Atmospheric Deposition Of Phosphorus Research Articles

Atmospheric phosphorus deposition in a near-coastal rural site in the NE Iberian Peninsula and its role in marine productivity

In this study, African red-rains were collected at Montseny (NE Spain) on a weekly basis and analyzed for total particulate phosphorus (TPP), total dissolved P (TDP) and soluble reactive P (SRP) for the period 1996–2008. Wet and dry weekly deposition of TPP was analyzed for all provenances in 2002–2003. In this period, African sources were found to contribute 66% of the 576 μmol m⁻² y⁻¹ of total particulate phosphorus (TPP) deposited in Montseny, split almost evenly between dry and wet deposition. Measurement of this dry deposition further allowed a direct determination of deposition velocity (Vd), which suggested significant depositional differences between African (Vd = 3.1 ± 0.80 cm s⁻¹) and non-African events (Vd = 1.07 ± 0.13 cm s⁻¹). Measurement of TDP concentrations during the African rains suggests a solubility of 11.2% TPP. SRP solubility was lower (2.2%), highlighting the importance of understanding the composition of the atmospherically derived P component. Samples were collected 25 km from the Mediterranean coast and were assumed to represent the atmospheric P input to coastal waters. On an annual basis, atmospheric-derived soluble P contributed <1% of annual new primary production in the western Mediterranean. However, one strong African dust event (22–27 May, 2008) accounted for 24–33 % of the atmospheric P-induced annual new production. These results highlight the potential biogeochemical importance of seasonality, source, and composition of aerosols deposited in the Western Mediterranean Sea.

Phosphorus loading of mountain lakes: Terrestrial export and atmospheric deposition

We studied the atmospheric deposition of phosphorus (P) forms along an elevation gradient, and its contribution to the total external P loading of lakes in the Tatra Mountains and the Bohemian Forest, from 1998 to 2009. The aim was to evaluate how topographical (soil and vegetation pools in the catchment) and morphological (catchment‐to‐lake area ratio) characteristics of catchment–lake systems affect in‐lake nutrient structures in remote mountain areas. Concentrations of dissolved organic carbon (DOC), total phosphorus (TP), and total organic nitrogen (TON) were closely related (p &lt; 0.001) to each other in lakes and their inlets. Terrestrial TP export (57–1183 μmol m−2 yr−1 on a catchment area basis) and lake‐water TP concentrations (0.05–1.0 μmol L−1) were closely associated with DOC leaching, exhibiting significant (p &lt; 0.001) exponential relationships with increasing soil cover in the catchments. Precipitation fluxes of TP (460–918 μmol m−2 yr−1, average 692 μmol m−2 yr−1, with 50% being soluble reactive P) increased with precipitation along the elevation gradient and were highest in windy mountain areas. The C : N and C : P ratios of external nutrient inputs to the lakes were higher for terrestrial than atmospheric sources by a factor of ∼ 4 and 32, respectively, and the relative atmospheric contribution to the total external P loading of lakes was inversely related to the soil cover of catchments and the ratio between catchment and lake areas. The different composition and proportion of terrestrial and atmospheric nutrient inputs to mountain lakes along the vegetation zones determine the stoichiometric balance between the DOC and P available as nutrients for the food webs of natural mountain lakes.

Seasonal and spatial distribution patterns of atmospheric phosphorus deposition to Lake Simcoe, ON

A decline in the water quality of Lake Simcoe, Ontario has been observed over the past few decades. This decline has been attributed to excessive loading of the limiting nutrient phosphorus. Atmospheric deposition of phosphorus is a major non-point source contributing 25–50% of the total phosphorus (TP) load entering Lake Simcoe. The objectives of this study were to quantify seasonal variability of atmospheric TP deposition on Lake Simcoe and to estimate spatial distribution patterns of atmospheric TP deposition on Lake Simcoe. Based on the 1995–2007 period of records, on average 35% of the annual bulk atmospheric TP load occurs in the spring, while the summer, autumn and winter account for 45%, 13% and 7%, respectively. The autumn and winter loads are more or less consistent and exhibit little change much from year to year; however, the summer load can vary greatly. Spatially, the Northwest and Southeast quadrants of the lake show the highest atmospheric TP deposition during the spring and summer months. Most of the soils with the highest vulnerability for wind erosion are located in these quadrants and the dominant winds blow in the NW–SE direction.

