Water Total Phosphorus Research Articles

A meta-analysis of water quality and aquatic macrophyte responses in 18 lakes treated with lanthanum modified bentonite (Phoslock®)

Lanthanum (La) modified bentonite is being increasingly used as a geo-engineering tool for the control of phosphorus (P) release from lake bed sediments to overlying waters. However, little is known about its effectiveness in controlling P across a wide range of lake conditions or of its potential to promote rapid ecological recovery. We combined data from 18 treated lakes to examine the lake population responses in the 24 months following La-bentonite application (range of La-bentonite loads: 1.4–6.7 tonnes ha−1) in concentrations of surface water total phosphorus (TP; data available from 15 lakes), soluble reactive phosphorus (SRP; 14 lakes), and chlorophyll a (15 lakes), and in Secchi disk depths (15 lakes), aquatic macrophyte species numbers (6 lakes) and aquatic macrophyte maximum colonisation depths (4 lakes) across the treated lakes. Data availability varied across the lakes and variables, and in general monitoring was more frequent closer to the application dates. Median annual TP concentrations decreased significantly across the lakes, following the La-bentonite applications (from 0.08 mg L−1 in the 24 months pre-application to 0.03 mg L−1 in the 24 months post-application), particularly in autumn (0.08 mg L−1 to 0.03 mg L−1) and winter (0.08 mg L−1 to 0.02 mg L−1). Significant decreases in SRP concentrations over annual (0.019 mg L−1 to 0.005 mg L−1), summer (0.018 mg L−1 to 0.004 mg L−1), autumn (0.019 mg L−1 to 0.005 mg L−1) and winter (0.033 mg L−1 to 0.005 mg L−1) periods were also reported. P concentrations following La-bentonite application varied across the lakes and were correlated positively with dissolved organic carbon concentrations. Relatively weak, but significant responses were reported for summer chlorophyll a concentrations and Secchi disk depths following La-bentonite applications, the 75th percentile values decreasing from 119 μg L−1 to 74 μg L−1 and increasing from 398 cm to 506 cm, respectively. Aquatic macrophyte species numbers and maximum colonisation depths increased following La-bentonite application from a median of 5.5 species to 7.0 species and a median of 1.8 m to 2.5 m, respectively. The aquatic macrophyte responses varied significantly between lakes. La-bentonite application resulted in a general improvement in water quality leading to an improvement in the aquatic macrophyte community within 24 months. However, because, the responses were highly site-specific, we stress the need for comprehensive pre- and post-application assessments of processes driving ecological structure and function in candidate lakes to inform future use of this and similar products.

Phosphorus forms and response to changes in pH in acid-sensitive soils on the Precambrian Shield

Baker, S. R., Watmough, S. A. and Eimers, M. C. 2015. Phosphorus forms and response to changes in pH in acid-sensitive soils on the Precambrian Shield. Can. J. Soil Sci. 95: 95–108. Soil acidification may explain declines in total phosphorus (TP) levels that have been observed in surface waters in central Ontario, Canada, but much of the research on phosphorus (P) mobility in pH manipulated soils has been performed at high P concentrations (i.e., >500 µM). This study investigated P fractionation in acidic (pH≤4.6) soils in south-central Ontario and relationships between soil pH and P sorption at relatively low P concentrations to test whether long-term declines in soil pH could have increased soil P sorption. Soils from three forested catchments that vary naturally in soil pH and outlet stream [TP] (0.1–0.4 µM in 2008) had very similar soil P concentrations and distributions (Hedley fractionation). Only hydrochloric-acid extractable P (i.e., apatite) differed amongst catchments and was greatest at the catchment with the highest stream [TP]. The fraction of P present as labile/soluble P did not decline with pH as expected and experiments indicated that P sorption at P concentrations between 4.52 and 452.1 µM was insensitive to manipulated solution pH. Soils were, however, able to sorb >90% of P added in sorption experiments at [P]≤452.1 µM. These results suggest that acidification-induced P sorption in upland soils has not contributed to observed decreases in surface water TP concentrations.

