Variation In Phosphorus Concentrations Research Articles

Variation in Phosphorus Concentration and Flux at Zhutuo Section in the Yangtze River and Source Apportionment

Phosphorus (P) is a pollutant of great concern in the Yangtze River Basin. The Xiangjiaba Reservoir and Xiluodu Reservoir on the lower reach of the Jinsha River began to operate in 2012 and 2013, respectively, which greatly changed the concentrations of suspended sediment and characteristics of P form and transport in the reservoirs and the downstream reach from Yibin to Jiangjin of the Yangtze River. The Zhutuo section is representative in the water quality of the Yibin-Jiangjin reach, which can not only reflect the comprehensive effects of the formation of the two reservoirs and changes in the aquatic environment in the Min-Tuo Rivers but also reflect the quality of water flowing into the Three Gorges Reservoir. The runoff, concentrations and fluxes of suspended sediments (SS), and P concentrations and fluxes at Zhutuo section were studied during 2002-2019, and the source of P was apportioned based on the principle of river base flow. The results showed that in the past 18 years, the concentrations and fluxes of total phosphorus (TP) and particulate phosphorus (PP) at Zhutuo section in the wet season were higher than those in the level and dry seasons; the rule of positive correlation between PP and SS concentrations remained unchanged. From 2002 to 2019, the concentrations and fluxes of TP, PP, and dissolved P (DP) generally increased first and then decreased, and the operation of the Xiangjiaba Reservoir was a time node for the trend turning. Compared with that in the period from 2002-2012, the SS concentration and flux decreased by 94% and 77%, TP and PP concentrations decreased by 46% and 70%, and TP and PP fluxes decreased by 58% and 74%, respectively, during 2014-2019. The decline mainly occurred in the wet season, followed by that in the level season. After the formation of the two reservoirs, the relationship between water and sediment and the form of P greatly changed, and the proportion of DP in TP increased significantly, whereas the proportion of PP was the opposite. The TP pool in overlying water in the dry and level seasons shifted from mainly particulate to mainly dissolved. The change in water and sediment conditions was the main driving force for the significant change in P concentration, flux, and form. Before the operation of the Xiangjiaba Reservoir, the Jinsha River was the maximum contributor to the whole and diffuse source part of the TP load at Zhutuo section among the contributing catchment sub-basins; however, the Minjiang River became the largest contributor after the operation. The average TP load at Zhutuo section from 2017-2019 was 3.575×104 t·a-1 (after deducting the natural background value), of which the contribution of diffuse sources and point sources accounted for 68% and 32%, respectively. The Minjiang River represented 49%, 43%, and 62% of the total TP load, diffuse source TP load, and point source TP load at Zhutuo section, respectively. Considering the load contribution and pollution intensity, the key area for P pollution control in the area upstream of the Three Gorges Reservoir was the Min-Tuo River Basin.

Variation of phosphorus concentration and flux in Wujiang River entering the Yangtze River and source apportionment

Variation of phosphorus concentration and flux in Wujiang River entering the Yangtze River and source apportionment

Impact of Selected Environmental Factors on Variation in Leaf and Branch Traits on Endangered Karst Woody Plants of Southwest China

We explored the adaptability of endangered plants in degraded karst habitats through functional trait variation, using three endangered woody plants (E. cavaleriei, H. bodinieri and K. septentrionalis) in karst peak-cluster depression. We investigated the variation decomposition and correlation analysis of 13 branch and leaf functional traits using a mixed linear model, variance decomposition, Pearson’s correlation analysis, random forest regression, and generalized linear regression. The degree of variation in phosphorus concentration in the branches was the highest, while that in the carbon concentration in the leaves was the smallest. The variation in the carbon concentration in the branches and leaves, and the dry matter concentration in the leaves was mainly within species, while the variation in other functional traits was mainly between species. We found significant correlations among leaf traits, branch traits, and leaf–branch traits to different degrees; however, there were no significant correlations among branch traits in H. bodinieri. The significant correlations were higher in E. cavaleriei and K. septentrionalis than in H. bodinieri. Plant functional traits were influenced by soil and topographic factors, and the relationship between them varied by species. Our findings will enhance our understanding of the variation in leaf and branch traits in karst endangered plants and the adaptative strategies of endangered plants in degraded habitat, and will provide a scientific basis for vegetation conservation in the karst region of southwest China.

