TP Retention Research Articles

Modeling the sources and retention of phosphorus nutrient in a coastal river system in China using SWAT

The Soil Water Assessment Tool (SWAT) was used for exploring the sources and retention dynamics of phosphorus nutrient in the river system of the Yong River Basin, China. The performance of the SWAT model was assessed. The retention dynamics of phosphorus nutrient in the river continuum and the factors contributing to those patterns were studied. The results showed that an average of 1828 tons of TP entered the river network of the Yong River Basin annually and in-stream processes trapped 1161 tons yr−1 of TP in the watercourse, which accounted for 63.5% of the annual TP inputs. The TP retention rates in the river network ranged from 3.08 to 63.43 mg m−2 day−1. An average of 666.9 tons of TP was delivered from the estuary to the East China Sea annually. The unit area riverine exports of TP ranged from 102.21 to 244.00 kg km−2 yr−1. The river network is a net sink for TP and is going through a phosphorus accumulation phase. The results confirm that the river system has a considerable phosphorus retention capacity that is highly variable on a spatiotemporal scale. Because of the cumulative effect of continued phosphorus removal along the entire flow path, the retention fractions of phosphorus removed from all streams at the basin scale is considerably higher than that of an individual river portion. The variations of hydrological regimes, water surface area, unit area inputs of phosphorus, and the concentrations of suspended sediments have a great influence on phosphorus retention.

Retention of nitrogen and phosphorus in Lake Chaohu, China: implications for eutrophication management.

Nutrient retention is an important process in lake nutrient cycling of lakes and can mitigate lake eutrophication. However, little is known about temporal lake nutrient retention efficiency and it varies due to changes in hydrological, ecological, and nutrient inputs to lake waters. Quantitative information about seasonal lake N and P retention is critical for developing strategies to reduce eutrophication in lake systems. This study investigated TN and TP retention efficiencies and retention masses using water and mass balance calculations, and statistically analyzed the seasonal variability of nutrient retention in Lake Chaohu, China, from 2014 to 2018. Lake Chaohu experienced large amounts of external loads inputs (23.2gNm-2year-1 and 1.3g P m-2year-1), and approximately 58% TN and 48% TP were retained annually. The lake acted more as a sink for N than for P. The mean annual TP retention efficiency decreased (P < 0.05) over the study period, indicating that TP retention capacity was gradually exceeded. Seasonal variability of TN and TP retention efficiency was high and ranged from - 18.7 to 144.1% and from - 58.8 to 170.7%, respectively, over the five study years. The internal P loads over the study period were equivalent to roughly 9% of the total external loads. The annual nutrient retention efficiency of TN and TP increased with hydraulic residence time, while water temperature was an essential factor for the contrasting seasonal variation patterns of TN and TP retention efficiencies.

Modeling the Effect of Enhanced Lateral Connectivity on Nutrient Retention Capacity in Large River Floodplains: How Much Connected Floodplain Do We Need?

Floodplains have been degraded in Central Europe for centuries, resulting in less dynamic and less diverse ecosystems than in the past. They provide essential ecosystem services like nutrient retention to improve overall water quality and thus fulfill naturally what EU legislation demands, but this service is impaired by reduced connectivity patterns. Along the second-longest river in Europe, the Danube, restoration measures have been carried out and are planned for the near future in the Austrian Danube Floodplain National Park in accordance with navigation purposes. We investigated nutrient retention capacity in seven currently differently connected side arms and the effects of proposed restoration measures using two complementary modeling approaches. We modelled nutrient retention capacity in two scenarios considering different hydrological conditions, as well as the consequences of planned restoration measures for side arm connectivity. With existing monitoring data on hydrology, nitrate and total phosphorus concentrations for three side arms, we applied a statistical model and compared these results to a semi-empirical retention model. The latter was originally developed for larger scales, based on transferable causalities of retention processes and set up for this floodplain with publicly available data. Both model outcomes are in a comparable range for NO3-N (77-198 kg ha-1 year-1) and TP (1.4- 5.7 kg ha-1 year-1) retention and agree in calculating higher retention in floodplains, where reconnection allows more frequent inundation events. However, the differences in the model results are significant for specific aspects especially during high flows, where the semi-empirical model complements the statistical model. On the other hand, the statistical model complements the semi-empirical model when taking into account nutrient retention at times of no connection between the remaining water bodies left in the floodplain. Overall, both models show clearly that nutrient retention in the Danube floodplains can be enhanced by restoring lateral hydrological reconnection and, for all planned measures, a positive effect on the overall water quality of the Danube River is expected. Still, a frequently hydrologically connected stretch of national park is insufficient to improve the water quality of the whole Upper Danube, and more functional floodplains are required.