Environment factors and expression of PC-IGS and<i> gvpC </i>genes in Meiliang Bay of Lake Taihu

以室内铜绿微囊藻7806(Microcystis aeruginosa 7806)为对照,运用反转录定量PCR技术研究太湖梅梁湾水体蓝藻藻蓝蛋白转录间隔区基因(PC-IGS)和伪空胞基因(gvpC)在2013年1月至2014年1月的相对表达量,并分析它们与环境因子的关系. 结果表明, PC-IGS相对表达量在2013年1—5月逐渐上升,并在5月达到最大值;gvpC相对表达量从2013年1月开始持续上升并在3月达到最大值;gvpC的表达早于PC-IGS. 相关分析表明,PC-IGS的相对表达量与硝态氮、溶解氧浓度均呈极显著正相关,与亚硝态氮、铵态氮以及正磷酸盐浓度均呈显著正相关,与pH值呈显著负相关,与温度、总氮和总磷浓度均无显著相关性;gvpC的相对表达量与硝态氮、铵态氮以及正磷酸盐浓度均呈极显著正相关,与总氮和亚硝态氮浓度呈显著正相关,与温度和pH值均呈显著负相关,与溶解氧和总磷浓度均无显著相关性.;The relative expression of intergenic spacer region-within the Phycocyanin (PC-IGS) and gas vesicle gene (gvpC) in cyanobacteria in Meiliang Bay, Lake Taihu from January of 2013 to January of 2014, was investigated using reverse transcription-quantitative PCR, compared to those in interior Microcystis aeruginosa. In addition, we analyzed the influence of environmental factors on the relative expressions of PC-IGS and gvpC gene. The results showed that the relative expression of PC-IGS increased from January to May of 2013, and reached the maximum in May of 2013. The relative expression of gvpC gene rose from January of 2013, and reached the maximum in March of 2013. The expression of gvpC gene increased earlier than that of PC-IGS. The data also showed that the relative expression of target gene PC-IGS was correlated significantly and positively with the concentrations of nitrate nitrogen, dissolved oxygen, ammonia, nitrite nitrogen and orthophosphate salt, negatively with pH value, and not significantly with temperature, total nitrogen and total phosphorus. The relative expression of target gene gvpC was correlated significantly and positively with the concentrations of ammonia, nitrate nitrogen and orthophosphate salt. They are positively correlated with the concentrations of total nitrogen and nitrite nitrogen, but negatively with pH value and temperature, and not significantly with the concentrations of dissolved oxygen and total phosphorus in water.

Impact of wetland disturbance on phosphorus loadings to lakes

Total phosphorus (TP) concentrations have declined in many lakes and streams across south-central Ontario, Canada, over the past three decades, and changes have been most pronounced in wetland-dominated catchments. In this study, long-term (1980–2007) patterns in TP concentrations in streams were assessed at four wetland-dominated catchments that drain into Dickie Lake (DE) in south-central Ontario. Two of the subcatchments (DE5 and DE6) have particularly large wetland components (31%–34% of catchment area), and these wetlands are characterized by numerous standing dead trees and many young live trees (18–27 years old). These two streams exhibited large peaks in TP and potassium (K) export in the early 1980s. In contrast, TP and K export from DE8 and DE10 (wetland cover 19%–20%) were relatively flat over the entire record (1980–2007), and field surveys indicated negligible standing dead biomass in these wetlands and a relatively healthy, mixed-age tree community. The coincidence of high TP and K concentrations in the DE5 and DE6 streams as well as evidence of a disturbance event in their wetlands during the early 1980s suggest that disturbance events (e.g., flooding) that lead to wetland tree mortality may contribute to patterns in surface water TP observed in this region.

