Total Phosphorus Accumulation Research Articles

Phosphorus accumulation during the ice-on season in macrophyte-dominated eutrophic lakes and its implications

Macrophyte overgrowth in eutrophic lakes can hasten the decline of shallow water bodies, yet the impact of macrophyte deposition on sediment phosphorus (P) accumulation in the ice-on season remains unclear. Comparative analyses of P variations among 13 semi-connected sub-lakes in Wuliangsu Lake in China, a typical MDE lake, considered external flow and macrophyte decomposition as driving forces. Sediment P fractions and water total phosphorus (TP) were analyzed at 35 sampling points across three ice-on season stages, along with macrophyte TP content to assess debris contributions.Our findings reveal that phosphorus accumulation occurs during the ice-on season in the MDE lake, with an average TP content increase of 16 mg/kg. However, we observed a surprisingly small sediment nutrient accumulation ratio (ΔTP/ΔTN=0.006) compared to macrophyte nutrient levels before decomposition. Further analysis of the dominant species, Potamogeton pectinatus, indicates that a significant portion (55%) of macrophyte phosphorus is released before the ice-on season. This highlights the critical importance of timing macrophyte harvesting to precede the phosphorus leaching process, which has implications for lake management and ecosystem restoration efforts.Additionally, our research demonstrates similar transformations among different sediment fractions as previously reported. Macrophyte debris decomposition likely serves as the primary source of Residual P (Res-P) or TP accumulation. In addition, Ca-bound P (Ca–P) generally showed a decrease, which mainly caused by its transformation to Fe/Al-bound P (Fe/Al–P), Exchange-P (Ex-P), and sometimes to Res-P. However, we emphasize the significant impacts of flow dynamics on Ca–P transport and transformations. Its hydrodynamic action increases water dissolved oxygen, which accelerates the transformation of Ca–P to more easily released Fe/Al–P and Ex-P. Furthermore, hydrodynamic transport also leads to upstream Ca–P transport to downstream. This underscores the necessity of considering flow dynamics when estimating phosphorus variations and formulating phosphorus restoration strategies.

Performance of pilot-scale gravel and sponge bed hydroponic systems vegetated with Duranta erecta treating wastewater in a developing country, Ethiopia, Africa

This study aimed to assess the performance of hydroponics vegetated with Duranta erecta in removing nutrients from domestic wastewater in a pilot-scale study. Domestic wastewater was fed to four lines of hydroponic-constructed filter systems (HCFS). The lines 1 and 3 were filled with gravel, but the lines 2 and 4 were filled with polyester sponges. The experimental biofilters (lines 1 and 2) were planted with Duranta erecta, and the control biofilters (lines 3 and 4) were unplanted. This experiment was operated at hydraulic retention times (HRT) of 1, 3, 5, and 7 days which were conducted sequentially. Results indicated that the planted biofilters in gravel media removed nutrients better than the other planted biofilters in sponge media. Better removal efficiencies of 55 and 47% for total nitrogen (TN) and of 32 and 26% for total phosphorus (TP) removal by planted and control lines, respectively, were obtained at 7 days HRT. At the end of the experiment, TN and TP accumulation in the plant biomass sample increased from 132 to 216 g TN/Kg of dry weight, and from 53to 86 g TP/Kg of dry weight, respectively at 7 days HRT. Hence, it can be concluded that nature-based hydroponic filters planted with Duranta erecta might have a promising potential, mainly with gravel media. HCFS represents a very welcome technology to treat domestic wastewater at a decentralized level in developing countries, including Ethiopia.

