High Levels Of Total Phosphorus Research Articles

Estimating reference nutrient criteria for Maryland ecoregions

Management of stream nutrients is becoming increasingly important in order to protect both water quality and aquatic resources throughout the USA. Using an extensive water quality database from the long-term Maryland Biological Stream Survey (MBSS), we describe nutrient relationships to landscape characteristics as total nitrogen (TN) and total phosphorus (TP) of small-order, non-tidal streams in USEPA L2 and L3 ecoregions in Maryland and by MBSS stream order at the L2 and L3 ecoregion levels. To protect stream ecosystem integrity, preliminary reference nutrient estimates (TN and TP) as percentiles (25th of all stream reaches and 75th of stream reference reaches) for the six Maryland L3 ecoregions are: Blue Ridge TN 0.29 and 0.64mg/L, TP 0.0065 and 0.0090mg/L; Central Appalachians TN 0.40 and 1.0mg/L, TP 0.0060 and 0.015mg/L; Middle Atlantic Coastal Plains TN 0.93 and 2.5mg/L, TP 0.094 and 0.065mg/L; Northern Piedmont TN 1.6 and 1.8mg/L, TP 0.010 and 0.015mg/L; Ridge and Valley TN 0.40 and 0.98mg/L, TP 0.0063 and 0.012mg/L; and Southeastern Plains TN 0.33 and 0.82mg/L, TP 0.016 and 0.042mg/L. High levels of both TN and TP are present in many streams found in non-tidal watersheds associated with all Maryland ecoregions, but are especially elevated in the Northern Piedmont and Middle Atlantic Coastal Plain ecoregions, with the latter second-order streams (average TN > 2.9mg/L) significantly higher than all other ecoregion-order combinations. Across all six ecoregions, mean nutrient loading for both TN and TP was generally equivalent in first-order streams to nutrient concentrations seen in both second- and third-order streams, indicating a definite need to increase efforts in preventing nutrients from entering first-order streams. Small-order stream nutrient levels are the drivers for subsequent TN and TP inputs into the upper freshwater tidal reaches of the Chesapeake Bay, resulting in a potential risk for altered estuarine ecosystems.

Phosphorus and nitrogen in waters of the ocoí river sub-basin, Itaipu reservoir tributary

Starting from spatial-temporal distribution of nitrogen and phosphorus species in Ocoi river Sub-basin, Itaipu's tributary, this work evaluated the environmental impact in surface waters. After rain, non-point sources are predominant, presenting higher levels of total phosphorus and nitrogen. In the case of phosphorus, trophic states varied from ultraoligotrophic to mesotrophic. Even though Brazilian legislation is obeyed for surface and drinking water, total nitrogen showed values above background levels, and nitrite concentration, 0.06 mg L-1 NO2--N, lies above the recommended value meant to protect aquatic life, according to the Canadian Water Quality Guidelines. Non-point and point sources control is advisable to minimize environmental phosphorus and nitrogen species impact, increasing the water support capacity and minimizing its discharge into Itaipu Reservoir.

Mobility of Different Phosphorus Pools in the Sediment of Lake Dianchi during Cyanobacterial Blooms

By the method of P fractionation, we examined sedimentary P fractions in Lake Dianchi before and during cyanobacterial blooms, namely in April 2004 and August 2004, respectively. In this study, the whole lake is divided into four areas to discuss P fractions in sediment and the relationship between them and water quality or the nutrient status. The results show that where the water body was much more eutrophic (higher levels of total phosphorus, total nitrogen, chlorophyll and trophic status index) in Lake Dianchi, there can be more potentially available phosphorus (BD-P and NaOH-P) and less no available phosphorus (HCl-P and residual P) in the corresponding sediments. Statistical analysis and statistical plots are used to compare the distribution of every P fraction during cyanobacterial blooms with that before cyanobacterial blooms, and the results indicate that the different P fractions had the different mobility. HCl-P and residual P were relatively stable, while NaOH-P, BD-P and NH4Cl-P were more mobile. BD-P can intensively be released from sediment to water and consequently promote cyanobacterial blooms, and at the same time the NaOH-P concentration increased in sediment, which can result from that BD-P released can be partly immobilized to NaOH-P. During cyanobacterial blooms BD-P can be as a source, but NaOH-P as a sink. Besides, total phosphorus in sediment had no significant differences between two samplings.