Sedimentation and internal phosphorus loads in Krishnagiri Reservoir, India

AbstractThis study examines sedimentation rate and its consequences on the bathymetry, capacity and internal phosphorus loading of Krishnagiri Reservoir in Tamil Nadu, South India, utilizing an acoustic Doppler profiler and remote sensing data in an ArcGIS environment. There was a significant change in the reservoir bathymetry for the year 2012, compared with the 2007. The sedimentation rate was 0.818 MCM from 1960 to 1990 and 0.83 MCM over past 5 years. The present reservoir volume is 35.57 MCM, having been reduced to nearly half of its original capacity over a 55 year span, pointing to a seriously threatened lifespan. The sediment total phosphorus (TP) load spatially varied from 6.84 to 23 394 kg, depending on the sediment deposition zones. Sequential extraction indicated the dominance of phosphate fractions to be Al‐P> Fe‐P> Ca‐P> SRP, with an average TP value of 27.27 mg g−1 dry weight. Aluminium‐ (35%) and iron(25%)‐bound forms are the major sediment phosphorus fractions, suggesting temperature, pH and redox or related chemical reactions may be important means of sediment P release in Krishnagiri Reservoir. The sediment phosphorus load in Krishnagiri Reservoir is estimated to be 44.50 tons, with an average TP release of 40.97 mg m−2 (range of 10.22–70 mg m−2). The measured pore water TP concentration and calculated sediment phosphate release exhibited a linear relation. Even with a reduced external P load, the eutrophication of Krishnagiri Reservoir cannot be reduced immediately because of its high internal load and nutrient remobilization.

The Simulation of the Rapid Measurement of Total Phosphorus Content in Sewage

The total phosphorus in water mainly exists in the forms of phosphate, condensed phosphate, and the compound of organophosphorus. Chemical sampling analysis method has low measuring accuracy and takes long time. NIPGA technology is used in order to detect the total phosphorus content in sewage quickly, and MCNP-4C is used to take simulating calculation. The calculating results show that the measuring accuracy is lower when the total phosphorus content is less than 0.10 mg/L. But this approach can meet the measurement requirements of total phosphorus content in II-type, III-type, IV-type and V-type water.

계절적 몬순에 의한 댐 인공호 및 농업용 저수지에서의 영양상태지수(TSI), 경험적 수질 모델 및 어류 트로픽 구조

The key objective of this study was to evaluate trophic state and empirical water quality models along with analysis of fish trophic guilds in relation to water chemistry (N, P). Trophic state index (TSI), based on total phosphorus (TP) and chlorophyll-a (CHL), ranged between oligotrophic and hypereutrophic state, by the criteria of Nurnberg(1996), and was lower than the trophic state of total nitrogen (TN). Trophic relations of Secchi depth (SD), TN, TP, and CHL were compared using an empirical models of premonsoon (Pr), monsoon (Mo), and postmonsoon (Po). The model analysis indicated that the variation in water transparency of Secchi depth (SD) was largely accounted (p < 0.001, range of R2 : 0.76.0.80) by TP during the seasons of Mo and Po and that the variation of CHL was accounted (p < 0.001, R2 = 0.70) up to 70% by TP during the Po season. The eutrophication tendency, based on the TSITP vs. TSIN:P were predictable (R2 ranged 0.85.0.90, p < 0.001), slope and y intercept indicated low seasonal variability. In the mean time, TSIN:P vs. TSICHL had a monsoon seasonality in relation to values of TSIN:P during the monsoon season due to a dilution of reservoir waters by strong monsoon rainfall. Trophic compositions of reservoir fish reflected ambient contents of TN, TP, and CHL in the reservoir waters. Thus, the proportions of omnivore fish increased with greater trophic conditions of TP, TN and CHL and the proportions of insectivore fish decreased with greater trophic conditions.

Effects of farm and commercial inputs on carp polyculture performance: participatory trial in an experimental field station

The carp polyculture production system is the most widely used system by small-scale fish farmers in southern Brazil (States of Parana, Santa Catarina and Rio Grande do Sul). The aim of this study was to compare biotechnical and economic parameters between a farm system (FS) using farm inputs (chicken manure, maize and grass) and a commercial system (CS) using commercial inputs (triple super phosphate, ammonium nitrate and balanced food) feeding to apparent satiation. The experiment was carried out for 196 days in earthen ponds of 500 m 2 , with three replicates per system. The stocking density was 2,000 fish ha -1 , consisting of 35% grass carp (Ctenopharyngodon idella), 30% of mirror common carp (Cyprinus carpio var. specularis), 20% of bighead carp (Aristichthys nobilis) and 15% silver carp (Hypophthalmichthys molitrix). In both systems, a low level of total phosphorus in water (0.06 mg L -1 ) and in the sediment (4 mg L -1 ) was observed. Production was significantly increased in the CS (76 kg 500 m -2 196 days -1 ) than in the FS (43 kg 500 m -2 196 days -1 ). Costs and revenues were higher in the CS and profits were similar in the two systems. Similar profits

Eco-physiological characteristics of Pistia stratiotes and its removal of pollutants from livestock wastewater.