Performance of a full scale constructed wetland as ecological practice for agricultural drainage water treatment in Northern Italy

Non-point sources of pollution, primarily agricultural drainage waters, can cause eutrophication and deterioration of water bodies. Surface flow constructed wetlands (SFCWs) are an ecological solution that can represent an efficient barrier and prevent agricultural pollutants from reaching other ecosystems. However, to better manage them and to understand removal processes occurring, it is important to study SFCWs that are functioning for longer periods of time and assess their efficiencies. This study concentrates on a full-scale SFCW in the Northern Italy that is used for agricultural drainage water treatment since the year 2000. An in-deep monitoring done for two years (2018 and 2019) showed that the system achieved satisfactory retention of up to 82% for TSS and up to 78% for TN and NO3--N. TP retention seemed to be poor (-27%), but further analysis showed that the SFCW performed well in this aspect as well, and that it is important to include precipitation loads in the overall balance. Soil content of nutrients and different trace elements did not show considerable differences in respect to the beginning of the monitoring period, and the uptake rates of TN and TP by above-ground vegetation were in the range 19.0-26.3 and 1.6-2.1 g m-2, respectively.

On the Role of a Large Shallow Lake (Lake St. Clair, USA‐Canada) in Modulating Phosphorus Loads to Lake Erie

AbstractIt is often assumed that large shallow water bodies are net sediment nondepositional annually and that if they have nutrient loads from multiple sources, those loads are quickly homogenized before exiting the water bodies. Where this is not the case, it impacts understanding and predicting consequences of nutrient load reductions, both for the water body and for those downstream of it. We applied a three‐dimensional ecological model to a large shallow lake, Lake St. Clair (US/Canada), to quantify the total and dissolved reactive phosphorus (TP and DRP) transport and retention, and construct tributary‐specific relationships between phosphorus load to the lake and the amount of phosphorus that leaves the lake for the three major tributaries. Lake St. Clair is situated between the St. Clair and Detroit rivers, the latter enters Lake Erie. Efforts to reduce Lake Erie's re‐eutrophication requires an understanding of nutrient transport and retention in each of its subwatersheds including those that feed indirectly via Lake St. Clair. We found that over the simulation period, the lake retained a significant portion of TP (17%) and DRP (35%) load and that TP and DRP retention was spatially variable and largely controlled by a combination of lake depth, resuspension, and plankton uptake. Compared to the Clinton and Sydenham rivers, the Thames River contributed a larger proportion of its load to the lake's outflow. However, because the lake's load is dominated by the St. Clair River, 40% reductions of nutrients from those subwatersheds will result in less than a 5% reduction in the load to Lake Erie.

Spatial and Temporal Distribution Characteristics and the Retention Effects of Nutrients in Xiangjiaba Reservoir

After the construction of the Xiangjiaba Dam, the hydrodynamic conditions, nutrient distributions, and transport conditions of the Jinsha River were changed. Here, the nutrient distribution characteristics and retention effects of Xiangjiaba Reservoir were investigated according to the results of water quality monitoring from 2015 to 2016. Spatial and temporal variations in TN, TP, SiO32-Si, and other nutrients, and retention flux and retention rate were analyzed. The results showed that the nutrient mass concentration of TN, TP, and SiO32--Si was 0.905 mg·L-1, 0.034 mg·L-1, and 7.98 mg·L-1, respectively. The distribution of TN was affected by point sources and the concentration of TN was large in urban areas. This distribution of TP was mainly granular and the mass concentrations decreased along the river path. The mass concentration of SiO32--Si did not significantly vary over time and space. Furthermore, Xiangjiaba Reservoir had a persistent effect on nutrient salts; the average annual retention of TN, TP, and SiO32--Si was 2.30×104 t·a-1, 0.146×104 t·a-1, and -2.4×104 t·a-1, respectively. During different seasons, the retention of TN and SiO32--Si varied between positive or negative; however, TP appeared to be consistent. The average monthly retention efficiency of TN, TP, and SiO32--Si was 17.5%, 32.8%, and -2.14%, respectively. Overall, retention efficiencies were higher during the dry season than that wet season, and phosphorus retention was most pronounced. The retention of TN in the reservoir may be related to denitrification and the input of external load; the flux of SiO32--Si was mainly affected by runoff; and the particle morphology of phosphorus, as well as reservoir period, were the main factors affecting TP retention. There were no clear correlations between nutrient retention and the mass concentrations of TN and SiO32--Si, but the nutrient retention effect of Xiangjiaba Reservoir reduced TP concentrations along the river path and increased TP concentration with vertical depth.