Spatiotemporal variations in phosphorus concentrations in the water and sediment of Jiaozhou Bay and sediment phosphorus release potential

Phosphorus contamination in urbanized bays has been a major concern because the bay restoration is often hindered by complex P sources and behaviors. This study examined the spatiotemporal changes of P species and exchange potential in/between the water and sediment of the Jiaozhou Bay. The results indicated that dissolved P (TDP) and inorganic P (DIP) in the water ranged from 7.8–128.7 and 1.8–14.1 μg/L, respectively; while total P (TP) in the sediment ranged from 213.4–638.7 mg/kg. The TDP and DIP concentrations in the water were high in winter and low in summer, and generally decreased from northeastern or northern areas to southwestern or southern areas mainly due to phytoplankton bloom cycles and riverine and wastewater inputs. TP in the sediment was lower in the northwestern area due to solid dilution effect by the settlement of settled coarser suspended particles. Changes in aquatic geochemical conditions from rivers to bay caused P accumulation in estuarine sediment, with higher P partition in organic fraction (40%). Compared to the estuarine sediment, higher fractions of P were associated with carbonate (34%) and iron oxide (17%) minerals in the bay sediment. Equilibrium P concentrations at zero sorption (EPC0) were 4.1–149.8 μg/L, which was substantially higher than the DIP concentration, demonstrating P release potential from the sediment. In addition, the P release potential was high in the northeastern area while P partition coefficient or buffer intensity (Kd) was high in the northwestern area. EPC0 was significantly positively correlated with soluble and exchangeable P in the sediment while Kd was significantly negatively correlated. These results can provide improved insights into P behaviors in an urbanized bay, particularly the P release potential and spatiotemporal change.

Adapting the dynamic LakeMab model to simulate seasonal variations of phosphorus concentration in reservoirs: a case study of Lake Bultière (France)

Controlling phosphorus is fundamental to limit the risk of eutrophication of continental aquatic ecosystems. Integrated modelling of its concentration in the aquatic continuum requires specific tools for water bodies. However, although simple static empirical models and complex biogeochemical models are numerous, there are few relatively simple and flexible models able to simulate seasonal variations in phosphorus concentrations in water bodies and particularly in reservoirs. In this study, the two-layer dynamic model, LakeMab, simulating phosphorus variations in water bodies, was enhanced to consider some tributary characteristics and reservoir specificities. It was then applied to the case of a reservoir in western France, Lake Bultiere. Without any calibration, the modified model reproduced reasonably well seasonal variations in phosphorus concentration in the lake. A sensitivity analysis showed the importance of improvements related to reservoir functioning (outlet depth, water level fluctuations) and the smaller importance of those related to tributaries (variable concentrations, depth of riverine inputs). The model can easily be applied to diverse lentic systems and could be coupled to stream models, thereby making it a useful tool for managing water quality in lakes and reservoirs.

Effects of winter weather and mixing regime on the restoration of a deep perialpine lake (Lake Lugano, Switzerland and Italy)

Long-term (1987–2015) monitoring data from Lake Lugano (Switzerland/Italy) were used to examine the effects of winter weather, solar radiation and mixing regime on the recovery of the trophic state of a lake undergoing nutrient management. Main hypotheses were that (H1) trends in trophic state were influenced not only by nutrient management, but also by winter weather and solar radiation, and (H2) the effects of management were more pronounced in the holomictic South basin than in the meromictic North basin of the lake. External loadings of phosphorus were strongly reduced during the study period, but key indicators of trophic state, including phosphorous concentration, primary production, chlorophyll a and deep-water oxygenation, showed inconsistent responses. Supporting H1, winter weather (parameterized using an index of the East Atlantic pattern) influenced temporal variation in phosphorus concentration and primary production in the North basin. Supporting H2, the effects of management on trophic state were clearer in the South basin, where most trophic-state indicators declined. Meromixis affected the restoration of the North basin lake by transmitting effects of climatic variation on trophic state. The added variability obscured the effects of restoration and caused sudden deteriorations in water quality, indicating that the restoration of meromictic lakes presents unique challenges.

