Surface water phosphorus dynamics in rice fields receiving fertiliser and manure phosphorus

A long-term randomised block field experiment was established in 1997 to study the dynamics of total P and dissolved P in the surface waters of rice fields receiving two application rates of fertiliser P and one rate of combined fertiliser and manure P. Preliminary results from the first two crops show that concentrations of both total P and dissolved P in the surface waters increased significantly following P application, especially during the first 2 weeks after application. P concentrations subsequently declined sharply within about 10 days, then declined steadily and remained almost constant from about 1 month after application. The initial increase in P concentration of surface waters was higher with increasing rate of fertiliser P, and the P concentration at the highest fertiliser rate peaked within about 1 week of application. The elevated P concentrations following fertiliser P application declined more rapidly than those following the combined application of fertiliser and manure P. When fertiliser and manure P were applied together, about 7 days later the surface water P concentrations were significantly higher than when the same rate of P (or double) was applied as fertiliser only. Disturbance of the surface soil by hand harrowing further increased the P concentrations in surface waters, with a subsequent decline to a steady value after about 1 week. Application of P fertiliser to the high P status soil in this experiment gave no crop yield response and may have increased the risk of pollution of adjacent surface waters through drainage from heavy rainfall events during the rice growing season. Therefore, fertiliser P should not be applied to such soils. If, however, fertiliser or manure P is applied, the application should be made during the dry winter to reduce P losses. Manure should be applied with particular care because of the higher risk of P losses to surface water arising from the relatively long period of high P concentrations in surface waters and the potential for greater release of P to field surface waters from the soil. Hand harrowing should also be avoided during wet weather to protect water quality.     

黄磷尾气中总磷及磷化氢的测定

电炉法生产黄磷的过程中会产生大量的尾气,其主要成分是CO(85％～95％)．还有磷、硫、氟、砷、CO2、N2、H2等杂质。黄磷尾气中的磷主要以P4、PH3、P2O5等形式存在。一般尾气经过水洗后．P2O5大部分被水吸收,尾气中主要是P4、PH3。采用分光光度法分析总磷和气体检测管测定磷化氢,效果良好。     

Sediment characteristics,phosphorus types and phosphorus release rates between river and lake sediments

The Han river is 469.7 km long with 26219-km2 area watershed, and is the primary drinking water source for the 20 million people that live in Seoul, Kangwon-Do and Kyunggi-Do, Korea. Phosphorus release from sediments impacts water quality, and is endangering the beneficial use of the river. This research measures phosphorus release and predicts future releases from bottom sediments of two tributary areas (Chungpyung Lake (CPL) and Jamsil submerged dam (JSD) area in the Han river). Sediment samples were taken over a 4-year period from four points in the Jamsil dam area and from 92 points in CPL. The sediments were analyzed for total phosphorus, the form of the phosphorus and release rates under different conditions to the water column. Sediment phosphorus distribution from CPL was 3-5% adsorbed-P (Ads-P), 15-20% non-apatite-P (NAI-P), 25-30% apatite-P (A-P) and 45-57% residual-P (R-P). In the JSD area, the phosphorus distribution ranges were 1-3% Ads-P, 22-39% NAI-P, 26-40% A-P and 30-39% R-P. Laboratory experiments showed that phosphorus release rates from 60 to 80 mg/m2 week in JSD area and ranged from 25 to 40 mg/m2 week in CPL sediments.     

Towards global phosphorus security: a systems framework for phosphorus recovery and reuse options

Human intervention in the global phosphorus cycle has mobilised nearly half a billion tonnes of the element from phosphate rock into the hydrosphere over the past half century. The resultant water pollution concerns have been the main driver for sustainable phosphorus use (including phosphorus recovery). However the emerging global challenge of phosphorus scarcity with serious implications for future food security, means phosphorus will also need to be recovered for productive reuse as a fertilizer in food production to replace increasingly scarce and more expensive phosphate rock. Through an integrated and systems framework, this paper examines the full spectrum of sustainable phosphorus recovery and reuse options (from small-scale low-cost to large-scale high-tech), facilitates integrated decision-making and identifies future opportunities and challenges for achieving global phosphorus security. Case studies are provided rather than focusing on a specific technology or process. There is no single solution to achieving a phosphorus-secure future: in addition to increasing phosphorus use efficiency, phosphorus will need to be recovered and reused from all current waste streams throughout the food production and consumption system (from human and animal excreta to food and crop wastes). There is a need for new sustainable policies, partnerships and strategic frameworks to develop renewable phosphorus fertilizer systems for farmers. Further research is also required to determine the most sustainable means in a given context for recovering phosphorus from waste streams and converting the final products into effective fertilizers, accounting for life cycle costs, resource and energy consumption, availability, farmer accessibility and pollution.     