The effectiveness of water lettuce in removing pollutants including organic pollutants, nitrogen (NH3-N) and total phosphorus (TP) from livestock wastewater along with the physiological effects and their correlations, was studied for the first time. The results showed that the water lettuce had higher removal efficiency with low concentrations of livestock wastewater. The removal efficiency of water lettuce for different initial concentrations of livestock wastewater within 8 d was as follows: chemical oxygen demand (CODcr) (68-82%) > NH3-N (57-69%) >TP (27-45%). The speed of purification of water lettuce for CODcr, NH3-N and TP conformed to first order kinetics equations. The water quality indices CODcr, NH3-N and TP had a higher linear correlation with peroxidase (POD) activity (R(2) > 0.9(2)) than with superoxide dismutase (SOD) and catalase (CAT) activity, which indicates that the main reacting enzyme of water lettuce under high CODcr stress is peroxidase.

Electrochemical microsensor based on gold nanoparticles modified electrode for total phosphorus determinations in water.

This work mainly describes an electrochemical microsensor based on the reduction of molybdophosphate complex for total phosphorus (TP) determinations in water. The microelectrode was fabricated using microelectromechanical systems (MEMS) techniques and porous, branching gold nanoparticles (AuNPs) were electrodeposited on the microelectrode to improve its sensitivity. Calibration of the microsensor was performed with standard phosphate solutions prepared with KH2PO4 with pH adjusted to 1.0. The experimental results showed that both sensitivity and current response are improved effectively using this modified microelectrodes: The limit of detection of the microsensor is 1.2 x 10(-7) mol/l and linear range is 3 x 10(-7) to 3 x 10(-4) mol/l. The sensitivity of unmodified electrode is -0.27nA/micromol x 1(-1) (R2 = 0.994), whereas the sensitivity of AuNPs modified electrode is -0.89 nA/micromol 1(-1) (R2 = 0.8). The current response of modified electrode is 6 times larger than that of unmodified electrode in average. Detection of TP was also carried out with digested TP standard solutions for both modified and unmodified electrodes, and results were consistent with the nominal value of phosphorus concentration. This microsensor provides the probability of combining TP detection device with micro-digesting device to form a TP detection system, which can realise the automotive and on-line monitoring of TP in surface water.

Nitrogen and phosphorus absorption capability in environmental culture by Taiwan gravestone Anadonta woodiana Lea

&lt;p&gt;Nitrogen and phosphorus in a water culture are derived from the metabolism of the farmed organism, feed residue and microbial activity in the water. One way of controlling water quality due to waste in the form of nitrogen and phosphorus from aquaculture is to utilize filter feeder organisms of &lt;em&gt;Anadonta woodiana&lt;/em&gt; Lea. This study aimed to analysis the effectiveness of the absorption of nitrogen and phosphorus in waters by &lt;em&gt;A. woodiana&lt;/em&gt; as filter feeder. A total of 0 (control), five, ten, and 15 gravestone were putted into a tank of 35 L of water derived from Cirata reservoir. Each treatment was given three times repetition. Measurement of total nitrogen and phosphorus in gravestones were performed at baseline and end of treatment. In addition, measurement of total nitrogen and phosphorus in the water tank was measured every ten days. Another measurement is the length and weight of gravestone. Direct observations made on gravestones barnacle survival, pH, dissolved oxygen, temperature, and turbidity every day. Aeration was provided in each aquarium. Based on the results obtained, the survival of gravestone in the density of five gravestones was 93.33%, in ten gravestones density was 90%, while in 15 gravestones was 95%. The percentage reduction in total nitrogen in the water at the end of treatment was 57% for the five gravestones density, and for ten gravestones was 88.2%. The decrease of total phosphorus in water in ten gravestones density was 37.4%, whereas the increase in density of 15 gravestones and total phosphorus water percentage was 26.9%. On the density of ten gravestones, the body weight decreased until to 3.3%, while in the density of 15 gravestones decreased until to 2.5% on day 30. Results of water quality analysis showed that the DO values decreased from baseline to end of treatment (from 5.08 to 4.86 mg/L), the average water temperature from 26.5 to 27.4 °C, pH values 7‒8, and highest turbidity values was obtained in the density of five gravestone. Decrease in the percentage of total nitrogen in the water suggested nitrogen and phosphorus have been absorbted for barnacle growth.&lt;/p&gt; &lt;p&gt;Keywords: total phosphorus, total nitrogen,waste,&lt;em&gt;Anadonta woodiana&lt;/em&gt; Lea,cultivation&lt;/p&gt;