Size dependence of phosphorus doping in silicon nanocrystals

Doping of silicon nanocrystals (Si-NCs) is one of the major challenges for silicon nanoscale devices. In this work, phosphorus (P) doping in Si-NCs which are embedded within an amorphous silicon matrix is realized together with the growth of Si-NCs by plasma-enhanced chemical vapor deposition under a tunable substrate direct current (DC) bias. The variation of phosphorus concentration with substrate bias can be explained by the competition of bonding processes of Si–Si and P–Si bonds. The formation of Si–Si and P–Si bonds is differently influenced by the ion bombardment controlled by the substrate bias, due to their bonding energy difference. We have studied the influences of grain size on P doping in Si-NCs. Free carrier concentration, which is provided by activated P atoms, decreases with decreasing grain size due to increasing formation energy and activation energy of P atoms incorporated in Si-NCs. Furthermore, we have studied the P locations inside Si-NCs and hydrogen passivation of P in the form of P–Si–H complexes using the first-principles method. Hydrogen passivation of P can also contribute to the reduced free carrier concentration in smaller Si-NCs. These results provide valuable understanding of P doping in Si-NCs.

Seasonal variation in phosphorus concentration–discharge hysteresis inferred from high-frequency in situ monitoring

High-resolution in situ total phosphorus (TP), total reactive phosphorus (TRP) and turbidity (TURB) time series are presented for a groundwater-dominated agricultural catchment. Meta-analysis of concentration–discharge (c–q) intra-storm signatures for 61 storm events revealed dominant hysteretic patterns with similar frequency of anti-clockwise and clockwise responses; different determinands (TP, TRP, TURB) behaved similarly. We found that the c–q loop direction is controlled by seasonally variable flow discharge and temperature whereas the magnitude is controlled by antecedent rainfall. Anti-clockwise storm events showed lower flow discharge and higher temperature compared to clockwise events. Hydrological controls were more important for clockwise events and TP and TURB responses, whereas in-stream biogeochemical controls were important for anti-clockwise storm events and TRP responses. Based on the best predictors of the direction of the hysteresis loops, we calibrated and validated a simple fuzzy logic inference model (FIS) to determine likely direction of the c–q responses. We show that seasonal and inter-storm succession in clockwise and anti-clockwise responses corroborates the transition in P transport from a chemostatic to an episodic regime. Our work delivers new insights for the evidence base on the complexity of phosphorus dynamics. We show the critical value of high-frequency in situ observations in advancing understanding of freshwater biogeochemical processes.

Available soil phosphorus, phosphorus buffering and soil cover determine most variation in phosphorus concentration in runoff from pastoral sites

Phosphorus (P) runoff from agricultural land contributes to elevated P concentrations in surface water. Although P concentrations in runoff are often higher when soil P is increased, attempts to quantify this relationship in field studies have been inconclusive, either because of confounding within experiments or methodological differences between experiments. The present study attempted to address these issues using simulated rainfall at 15 pastoral locations with varied lithology, land-use intensity, plant cover and soil-P properties in SE Australia, at a total of 38 on-farm sites, each with paired plots. At 27 sites, one of each pair was covered with 70 % shade-cloth to reduce rainfall energy. Although these were uncultivated pastoral sites and surface soil erosion rates were all relatively low, eroded surface soil had sufficiently high concentrations of P to make a major contribution to total P in runoff from some sites, even when plant-available soil P was low. We conclude that greater vegetative cover is required to manage P in runoff than to manage soil erosion. When soil was adequately protected against erosion by either high vegetative cover or shade-cloth, greater than 90 % of the variation in both dissolved reactive P and total P was explained by two commonly measured soil variables: soil-test P (bicarbonate extract) and P-buffering index (where P was in the range where plants may respond to fertiliser). It appears that available soil P can be raised with fertiliser to improve agronomic production without fear of significantly increasing P losses in runoff provided soil test P remains below the agronomic critical concentration defined by the soil P-buffering index. These findings have broad relevance for environmental risk assessment and management where the data required for more complex procedures are unavailable.

