Search

This study evaluates the use of visible and near-infrared spectroscopy for rapid prediction of total carbon, total nitrogen, and total phosphorus concentrations in field crop samples. Two multivariate models (partial least squares regression and support vector machine regression) were compared. In addition, four spectral variable selection algorithms (competitive adaptive reweighted sampling, genetic algorithm, uninformative variable elimination, and variable importance for projection) were applied with support vector machine regression to determine the most accurate predictions. The results showed that support vector machine regression performed better than partial least squares regression for predicting the three chemical compositions. The combination of competitive adaptive reweighted sampling and support vector machine regression outperformed the other models for the predictions of total carbon and total nitrogen with high coefficients of determination of 0.91 and 0.90, respectively. For the determination of total phosphorus, the prediction accuracy of competitive adaptive reweighted sampling was comparable with the best result obtained from genetic algorithm with the coefficients of determination of 0.73 and 0.77, respectively. In conclusion, the support vector machine regression combined with competitive adaptive reweighted sampling has great potential to accurately determine the chemical composition of field crops using the visible and near-infrared spectroscopy.

Introduction: Laguna Cartagena (LC), a wetland in Lajas, Puerto Rico, has been negatively impacted by nutrients, mainly phosphorus run-off from agricultural activities until the end of sugar cane cultivation in the late 1900s. This led to P concentration remain high at hypereutrophic state that was irremediable even after a 5-fold reduction in source water nutrient concentration. Objective: The main goal of this research paper is to apply two different mathematical approaches to assess the eutrophication level of a wetland in Puerto Rico. Method: Grey Cluster Method (GCM) was used to classify LC’s eutrophic state by applying the International and Chinese trophic standards and two parameters, total phosphorous (TP) and total nitrogen (TN). Mean TP and TN from LC consolidated bottom substrate and flocculence samples were used to classify LC. To address whether LC can recover, soluble reactive phosphorus (SRP) and TP from LC inlet, outlet and center water samples were used to model (differential equation) the input and loss of phosphorus in LC and determine whether an equilibrium point exists. GCM analysis classified LC as a eutrophic wetland using the International standard and hypereutrophic using the Chinese standard. Results: Trophic state classification did not vary with use of consolidated bottom substrate versus flocculence samples. The differential equation model showed that SRP and TP levels within LC were higher than levels of SRP and TP entering LC, which could be caused by a nutrient recycling process within LC that may predict failure of remediation efforts. An equilibrium point was found at the eutrophic level, which means that even if there is a reduction in phosphorus input, there will not be a change in LC’s eutrophic state. Conclusions: Chinese trophic standard indicated LC was in a hypertrophic state. Similar results were found using the international standard. The differential equation model showed that LC is irreversible.

Although satellite remote sensing technology is intensively used for the monitoring of water quality, the inversion of coastal water bodies and non-optically active parameters is still a challenging issue. Few ongoing studies use remote sensing technology to analyze the driving forces of changes in water quality from multiple aspects based on inversion results. By the use of Landsat 5/8 imagery and measured in situ data of the total nitrogen (TN) and total phosphorus (TP) in the Shenzhen-Hong Kong Bay area from 1986 to 2020, this study evaluated the modeling effects of four machine learning methods named Tree Embedding (TE), Support Vector Regression (SVR), Gaussian Process Regression (GPR), and Back-propagation Neural Network (BPNN). The results show that the BPNN creates the most reliable and robust results. The values of the obtained correlation coefficients (r) are 0.83, 0.92, 0.84, and 0.90, and that of the coefficients of determination (R2) are 0.70, 0.84, 0.70, and 0.81. The calculated mean absolute errors (MAEs) are 0.41, 0.16, 0.06, and 0.02, while the root mean square errors (RMSEs) are 0.78, 0.29, 0.12, and 0.03. The concentrations of TN and TP (CTN, CTP) in the Shenzhen Bay, the Starling Inlet, and the Tolo Harbor were relatively high, fluctuated from 1986 to 2010, and decreased significantly after 2010. The CTN and CTP in the Mirs Bay kept continuously at a low level. We found that urbanization and polluted river discharges were the main drivers of spatial and inter-annual differences of CTN and CTP. Temperature, precipitation, and wind are further factors that influenced the intra-annual changes of CTN and CTP in the Shenzhen Bay, whilethe expansion of oyster rafts and mangroves had little effect. Our research confirms that machine learning algorithms are well suited for the inversion of non-optical activity parameters of coastal water bodies, and also shows the potential of remote sensing for large-scale, long-term monitoring of water quality and the subsequent comprehensive analysis of the driving forces.