The U.S. EPA Lake Erie Indicators Monitoring Program 1983–2002: Trends in Phosphorus, Silica, and Chlorophyll a in the Central Basin

During the past 20 years, Lake Erie has exhibited a series of complex chemical changes resulting from changing anthropogenic influences and introductions of exotic species. Since 1990, some apparent trends in nutrient concentrations have been inconsistent with the predictions of models originally used to guide Lake Erie water quality management. We performed time trend analysis on total phosphorus (TP), chlorophyll a (Chl a), and dissolved reactive silica (DRS) measurements collected during spring and summer in the central basin of Lake Erie between 1983 and 2002. Three distinct time trends in basin-specific, station-averaged open-water TP concentrations were observed over the 20-year period: 1983–1989 decreases, 1990–1997 increases, and 1997–2001 decreases. Exceptionally high levels of turbidity and TP were observed in spring 2002, possibly reflecting increasing frequency of winter storm events. Open-water concentrations of TP declined during the 1980s as annual TP loadings to Lake Erie declined below the 11,000 metric ton target level that had been expected to reduce central basin eutrophication. This was accompanied by a significant increase in available silica and in Chl a concentrations. During the period 1990–2002, when dreissenid mussels were abundant, spring TP concentrations increased but summer TP concentrations declined. Unexpected increases in spring central basin concentrations of DRS (exceeding 1 mg/L) were observed. During the same period, Chl a concentrations declined in the spring and rose slightly during summer.

Water quality of the Canchim’s creek watershed in São Carlos, SP, Brazil, occupied by beef and dairy cattle activities

The Canchim’s creek watershed in São Carlos, SP, Brazil, was chosen to evaluate water quality affected by dairy and beef cattle production systems based on tropical pasture. The water samples were collected monthly, during three years, at six sampling points: spring in a tropical forest, spring in an intensive dairy production system, two dam springs, and stream water upward and at the delta. Results showed differences (P<0.01) among sampling points for the mean parameters. True color, hardness, turbidity, electric conductivity, alkalinity, pH, chemical oxygen demand and consumed oxygen explained well differences among sampling points. According to current legislation standards, water quality fitted with most of the established parameters for class 2, with exception of phosphate and iron. The high levels of total phosphorus, except in the forest spring, classified this water in an eutrophic class, even where soil and water conservation practices were considered adequate.

An assessment of recent environmental change in Llangorse Lake using palaeolimnology

1. The diatom record preserved in a sediment core from Llangorse Lake in South Wales, a site of national and international conservation importance, was analysed to evaluate the post-1850 nutrient history of the lake. Fossil diatom assemblages were analysed in 13 samples of a dated sediment core from the easterly lake basin. 2. A diatom-based transfer function was applied to the fossil diatom data to generate a quantitative reconstruction of in-lake total phosphorus (TP) concentrations, following taxonomic harmonization between the training set and core species data. The TP reconstruction was calculated using a north-west European calibration set of 152 lakes. 3. The diatom assemblages were dominated by non-planktonic taxa, in particular Fragilaria spp. until ca 1950, since which time there has been a switch to domination by planktonic diatoms. This switch is most likely a response to reduced light conditions and the decline in submerged macrophytes in the lake, brought about by nutrient enrichment perhaps coupled with enhanced inwash of soils, and thus a loss of habitats for epiphytic and benthic taxa. The exact causes of enrichment remain unclear and are currently under investigation, although increased use of fertilizers, agricultural intensification, afforestation and development of tourism and recreation have all been suggested as possible factors. The recent (post-1985) diatom assemblages are associated with mesotrophic conditions and indicate some degree of lake recovery. 4. Application of the transfer function showed that Llangorse Lake has experienced a decline in TP concentrations since the mid-1980s, following at least a century of high and stable TP levels of ca 150 μg TP L−1. The timing of this decrease appears to be related to the sewage diversion in 1981 and a further smaller diversion in 1992. Future monitoring of the lake is recommended in order to observe whether the improvement in water quality is maintained or indeed enhanced. Copyright © 1999 John Wiley & Sons, Ltd.