광주천 고수부지에 조성한 자유수면인공습지의 인 제거

하천수를 정화하는 자유수면인공습지의 정수식물 성장기(4~9월)와 비성장기(1~3월과 10~12월)의 <TEX>$PO_4-P$</TEX>와 TP제거율을 비교 연구하였다. 실험 습지 시스템은 광주광역시를 흐르는 광주천 중류 고수부지에 2008년 조성되었으며, 길이 46m, 폭 5m 규모이다. 2008년 포트에서 2년 자란 부들(Typha angustifloria L.)과 줄(Zizania latifolia Turcz)을 시스템의 1/2씩 각각 식재하였다. 광주천의 물이 자연유하로 시스템에 유입되며, 처리수는 광주천으로 방류된다. 유입수의 양과 수심은 밸브와 위어(weir)로 조절할 수 있다. 유입수 및 유출수의 인 농도를 2010년 1월부터 12월까지 7~10일 간격으로 조사 분석하였다. 하루에 약 <TEX>$710m^3$</TEX>의 하천수가 시스템으로 유입되어, 체류시간은 약 1.5hr이었다. 조사기간 유입수와 유출수의 <TEX>$PO_4-P$</TEX> 평균농도는 각각 0.144, 0.105mg/L이었으며, <TEX>$PO_4-P$</TEX> 평균제거율은 28.1%였다. 유입수와 유출수의 TP평균농도는 각각 0.144, 0.105mg/L이었으며, TP 평균제거율은 20.7%를 보였다. t 검정결과, 정수식물 성장기의 <TEX>$PO_4-P$</TEX> 제거율(31.448)이 비성장기 <TEX>$PO_4-P$</TEX> 제거율(25.829)보다 높았으며(p<0.001), 정수식물 성장기의 TP 제거율(27.230)도 비성장기의 TP 제거율(14.856)보다 높게(p<0.001) 나타났다. 인공습지에서 인 제거는 잔재물-토양 층의 흡착, 입자성 인과 Ca, Fe, Al과 결합된 인산염의 침전, 그리고 정수식물의 흡수가 중요하다. 정수식물 성장기가 비성장기보다 <TEX>$PO_4-P$</TEX>와 TP의 제거율이 상대적으로 높은 원인은 흡착과 침전에 의한 인 제거는 계절에 관계없이 일어나나, 정수식물의 흡수는 성수식물 성장기에만 일어나기 때문이다. Removal rates of <TEX>$PO_4-P$</TEX> and TP in a free water surface wetland system were investigated. The system was established in 2008 on a floodplain in the middle reach of the Gwangju Stream flowing through Gwangju City. Its dimensions were 46 meters in length and 5 meters in width. Two year old Typha angustifloria L. growing in pots were planted on half of the area and Zizania latifolia Turcz on the other half in 2008. Stream water was funneled into the wetlands by gravity flow, and its effluent was discharged back into the stream. The influent volume was controlled by valves and water depth was adjusted by wires. Volume and water quality of inflow and outflow were analyzed from January to December in 2010. Inflow into the system averaged approximately <TEX>$710m^3/day$</TEX> and hydraulic residence time was about 1.5 hours. Average influent and effluent <TEX>$PO_4-P$</TEX> concentration were 0.144 and 0.103mg/L, respectively, and <TEX>$PO_4-P$</TEX> abatement amounted to 28.6%. Influent and effluent TP concentration averaged 0.333 and 0.262mg/L, respectively, and TP retention reached to 20.7%.<TEX>$PO_4-P$</TEX> removal rate(%) during plant growing season(31.448) was significantly high(p<0.001) when compared with that during plant non-growing season(25.829). TP abatement rate(%) during plant growing season(27.230) was also significantly high(p<0.001) when compared with that of the non-growing season(14.856). Major phosphorous removals in the system resulted from adsorption of phosphorous in the litter-soil layers; sedimentation of particulate phosphorous and Ca, Al, Fe bounded phosphates; and absorption of phosphorous by emergent plants. The adsorption and sedimentation occurred throughout the year, however, the absorption took place during plant growing season. This resulted in higher removals of <TEX>$PO_4-P$</TEX> and TP during plant growing season.