Afforestation plays an important role in controlling soil erosion and nutrient loss on the Loess Plateau in China. However, previous studies on soil nutrient changes have mainly focused on the effects of tree species, whereas little is known about how changes in shrubs and herbs caused by afforestation drive soil nutrient changes. In this study, we examined the variation characteristics of understory vegetation and soil nutrients for different vegetation types. The results showed that compared to abandoned farmland, plantations significantly increased soil organic carbon and total nitrogen but had no significant effect on total phosphorus. Robinia pseudoacacia L. forests were more effective than Pinus tabuliformis Carr. forests in increasing soil nutrient content. In addition, herbaceous vegetation in the R. pseudoacacia forest better explained the soil nutrient variation, and herb abundance was the best explanatory variable; however, shrub vegetation contributed more to soil nutrient variation in the P. tabuliformis forest, and shrub abundance contributed the most. Accordingly, we determined that understory plant abundance, rather than species richness, may be the most important factor driving soil nutrient changes. Specifically, herb abundance in the R. pseudoacacia forest may drive soil nutrient changes mainly by regulating herb biomass and litter biomass. By contrast, shrub abundance in the P. tabuliformis forest indirectly affected soil organic carbon mainly by altering shrub biomass. Furthermore, although the phylogenetic relationships had less effect on soil nutrients than species composition, they also made important contributions. Therefore, the phylogenetic relationships should also be considered in addition to species composition when assessing the impact of vegetation on soil properties in the future.

The Ashe River Basin (ARB), long known as the “Golden Waterway” in Manchu, has become one of China’s most polluted rivers. The basin area of the Ashe River is 3545 km2 and the total length of the river is 257 km. There have not been specific studies on land use change and non-point pollution in the ARB region. This paper uses the ARB watershed as the study area, simulates the watershed using the SWAT (Soil and Water Assessment Tool) model, and analyzes the hydrological processes and the temporal and spatial changes of total nitrogen and total phosphorus in the watershed with hydrology and water quality as the objectives under different periods of land use to reduce pollution in the watershed and protect the environment. The results show that the simulation of runoff, and even the R2 and NS (both the coefficient of determination and the Nash–Sutcliffe efficiency coefficient are simulated by SWAT-CUP, which is generally used to validate the simulation results of the hydrological model, where the closer the result is to 1, the better the effect) of total nitrogen and total phosphorus in the watershed, are also all above 0.75 and have good applicability during regular and validation periods. Since 2000, the simulated monthly average total nitrogen and total phosphorus levels have progressively grown. The most polluted areas are concentrated in the middle and lower reaches of the watershed near the main streams owing to the rise in load per unit area caused by the collection of pollutants from the upper watershed to the watershed outlet, and even an increase in fertilizer application due to the larger area of cultivated land.

Protecting the quality of coastal water bodies requires the assessment of contaminant discharge brought by rivers. Numerous methods have been proposed for calculating sediment and nutrient loads. The most widely used and generally recommended are the flow-weighted mean concentration method (FWMC) and the flow duration rating curve method (FDRC). In the Mediterranean basin, the hydrology is characterized by infrequent but very intense rainfall events. The flows taking place during these periods last only a few hours to a few days but can represent the largest part of the annual flow. The loads associated with these events can also account for most of the annual load. A reinforced water-quality monitoring program (especially during floods) was carried out for five years (August 2015–July 2020) on six tributaries of French Mediterranean lagoons. The loads calculated by FWMC and FDRC methods were very different. Total suspended solid loads calculated by FWMC were on average 5.0 times higher than those calculated by FDRC. Similarly, total phosphorus loads were 3.5 times higher and total nitrogen loads were 1.6 times higher. The results show that too many flood samples can lead to considerable overestimation of particulate loads calculated by the FWMC method. Dissolved nutrients, on the other hand, are much less subject to overestimation.

Total phosphorus (TP) is a significant indicator of water eutrophication. As a typical macrophytic lake, Lake Baiyangdian is of considerable importance to the North China Plain’s ecosystem. However, the lake’s eutrophication is severe, threatening the local ecological environment. The correlation between chlorophyll and TP provides a mechanism for TP prediction. In view of the absorption and reflection characteristics of the chlorophyll concentrations in inland water, we propose a method to predict TP concentration in a macrophytic lake with spectral characteristics dominated by chlorophyll. In this study, water spectra noise is removed by discrete wavelet transform (DWT), and chlorophyll-sensitive bands are selected by gray correlation analysis (GRA). To verify the effectiveness of the chlorophyll-sensitive bands for TP concentration prediction, three different machine learning (ML) algorithms were used to build prediction models, including partial least squares (PLS), random forest (RF) and adaptive boosting (AdaBoost). The results indicate that the PLS model performs well in terms of TP concentration prediction, with the least time consumption: the coefficient of determination (R2) and root mean square error (RMSE) are 0.821 and 0.028 mg/L in the training dataset, and 0.741 and 0.029 mg/L in the testing dataset, respectively. Compared with the empirical model, the method proposed herein considers the correlation between chlorophyll and TP concentration, as well as a higher accuracy. The results indicate that chlorophyll-sensitive bands are effective for predicting TP concentration.