Accumulation and Origin of Phosphorus and Heavy Metals in Citrus Orchard Soils in Jeju Island, South Korea: Potential Ecological Risks and Bioavailability

This study investigated the accumulation of total phosphorus (TP) and heavy metals (HMs; Pb, Zn, Cu, Cd, Cr, and Ni) in citrus orchard soils in Jeju Island, Korea, identifying potential soil pollution sources using statistical analysis. Anthropogenic HM pollution was evaluated using the geoaccumulation index and enrichment factors, whereas HM bioavailability was assessed via single extraction. TP, Zn, Cu, and Cr concentrations in citrus orchard topsoil were significantly higher than those in forestland soils, indicating their accumulation in the surface layer. Statistical analyses confirmed that elements with high concentrations were closely related to potential pollution sources accumulated on the surface layer of citrus orchards owing to agricultural activities. Particularly, Zn and Cu accumulation was confirmed to originate from intensive compost and pesticide use in citrus orchards. Cu showed the highest contamination and enrichment of all HMs. However, Zn and Cu fractions, determined via an availability assessment, were dominated by acid or complex compounds, indicating that labile Zn and Cu have potential bioavailability for plants. Nevertheless, their fractions accounted for a small proportion (mean < 15%). Therefore, despite the high pollution levels of Zn and Cu, their availabilities were extremely low, indicating a negligible bioavailability in crops and no impact on aquatic ecosystems.

Exploration of the factors that influence total phosphorus in surface water and an evaluation of surface water vulnerability based on an advanced algorithm and traditional index method

Due to the continuous influence of human activities, phosphorus pollution in surface water has become a persistent problem that needs to be addressed since phosphorous entails certain risks and degrees of damage to ecosystems and humans. The presence and accumulation of total phosphorus (TP) concentrations in surface waters is the result of a combined effect of many natural and anthropogenic factors, and it is often difficult to intuitively identify the individual importance of each factor in regard to the pollution of the aquatic environment. Considering these issues, this study provides a new methodology to better understand the vulnerability of surface water to TP pollution and the factors that influence TP pollution through the application of two modeling approaches. This includes the boosted regression tree (BRT), an advanced machine learning method, and the traditional comprehensive index method (CIM). Different factors, such as natural variables (including slope, soil texture, normalized difference vegetation index (NDVI), precipitation, and drainage density) and point and nonpoint source anthropogenic factors were included to model the vulnerability of surface water to TP pollution. Two methods were used to produce a vulnerability map of surface water to TP pollution. Pearson correlation analysis was used to validate the two vulnerability assessment methods. The results showed that BRT was more strongly correlated than CIM. In addition, the importance ranking results showed that slope, precipitation, NDVI, decentralized livestock farming and soil texture had a greater influence on TP pollution. Industrial activities, scale livestock farming and population density, which are all contributing sources of pollution, were all relatively less important. The introduced methodology can be used to quickly identify the area most vulnerable to TP pollution and to develop problem specific adaptive policies and measures to reduce the damage from TP pollution.

Effect of Watering Number and Inorganic Fertilizers on Accumulation of Total Phosphorus in Above Ground Biomass of Avena in Gray-Brown Soils of Azerbaijan

An assessment of the effect of mineral fertilizers on the accumulation of total phosphorus in the above-ground mass of oat plants on irrigated gray-brown soils of Azerbaijan was carried out. The studies were carried out in 2021. As a result of the work, it was found that, depending on the number of irrigations and the norms of mineral fertilizers on irrigated gray-brown soils of the western region, the yield of the aerial part varied. Various fertilization methods and rates tested. High total phosphorus was observed with double vegetative irrigation with N90P90K60 and triple irrigation with N120P120K90.

Green Manure Amendment Increases Soil Phosphorus Bioavailability and Peanut Absorption of Phosphorus in Red Soil of South China