Investigating phosphorus limitation in a fixed bed filter with phosphorus and nitrogen profile measurements

In 2000, the European Union adopted the European Water Framework Directive (WFD) (European Commission, 2000). The WFD focuses on increasingly stringent nutrient standards including ultra low nitrogen (< 2.2 mg N-total/L) and phosphorus concentrations (< 0.15 mg total phosphorus/L) in receiving surface waters and in relevant point sources like wastewater treatment plant (WWTP) effluent. Expansion of WWTPs with advanced post-treatment processes, like effluent filtration, is widely proposed to meet possible future effluent discharge standards. When combining biological nitrate-nitrogen and chemical phosphorus removal in one filter, phosphorus limitation in the denitrifying process may occur. This study investigated where in the filter bed and under which conditions phosphorus limitation occurs. Profile measurements for nitrate, nitrite, and orthophosphorus (PO4-P) combined with chemical oxygen demand (COD) and 02 were conducted. Results showed that the required PO4-P/NOx-N ratio is approximately 0.006 mg/mg after phosphorous precipitation and flocculation. Profile measurements have proven to be an applicable and useful tool. It showed how nitrate and orthophosphorus are removed through the filter bed based on the PO4-P/NOx-N ratio. When orthophosphorus is removed more rapidly and efficiently compared to nitrate, the PO4-P/NOx-N ratio decreases. When PO4-P/NOx-N ratio thresholds are approximately 0.006 mg/mg for a certain period of time and water temperatures varied significantly, orthophosphorus limitation may occur. Changing the filter-bed configuration or decreasing the coagulant dosage can prevent limitation of the denitrifying process because of a phosphorous shortage.     

Effect of organic and inorganic phosphorus fertilizers on phosphorus availability and its leaching over incubation time

Environmental Science and Pollution Research - The use of organic and inorganic phosphorus (P)&nbsp;fertilizers in agricultural soils is very common, and few studies have been conducted to...     

Enhanced biological phosphorus removal and recovery

Activated sludge systems designed for enhanced nutrient removal are based on the principle of altering anaerobic and aerobic conditions for growth of microorganisms with a high capacity of phosphorus accumulation. Most often, filamentous bacteria constitute a component of the activated sludge microflora. The filamentous microorganisms are responsible for foam formation and activated sludge bulking. The results obtained confirm unanimously that the filamentous bacteria have the ability of phosphorus uptake and accumulation as polyphosphates. Hydrodynamic disintegration of the foam microorganisms results in the transfer of phosphorus and metal cations and ammonium-nitrogen into the liquid phase. It was demonstrated that the disintegration of foam permits the removal of a portion of the nutrients in the form of struvite.     

反硝化聚磷一体化设备中的聚磷菌

研究了新型生物脱氮除磷新工艺反硝化聚磷一体化设备中反硝化厌氧池活性污泥的兼性厌氧微生物组成，数量及其在该除磷系统中功能，结果表明，稳定运行期反硝化厌氧池内活性污泥混合液的兼性厌氧微生物总数大大多于启动期，稳定期和启动期分离的兼性厌氧微生物有假单胞菌属，副球菌属和肠杆菌科，通过对三种纯菌株进行吸放磷研究，三种菌都有不同程度的聚磷功能，说明反硝化菌也具有聚磷作用。     

Soil phosphorus quantity-intensity relationships to predict increased soil phosphorus loss to overland and subsurface flow