Effect of sludge return ratio on the treatment characteristics of high-efficiency sedimentation tank

An advanced treatment experiment on secondary effluent water of the municipal wastewater treatment plant by utilizing a high-efficiency sedimentation tank was conducted. The removal efficiencies of suspended solids (SS), total phosphorus (TP) and chemical oxygen demand (COD) as well as the characteristics of sludge settling under different sludge reflux ratios were studied. In addition, the optimal working conditions were analyzed in this experiment. The experimental results show that sludge reflux ratio plays an influential role in contaminant removal and sludge settling. In case the reflux ratio is 50%, concentrations of SS, TP and COD in effluent water are 10, 0.48 and 49 mg/L, respectively. The effluent water is up to Grade 1A of the Standard (GB18918-2002), and the sludge can be settled well. The high-efficiency sedimentation tank presented a remarkable effect in removing suspended particles, as suspended substances with particle diameters above 3μm could be removed effectively and those with particle size(s) of or above 12μm could be completely removed. Experimental results show that the adoption of high-efficiency sedimentation tank significantly improves the treatment effects of SS, TP and COD in sewage. The experimental parameters acquired under the optimal working conditions can be served as references for the actual running of high density sedimentation tank in the municipal sewage treatment plant.

Evaluación analítica para la determinación de fósforo total en aguas por el método del ácido ascórbico

Se hallaron los límites de detección y cuantificación, la precisión y la exactitud para las determinaciones de fosforo total en aguas por método colorimétrico del acido ascórbico. El objetivo fue confirmar la aplicación correcta del método para el análisis de aguas. Se trabajó con muestras de agua de diferente procedencia, siguiendo estrictamente los protocolos de verificación. Los resultados encontrados son satisfactorios en precisión y exactitud.

Eutrophication impacts littoral biota in Lake Ohrid while water phosphorus concentrations are low

Eutrophication has traditionally been measured as increased phosphorus concentrations. In some lakes, however, such as transboundary Lake Ohrid situated between Macedonia and Albania, pelagic phosphorus concentrations are low, in spite of known sources of nutrient input. We assumed that littoral biota may be more responsive to phosphorus load than water chemistry, and studied nearshore water chemistry, macrophytes, diatoms and macroinvertebrates at 30 sites around the lake, analyzing functional groups as well as standard eutrophication metrics. We hypothesized that the incorporation of nutrients into benthic biomass will conceal correlations between water phosphorus concentrations and biological eutrophication metrics, but that analysis of functional groups in addition to eutrophication metrics may help draw a plausible picture of how phosphorus is transferred through the food web. Water total phosphorus concentrations in the Lake Ohrid littoral were generally low, while all three analyzed organism groups indicated at least some degree of eutrophication. This shows that littoral biota are more sensitive indicators of nutrient input than hydrochemistry. The abundance of the benthic alga Cladophora sp. correlated positively with water total phosphorus concentrations, indicating that P-loading at local scales may be an important driver of Cladophora biomass. In contrast, none of the biotic metrics (macrophyte index, diatom index, and macroinvertebrate ICM) correlated with ambient water P-concentrations. We argue that this is not a sign of poorly working biological metrics, but a consequence of ecosystem processes in the lake littoral. Analysis of macrophyte and benthic algae abundance, and macroinvertebrate feeding types together with the biotic metrics suggests a meso- to slightly eutrophic littoral ecosystem where nutrient supply is incorporated into macrophyte and benthic algae biomass, and transferred through the food web from benthic algae to grazers, and from macrophytes to shredders and gatherers. Macroinvertebrate filter feeders correlate negatively with water total phosphorus concentrations, suggesting they remove phosphorus from the water. Our results indicate that the combined use of classical biological eutrophication metrics and functional groups may be a way to not only distinguish between oligotrophic and eutrophic ecosystems, but in addition give information as to whether or not nutrient input and nutrient removal in an ecosystem are balanced. This may eventually also give information about ecosystem functioning and ecosystem stability, and thus provide a basis for the development of “second generation” metrics for ecosystem assessment.