Atmospheric phosphorus deposition at a montane site: Size distribution, effects of wildfire, and ecological implications

The dry deposition of atmospheric particulate matter can be a significant source of phosphorus (P) to oligotrophic aquatic ecosystems, including high-elevation lakes. In this study, measurements of the mass concentration and size distribution of aerosol particles and associated particulate P are reported for the southern Sierra Nevada, California, for the period July–October, 2008. Coarse and fine particle samples were collected with Stacked Filter Units and analyzed for Total P (TP) and inorganic P (IP) using a digestion-extraction procedure, with organic P (OP) calculated by difference. Particle size-resolved mass and TP distributions were determined concurrently using a MOUDI cascade impactor. Aerosol mass concentrations were significantly elevated at the study site, primarily due to transport from offsite and emissions from local and regional wildfires. Atmospheric TP concentrations ranged from 11 to 75 ng m −3 (mean = 37 ± 16 ng m −3), and were typically dominated by IP. Phosphorus was concentrated in the coarse (>1 μm diameter) particle fraction and was particularly enriched in the 1.0–3.2 μm size range, which accounted for 30–60% of the atmospheric TP load. Wildfire emissions varied widely in P content, and may be related to fire intensity. The estimated dry depositional flux of TP for each daily sampling period ranged between 7 and 118 μg m −2 d −1, with a mean value of 40 ± 27 μg m −2 d −1. Relative rates of dry deposition of N and P in the Sierra Nevada are consistent with increasing incidence of N limitation of phytoplankton growth and previously observed long-term eutrophication of lakes.

Application of Weather Radar in Estimation of Bulk Atmospheric Deposition of Total Phosphorus Over Lake Simcoe

The decline of Lake Simcoe water quality has been attributed to high phosphorus inputs that result in excessive algae and macrophyte growth subsequently contributing to end-of-summer hypolimnetic dissolved oxygen depletion and loss of fish habitat. Out of the estimated 53 to 67 tonne/annum (1998 to 2004 water years) of phosphorus entering the lake, atmospheric deposition is believed to be responsible for 16 to 38 tonne/annum. Historical estimates for atmospheric deposition involved averaging rain gauge (rainfall depth) and rain quality (phosphorus concentration) station data. Through use of this procedure, any spatial variability in the data (quality and quantity) is lost as each gauge is given an equal weighting. This study proposes a methodology to use Next Generation Radar (NEXRAD) to spatially represent rainfall data and a method to correct radar-rainfall estimates to rainfall recorded by local rain gauges. From this analysis it was found that the radar generally represented localized rainfall well, with the majority of correlation coefficients (R2) being over 0.90. Radar related issues that resulted in poor R2 values included virga, overshooting beam, beam attenuation, range related issues and ground clutter. For large bulk atmospheric total phosphorus (TP) deposition events the dominant parameter in calculating TP loads was rainfall depth. Results from this analysis demonstrated a large (−88% to +44%) difference between historical and revised estimates of bulk atmospheric deposition of phosphorus over Lake Simcoe.

Atmospheric Phosphorus Deposition in Ashiu, Central Japan – Source Apportionment for the Estimation of True Input to a Terrestrial Ecosystem

Atmospheric bulk depositions of soluble reactive phosphorus (SRP), soluble unreactive phosphorus (SUP), particulate inorganic phosphorus (PIP), particulate organic phosphorus (POP), total phosphorus (TP) and some other dissolved and particulate components were monitored for 3 years in Ashiu, Central Japan. The mean bulk depositions of SRP, SUP, PIP, POP, TP, dissolved components (Na, Mg, nss-Ca, K, V, Mo, nss-SO4) and particulate components (Al, Fe, Ti, Ca, Mg, Mn, Ba, Sr, Zn) were 175, 76, 136, 397, 783, 156,000, 10,900, 7450, 5470, 10.3, 1.52, 40,100, 13,200, 3590, 2630, 576, 624, 42.3, 30.2, 17.4, 8.2 μmol m−2 year−1, respectively. The value for TP deposition was in the lower range of previous literature. The low P deposition probably reflected the method applied to reduce the contribution of local particles, including (1) placement of samplers off the ground surface, (2) installation of multiple samplers, and (3) rejection of contaminated samples. Al data suggested that 15 ± 5% of TP was brought by lithogenic dust from East Eurasia. Nss-SO4 and Mo data and air-mass backward trajectories suggested that 39 ± 4% of TP was derived from coal combustion in China. It was speculated that the rest (47 ± 6%) of the TP deposition might be predominantly attributed to the contribution of local biogenic particles. Net atmospheric TP input (lithogenic dust and fossil fuel combustion) was almost equal to the TP outflow from Japanese forests on granitic soils.