Characterization of water quality variation in the Mekong River at Vientiane by frequent observations

AbstractTo better understand the variation of water quality in the Mekong River, sampling and measurement were scheduled twice a week for about 3 years at Vientiane, followed by basic statistical analysis of the observed data. The frequent measurement revealed detailed characteristics of the water quality variation, which had not been detected by monthly observation in the previous studies. The variation in total ionic content was considered to be governed by dilution of the amount of water. Increases in turbidity could be attributed to physical effects including surface soil erosion and bed material resuspension at the time of discharge increase. Nitrogen concentrations were stably low during the low flow period and abruptly increased in May. After the annual maximum in late May, the nitrate concentration steadily decreased regardless of the remarkable rise in the discharge from mid‐July, whereas the ammonium concentration remained at a similar level until October. It was considered that the first small discernable runoff after the long dry season flushed the accumulated nitrogen in the surface soil and mobilized the nitrogen in the riverbed. The variation in phosphorus concentrations was different from that in nitrogen concentrations. During the high flow period, continual dilutions at discharge peaks and occasional large additions of phosphorus by surface runoff were suggested. Copyright © 2011 John Wiley & Sons, Ltd.

The distribution of phosphorus in sediment and water downstream from a sewage treatment works

In order to ensure the good ecological status of a range of waterbodies, as set out in the EU Water Framework Directive, a clearer understanding of nutrient sources and delivery mechanisms is required. Therefore, this study aimed to investigate the quantity and distribution of phosphates in Cam Brook, downstream from Paulton sewage treatment works (STW). Nine sites along a 2.6 km stretch of the river were surveyed; including one upstream of the STW, in October 2008 and the following February to determine whether there is seasonal variation in phosphorus concentrations. Water samples taken from each site were analysed for orthophosphate although sediment samples were analysed for orthophosphate and total phosphate. In February, water samples were further analysed for total phosphorus. Other variables such as dissolved oxygen (DO), water velocity, substrate, width, depth and land use were also surveyed to determine whether they influence the distribution of phosphorus. The water orthophosphate concentrations in Cam Brook significantly increased downstream from the STW in both October and February, rising from mean concentrations of 0.07-0.23 mg l −1 . This suggests that the STW was the major contributor to water orthophosphate concentrations. There was also strong negative correlation between water orthophosphate and DO concentrations in October (r-value −0.414) which could be due to the high biological oxygen demand of decomposers in the Autumn. There were large concentrations of total phosphate in the sediment which can be attributed to the small particle size of the substrate (clay) which increases its adsorption capacity. There were no seasonal variations in the water orthophosphate or sediment total phosphate concentrations although sediment orthophosphate concentrations were significantly higher in February (p-value < 0.001). However, orthophosphate still only accounted for a small proportion, at 3.47%, of the total phosphate concentrations in the sediment. The orthophosphate entering Cam Brook from the STW appears to be subject to a complex set of storage and transformation mechanisms which results in its storage as the non-bioavailable fraction of the total phosphate. Further research needs to be undertaken to determine the phosphorus cycling mechanisms that cause seasonal variation in sediment orthophosphate concentrations.

Resuspension‐Mediated Temporal Variation in Phosphorus Concentrations and Internal Loading

Sediment resuspension is an important factor for nutrient cycling in shallow lakes. Temporal variation in sediment resuspension and its influence on P concentrations and internal loading were studied in the shallow and eutrophic Kirkkojärvi basin. Gross sedimentation and sediment resuspension were estimated with sediment traps during three exposure periods in spring, midsummer, and autumn. The effects of resuspension on the concentrations of suspended solids, total phosphorus (TP), soluble reactive P, and chlorophyll a were followed. The level of sediment resuspension was greatest in midsummer (July-August 63.9 g dw m(-2) d(-1)), due to strong phytoplankton blooms modifying the surface film of the sediment more prone to resuspension. The dependence of high total P concentrations (226-385 microg L(-1)) on sediment resuspension and suspended solids was significant at the time. The concentrations of soluble reactive P were also high in midsummer (52-91 microg L(-1)), but had a negative dependence on suspended solids. This dependence was due to algal assimilation as was proved by a negative effect of chlorophyll a on soluble reactive P. Consequently, we suggest that the increase in the total P concentrations caused by sediment resuspension in midsummer was possibly intensified by strong algal blooms occurring at the time because strong assimilation resulting in high pH (pH 7.3 in May, 9.3-10.2 in July-August, 7.6 in October) may have increased the desorption of P from the suspended inorganic particles and intensified the P transfer into the phytoplankton biomass in midsummer.