The foundation of managing excess nutrients in river is the identification of key physical processes and the control of decisive influencing factors. The existing studies seldom consider the influence of rainfall-runoff relationship and only focus on a few anthropogenic activities and natural attributes factors. To address this issue, a comprehensive set of influencing factors including rainfall-runoff relationship (represented by runoff coefficient), basic physical and chemical parameters of water quality, land use types, landscape patterns, topography, and socioeconomic development was constructed in this study. M–K test and cluster analysis were conducted to identify the temporal mutation and spatial clustering characteristics of NH3-N and TP in Huangshui River basin, respectively. Partial least squares regression was used to elucidate the linkages between water contaminants and the factors. As shown in the results, the temporal mutations of NH3-N and TP were obvious in the middle reaches, with 4 out of 7 catchments in the middle reaches have a larger number of mutations of NH3-N than other catchments. The cluster analysis results of NH3-N and TP among catchments were similar. This study also indicated that although the Huangshui River basin was located in the upper reaches of the Yellow River, the influences of rainfall-runoff relationship on spatiotemporal changes of NH3-N and TP in its sub-basins were limited. Only the temporal change of NH3-N in Jintan catchment in the upstream area was significantly affected by runoff coefficient. The indexes of proportion of water area (PWA), proportion of impervious area (PIA), and proportion of primary industry (PPI) were the top three influencing factors of temporal variation of NH3-N and TP for most catchments in the middle reaches. The temporal change of NH3-N in Jintan catchment in the upstream area was obviously affected by runoff coefficient. The spatial variation of NH3-N and TP were all affected by PWA and proportion of secondary industry significantly. The results of this study can provide theoretical basis and technical support for the control and management of nitrogen and phosphorus pollution in upper reaches of rivers. [ABSTRACT FROM AUTHOR]

Background: Cyanobacterial blooms are of increasing concern for drinking water supply. In Sweden, a survey among drinking water producers showed that the sense of urgency was little. At 60% of the Swedish drinking water treatment plants, operators lacked monitoring strategies. To get a picture of the size of the problem the presence of cyanobacterial risk in 108 Swedish lakes was evaluated from 23 years of environmental monitoring data. The drivers and indicators for cyanobacterial growth were investigated by analyzing water quality in 9 lakes that have more frequent cyanobacteria bio-volume above the WHO drinking water alert level 1: 0.2 mm3L−1. Results: The study shows that the most common species in those lakes are Anabaena/Dolichospermum and Aphanizomenon followed by Microcystis, Woronichinia and Planktothrix, which can produce a variety of toxins such as anatoxins, cylindrospermopsins, microcystins and saxitoxins, supported by literature study. Our results show that cyanobacterial risk in those problematic 9 lakes are mainly nutrients driven with possibly contribution of increased organic matter. By applying non-linear quantile regression with total phosphorus (TP) as an example, we demonstrated that certain drivers such as TP can be useful for cyanobacterial risk assessment and provide control measures by setting nutrients targets. We also evidenced that cyanobacterial peaks presented at low TN:TP ratio while not necessarily vice versa. We also further evaluated that chlorophyll-a and transparency might be suitable as indicators for cyanobacterial blooms in certain lakes, while for most of the lakes, their connection is low. Conclusion: Nutrients are main drivers for higher cyanobacterial occurrence in the 9 lakes. We suggest TP concentrations should be investigated thoroughly to provide important knowledge which can be used to set nutrient targets to sustain safe drinking water supply and recreational services. The complexity of indicating cyanobacterial risk in a local condition was also highlighted in this study and future study is suggested. To classify different types of lake and identify their drivers and the similarities of species composition changes in those lakes will be future studied. [ABSTRACT FROM AUTHOR]

From a water quality perspective, adaptation to climate change means reducing pollutants (total phosphorus in this study) increased by climate change to the current state. In this study, best management practices (BMPs) are presented to maximize the cost-effective pollutant reduction effect for adapting to climate change. Multi-purpose optimization by direct driving of soil water assessment tool (SWAT) requires unrealistic simulation time. Therefore, in this study, after setting various BMPs scenarios based on the identification of BMPs applicable for each land use, TP reduction efficiency, and cost required for each scenario were databased. Using this database, multi-purpose optimization was performed without direct simulation of SWAT. The method proposed in this study significantly reduced the number of SWAT simulations and climate change adaptation in the upper reaches of Namgang Dam in Korea was possible with sufficient investigations with only 18 SWAT simulation results. The finally derived BMPs plans was displayed on a map so that the exact location of the BMPs facilities could be identified. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published reports suggest efforts designed to prevent the occurrence of harmful algal blooms and hypoxia by reducing non‐point and point source phosphorus (P) pollution are not delivering water quality improvements in many areas. Part of the uncertainty in evaluating watershed responses to management practices is the lack of standardized estimates of phosphorus inputs and outputs. To assess P trends across the conterminous United States, we compiled an inventory using publicly available datasets of agricultural P fluxes, atmospheric P deposition, human P demand and waste, and point source discharges for 2002, 2007, and 2012 at the scale of the 8‐digit Hydrologic Unit Code subbasin (∼1,800 km2). Estimates of agricultural legacy P surplus accumulated from 1945 to 2001 were also developed. Fertilizer and manure inputs were found to exceed crop removal rates by up to 50% in many agricultural regions. This excess in inputs has led to the continued accumulation of legacy P in agricultural lands. Atmospheric P deposition increased throughout the Rockies, potentially contributing to reported increases in surface water P concentrations in undisturbed watersheds. In some urban areas, P fluxes associated with human waste and non‐farm fertilizer use has declined despite population growth, likely due, in part, to various sales bans on P‐containing detergents and fertilizers. Although regions and individual subbasins have different contemporary and legacy P sources, a standardized method of accounting for large and small fluxes and ready to use inventory numbers provide essential infromation to coordinate targeted interventions to reduce P concentrations in the nation's waters. Plain Language Summary: Excessive phosphorus (P) concentrations in surface water endanger public health and welfare by contributing to harmful algal blooms and hypoxic zones. Many efforts to decrease P pollution to the nation's waters have not achieved desired outcomes. To help decision‐makers develop strategies to decrease P loads, we developed an inventory of inputs and outputs of P across the United States. This inventory reveals the source and magnitude of P in a local area and how it changes through time. We found that agricultural P inputs were the largest source of P nationwide and inefficiencies in use contribute to the continued accumulation of phosphorus across the landscape. This excess phosphorus may make it more difficult to achieve water quality goals. However, many agricultural regions in the eastern and western United States demonstrated more efficient use of phosphorus fertilizer in 2012. On another positive note, urban areas in certain regions have likely decreased their fertilizer application rates, the amount of P being released by detergents, and point source loads. These efforts may have contributed to recent reports of improved water quality in more urbanized watersheds. Decision makers should consider the role of current fluxes and legacy P when designing strategies to reduce P pollution. Key Points: Agricultural surplus declined by 8% for the entire US and declines are seen in many subbasins of the eastern and western United StatesAtmospheric phosphorus (P) deposition increased by 9% from 2002 to 2012, coincident with increases in stream P concentrations in undisturbed watershedsSummed legacy P surplus accumulation is more than 50 times contemporary P surplus and may perpetuate eutrophication in the nation's waters [ABSTRACT FROM AUTHOR]