Soil phosphorus (P) quantity-intensity (q-i) relationships, based on common extraction methods, may potentially be used to estimate the risk of P loss in overland flow and subsurface drainage water. Some workers have used nonlinear q-i relationships to derive thresholds in soil test P (STP; a quantity factor) above which the risk of P loss increases, while others find linear relationships and no threshold. We present here a simple modelling exercise (based on Langmuir adsorption theory) along with data from literature to explain the behaviour of q-i relationships, and to give an explanation for this apparent discrepancy. The data indicate that q-i relationships are dependent upon the soil to solution ratio of the P intensity parameter, adsorption capacity (Qmax) and strength (K) of the soil, and the total range in STP. In turn, this affects the calculation of a threshold in STP. The q-i relationship tends towards linearity under conditions of a narrow total range of STP and/or when using a wide soil to solution ratio for estimating the P intensity parameter. Under such conditions, a threshold is difficult to detect, and uncertain. We conclude that the sensitivity of thresholds to experimental conditions and soils needs to be considered if thresholds are to be successful in environmental management to decrease P loss to surface waters.     

沉积物中磷形态及影响其释放的环境因素研究进展

磷是控制水体富营养化最关键的营养物质,在外源磷得到控制之后,内源磷通过各种复杂过程再次进入水体,成为水体富营养化的主要磷污染源。目前,国内外对底泥磷的相关研究已非常多,但缺乏系统的整理和总结。从底泥磷的形态和影响其释放的环境因素2个方面进行了系统总结,介绍了底泥磷的主要形态、释放机制,分析了环境因素对于底泥磷释放的影响。     

Effect of low levels of dietary available phosphorus on phosphorus utilization,bone mineralization,phosphorus transporter mRNA expression and performance in growing pigs

A study was conducted to examine the effects of different dietary levels of available phosphorus (aP) on P excretion, bone mineralization, performance and the mRNA expression of sodium-dependent P transporters in growing pigs. Sixty-day old growing pigs (n = 54) with an average initial BW of 19.50 ± 1.11 kg were randomly allocated to a control diet (C) containing 0.23% available phosphorus (aP), T1 containing 0.17% aP and T2 containing 0.11% aP. There were 6 pens per treatment with 3 pigs per pen. Body weight and feed intake were measured weekly. At the end of each week, one pig from each pen was housed in a metabolic crate for 24 h to collect fecal and urine samples and then sacrificed to obtain third metacarpal (MC3) bones and jejunal and kidney samples. Bones were scanned by Dual Energy X-ray Absorptiometry (DEXA). Fecal and urine samples were sub-sampled and analyzed for P content. The expression of P transporter mRNA in jejunum and kidney samples was measured using quantitative real-time polymerase chain reaction (qRT-PCR). Data were analyzed using GLM procedure of the Statistical Analysis System (SAS Institute version 9.2). Pigs fed the T2 diet had reduced (P < 0.05) average daily gain (ADG) and gain to feed (G:F) compared to those fed the C diet during week 2. Overall, ADG and G:F were also reduced (P < 0.05) in pigs fed the T2 diet compared to those fed the C and T1 diets. Bone mineral density (BMD) and bone mineral content (BMC) were reduced (P < 0.05) in pigs fed the T2 diet compared to those fed the C diet throughout the experiment. At week 1, jejunal mRNA expression of Na (+)-dependent phosphate transporter 2 (SLC34A2) was increased (P < 0.01) in pigs fed the T2 diet compared to C diet. Renal mRNA expression of Na(+)-dependent phosphate transporter 1 (SLC34A1) and SLC34A3 were increased (P < 0.05) in pigs fed the T2 diet compared to those fed the C diet at week 2 and was accompanied by lower (P < 0.05) urinary P in pigs fed the T2 diet during week 2 and week 3. In conclusion, growing pigs are highly sensitive to low dietary P as shown by reduced ADG, bone mineralization and urinary P level, but moderate reduction in dietary P up to 0.17% aP in the diet has the potential to reduce environmental pollution by reducing P concentration in swine manure and without compromising performance.     

Past,present, and future use of phosphorus in Chinese agriculture and its influence on phosphorus losses

Large inputs of phosphorus (P) in chemical fertilizers and feed supplements since 1978 have improved soil P status in arable land in China, but have also created challenges by increasing P concentrations in manure and exacerbating water quality degradation. Arable land in China can be divided into five management zones based on soil P chemistry, with 15–92 % of arable land having lower P status than the agronomic optimum and 0.3–7.2 % having severe risks of P leaching losses. A scenario analysis of soil P budget and agronomic P demand during 2011–2030 highlighted the great pressure China faces in sustainable P management and the need for drastic changes in current practices. This includes new policies to reduce P supplementation of feed and improved P use efficiency by livestock and programs to expand the adoption of appropriate fertilization, soil conservation, and drainage management practices to minimize P losses.     