Rhizosphere effect of different aquatic plants on phosphorus depletion

A series of pot experiments with Alternanthera philoxeroides, Typha latifolia, Sagittaria sagittifolia and Phragmites communis were conducted to assess the phosphorus depletion effect in the rhizosphere. The ratio of root to shoot, root morphology, phosphorus uptake efficiency and phosphorus utilization efficiency were analyzed. An obvious variation in phosphorus concentrations between the rhizosphere soil and non-rhizosphere soil was observed. The water-soluble P contents in the rhizosphere soil of A. philoxeroides, T. latifolia, S. sagittifolia and P. communis were reduced by 81%, 42%, 18% and 16%, respectively, compared with that in the non-rhizosphere soil. A. philoxeroides had the highest phosphorus uptake efficiency (1.32 mg/m), while T. latifolia achieved the effective phosphorus depletion by the strong rooting system and the high phosphorus uptake efficiency (0.52 mg/m). T. latifolia not only used phosphorus to produce biomass economically, but also adjusted carbon allocation to the roots to explore the soil for more available phosphorus. A. philoxeroides and T. latifolia were more effective in depleting phosphorus in the rhizosphere than S. sagittifolia and P. communis.

Eutrophication-driven sediment microbial processes can explain the regional variation in phosphorus concentrations between Baltic Sea sub-basins

Despite the ecological significance of microbial iron and sulphate reduction in aquatic environments, the processes involved have been poorly studied in Baltic Sea sediments. On the basis of indirect evidence, we conclude that the bottom sediments of the non-stratified and oligotrophic northernmost, and the poorly stratified and mesotrophic next northern, sub-basins of the Baltic have tolerated the external nutrient load rather well, as they are still in a state in which iron reduction and coupled cycling of iron and phosphorus prevail in the surface sediments. Since iron-reducing bacteria are unable to reduce ferric oxides completely, part of the iron-bound phosphorus may be permanently buried in the sediments. The good ability of the sediment to retain phosphorus results in low concentrations of phosphorus in water, a state that in turn promotes phosphorus limitation of primary production. In contrast, the sediments of the nutrient-loaded and stratified sub-basins, the Gulf of Finland (the most eutrophied sub-basin) and the Baltic Proper, appeared to have reached a state in which sulphate reduction is the dominant mineralisation pathway. Sulphate reduction followed by sulphide formation leads to efficient reduction of ferric oxides. Subsequently, iron-bound phosphorus dissolves into the pore water and is transported to the overlying water, whereas iron is buried as sulphides (uncoupled iron and phosphorus cycling). The capacity of sediments to retain phosphorus is limited; high amounts of bioavailable phosphate exist in the water column, primary production tends to be nitrogen limited and extensive blue-green algal blooms are common. We maintain that the decisive factors controlling the above regional distribution of iron and sulphate reduction are the flux of labile organic matter to the sediments and the variation in hydrodynamics. Sulphate reduction will be triggered when the flux of organic matter reaches a critical threshold value, resulting in anoxia at the sediment–water interface, followed by the collapse of benthic fauna and inhibition of iron re-oxidation. The only way to drive the sediments back into an iron-reduced state is to strongly reduce bioavailable nitrogen and phosphorus loading to the Baltic Sea, and thus the flux of labile organic matter to the sediments. Even so, recovery may also necessitate favourable hydrodynamic conditions.