Olive oil mill wastewater is a strong pollutant with low pH (4.63) and high salinity (2.70 dS m−1), organic matter (chemical oxygen demand (COD) = 7910 mg L−1), total phosphorus (1049.7 mg L−1), total phenols (540.4 mg L−1) and turbidity (280.1 NTU). This study provides the first application of precipitation processes using HCl, H2SO4, HNO3, NaOH and Ca(OH)2 to olive oil mill wastewater in order to reduce COD, total phosphorus, turbidity, calcium, total phenols and absorbances at 220, 254, 410 and 600 nm. Application of HCl was capable of reducing initial COD (11.4%), turbidity (87.8–98.4%), calcium (100%), total phosphorus (22.1%) and absorbances at 254 nm (12.5–23.5%), 410 nm (46.1–57.9%) and 600 nm (47.4–63.6%) due to the destabilization of suspended and colloidal matter. H2SO4 process allowed removals of turbidity (82.5–97.4%), total phosphorus (14.3–26.9%), calcium (100%) and absorbances at 254 nm (10.9–22.9%), 410 nm (43.4–56.6%) and 600 nm (94.2–96.8%). Experiments conducted using HNO3 showed a positive effect on the removal of COD (10.5–23.6%), total phosphorus (18.9%), turbidity (78.3–94.3%), total phenols (4.6–24.6%) and absorbances at 254 nm (40.5–72.0%), 410 nm (59.1–70.3%) and 600 nm (82.5–91.4%). The advantages of the application of Ca(OH)2 precipitation constituted the removals of COD (11.4–17.8%), total phosphorus (23.6–42.2), turbidity (60.9–100%), total phenols (25.9–48.0%) and absorbances at 220 nm (10.3–33.5%), 254 nm (18.5–45.9%), 410 nm (34.2–81.6%) and 600 nm (22.1–77.3%) owing to formation and precipitation of calcium and magnesium carbonates, magnesium hydroxide and phosphates. Similar results were obtained for NaOH precipitation: COD (19.9–21.5%), total phosphorus (5.9–22.7%), turbidity (80.3–99.4%), total phenols (32.9–55.4%) and absorbances at 220 nm (2.8–11.9%), 410 nm (10.4–44.5%) and 600 nm (24.4–91.9%). [ABSTRACT FROM AUTHOR]

To improve the precision of water quality forecasting, the variational mode decomposition (VMD) method was used to denoise the total nitrogen (TN) and total phosphorus (TP) time series and obtained several high- and low-frequency components at four online surface water quality monitoring stations in Poyang Lake. For each of the aforementioned high-frequency components, a long short-term memory (LSTM) network was introduced to achieve excellent prediction results. Meanwhile, a novel metaheuristic optimization algorithm, called the chaos sparrow search algorithm (CSSA), was implemented to compute the optimal hyperparameters for the LSTM model. For each low-frequency component with periodic changes, the multiple linear regression model (MLR) was adopted for rapid and effective prediction. Finally, a novel combined water quality prediction model based on VMD-CSSA-LSTM-MLR (VCLM) was proposed and compared with nine prediction models. Results indicated that (1), for the three standalone models, LSTM performed best in terms of mean absolute error (MAE), mean absolute percentage error (MAPE), and the root mean square error (RMSE), as well as the Nash–Sutcliffe efficiency coefficient (NSE) and Kling–Gupta efficiency (KGE). (2) Compared with the standalone model, the decomposition and prediction of TN and TP into relatively stable sub-sequences can evidently improve the performance of the model. (3) Compared with CEEMDAN, VMD can extract the multiscale period and nonlinear information of the time series better. The experimental results proved that the averages of MAE, MAPE, RMSE, NSE, and KGE predicted by the VCLM model for TN are 0.1272, 8.09%, 0.1541, 0.9194, and 0.8862, respectively; those predicted by the VCLM model for TP are 0.0048, 10.83%, 0.0062, 0.9238, and 0.8914, respectively. The comprehensive performance of the model shows that the proposed hybrid VCLM model can be recommended as a promising model for online water quality prediction and comprehensive water environment management in lake systems.