Determining algal-available phosphorus in pulp and paper mill effluents: algal assays vs routine phosphorus analyses

We determined the potentially algal-available P (P(aa)) in pulp and paper mill effluents by two bioassay techniques (a dual-culture assay and a batch approach) and compared it with chemically analysed P (total P, total dissolved P, reactive P, dissolved reactive P and dissolved hydrolysable P). The mean P(aa) given by the dual-culture assay was within a 40% range of that given by the batch approach. The P(aa) obtained by both bioassays differed from total P. Dissolved reactive P appeared to be the most readily available chemical P fraction, but other P fractions also contributed to P(aa). The analysis of reactive P, which involves direct staining of an unfiltered sample, best approximated the P(aa) given by the dual-culture assay (relative error 9%). The results suggest that assessment of eutrophying effluent P can be improved by analysing simple chemical P fractions in wastewater. The fractions to be analysed, however, may be site specific.     

溶解氧对EBPR主流除磷及侧流磷回收性能的影响

采用交替厌氧/好氧(An/O)模式下运行的SBR,考察不同溶解氧(DO)浓度(1.0、0.5、0.1 mg·L~(-1))对同步侧流磷回收的强化生物除磷(enhanced biological phosphorus removal,EBPR)主流系统除磷及侧流磷回收性能的影响。结果表明,整个实验阶段主流系统对COD、NH_4~+-N及TN的去除均能稳定达到《城镇污水处理厂污染物综合排放标准》一级A标准,其中TN因出水NO_3~--N浓度的降低而降低,故TN去除率升高。DO为1.0 mg·L~(-1)和0.5 mg·L~(-1)时对磷的去除率分别为99.0%和95.4%,主流系统出水磷达标率分别为96.0%和84.0%。而当DO浓度过低(0.1 mg·L~(-1))时,硝化与吸磷对有限电子受体的竞争及吸磷时间不足导致反应结束时系统内平均磷残留量达1.02 mg·L~(-1),除磷率降至87.2%。鉴于侧流磷回收是对主流系统的磷剥夺,会影响污泥的好氧吸磷能力,继而厌氧阶段释磷量因侧流提取降低。与此同时,DO为1.0 mg·L~(-1)时,侧流磷回收率较其余2个工况高,且此工况下主流系统的厌氧释磷及好氧吸磷能力均最高,考虑到主流工艺的可靠运行及出水稳定性,认为DO=1.0 mg·L~(-1)为最优工况。     

Soil-extractable phosphorus and phosphorus saturation threshold in beef cattle pastures as affected by grazing management and forage type