Physiological Responses of Salvinia Minima to Different Phosphorus and Nitrogen Concentrations

This study was designed to evaluate the effectiveness of salvinia (Salvinia minima) in accumulating nitrogen and phosphorus under different imitating eutrophic environments. Nitrogen concentrations of 1.0 (control), 10.0, and 100 mg/l and phosphorus concentrations of 0.1 (control), 1.0, and 10.0 mg/l were used in this study. Plants were grown under laboratory conditions at 25 ± 2°C with a light intensity of 120 μmol/m2/s, and a 14 hr photoperiod. Salvinia's growth, expressed as frond production and plant fresh weight doubling time, was significantly increased with increasing nitrogen concentration from 1.0 mg/l to 100.0 mg/l in the growth media. The increase in growth rate was independent from the variation in phosphorus concentrations. However, the highest growth rate was obtained for days 1 through 7 when the levels of both nitrogen and phosphorus were elevated 100 fold (100 mg/l N and 10.0 mg/l P) from that of control treatments. This treatment also resulted in the highest photosynthetic rate, chlorophyll α and b content, carotenoids and anthocyanins concentrations. Nitrogen and phosphorus concentration did not influence soluble sugar (SS) accumulation. Starch and total-nonstructural carbohydrate (TNC) accumulation was significantly lower in treatments receiving elevated levels of nitrogen or phosphorus when compared to the control. The highest uptake of nitrogen and phosphorus into plant tissues resulted when both nutrients were elevated 100 fold (100 mg/l N and 10.0 mg/l P) and were higher at day 14.

Preparation and characterization of autocatalytic low phosphorus nickel coatings containing submicron silicon nitride particles

This paper addresses the structural characteristics and phase transformation behavior of plain electroless Ni–P and Ni–P–Si 3N 4 composite coatings. Composite coatings were prepared using a low phosphorus electroless nickel bath containing 1 and 5 g/L submicron silicon nitride particles at pH 6.5 and temperature 85 ± 2 °C. Deposition rate was around 6 μm/h for both plain and composite coatings. The amount of silicon nitride particles codeposited in the Ni–P matrix is 3.5 wt.% (N1) and 4.5 wt.% (N2) with the addition of 1 and 5 g/L particles in the bath. Deposit surface composition analysis carried out by energy-dispersive analysis of X-ray (EDX) results shows that plain Ni–P and Ni–P–Si 3N 4 deposits are having around 3.5 wt.% phosphorus. The X-ray diffraction (XRD) patterns of Ni–P–Si 3N 4 coatings are very similar to that of plain electroless Ni–P coating in as-deposited condition. Presence of a single high intensity peak at 44.8° 2 θ which corresponds to Ni(1 1 1) peak is present in both deposits. Presence of Ni(2 0 0) and (2 2 0) peaks is also observed in composite coatings apart from Ni(1 1 1) peak. The calculated grain size using Debye–Scherrer method for both deposits is between 11 and 14 nm. It shows that inclusion of silicon nitride particles has a marginal influence on the grain size of the composite coatings. Optical micrographs of deposit cross-sections reveal that particles incorporation is uniform throughout the thickness of the coating. Anodically etched metallographic cross-sections of both deposits revealed no banded/lamellar structure. It shows that the phosphorous content in the deposit is uniform. This was confirmed with the cross-sectional scanning electron microscope (SEM)–EDX carried out on the deposits. A marginal variation in phosphorus concentration is observed. Phase transformation behavior studied at different scanning rates by differential scanning calorimeter (DSC) indicates that there is a slight increase in crystallization temperature around 20 °C with the incorporation of silicon nitride particles compared to plain Ni–P coatings. Microhardness measurements made on the cross-section of as-deposited coatings showed that there is about 15% improvement in microhardness with the codeposition of silicon nitride particles in Ni–P matrix.

The Bacteria in the Sediment of the Sahela Reservoir (Morocco): Potential Impacts On Phosphorus Budget

Temporal variations of phosphorus concentrations, bacterial abundance and activity of fractionated (i.e: size fractions: 0.22 to 0.65 μm; 0.65 to 100 μm and 0.22 to 100 μm) alkaline phosphatase (APA) were studied in situ in a benthic chamber placed in a station near urban inputs in the Sahela reservoir (Morocco) on September and October 98. Results show that low oxygen concentrations induced enhanced concentrations of orthophosphates, and bacterial numbers and APA activity reached their highest values. Anoxic conditions and the decrease of pH favour the dissolution of particulate phosphorus and the release of soluble reactive phosphorus. This release is accompanied simultaneously by an increase in the abundance of anaerobic bacteria and a progressive reduction in APA. Lastly, the release of phosphorus together with urban inputs from the city of Taounate should be considered as potential inducers of the eutrophication of the reservoir.