Exploring the Role of Ecological Groin in Improving River Water Quality: A Case Study in Wangyu River, China

The ecological groin being built using elastic filter bulb with biologic filler, has received attention in the community for its role in improving stream water quality through altering stream hydrodynamics, intercepting sediment and thereby reducing the sediment-attached nutrients. As an important watercourse for the project Transferring Yangtse River into Taihu Lake, Wangyu River, was chosen in this study to investigate the effect of ecological groin based on two sampling campaigns in April 2012. The results showed that suspended solid (SS) and total phosphorus (TP) concentration in the water decreased significantly after the ecological groin. The SS and TP concentration in the surface, intermediate and bottom water decreased after the ecological groin by 53.5% and 12.7%, 44.0 %and 14.5%, and 35.5% and 9.3%, respectively, which were greatly related to the facts that ecological groin favored sedimentation and that the total particulate phosphorus accounted for up to 75.0% of TP in the water. Comparatively, TN concentration in the surface, intermediate and bottom water decreased after the ecological groin by 5.6%, 2.4% and 5.1%, respectively. The findings of this study enable us to gain insight into the role of ecological groin in improving river water quality.

Impacts of soil erosion on organic carbon and nutrient dynamics in an alpine grassland soil

The impact of soil erosion on the nutrient dynamics in alpine grassland soils is still an essential problem. Selecting a grass-covered hillslope in eastern Tibet Plateau, the cesium-137 (137Cs) technique was used to determine the impacts of soil erosion on soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK). The 137Cs data revealed that there were distinct soil redistribution patterns in different hillslope positions because of the influences of slope runoff, plant coverage and grazing activity. For the upper slope, soil erosion first decreased downward, followed by soil deposition in its lower part. In contrast, for middle and toe slopes, there was an increasing soil erosion along a downslope transect. Across the lower slope, soil erosion showed an irregular variation. Influenced by the selective transport of water erosion, SOC, TN and TP storage decreased with increasing soil erosion in upper, middle and toe slopes. In contrast, SOC, TN and TP storage varied little with soil erosion in the lower slope. On the whole hillslope, TK storage also varied little with soil erosion due to the large amount of potassium elements derived from soil parent materials. Particularly noteworthy was the greatest storage of SOC, TN and TP in the lower slope where most obvious net soil erosion occurred, which is closely related to the humus accumulation combined with gravel separation as well as weathering and pedogenesis of parent rocks induced by soil freeze-thaw.

대청호에 설치된 수중폭기시설이 조류 발생에 미치는 영향

Abstract : To evaluate the effects of submerged aerators installed at Chudong and Muneui areas in Daechung Reservoir on im-provement of water quality and reduction of algal bloom, the water quality was monitored at the effected and control areas at the time of operation. The water temperature and concentrations of dissolved oxygen, total phosphorus, and total nitrogen in depth at the effected and control areas were not different each other, indicating the submerged aerators at these areas are not effective for circulation of water body and reduction of nutrients. In warmer season, the concentrations of total phosphorus in deep water, which was probably released from contaminated sediment or inflowed from watershed, was high. To decide the operation of aerators in this season, the concentration of total phosphorus in water should be considered because the dispersed phosphorus by operation of aerators can enhance the algal growth. Key Words : Submerged Aerator, Daechung Reservoir, Water Quality Improvement, Reduction of Algal Bloom, Contaminated Sediment