The atmospheric deposition of phosphorus in Lake Victoria (East Africa)

Wet and dry atmospheric fluxes of total phosphorus (TP) and soluble reactive phosphorus (SRP) measured at four sites over a 12-month period were used to estimate lake-wide atmospheric phosphorus (P) deposition to Lake Victoria, East Africa. Atmospheric samples were collected in plastic buckets with top diameter of 25.5 cm by 30 cm deep. The highest P loading rates of 2.7 (TP) and 0.8 (SRP) kg ha−2 year−1 were measured at Mwanza compared to less than 1.9 (TP) and 0.65 (SRP) kg ha−2 year−1 measured in other three sites. By applying these loading rates to the lake surface, it was estimated that 13.5 ktons (13.5 × 103 kg) of TP were deposited annually into the lake from the atmosphere. Thirty-two percent of the total was found to be in the SRP form. Dryfall, a component ignored in previous studies exceeded wet deposition by contributing 75% of the total P input. However, materials deposited by dryfall made a lesser contribution to soluble form of phosphorus, as SRP concentrations in the wet samples were 2–3 times higher than SRP concentrations in dry samples. The annual fluxes of phosphorus measured on the south and western shores of Lake Victoria (1.8–2.7 kg ha−2 year−1) are near the upper range of similar fluxes measured in the tropics. In comparison with the existing estimates of municipal and runoff P inputs from other studies, it is estimated that atmospheric deposition represent 55% of the total phosphorus input to the Lake Victoria. The four sampling sites were fairly clustered and wet and dry P deposition data were collected from shore/land stations and applied to open lake areas to estimate lake-wide P deposition. In this regard, the estimates determined here should be viewed as a first order approximation of actual P load deposited into the lake.

Rainfall Concentrations and Wet Atmospheric Deposition of Phosphorus and Other Constituents in Florida, U.S.A.

Concentrations of phosphorus (P) and other constituents inweekly composited rain samples and concurrently acquired rainfallvolumes, collected from September 1992 through October 1993, wereused to estimate volume-weighted concentrations and wetatmospheric deposition rates, and compared to estimates fromprevious studies. Since this study’s purpose was to estimateregionally representative concentrations and rates of wetatmospheric deposition, sampling locations were chosen to avoidsites characterized by substantial local resuspension orrecycling phenomena. Significant differences were found in the wet deposition rates of calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), hydrogen (H), and chloride (Cl) ions between sampling stationsin Florida. Consequently, statewide deposition rates and volume-weighted concentrations were estimated only for P, and fororthophosphate (PO4), ammonium (NH4), nitrate (NO3) and sulfate (SO4) ions that were not found to be spatially variable. Over the period of record, the mean rate of wet atmospheric P deposition across the state, and the mean rainfall P concentration, were found to be 25±>5 μg P M-2 wk-1 and 1.3±0.1 μg P L -1, respectively.

Atmospheric deposition of phosphorus to the everglades: concepts, constraints, and published deposition rates for ecosystem management.

