l Chlorella suspensions were obtained using both autoclave and microwave heating. For the Pond Sediment complete recoveries of phosphorus (99–107%) from the 20 and 50 μg P/l suspensions were obtained using both heating methods. Higher recoveries from the 100 μg P/l Pond Sediment suspensions were obtained using microwave heating (96 ± 1%) than autoclaving (88 ± 5%). Recoveries of phosphorus compounds (phosphates, and phosphonates) added to distilled deionized water and turbid lake water were near quantitative (91–117%) for both digestion procedures. Further analysis of Pond Sediment suspensions showed that complete recovery of phosphorus (98 ± 1%) from 60 μg/l suspensions was achieved with incomplete recoveries (92.3 ± 0.7%, 91 ± 2% and 91 ± 1%) from 70 μg P/l, 80 μg P/l and 90 μg P/l suspensions respectively. Comparison with the APHA-AWWA WPCF, nitric-sulphuric acid digestion method showed no difference in phosphorus measurements for the microwave procedure but that the autoclave procedure gave significantly lower recoveries of phosphorus ( p < 0.01), however, differences were only 2–8%.

Fish production in freshwaters: Are rivers more productive than lakes?

Community fish production data were summarized from the literature to test the hypothesis that production is higher in rivers than in lakes. Average community production at 55 river sites was three times greater (273 kg∙ha−1∙year−1) than at 22 lakes (82 kg∙ha−1∙year−1). Higher production (P) in rivers resulted from much higher densities of fish (14 times) and greater biomass (B) (about 2 times). Average fish weight and P/B ratios were inversely correlated. Average fish weight was 7 times less, and P/B ratios were 1.5 times higher (after correction for fish size), in rivers than in lakes. Thus, rivers not only had higher average biomasses of fish but also the turnover rate of the biomass was greater. Fish production was positively correlated with phosphorus in both lakes and rivers. Information on community fish production supported the hypothesis that the productivity of river habitat is, on average, higher than the productivity of lake habitat. The productive capacity of freshwater habitats can be predicted using a multiple regression model developed by Boudreau and Dickie (Can. J. Fish. Aquat. Sci. 46: 614. 1989), where fish production is calculated from average fish biomass and body mass.

Models to predict lake annual mean total phosphorus

A lake is a product of processes in its watershed, and these relationships should be empirically quantifiable. Yet few studies have made that attempt. This study quantifies and ranks variables of significance to predict annual mean values of total phosphorus (TP) in small glacial lakes. Several new empirical models based on water chemistry variables, on ‘map parameters’ of the lake and its catchment, and combinations of such variables are presented. Each variable provides only a limited (statistical) explanation of the variation in annual mean values of TP among lakes. The models are markedly improved by accounting for the distribution of the characteristics (e.g., the mires) in the watershed. The most important map parameters were the proportion of the watershed lying close to the lake covered by rocks and open land (as determined with the drainage area zonation method), relief of the drainage area, lake area and mean depth. These empirical models can be used to predict annual mean TP but only for lakes of the same type. The model based on ‘map parameters’ (r 2=0.56) appears stable. The effects of other factors/variables not accounted for in the model (like redox-induced internal loading and anthropogenic sources) on the variation in annual mean TP may then be estimated quantitatively by residual analysis. A new mixed model (which combines a dynamic mass-balance approach with empirical knowledge) was also developed. The basic objective was to put the empirical results into a dynamic framework, thereby increasing predictive accuracy. Sensitivity tests of the mixed model indicate that it works as intended. However, comparisons against independent data for annual mean TP show that the predictive power of the mixed model is low, likely because crucial model variables, like sedimentation rate, runoff rate, diffusion rate and precipitation factor, cannot be accurately predicted. These model variables vary among lakes, but this mixed model, like most dynamic models, assumed that they are constants.