Peanut (Arachis hypogaea L.) is one of the most important crops produced worldwide. Peanut is the dominant crop in the typical upland red soil areas of China; however, phosphorus bioavailability in red soil is very low, which severely affects peanut production. To improve the phosphorus bioavailability, which substantially promotes the green development of peanut production, a peanut–green manure rotation field experiment was conducted with six treatments (milkvetch; radish; brassica rape; mustard rape; winter fallow and no-tillage), commencing in September 2017 in the red soil area of Jiangxi province, China. The results show that compared with no-tillage (NT) treatments, different green manure returning treatments had significant effects on soil pH, soil phosphorus components and available potassium content. The particulate phosphorus and soil available phosphorus contents in the green manure treatments were significantly higher than those in the winter fallow (WF) treatment. Compared with the WF treatment, the content of particulate phosphorous in brassica rape (BR), radish (R) and milkvetch (MV) treatments was significantly increased by 6.55%, 3.66% and 2.50%, respectively; the available phosphorus content in mustard rape (MR), BR, R and MV was significantly increased by 20.93%, 25.60%, 23.76% and 18.10%, respectively. In addition, the total phosphorus content of peanut shell in the MV and R treatment was significantly higher than that in the WF treatment, increasing by 33.47% and 60.66%, respectively. Compared with the WF treatment, the peanut biomass of MR, BR and R treatments increased significantly by 19.51%, 29.83% and 19.77%, respectively. The total phosphorus accumulation in all green manure treatments was higher than that in the WF treatment, and the MV treatment reached a significant level at 18.83%. Based on these results, the particulate phosphorus (PP) and available phosphorus were significantly affected by different green manure treatments; green manure amendment improves peanut phosphorus uptake. The use of green manure (especially milkvetch and brassica rape) can be recommended to improve phosphorus bioavailability and yield of peanut in red soil areas.

Amplified cyanobacterial bloom is derived by polyphosphate accumulation triggered by ultraviolet light

Cyanobacterial blooms appear more strongly, constantly and globally, yet the positive effect of surface solar ultraviolet radiation (UV) on cyanobacterial bloom in natural freshwater habitats is largely ignored. Here in-situ and laboratory studies were jointly designed to probe the mechanism of cyanobacterial bloom promoted by solar UV light. The results showed that solar UV light is a key trigger factor for the accumulation of total phosphorus, dissolved inorganic phosphorus and polyphosphate (polyP) in blooming cyanobacterial cells. The increase of UV dose induces polyP accumulation to result in the excessive phosphorus uptake of blooming cyanobacteria, which provides sufficient phosphorus for cyanobacterial growth in suitable environment. Solar UV light also can promote the contents of phycocyanin, allophycocyanin, and phycoerythrin, producing sufficient ATP by photosynthesis for polyP synthesis in cyanobacterial cells in lake enviroment. The frequent variations of UV irradiance exposure prompts cyanobacteria to absorb excessive phosphorus from suspended solid or sediment. Cyanobacterial intracellular phosphorus is accumulated for their growth. UV light promotes polyP accumulation in blooming cyanobacterial cells to avoid damage. The adsorption amount of phosphorus increases for exuberant growth and then more surface blooming cyanobacteria are exposed to UV light to absorb ample phosphorus. Thus, the positive feedback occurs in lake water bodies with abundant phosphorus. This amplified cycle of cyanobacterial density and phosphorus due to solar UV light in eutrophic water bodies is analogous to a triode to amplify visible photosynthesis by UV light as a base electric current in the energy flow process in lake environment, therefore, “Cyanobacterial Phosphorus Assimilation Ultraviolet Effect” is used to describe this phenomenon. A new explanation is provided for the continuing proliferating mechanism of cyanobacterial bloom. Besides, a new perspective appears on the outbreak of cyanobacterial blooms in natural eutrophic lake water bodies worldwide.

Distribution and accumulation characteristics of nitrogen and phosphorus of 16 species of plants on ecological floating-bed

The distribution and accumulation characteristics of total nitrogen (TN) and total phosphorus (TP) in the aerial and underground parts of 16 species of plants on ecological floating-bed were studied, and showed significant differences. The TN contents in the aerial part and underground part were 1.09%-2.91% and 0.68%-2.22%, respectively. The TN contents in the aerial and underground parts of Dracaena sanderiana were both the highest among the 16 species of plants. The TP content in the aerial part ranged from 0.15% to 0.45%, and in the underground part ranged from 0.12% to 0.76%, respectively. The TP contents in the aerial part of Dieffenbachia picta was the highest, while in the underground part of Anthurium andraeanum was the highest. Translocation factors of 14 species of plants for TN were greater than 1, and 12 species of plants for TP were greater than 1, respectively. Arundo donax var. versicolor which had considerable absolute accumulation of TN and TP both in the aerial and underground parts, can effectively remove nitrogen and phosphorus from water, will be a promising potential plant in applying of ecological floating-bed technology.