This paper summarizes concepts underlying the atmospheric input of phosphorus (P) to ecosystems, published rates of P deposition, measurement methods, and approaches to future monitoring and research. P conveyed through the atmosphere can be a significant nutrient source for some freshwater and marine ecosystems. Particle sources and sinks at the land-air interface produce variation in P deposition from the atmosphere across temporal and spatial scales. Natural plant canopies can affect deposition rates by changing the physical environment and surface area for particle deposition. Land-use patterns can alter P deposition rates by changing particle concentrations in the atmosphere. The vast majority of P in dry atmospheric deposition is conveyed by coarse (2.5 to 10 μm) and giant (10 to 100 μm) particles, and yet these size fractions represent a challenge for long-term atmospheric monitoring in the absence of accepted methods for routine sampling. Most information on P deposition is from bulk precipitation collectors and wet/dry bucket sampling, both with questionable precision and accuracy. Most published annual rates of P deposition are gross estimates derived from bulk precipitation sampling in locations around the globe and range from about 5 to well over 100 mg P m year, although most inland ecosystems receive between 20 and 80 mg P m year. Rates below 30 mg P m year are found in remote areas and near coastlines. Intermediate rates of 30 to 50 mg P m year are associated with forests or mixed land use, and rates of 50 to 100 mg P m year or more are often recorded from urban or agricultural settings. Comparison with other methods suggests that these bulk precipitation estimates provide crude boundaries around actual P deposition rates for various land uses. However, data screening cannot remove all positive bias caused by contamination of bucket or bulk collectors. As a consequence, continued sampling with these standard collectors in a region will not reduce the large uncertainty in rates derived from existing data. Calibrated surface accumulation methods hold promise as a primary means to estimate P flux in future monitoring. New methods for long-term P deposition monitoring will require an intercomparison of P flux estimates from surrogate surfaces, impactor sampling of particle concentrations combined with deposition models, and “throughfall” estimates for natural canopies. With better sampling methods and more long-term monitoring data, the importance of atmospheric P deposition in ecosystem dynamics and management can be better understood and predicted.

Temporal and Spatial Patterns of Porewater Phosphorus in Shallow Sediments, and its Potential Transport into Narrow Lake, Alberta

During 1985 and 1986, summer and spatial patterns of porewater soluble reactive phosphorus (SRP) from sediments ≤ 15-m depth were examined at Narrow Lake, a deep, mesoeutrophic Albertan lake. At three sites (different in depth and macrophyte colonization), trends in porewater SRP concentrations ([SRP]) in the top 5 cm of the sediment from May to August varied, possibly due to root uptake of SRP by macrophytes. At a depth of 5 m, mean (in the top 5 cm of the sediment) and variance of porewater [SRP] at one site (&lt;0.15 m2) were the same as over the entire lake. Excluding data from macrophyte sites, porewater [SRP] were positively related to depth of the water column (P &lt; 0.0001). Molecular diffusion of SRP from sediments with and without macrophytes located in the trophogenic zone was calculated. During summer, molecular diffusion from shallow sediments to the trophogenic zone was 0.05 mg∙m−2 d−1, or 29% of atmospheric deposition of phosphorus (P) (the major external source of P to the lake). A sampling strategy is discussed to enable the calculation of whole-lake P transport from shallow sediments to the trophogenic zone in lakes with similar morphometry and trophic status to Narrow Lake.

Atmospheric deposition of phosphorus and nitrogen in Central Alberta with emphasis on Narrow Lake

Average rates of atmospheric deposition of total phosphorus (TP) and total nitrogen (TN) to Narrow Lake, located on sedimentary bedrock in the boreal forest of central Alberta, were 20 and 424 mg m−2 yr−1, respectively, between 1983–1986. There were no significant differences (P > 0.05) in deposition rates between sites on Narrow Lake, on the lake shore, and on land 18 km away. Deposition of TP, but not TN, followed a distinct pattern during the open-water season; TP was highest just after ice-off (May) and decreased throughout the remainder of the open-water season. Deposition during the winter accounted for only 4 and 12% of the annual TP and TN loads, respectively. Dry fallout contributed 50 and 33% of atmospheric deposition of TP and TN, respectively. In both dry and wet fallout, dissolved P (< 0.45 μm) and organic N were the predominant fractions of TP and TN, respectively. During July 1986, unusually heavy rainfalls caused an increase in TP, but not TN, concentrations in the epilimnion of Narrow Lake. Wet fallout accounted for only 9% of the observed increase of epilimnetic TP; the rest was from surface runoff from the drainage basin. The design of sampling programs to measure atmospheric deposition of nutrients to lakes is discussed.

Atmospheric Deposition of Phosphorus in a Coastal Fynbos Ecosystem of the South-Western Cape, South Africa

(1) Results are presented to the atmospheric deposition of phosphorus over a 1 year period in coastal fynbos vegetation on aeolian sandy soils of low phosphorus content. (2) Annual precipitation during 1980-8 1 was 381 mm. (3) Phosphorus input was estimated as 0. 19 kg ha-' year-'; it occurred mainly during the winter. (4) It is concluded that phosphorus input from bulk precipitation is an important contribution to the fynbos biome.