First, this paper presents a thorough review of water quality data using a rainwater tank, categorizing the data as with and without sedimentation. Data are presented showing minimum, maximum, and mean values for the different parameters. The data measured from several sources reveal that water collected from the tank is much better than the water directly collected from the roof. In addition, to analyse the phenomena through a mathematical model, a hypothetical 5 kL rainwater tank with a 200 m2 roof was modelled with the MUSIC model. The simulations were compared with the measured water quality data from a rainwater tank in Melbourne. In general, we found that MUSIC’s simulations on the mean daily concentrations of total suspended solids (TSS) and total phosphorus (TP) are slight underestimations compared to the measured data from Melbourne. Further MUSIC simulations reveal that significant reductions in the daily maximum concentrations of TSS, TP, and total nitrogen (TN) are expected through a rainwater tank.

Total phosphorus and nitrate nitrogen can be analyzed simultaneously and rapidly in denitrifying phosphorus removal with near infrared spectroscopy technology and extreme learning machine. In modeling, the second derivative, multiple scattering correction, wavelet denoising and principal component analysis were applied to preprocess the raw spectral data. The results show that wavelet denoising combined with principal component analysis is the optimal preprocessing method. The model for rapid analysis of total phosphorus showed that the corrected correlation coefficient (rc) and predictive correlation coefficient (rp) were respectively 0.9232 and 0.9024, and that the corrected root mean square error (RMSECV) and predicted root mean square error (RMSEP) were 0.0203 and 1.4013, respectively. The model for rapid analysis of nitrate nitrogen showed that the rc and rp were respectively 0.9028 and 0.8958, and that the RMSECV and RMSEP were 0.0222 and 0.0299, respectively. The study shows that the extreme learning machine, combined with near infrared spectroscopy technology, is capable of simultaneous rapid analysis of total phosphorus and nitrate nitrogen in denitrifying phosphorus removal system, which provides a theoretical basis for real-time monitoring of water quality indicators in wastewater treatment. [ABSTRACT FROM AUTHOR]

Retention efficiency of the sewage treatment plant of Trenque Lauquen city (Buenos Aires). The Trenque Lauquen sewage treatment plant was created in 1992 when the population was substantially smaller. The objective was to determine its retention efficiency since its effluents could cause a strong negative impact on the environment. To evaluate the efficiency under extreme temperature conditions, samples of total suspended solids (TSS), chlorophyll, and total nitrogen (TN) and phosphorus (TP) were taken throughout the plant in winter and summer. The Imhoff well retained 2437 % TSS and always retained 100 % of the inorganic suspended solids. Although the plant retained between 1120 % TN and 1117 % TP, the plant discharge values (2341 mgNT/L and 3.94.1 mgPT/L) still exceed the law allowance. Variations in retention between contrasting seasons were mainly due to an increase in biological activity in summer. Retention efficiency could be improved by the use of phytoremediation, plant maintenance and expansion of existing facilities. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Hydrobiology is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The information on changes in total phosphorus and total nitrogen concentrations of lake in response to variations of different nutrients loading is critical for the selection of an appropriate lake management strategy. This study aimed to evaluate the influence of internal and external nutrients loading in controlling in-lake nutrient concentrations in a shallow lake system. This study was conducted in Slim River Lake for 12 months to quantify internal, external total phosphorus and total nitrogen loading, and in-lake total phosphorus and total nitrogen concentrations. Total phosphorus and total nitrogen in storm water and grab water samples were quantified using ascorbic acid and hydrazine reduction method. Study results indicated that internal total phosphorus and total nitrogen loading fluctuated from 150.17 kg to 7,538.33 kg and 2.72 kg to 42.23 kg, respectively, thus suggesting the significant sediment phosphorus and nitrogen released into the water column. Mobilization of nutrients from the surrounding area was indicated by external total phosphorus and total nitrogen loading, which ranged from 19,800 kg to 401,500 kg and 67.81 kg to 4,611.67 kg, respectively. In-lake total phosphorus and total nitrogen concentrations ranged from 1.2 mg/L to 46.22 mg/L and from 0.14 mg/L to 0.65 mg/L, respectively. Pearson correlation analysis suggests that in-lake nutrient concentrations were only significantly correlated to the internal total phosphorus (r = 0.82, p < 0.05) and internal total nitrogen (r = 0.60, p < 0.05) loading. These results indicated that the internal total phosphorus and total nitrogen loading could have more impact on the lake eutrophication as compared to external sources. Hence, future restoration strategies that include internal and external nutrients management should be considered to restore Slim River Lake. [ABSTRACT FROM AUTHOR]