The Content of Phosphorus in the Needles of Pinus sylvestris L. Affected by Industrial Air Pollution

A facility for disposal of toxic substances had been functioning in Kirov Oblast between 2006 and 2015. Destruction of phosphorus-containing substances resulted in formation of inorganic phosphorus compounds, which could enter the environment as components of gaseous emissions. The aim of the present work was to study the spatial patterns of accumulation of phosphorus compounds in the needles of Pinus sylvestris L. in the production area. The study was carried out at monitoring sites, which were represented by forest communities (southern taiga subzone) located at different distances from the pollution source (0.96–9.63 km). The total phosphorus in second-year pine needles was determined by the spectrophotometric method. During the research period (2011–2017), total phosphorus in the needles of P. sylvestris varied between 730 and 2229 μg/g. Based on results of cluster analysis, the sites were classified into two groups, which differed in levels of phosphorus accumulation in the needles of Р. sylvestris. The first group included sites with increased accumulation of total phosphorus in pine needles, which were located near the source of pollution in the direction of the prevailing winds. In sites belonging to the second group, the needles contained reduced amounts of phosphorus compounds. During the research period, variations in the amount of phosphorus in pine needles followed a similar pattern. From 2011 to 2016, the accumulation of phosphorus in the needles increased at monitoring sites of both groups. A decrease in total phosphorus in needles in 2017 was caused by a decrease in the release of phosphorus compounds to the environment and the involvement of accumulated phosphorus in the life processes of P. sylvestris. The increased accumulation of phosphorus compounds in needles in the sites near the source of air pollution was not favorable for vital processes of P. sylvestris needles and resulted in a reduction in their lifespan. Thus, the needles of P. sylvestris can be used as an accumulative indicator in areas affected by industrial air pollution by phosphorus compounds

In situ purification experiment of a mangrove–aquaculture coupling system: A case study of a crab pond in Wanning, Hainan Province

AbstractAquaculture development and expansion can destroy and reduce tropical mangrove systems, while discharging sewage into the ocean. This study introduced a new mangrove system into an aquaculture pond to establish a mangrove–aquaculture coupling system. This study aims to reduce pond water eutrophication and decrease nutrient discharge into the ocean without affecting aquaculture. Results show that mangrove planting does not affect Scylla serrata growth (mud crabs), but does stabilize pond environments. While mangrove‐planting inhibits nitrogen and reactive P (PO43−) accumulation in ponds, it is a poor inhibitor of total phosphorus accumulation. The average nitrite (NO2−), reactive P (PO43−), and total nitrogen (TN) contents decreased by 80.46, 35.47, and 31.01%, respectively. This mangrove–aquaculture coupling system provides a method to balance economic development needs with the ecological needs of mangrove wetlands. This study offers suggestions for establishing this system and its associated waste aquaculture pond transformation.

Natural wetlands contribution on phosphorus removal in small northern communities in Canada

ABSTRACT This study focuses on understanding the role of passive wastewater treatment (wastewater lagoon plus wetland) in reducing the phosphorus discharge levels in a northern small community in Manitoba, Canada. The facultative lagoon system of that small community treats domestic wastewater and seasonally discharges effluent into a wetland that connects to Lake Manitoba. This research assesses phosphorus removal efficiency through the natural wetland during the vegetation growing season. The average total phosphorus (TP) concentration reduction for the observed treatment area of 1.3 ha was more than 70%, achieving the desired TP discharge concentration below 1 mg/L. Data analysis showed that the main accumulation of TP occurred at the 21–40 cm soil depth, which indicates the potential of natural wetland treatment applications under cold continental climate conditions as an effluent polishing step to satisfy regulatory requirements for phosphorus reduction.