Grazing can accelerate and alter the timing of nutrient transfer, and could increase the amount of extractable phosphorus (P) cycle from soils to plants. The effects of grazing management and/or forage type that control P cycling and distribution in pasture's resources have not been sufficiently evaluated. Our ability to estimate the levels and changes of soil-extractable P and other crop nutrients in subtropical beef cattle pastures has the potential to improve our understanding of P dynamics and nutrient cycling at the landscape level. To date, very little attention has been paid to evaluating transfers of extractable P in pasture with varying grazing management and different forage type. Whether or not P losses from grazed pastures are significantly greater than background losses and how these losses are affected by soil, forage management, or stocking density are not well understood. The objective of this study was to evaluate the effect of grazing management (rotational versus “zero” grazing) and forage types (FT; bahiagrass, Paspalum notatum, Flugge versus rhizoma peanuts, Arachis glabrata, Benth) on the levels of extractable soil P and degree of P saturation in beef cattle pastures. This study (2004–2007) was conducted at the Subtropical Agricultural Research Station, US Department of Agriculture–Agricultural Research Service located 7 miles north of Brooksville, FL. Soil (Candler fine sand) at this location was described as well-drained hyperthermic uncoated Typic Quartzipsamments. A split plot arrangement in a completely randomized block design was used and each treatment was replicated four times. The main plot was represented by grazing management (grazing vs. no grazing) while forage types (bahiagrass vs. perennial peanut) as the sub-plot treatment. Eight steel exclosures (10?×?10 m) were used in the study. Four exclosures were placed and established in four pastures with bahiagrass and four exclosures were established in four pastures with rhizoma peanuts to represent the “zero” grazing treatment. The levels of soil-extractable P and degree of P saturation (averaged across FT and soil depth) of 22.1 mg kg^?1 and 11.6 % in pastures with zero grazing were not significantly (p?≤?0.05) different from the levels of soil-extractable P and degree of P saturation of 22.8 mg kg^?1 and 12.9 % in pastures with rotational grazing, respectively. On the effect of FT, levels of soil-extractable P and degree of P saturation were significantly higher in pastures with rhizoma peanuts than in pastures with bahiagrass. There was no net gain of soil-extractable P due to the presence of animals in pastures with rotational grazing. Averaged across years, soil-extractable P in pastures with rotational grazing and with “zero” grazing was less than 150 mg kg^?1, the water quality protection. There had been no movement of soil-extractable P into the soil pedon since average degree of P saturation in the upper 15 cm was 14.3 % while the average degree of P saturation in soils at 15–30 cm was about 9.9 %. Overall, average extractable P did not exceed the crop requirement threshold of 50 mg P kg^?1 and the soil P saturation threshold of 25 %, suggesting that reactive P is not a problem. Our study revealed that rhizoma peanuts and bahiagrass differ both in their capacity to acquire nutrients from the soil and in the amount of nutrients they need per unit growth. Rhizoma peanuts, which are leguminous forage, would require higher amounts of P compared with bahiagrass. The difference in the amount of P needed by these forages could have a profound effect on their P uptake that can be translated to the remaining amount of P in the soils. Periodic applications of additional P may be necessary especially for pastures with rhizoma peanuts to sustain their agronomic needs and to potentially offset the export of P due to animal production. Addition of organic amendments could represent an important strategy to protect pasture lands from excessive soil resources exploitation.     

Capturing the lost phosphorus

Minable phosphorus (P) reserves are being depleted and will need to be replaced by recovering P that currently is lost from the agricultural system, causing water-quality problems. The largest two flows of lost P are in agricultural runoff and erosion (∼46% of mined P globally) and animal wastes (∼40%). These flows are quite distinct. Runoff has a very high volumetric flow rate, but a low P concentration; animal wastes have low flow rates, but a high P concentration together with a high concentration of organic material. Recovering the lost P in animal wastes is technically and economically more tractable, and it is the focus for this review of promising P-capture technologies. P capture requires that organic P be transformed into inorganic P (phosphate). For high-strength animal wastes, P release can be accomplished in tandem with anaerobic treatment that converts the energy value in the organic matter to CH₄, H₂, or electricity. Once present as phosphate, the P can be captured in a reusable form by four approaches. Most well developed is precipitation as magnesium or calcium solids. Less developed, but promising are adsorption to iron-based adsorbents, ion exchange to phosphate-selective solids, and uptake by photosynthetic microorganisms or P-selective proteins.     

污水中磷的回收和利用途径

综述了近年来污水中磷回收的主要技术方法,重点针对磷酸铵镁结晶法,对磷酸铵镁的形成、用途及该方法的可行性做了详细的介绍与评述.同时,阐述了利用磷酸盐溶解微生物,实现磷产品肥效的回收.并对今后磷回收、回用工作的开展,提出了建议.     

催化铁耦合生物除磷工艺中生物与化学除磷的关系

研究证明,将催化铁添加至传统生物除磷工艺的厌氧段,可使得生物除磷和化学除磷两者作用耦合。为了研究工艺中生物除磷与化学除磷的关系,采用不同催化铁投配率分别为0、1和2 g Fe/(mg P·d)的3组反应器进行实验。结果表明,催化铁投配率为1 g Fe/(mg P·d)时,系统的除磷效率最佳,去除率在90%以上,生物除磷与化学除磷耦合作用好;负荷为2 g Fe/(mg P·d)时,系统在未达到稳定之前即发生恶化,生物除磷作用受到抑制。铁化合物的积累量过多是系统出现恶化的主要原因:在污泥中铁含量小于30 mg Fe/g MLSS时,生物除磷作用与化学除磷作用两者协同,除磷效率提高;当污泥中铁含量超过52.8 mg Fe/g MLSS时,出现竞争,生物除磷作用受到抑制;通过排泥,降低污泥中铁含量,则除磷功能可以得到恢复。