A winter rainfall simulation study of sediment and phosphorus loss in arable land in Denmark

Geografisk Tidsskrift, Danish Journal of Geography 106(1):57–69, 2006 Most of the Danish freshwater environments do not live up to the high ecological standards set by the European Water Framework Directive. This is mainly due to high phosphorus loadings originating from agricultural areas. Phosphorus pollution caused by soil erosion is generally considered to be insignificant in Denmark, even though soils are rich in phosphorus. There have only been a few erosion monitoring programs conducted in Denmark resulting in little specific data. This paper presents the results of a rainfall simulation study with a low rainfall intensity of 10 mm h−1 conducted in winter conditions in the Haraldsted catchment on Zealand. The test nozzle (Hardi 37E) proved suitable for generating kinetic energy to represent yearly recurring rainstorm events in eastern Denmark. A correlation of sediment and phosphorus loss (total phosphorus (TP), dissolved phosphorus (DP) and dissolved reactive phosphorus (DRP)) compared to different physical soil parameters showed a dependency of soil loss when compared to runoff while total phosphorus could be correlated with both the soil loss and total runoff. Carbon and initial soil conditions were important parameters in determining runoff and soil loss. The average concentration of particulate phosphorus when compared to the total P in runoff was 95.8%. To calculate the percent of DRP of TP in runoff, a multivariate linear regression model was determined. The average phosphorus enrichment ratio was found to be 2.25 but the variation of phosphorus concentration in the eroded sediment was high. In 91% of all the runoff samples, the critical load of DRP was exceeded which may indicate that eroded sediment may pose a potential risk of eutrophication of Danish water bodies.

Pyrometamorphic formation of phosphorus-rich olivines in partially molten metapelitic gneisses from a prehistoric sacrificial burning site (Otz Valley, Tyrol, Austria)

Phosphorus-rich olivine with up to 8.8 wt.% P 2 O 5 was observed in partially molten biotite-plagioclase gneisses recovered from a presumably La-Tene (450 - 15 B.C.) age sacrificial place in the Otz Valley, Northen Tyrol, Austria, where immolation of ritual offerings took place. The formation of this unusually P-rich olivine is thought to be due to incongruent melting of biotite through a reaction such as biotite + quartz = olivine + Ti-magnetite + K-rich melt. During partial melting, foamy patches of dark glassy material formed at the surface of the rocks and also as layers within the rocks. Phosphorus was supplied as apatite from animal bones which also led to the formation of whitlockite in the foamy, glassy surface layer. In this layer, microdomains with the assemblages olivine + plagioclase + whitlockite + glass and clinopyroxene + plagioclase + whitlockite + glass were found. Away from the contact area in the residual rock, the assemblage olivine + Ti-bearing magnetite + clinopyroxene + plagioclase + glass occurs. Phosphorus-rich olivine associated with whitlockite shows a wide range in composition with 0 - 8.8 wt.% P 2 O 5 and X Mg ranging from 0.48 to 0.74. The heterogeneity in olivine compositions is thought to be due to disequilibrium and/or local variations in phosphorus concentration. The systematics of Mg, Fe, Si, and P concentrations in olivine indicates that phosphorus is incorporated into olivine via the coupled substitution 2P + (□)M 1,2 ↔ 2Si + (Mg, Fe)M 1,2 and that phosphorus contamination through whitlockite or glass inclusions can be excluded. A slight negative correlation between the Fe contents and the P contents was also observed. The high chemical variability of the newly formed phases (melt and crystals), dendritic textures and the coexistence of forsterite-rich olivine with a SiO 2 -rich melt (>62 wt.% SiO 2 ) strongly indicate rapid, non-equilibrium growth of the phosphorus-rich olivines in agreement with previous natural observations from meteorites and terrestrial occurrences. These data show that mineralogical constraints such as phosphorus-rich olivine and whitlockite can provide evidence for the burning of bone material and thus be very helpful in the identification of prehistoric burning sites in cases where clear archeological evidence is lacking.

Variation in Phosphorus Concentration of Soil Solution and Ponding Water in Nontillage Direct Sowing Culture of Paddy Rice

Variation in Phosphorus Concentration of Soil Solution and Ponding Water in Nontillage Direct Sowing Culture of Paddy Rice