Effects of nitrogen deep placement coupled with straw incorporation on grain quality and root traits from paddy fields

AbstractThe present study was conducted to investigate the effects of deep application of nitrogen (N) fertilizer and straw incorporation on grain yield and quality, nutrient accumulation, and root morphological and physiological traits in both rice (Oryza sativa L.) cultivars during 2019 and 2020. The experimental treatments were comprised of deep N fertilization with (DF+S) and without straw incorporation (DF) as well as broadcasting fertilization with (BF+S) and without straw return (BF). No fertilizer and no straw return treatment were taken as control. Results depicted that the DF+S and DF treatment significantly increased the grain yield by 46.4 and 42.2%, respectively, compared with BF. The DF+S also significantly increased total N accumulation by 37.9 and 44.0%, total phosphorus accumulation by 39.3 and 41.7%, total potassium accumulation by 63.6 and 73.3% for the cultivars Yuxiangyouzahn (YXYZ) and Wufengyou615 at maturity, respectively, compared with BF. Moreover, nutrient accumulation and grain yield of BF+S were slightly higher than BF. Straw incorporation resulted in better total root volume and total root length than no straw incorporation treatments in YXYZ, regardless of fertilizer application method. Root morphology traits are positively associated with other positive traits such as yield or nutrient uptake. The DF+S treatment also significantly increased the milled rice rate and remarkably reduced the chalkiness degree for both rice cultivars, compared to BF treatment. Overall, DF+S is recognized as the optimal method to improve rice productivity and quality with better nutrient acquisition.

Nitrogen and Phosphorus Accumulation in Horizontal Subsurface Flow Constructed Wetland

The article presents the results of studies aimed at determining the level of accumulation of total nitrogen and total phosphorus in parts of reeds (Phragmites australis (Cav.) Trin. ex Steud.), as well as in a constructed wetland bed. The influence of the vegetative phase and dormancy of plants on the level of accumulation of biogenes in plant parts and in the bed of constructed wetland was investigated. Young plants at the stage of intensive growth were found to contain the most total nitrogen and total phosphorus. The leaves of the common reed, on the other hand, revealed the highest ability for the phytoaccumulation of nitrogen (32.21 gN/kg d.m.). Accumulation of total phosphorus in the leaves of reeds was, on average 1.54 gP/kg d.m. The results of studies on the filtration material filling the beds showed that the surface layer of up to 20 cm in depth was characterized by the highest total nitrogen content and total phosphorus content (average: 12.53 gN/kg d.m. and 3.01 gP/kg d.m.). The accumulation of these compounds decreased along with the depth of the deposit as well as in the direction of the outflow of sewage from the constructed wetland.

Field Scale Demonstration of Fly Ash Amended Bioretention Cells for Stormwater Phosphorus Removal: A Review of 12 Years of Work

In 2007, ten bioretention cells were constructed in Oklahoma as part of a full-scale technology project to demonstrate stormwater phosphorus reduction. The filter media used was amended with 5%, Class C fly ash by weight to increase phosphorus and heavy metal retention. In 2014, core samples were collected from four of the cells, and three were instrumented for continuous water monitoring for the following year. This paper will review the design, construction, computer modeling of phosphorus retention, and measured phosphorus removal after seven years of operation. Total phosphorus retained in the sampled cells showed reductions in effluent water concentrations of 68 to 75%, while total effluent mass reductions of 51 to 93% were achieved. Total phosphorus accumulation in the cells measured in cores ranged from 0.33 to 0.60 kg/year, which was somewhat greater than the annual calculated effluent reduction of 0.27 to 0.41 kg/year. While good, phosphorus retention was not as high as computer modeling predicted. Other research on the cells, including hydraulics, heavy metal adsorption, and microbial transport, is summarized. Experimental challenges with phosphorus extraction from samples are also discussed. All experience and results suggest that fly ash amendments are an effective option for phosphorus removal in bioretention cells.