To understand the relationship between planktonic diatoms and environmental variables in the lakes on the Songnen Plain, northeast (NE) China, we investigated water quality and planktonic diatoms from 71 sampling points in 27 lakes, based on which Canonical Correspondence Analysis (CCA) was conducted. The result show that planktonic diatoms displayed certain responses to environment gradients, and the total phosphorus (TP) explained the maximum variation of planktonic diatom species among the 15 environmental variables, suggesting that TP was the most important and significant environmental parameter affecting the distribution of diatom species. In addition, we established a diatom-total phosphorus transfer (DTPT) function, of which component 5 of the weighted averaging partial least squares regression (WAPLS) was chosen to and compared with a series of weighted average regression (WA) models and WA-PLS models. According to the jackknifing statistical test, the component 5 of WA-PLS models provided a lower root-mean-square error prediction (RMSEP=0.202) and a higher correlation coefficient between observation and prediction (R2_Jack=0.759). After deletion of three outliers, the root-mean-square error prediction of the DTPT function was reduced (RMSEP=0.169) while the correlation coefficient between observation and prediction was increased (R2_Jack=0.823). Therefore, this DTPT function performed better than other regional TP models in the world. However, it remains demanding for expanding the background dataset to improve the prediction ability of the model. [ABSTRACT FROM AUTHOR]

Bluegills Lepomis macrochirus R. provide popular sport fisheries but the quality of these fisheries has declined across much of their range. Factors that may influence bluegill demographics were examined in 18 Midwestern (USA) impoundments which contained largemouth bass Micropterus salmoides L., the main apex predator, as well as varying abundances of gizzard shad Dorosoma cepedianum L. and common carp Cyprinus carpio L., which can negatively influence the quality of bluegill populations. Regression models revealed that the relative abundance (catch-per-unit-effort [CPUE], number per hour of electrofishing) of bluegill was positively associated with largemouth bass CPUE and total phosphorous concentration. The total lengths (TL) and ages of the largest and oldest bluegills were negatively associated with common carp CPUE and total annual mortality of bluegills, and positively associated with the TL and age of bluegills when 50% were sexually mature and largemouth bass CPUE. Total annual mortality negatively influenced the TL and age at sexual maturity. Bluegills matured at larger sizes and older ages in impoundments with clearer water. This study revealed the strong influence of mortality on size and age structure and the onset of sexual maturity of bluegill, and the negative influence of common carp on these populations. Management strategies to improve bluegill populations should involve reducing bluegill mortality and common carp populations. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To assess the performance and the impact of nutrient discharges of the wetland on the receiving river, the Hydrologic Engineering Centers River Analysis System (HEC-RAS) and the River and Stream Water Quality (QUAL2K) models are examined in this study to evaluate a constructed wetland in the City of Edmonton in Canada. According to the simulation results from the HEC-RAS model and the QUAL2K model, the removal efficiencies of total nitrogen (TN) by the wetland are 25.64% and 13.59%, respectively. For the total phosphorus (TP), the removal efficiencies are similar to the simulation results between the HEC-RAS model and the QUAL2K model, which are 50.00% and 50.91%, respectively. The water quality simulation results from the HEC-RAS model of the wetland and QUAL2K model are both acceptable compared to the on-site field data. With the analysis of the two modeling systems and comparison between their water quality simulation results, the HEC-RAS model gives better performance than the QUAL2K model for this field case. Subsequently, the validated and customized HEC-RAS model is applied for analyzing and predicting the wetland performance, water quality parameter changes and the risks of the wetland effluents on the receiving river water under wetland design scenarios. [ABSTRACT FROM AUTHOR]

Abstract The effects of an invasive species on the environment can be altered by anthropogenic activities such as nutrient pollution or the presence of additional invasive species with similar or unique traits. Using experimental mesocosms, we tested the separate and combined effects of three invasive mollusks (zebra mussels, Asian clams, and banded mystery snails) on freshwater environments in nutrient‐poor and nutrient‐enriched conditions. We predicted that in nutrient‐poor conditions, single mollusk species would reduce the abundance of algae and zooplankton, but nutrient enrichment would mitigate these effects. Regardless of nutrient additions, paired bivalve species would reduce phytoplankton and zooplankton abundance, increasing periphyton biomass. Bivalves and snails paired together would reduce periphyton, phytoplankton, and zooplankton compared to communities with paired bivalve species. Finally, nutrient enrichment would increase the survival or biomass of paired bivalves and snails. Single, paired, and three co‐occurring invasive mollusks did not affect algae or zooplankton abundance. Banded mystery snails reduced nutrient concentrations in high‐nutrient conditions more than other invasive species, but the reduced nutrients did not affect algal abundance. Paired invasive species did not affect the survival or biomass of other invasive species. Nutrient enrichment increased the biomass of zebra mussels and mystery snails, but not Asian clams. Additionally, zebra mussel reproduction increased in the high‐nutrient treatment when banded mystery snails were present, but not when all three species were together. We conclude that human‐induced trophic states might determine the effects that single and multiple invasive species have in freshwater environments.