Development of small outdoor microcosms for studying contaminant transformation rates and mechanisms under various water column conditions

AbstractThree outdoor microcosm treatments were developed to simulate aerobic (aerobic), thermally stratified (stratified), and anaerobic (anaerobic) water columns for assessing contaminant transformation rates under controlled, quasi‐natural conditions. Twelve 3.2‐m‐diameter by 1.4‐m‐deep fiberglass tanks (11.3 m3 water volume) were used in the study, four for each treatment. The tanks were variably manipulated both physically (with internal frames and plastic layers) and chemically (with sediment trays and grass supplements) to facilitate the three environments. The manipulations successfully created three different and reproducible (both between tanks with common treatments and over time) aquatic systems for further study. The aerobic treatment produced a good simulation of a P‐limited, mesotrophic water column. Alternately, both the stratified and anaerobic treatments developed eutrophic to hypereutrophic water conditions and had nutritionally balanced total nitrogen (TN) and total phosphorus (TP) levels (approximately 14:1 mg N/mg P). Mild thermal stratification was achieved in the stratified units and low‐oxygen conditions were established in the anaerobic units. A trial study, using the herbicide alachlor [2‐chloro‐2′,6′‐diethyl‐N‐(methoxymethyl)acetanilide], was performed to test the utility of the three microcosm designs for assessing comparative in situ contaminant transformation rates. This experiment was initiated by adding alachlor to all tanks to a final concentration of 50 μg/L. Alachlor levels and other chemical parameters were then monitored for 36 d. The estimated first‐order alachlor decay coefficients and half‐lives for the aerobic, stratified, and anaerobic treatments were 0.011/d (63 d), 0.024/d (29 d), and 0.020/d (35 d), respectively. Subsequent analyses showed that the highest rates of alachlor decay occurred in units with grass supplements, low DO and pH levels, and comparatively high TP levels. These results suggest that lower nutrient (i.e., low TP levels), photosynthesis‐dominated aquatic systems produce lower alachlor decay rates, whereas higher nutrient, decomposition‐dominated systems produce higher decay rates. This project shows that diverse physical and chemical environments can be created in small outdoor microcosms and that these systems can be used successfully to assess contaminant decay rates in natural systems.

Patterns in phytoplankton taxonomic composition across temperate lakes of differing nutrient status

We describe the relationships between summer average total phosphorus (TP) and the biomass of six major phytoplankton taxonomic groups from 91 north temperate lakes. Both regression and a locally weighted smoothing (LOWESS) analyses show that all groups increase with TP but over different nutrient ranges. At nutrient extremes, i.e. very low and high levels of TP, the few taxonomic groups that dominate total biomass are generally dissimilar. In oligotrophic and eutrophic lakes, most group biomass curves show corresponding increases or decreases, but different rates of change. The curves converge at intermediate TP levels (∼10–30 µg liter−1) where there is increased equitability among algal groups. In highly eutrophic lakes, the slope of the total biomass curve decreases, as do all the relative abundances of all groups except blue-greens and diatoms. We conclude that the curvilinearity of the TP-total biomass curve is not attributable to a single taxonomic group, because all groups show some nonlinearity in relation to TP. We suggest that morphological diversity, differential herbivory, and, in particular, mixing regime may explain some of the observed patterns.

Postsettlement eutrophication histories of six British Columbia (Canada) lakes

Eutrophication is a serious problem in many British Columbia lakes. However, long-term nutrient data are rare or unavailable for most lake systems, so the natural, predisturbance characteristics of lakes are unknown, as are the trajectories of past environmental change. We used paleolimnological analyses of diatoms to quantitatively assess eutrophication trends for approximately the last 150 years in six British Columbia lakes. A transfer function was used to infer past lake-water total phosphorus concentrations from the sedimentary diatom assemblages in210Pb-dated sediment cores: all of the lakes had relatively high total phosphorus levels (> 13 μg/L) prior to European settlement. Three of the lakes showed significant eutrophication since that time, whereas the others were only mildly affected. Total phosphorus inferences using the transfer function satisfactorily estimated the modern total phosphorus concentrations of our six study lakes. Minor quantitative problems arose when some fossil assemblages provided poor analogues to the calibration function, but eutrophication trends were still clearly apparent. Our results confirm that some British Columbia lakes have suffered considerable eutrophication as a result of anthropogenically related nutrient inputs, while others, although situated within human-influenced regions, have been relatively unaffected. These results can now be used to help set realistic goals for restoration projects.