주암호 복내 저수구역내 침수 자생식물의 질소 및 인 모니터링

BACKGROUND: Eutrophication occurs occasionally in reservoirs around lake in summer and early autumn. Lakeside macrophyte which is one of internal pollutants effects on water quality when it is submerged during rainy season. To improve water quality of water supply source in Boknae reservoir around Juam lake, characteristics of nutrient(N, P) uptake and release by submerged plants were investigated. METHODS AND RESULTS: In order to establish the management plan of submerged plants in Boknae reservoir around Juam lake, water level, rainfall, flooding and non-flooding areas, biomass of dominant plants, contents of nitrogen and phosphorus were investigated during 7 months(August, 2010 through February, 2011). Dominant plants were Miscanthus sacchariflorus(MISSA) and Carex dimorpholepis(CRXDM) in Boknae reservoir. Total plant area of Boknae reservoir in August, 2010 was 987,872 . In Boknae reservoir, flooding occurred from August until February caused by rainfall during rainy season. The total amounts of nitrogen and phosphorus uptakes by MISSA were 247 and 22 kg/total reservoir area, respectively. By CRXDM, the total amounts of nitrogen and phosphorus uptakes were 11,340 and 1,231 kg/total reservoir area, respectively. The total amounts of nitrogen and phosphorus residues by MISSA were 34 and 11 kg/total reservoir area, respectively. By CRXDM, the total amounts of nitrogen and phosphorus residues were 491 and 68 kg/total reservoir area, respectively. CONCLUSION(S): Total amounts of nitrogen and phosphorus releases in Boknae reservoir were 12,212 and 1,324 kg/total reservoir area, respectively. The results demonstrate that total nitrogen and total phosphorus in water were strongly influenced by submerged plants. Therefore, management plan for submerged plants during rainy season will be needed to improve water quality of water supply source in Boknae reservoir around Juam lake.

Within-lake variability of subfossil chironomid assemblage in a large, deep subtropical lake (Lugu lake, southwest China)

The present study analysed the distribution of subfossil chironomid larval head caspules in a suite of surface sediment samples from a large deep subtropical lake, i.e. Lugu lake, located in southwest China. In order to identify the relationships between environmental variables and the chironomid assemblages ordination methods were used. A total of 41 chironomid taxa were found across the 46 samples, 21 of which had a minimum abundance &gt;1% and were present in more than one site. The samples were dominated by 12 taxa, which together accounted for 97% of the fauna. Redundancy analysis (RDA) revealed that the predominant drivers of chironomid distribution within Lugu lake were bottom water temperature, water depth, loss-on-ignition (LOI) and water total phosphorus (TP) concentration. Abrupt changes in chironomid assemblages occurred at 10 m of water depth, which is closely related to the macrophyte distribution and the position of the thermocline. The chironomid assemblages became uniform below a water depth of ca. 15 m, and the anthropogenic impact on the chironomid fauna was then limited to the edge of Lugu lake. The depth-related faunal shifts primarily reflect the dominant controls of temperature and macrophyte distribution on the chironomids in Lugu lake. This is the first within-lake subfossil chironomid study from this region and the understanding of key environmental influences on contemporary faunas within the lake will aid interpretations of palaeolimnological datasets to reconstruct past trends and magnitude of environmental change over a range of timescales.

Micro cobalt electrodes for detection of total phosphorus in water

In this study, the characterisation and calibration of microfabricated cobalt electrodes for the detection of total phosphorus (TP) in water are presented. The microelectrode chips were fabricated by microelectromechanical systems technology, and cobalt was used as the sensing material modified on the surface of microelectrodes using the electrodepositing method. The surface morphology and crystal direction of modified cobalt were examined and the electrochemical characterisation of cobalt electrodes was performed. The cobalt microelectrode showed good linear response to phosphate in the range of 10−6–10−2 M/l with the slope of about 28 mV/dec. The microelectrodes also presented good stability, consistency and reproducibility. These electrodes were applied to detect TP concentration in water samples from a lake. Calibration was performed for each electrode before the test. The test result using these cobalt microelectrodes was consistent with the concentration given in the certificate of qualified water of the quality detection institute.