Whether or not chlorophyll a (Chla) is limited by nitrogen (N) or phosphorus (P), or both, remains highly debated. In part this is due to the lack of a robust statistical rarely considered using a statistical method in studies of peer-review research of lakes. Individual studies only used the use of the relationship between Chla and nutrients to judge the effects of N and P, ignoring the spatial heterogeneity of the ecological environment. Here, we evaluated the effects of nitrogen and phosphorus on Chla via a meta-analysis. The dataset consists of 1024 observations from 34 lakes in China. The results show that Chla is one of the most important indicators of water eutrophication, both nutrients were related Chla trophic state, and that TP plays an important role over TN, especially in the hypereutrophic Chla conditions. With the increase of TN/TP, Chla concentration is decreased, which may be the co-limited of TN and TP. These three values largely explained the increment of eutrophication Chla, although the relative effects differed across nutrients, with changes in the TN total contributing 5.2% of the increment in Chla, while the TP change contributed 272.0% of the increment in Chla. At spatial scales, logarithm-transformed response ratio ( $\ln RR$ ) of Chla indicated that the lake shifts from N limitation (64.0% > 28.0%) in oligo-mesotrophic to P limitation (170.0% > 99.0%) in eutrophic and co-limitation (66.0% and 46.0%) by N & P in hypereutrophic. These results demonstrate that TP reduction can mitigate eutrophication in most large lakes but a dual TN and TP reduction may be needed in eutrophic lakes, especially in hypereutrophic states. This study highlights the differential effects of the three factors concentration, which may offer important implications for better management of the response of the eutrophication lakes to nutrients (N and P) in the future.

Large rivers are important links between continents and oceans for material flows that have a global impact on marine biogeochemistry. Processes in the catchment areas of large rivers can affect the flow of solutes into the global ocean. The goal was to determine how the concentration of individual components of nutrients in the rivers of Eastern Siberia changes depending on the active layer thickness of the permafrost (ALT) and to elucidate whether the ALT is a factor that can control nutrient flux to the Arctic Ocean. The method of canonical correlation analysis was applied to the data on the concentration of nutrients in the 12 largest rivers of Eastern Siberia and the active layer thickness in their catchments. We found that the concentration of nutrients such as ammonium ion (NH4) and total phosphorus (Ptotal) in river waters is higher in catchments with a deeper active layer. The waters of the mountain rivers in the south of the region (the Chara and Vitim rivers) are the richest in nutrients. Arctic rivers such as the Indigirka and Anabar were low in nutrients. The permeability of soils also affects the discharge of nutrients into rivers with surface runoff. We conclude that in the future, in the context of global climatic changes and the projected deepening of the active layer throughout the permafrost zone of the Northern Hemisphere, an increase in the supply of nutrients to the Arctic Ocean is possible.

In recent years, freshwater resource contamination by non-point source pollution has become particularly prominent in China. To control non-point source (NPS) pollution, it is important to estimate NPS pollution exports, identify sources of pollution, and analyze the pollution characteristics. As such, in this study, we established the modified export coefficient model based on rainfall and terrain to investigate the pollution sources and characteristics of non-point source total nitrogen (TN) and total phosphorus (TP) throughout the Huangqian Reservoir watershed—which serves as an important potable water source for the main tributary of the lower Yellow River. The results showed that: (1) In 2018, the non-point source total nitrogen (TN) and total phosphorus (TP) loads in the Huangqian Reservoir basin were 707.09 t and 114.42 t, respectively. The contribution ratios to TN export were, from high to low, rural life (33.58%), farmland (32.68%), other land use types (20.08%), and livestock and poultry breeding (13.67%). The contribution ratios to TP export were, from high to low, rural life (61.19%), livestock and poultry breeding (21.65%), farmland (12.79%), and other land use types (4.38%). The non-point source pollution primarily originated from the rural life of the water source protection zone. (2) Non-point source TN and TP pollution loads and load intensities showed significantly different spatial distribution patterns throughout the water source protection area. Specifically, their load intensities and loads were the largest in the second-class protected zone, which is the key source area of non-point source pollution. (3) When considering whether to invest in agricultural land fertilizer control or rural domestic sewage, waste, and livestock manure pollution control, the latter is demonstrably more effective. Thus, in addition to putting low-grade control on agricultural fertilizer loss, to rapidly and effectively improve potable water quality, non-point source pollution should, to a larger extent, also be controlled through measures such as establishing household biogas digesters, introducing village sewage treatment plants, and improving the recovery rate of rural domestic garbage. The research results discussed herein provide a theoretical basis for formulating a reasonable and effective protection plan for the Huangqian Reservoir water source and can potentially be used to do the same for other similar freshwater resources.

A laboratory experiment was conducted to determine the extent and the importance of phosphorus (P) fractions of some agriculturally important Sudanese soils on P availability. The soils were gathered from different locations in Sudan, to represent three different orders: Aridisols (Um Dum soil, North Kordofan state), Alfisols (Hagu soil, Senar state), and Vertisols (Hosh soil, Gezira state). The soil P was fractionated using an authenticated procedure. The results showed that the soils had low total, organic and available P contents. Most of the inorganic soil P was present in the Fe-Al fraction in Um Dum soil (> 50%), and about 40% of this fraction in Hagu soil, but, only 20% in alkaline Hosh soil. The Ca-P fraction constituted > 60% in Hosh soil, about 40% in Hagu soil and 20 % in Um Dum soil. The available P in the top soils studied was positively related to the percent sum of Al+Fe -P of the total P, and was negatively related to the percent Ca-P fraction content of the total P. It has been proposed that the P sorption starts by exchange with singly coordinate Fe or Al- OH clay (OH− edge group) and quickly reorganizes into more stable and less soluble ring forms especially at pH more than 7.0, Alkaline pH more than 8.0 in soil like Hosh, will in presence of Ca, favour with time, the formation of inactive less soluble form like octacalcium phosphates and apatites at expense of the initial Al and Fe-P forms which are less stable at alkaline pH.