Protein separation using toroidal columns by type-J synchronous counter-current chromatography towards preparative separation

Separation of large bioactive molecules such as proteins, DNAs and RNAs using aqueous two-phase systems (ATPSs) and liquid–liquid partition-based counter-current chromatography (CCC) can avoid risks of sample loss and denaturation, and greatly reduce processing time. We have constructed toroidal columns (length 26–140 m, column volume 51–280 ml, bore size 1.6 mm) suitable for mounting onto a commercially available preparative CCC apparatus. With the use of an ATPS containing 12.5% (w/w) PEG1000 and 12.5% (w/w) K 2HPO 4 and at a rotational speed of 800 rpm for the rotor of the CCC device, the lower phase (i.e. the phosphate-enriched phase) has been used as the mobile phase and a pair of proteins, myoglobin and lysozyme, as model proteins for demonstrating the separation capability of the CCC system. For a toroidal column with a length of 53.5m and a column volume of 107.5 ml, and operated for the Coriolis force parallel flow mode at 0.62 ml/min, protein sample loading (containing 2.2 mg/ml myoglobin and lysozyme, respectively) at 1.7% and 7.4% to the column volume led to peak resolution (with theoretical plate number TP and stationary phase retention S f shown in the parenthesis) of R s = 1.5 ( N = 211 and N = 113 TP for myoglobin and lysozyme, respectively, and S f = 45.0%), and R s = 1.4 (218 and 152 TP, and S f = 34.0%). However, further increase of the loading to 13% failed to separate the two proteins. Although proteins eluted at positions predictable from the distribution coefficients, they showed broader peaks when compared with small dipeptides under identical CCC operating conditions. This confirms that the molecular weight of the partitioned species is an important factor causing peak broadening on CCC chromatograms. These results paved the way for further scaling-up toroidal CCC columns for processing larger quantities of samples containing large biomolecules.

Performance of pilot-scale vertical flow constructed wetlands treating simulated municipal wastewater: effect of various design parameters

Abstract Ten pilot-scale, cylindrical, vertical flow constructed wetland units, of diameter 0.82 m and height 1.5 m, were designed, constructed, and operated treating a simulated municipal wastewater in parallel experiments. The operation scheme was 2 days feeding and 6 days resting. The 10 wetland units had various porous media materials (i.e., carbonate material, material from river bed, zeolite, and bauxite), two vegetation types (i.e., common reeds and cattails), and three total thicknesses of the porous media (i.e., 50, 80, and 90 cm). Water quality samples were collected at the inlet and the outlet of each unit, and were analyzed in the laboratory for BOD5, COD, TKN, ammonia nitrogen, nitrate, nitrite, TP, and ortho-phosphate. This article presents the results obtained after operation of these systems for one full year. Organic matter removal proved to be very good in all 10 units, since it reached on the average 71.1% and 66.9% for BOD5 and COD, respectively. Nitrogen removal was also satisfactory (47.1% for TKN and 42.2% for NH4+—N). TP and ortho-phosphate retention rates reached about 36.9% and 37.9%, respectively.

Nutrient retention function of a stream wetland complex—A high-frequency monitoring approach

The ability of riverine ecosystems to retain nutrients depends on different hydrological, chemical and biological conditions including exchange processes between streams and wetlands. We investigated nutrient retention in a stream wetland complex on the time scale of daily hydrological exchange between both systems. Daily mass balances of NO 3-N, NH 4-N, TP and SRP were calculated with data obtained by two automated measurement stations in a stream reach upstream and downstream of a wetland. The pattern of hydrological exchange between stream and wetland was used to classify characteristic hydrological periods like floods, base and low flows. The nutrient retention function of the stream wetland complex varied considerably during phases of similar hydrologic conditions. Despite re-wetting measures in the wetland, an overall net export of all nutrients except for NH 4-N characterised the whole growing season. Nitrate retention occurred during summer flood (retention in the wetland, 23 kg NO 3-N d −1, 17% of the input load) and low flow (retention in the stream, 1 kg NO 3-N d −1, 2% of the input load). TP retention during summer could be assigned to sedimentation (0.7 kg TP d −1, 7% during flooding in the wetland, 0.2 kg TP d −1, 4% during low flow in the stream). SRP retention was only intermittent. We concluded that the nutrient retention of streams and wetlands can only be optimised by restoration measures that regard both systems as one functional unit in terms of nutrient retention.