Genotypic variation of bambara groundnut (Vigna subterranea L.Verdc) for phosphorus efficiency

ABSTRACT Low phosphorus (P) in agricultural ecosystems limits growth of bambara. Field trials were carried out at 2 P levels (0 and 35 kg/ha) to determine the variation of 12 bambara genotypes in phosphorus efficiency, identify P-efficient and responsive genotypes for cultivation in sub-optimal P environments. Genotypes differed significantly (P ≤ .05) in plant biomass, grain and biological yields due to P levels and seasonal effects. BAM002, BAM010 and BAM011 recorded high grain yields in both seasons. Phosphorus accumulation (PA) in biomass, grain and biological yields was influenced by genotype, P levels and genotype * P levels interaction. High yielding P-efficient and responsive genotypes including BAM002, BAM010 and BAM011 also had high values of phosphorus physiological efficiency index and phosphorus harvest index at low P indicating that they are P-efficient. Genotypes were classified into four and three groups based on the relationship between total PA and grain yield at low and adequate P, respectively. Moreover, genotypes were categorised into in-efficient, medium and efficient based on total index score. Principal component analysis grouped together the genotypes BAM002, BAM010 and BAM011 at both P levels. These genotypes are adapted to P-deficient soils and utilise acquired P efficiently for optimum grain production.

Spatial variation of soil properties impacted by aquaculture effluent in a small-scale mangrove

Small-scale mangroves serve ecological functions similar to large-scale mangroves regarding biological conservation, environmental purification, and supporting biogeochemical processes. The rising aquaculture neighboring mangroves results in their serving as an important sink for massive nutrients and pollutants from aquaculture effluent. We assessed how long-term aquaculture effluent discharge influenced the soil properties of a mangrove-tidal flat continuum using field survey and geostatistics. Common soil physical-chemical properties presented significant spatial variability. Continued aquaculture effluent discharge caused a significant cumulation of soil total organic carbon (SOC) (64.13 g·kg−1), total nitrogen (TN) (2.44 g·kg−1) and total phosphorus (TP) (1.12 g·kg−1) in the mangrove soil, which were as 2–3 times as those on the mudflat. Most of the soil properties changed significantly with increasing distance from the effluent outlet along a tidal channel, and the maximum concentrations of SOC, TN and TP all occurred at 50 m away from the outlet. The results of principal component analysis indicated that aquaculture effluent significantly affected the spatial pattern of soil properties along the mangrove-tidal flat continuum. Continued aquaculture effluent input rendered extensive accumulation of SOC, TN and TP in the mangroves. The spatial heterogeneity of mangrove is the key driver to process the nutrient input spatially differently.

Accumulation of Cu, Cd, Pb, Zn and total P from synthetic stormwater in 30 bioretention plants.

The uptake and distribution of four heavy metals, including copper (Cu), cadmium (Cd), lead (Pb) and zinc (Zn), and those of total phosphorus (TP) in 30 plants in North China were investigated through pot trial experiments. Accumulation and distribution of heavy metals or TP were associated with plant species, tissues, metal elements and pollutant loading. The highest amount of heavy metal and TP accumulation was found in the whole plants of Hylotelephium erythrostictum (Miq.) H. Ohba (C1) and Chlorophytum laxum R. Br. (L4), respectively. Considering the biological concentration factor, translocation factor, retention factor and biomass indices, C1 is the suitable plant for Cd and Cu uptake, whereas Hosta plantaginea (Lam.) Aschers (L3) and Viola verecunda A. Gray (V1) are the suitable plants for Pb removal. Rehmannia glutinosa (Gaetn.) Libosch. ex Fisch. (S1) and L4 can be chosen for Zn and TP removal, respectively. Cluster analysis was applied to select suitable plants for heavy metal and TP removal. Results showed that C1, L4 and Pennisetum alopecuroides (L.) Spreng (G1) have a good capability of accumulating heavy metals and TP. Results demonstrated that the plant species rather than the families considerably influenced the accumulation of pollutants.