Graded levels of phytase past industry standards improves broiler performance

This study evaluated the overall performance of 0-to-16-d-old, mixed-sex, Cobb x Cobb broiler chicks when dietary phytase levels were supplemented in excess of industry standards. The experimental diet used consisted of a basal corn-soybean meal diet that contained an analyzed 22.2% CP, 0.88% Ca, a deficient total P (tP) level of 0.46% (phytate P = 0.272%), and calculated ME of 3.123 kcal/g diet on an as-is basis. In addition to a positive control diet [0.70% tP], the dietary phytase levels evaluated were 0, 93.75, 187.5, 350, 750, 1,500, 3,000, 6,000, and 12,000 U/kg of diet. Supplementing phytase from 0 to 12,000 U significantly increased body weight gain from 287 to 515 g/chick, feed intake from 381 to 595 g/chick, gain to feed from 0.755 to 0.866, plasma P from 2.5 to 7.1 mg/100 mL, tibia ash from 26 to 41%, tibia ash weight from 0.200 to 0.601 g/tibia, tP retention from 51 to 80%, phytate P disappearance from 40% to 95%, apparent N retention from 58 to 78%, AMEn from 3,216 to 3,415 kcal/kg diet, and reduced P rickets from 80 to 3%. Using nonlinear regression analysis on log-transformed phytase levels, gain to feed, apparent N retention, and AME, responded linearly with respective R2 values of 0.76, 0.82, and 0.72, whereas body weight gain, feed intake, plasma P, P rickets, tP retention, phytate P disappearance, tibia ash percentage, and tibia ash weight responded quadratically with respective R2 values of 0.93, 0.88, 0.85, 0.84, 0.91, 0.96, 0.96, and 0.98. Few statistical differences existed between response data for broilers consuming the positive control diet or diets containing 1,500 to 12,000 U of phytase (P > 0.05). This finding indicates that broilers consuming a tP-deficient corn-soybean meal diet can achieve maximum performance when phytase is supplemented to 12,000 U/kg diet and that current phytase supplementation levels within the poultry industry may need to be reevaluated.

Changes in the cycling of phosphorus in the Upper Kis‐Balaton Reservoir following external load reduction

1. The Upper Kis‐Balaton Reservoir was opened in 1985 to control eutrophication in Lake Balaton. High external TP load of the reservoir halved in 1991 due to improved sewage treatment. Annual TP retention efficiency of the reservoir dropped immediately from 50 to 20%, while the hypertrophic algal biomass started to decrease after 1995.2. We examine mass balances of the main forms of P in three consecutive areas (1, 2 and 3) of the reservoir. Biologically available P (BAP) includes soluble reactive P and algal P, whereas the rest of TP is considered to be non‐available (nBAP).3. Important pathways for P cycling varied in both space and time. A reduction in external load induced an enhanced net internal P load in the reservoir, and a variety of changes in the three areas. Thus, in the smallest Area 1, BAP retention dropped almost to zero, and the net sedimentation of nBAP decreased significantly. In Area 2 net BAP retention was characteristic before management, and net internal P load was observed afterwards. In Area 3 net internal P load has been substantial in some years ever since the reservoir was filled. The OECD model, corrected for internal P load, reasonably predicted the measured TP concentration in each area both before and after reduction in load.4. The external load‐algal biomass curve differed in the three areas. An immediate response occurred in the upstream Areas 1 and 2, while a delay of 4–5 years was observed in Area 3. Different long‐term sediment dynamics may underlay these load‐response relations in the three areas. Intense sediment redistribution, however, sets a serious constraint to the simple calculation of a mass balance. An evaluation of the long‐term sediment dynamics is needed in order to predict future performance of the reservoir.

Effects of Multiple Fires on Nutrient Yields from Streams Draining Boreal Forest and Fen Watersheds: Nitrogen and Phosphorus

Wildfire in the boreal forests at the Experimental Lakes Area in Ontario caused significant losses of nitrogen and phosphorus in streams. Both watershed type and fire intensity appear to determine the extent of losses. The Northeast wetland basin lost more N and P, especially TDN, TDP, TN, and TP, than did terrestrial basins, although nitrate losses were higher from terrestrial basins. Losses of nutrients after the second fire generally were not as high as after the first fire. In the East basin, which burned twice with a high fire intensity, stream concentrations of NO3−, TDN, and TN were elevated for 6 yr between the fires and remained elevated for 9 yr after the second fire In contrast, the Northwest basin burned with a lower intensity and had no significant increase in annual concentrations of P or most forms of N in the first 3 yr after the fire; only NCV concentrations increased during this period. Despite the increases in export after wildfire, net retention of TN and TP over the 18-yr period was high. In the Northeast, East, and Northwest basins, retention of TN averaged 77, 80, and 87% compared with TP retention of 51, 67, and 84%.