The effect of Phragmites australis and Eichhornia crassipes in the removal of high total phosphorus concentrations from water

In order to evaluate the accumulation of high phosphorus and the distribution on macrophytes part, the experiment was conducted by arranged vegetated and unvegetated treatment in a greenhouse experiment. Reactor containing 5L of phosphorus solution (50 or 500 mg/L), 4 kg of sediment and plants (Phragmites australis or Eichhornia crassipes) were prepared. The studied concentrations tried to stimulate an accumulation of Total Phosphorus (TP) in plants. Water were sampled every 5 days during 30 days of experiments while sediment and plant samples (roots, submerged leaves and aerial leaves) were collected at the beginning and at end of this study. Relative growth rate (RGR) of plants was determined considering initial and final plant height. As results, more than 60% of TP was removed by P. australis and E. crassipes from the water. Both P. australis and E. crassipes has great capability to accumulated TP in their tissues, submerged part of leaves accumulated highest TP than other part, due to directly contact with water. RGR was positive suggested both plant able to tolerance TP in high concentration. P. australis was accumulated higher TP than E. crassipes. Therefore P. australis is suitable for phytoremediation practice, being capable to tolerate high TP concentration.

Accumulation and distribution of phosphorus in the soil profile under fertilized grazed pasture

The fate of phosphorus originating from long-term fertilizer inputs in the soil profile is of great agronomic and environmental concern but remains poorly understood. Sequential fractionation was used to investigate accumulation and distribution of phosphorus in the soil profile to 100cm (0–7.5, 7.5–15, 15–25, 25–50, 50–75, 75–100cm) under fertilized and grazed pasture. The trial site had received annual superphosphate fertilizer inputs at different rates (0, 188 and 376kg superphosphate ha−1year−1; control, 188PA and 376PA, respectively) for 57 years. While there was significant accumulation of total phosphorus in the topsoil (0–7.5cm), no corresponding differences were observed in organic or residual (non-extracted) phosphorus between treatments. However, fractionation data showed that inorganic forms of phosphorus were significantly higher in the 376PA treatment for all soil depths to 50cm compared with the other treatments. Furthermore, the relative magnitude and significance of differences between the 376PA and other treatments in soil to 50cm were greater for readily-soluble inorganic phosphorus (NaHCO3 and NaOH I extractable) compared with more recalcitrant inorganic phosphorus (HCl and NaOH II extractable). As such, phosphorus applied in excess of agronomic requirements and soil retention capacity was transferred below the topsoil and root zone by leacing, and most of the transfer of phosphorus was in readily-soluble inorganic forms. This presents an enhanced risk of elevated phosphorus transfer to groundwater with associated adverse impacts on water quality under fertilized and irrigated pastures. Our findings highlight the need to carefully assess and manage fertilizer phosphorus inputs in accordance with agronomic demand and soil retention capacity to minimize downward phosphorus movement and phosphorus transfer to water bodies.

Hydrochemical transformations of river waters during the flow in the reception basin on the basis of Olechówka River in Łódź

This work presents the results of the research experiment of conducting hydrochemical observation of the Olechowka River in Łodź and its flow from the river source until its estuary. The main aim of the research was to set tendencies of changes in waters flowing down from municipal reception basin with developed rain drain system and in waters flowing into bathing areas at the same time. Along with the flow of the river, 12 measuring-research points were established. In each of those points, measurements of the discharge rate and mean flow velocity of water in the channel were performed, which enabled to set average time of the flow of water between individual measuring-research points. The time of storing water in reservoirs was taken into consideration. The total time of the flow of water in the Olechowka River amounted to 856 h and 15 min. The analyses included in situ measurements (T, pH, SEC), analytical determinations Cl− , NH4 + , NO3 − , TN, PO4 3− , TP and Oxidability. The interchangeability of values of tested indicators and discharge point out to their decrease along with the increase of water flowing in the riverbed. There were self-cleaning processes identified in the Olechowka River: dilution and denitrification, along with the accumulation of total phosphorus in the river flow.