Objective Swine manure in Korea is separated into solid and liquid phases which are composted separately and then applied on land. The nutrient accumulation in soil has been a big issue in Korea but the basic investigation about nutrient input on arable land has not been achieved in detail. Within the nutrient production from livestock at the national level, most values are calculated by multiplication of the number of animals with the excreta unit per animal. However, the actual amount of nutrients from swine manure may be totally different with the nutrients applied to soil since livestock breeding systems are not the same with each country. Methods This study investigated 15 farms producing solid compost and 14 farms producing liquid compost. Composting for solid phase used the Turning+Aeration (TA) or Turning (T) only methods, while liquid phase aeration composting was achieved by continuous (CA), intermittent (IA), or no aeration (NA). Three scenarios were constructed for investigating solid compost: i) farm investigation, ii) reference study, and iii) theoretical P changes (ΔP = 0), whereas an experiment for water evaporation was conducted for analyzing liquid compost. Results In farm investigation, weight loss rates of 62% and 63% were obtained for TA and T, respectively, while evaporation rates for liquid compost were 8.75, 7.27, and 5.14 L/m2·d for CA, IA, and NA, respectively. Farm investigation provided with the combined nutrient load (solid+liquid) of VS, N, and P of 117.6, 7.2, and 2.7 kg/head·yr. Nutrient load calculated from farm investigation is about two times higher than the calculated with reference documents. Conclusion The nutrient loading coefficients from one swine (solid+liquid) were (volatile solids, 0.79; nitrogen, 0.53; phosphorus, 0.71) with nutrient loss of 21%, 47%, and 29%, respectively. The nutrient count from livestock manure using the excretion unit has probably been overestimated without consideration of the nutrient loss.

Flood events, worse condition of surface waters, and pollution of sea waters are associated with the anthropogenic changes in the environment. Increasing pollution and the amount of rainwater – raise the pollution load as a result of increasing the built-up area. The aim of the study was to investigate the pollution load coming from a catchment in Gdansk to the Baltic Sea by stream. The study presents the results of water quality tests in the Oliwa Stream. It is one of the largest rainwater receivers in Gdansk with a catchment area of almost 29 km 2 . Water samples were collected at six points (three in the natural catchment and three in urbanized catchment). The pollutant concentrations were obtained from the tests On the basis of the results, the loads of biogenic compounds introduced into the Gulf of Gdansk were calculated. The largest load of nitrates (V) and total phosphorus is discharged in the summer and amounts to 4 tons NO 3 - and almost 2 tons of total phosphorus per year, respectively. Orthophosphates are discharged mainly in autumn, and their annual load is almost 4 tons. The majority of biogenic substances comes from the urbanized catchment; therefore, it is necessary to locate and limit the sources of pollution in this area.

Blidinje lake is an integral part of the Nature Park Blidinje established in 1995. Blidinje lake is largest mountain lake in Bosnia and Herzegovina (B&H) according to the surface and water supplies. Considering the surface, it is surprising to its low depth and large surface changes.

Study region: The Warnow River Basin, an agriculturally dominated lowland watershed in North-Eastern Germany with a considerable extent of artificial drainage. Study focus: We analyzed a 21-year data set (1990–2010) of dissolved reactive (DRP) and total phosphorus (TP) concentrations in surface waters to evaluate trends and seasonality of phosphorus (P) concentrations and pathways of P losses from soils. New hydrological insights for the region: Phosphorus concentrations were moderately spatially variable over the investigation period and mean DRP and TP concentrations ranged from 57 to 132 mg l−1 and 114 to 184 μg l−1 respectively. The mean annual DRP and TP loads ranged from 0.04 ± 0.01 to 0.15 ± 0.05 and 0.12 ± 0.05 to 0.27 ± 0.06 kg ha−1 a−1, respectively. We detected significant negative temporal trends of P concentrations and loads in the decade 1990–2000. In the 21st century, the TP concentrations and loads tend to increase moderately. The results underline the importance of baseflow for DRP export and storm flow events for TP export, and emphasize the importance of artificial drainage systems modifying the hydrological regime of soils and surface waters alike. The P export rates during storm events and the proportion of particulate phosphorus in artificial drainage systems should be monitored at a higher temporal resolution to obtain a comprehensive database necessary for developing management strategies to reduce P loads in agricultural used landscapes.

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effects of an invasive species on the environment can be altered by anthropogenic activities such as nutrient pollution or the presence of additional invasive species with similar or unique traits. Using experimental mesocosms, we tested the separate and combined effects of three invasive mollusks (zebra mussels, Asian clams, and banded mystery snails) on freshwater environments in nutrient‐poor and nutrient‐enriched conditions. We predicted that in nutrient‐poor conditions, single mollusk species would reduce the abundance of algae and zooplankton, but nutrient enrichment would mitigate these effects. Regardless of nutrient additions, paired bivalve species would reduce phytoplankton and zooplankton abundance, increasing periphyton biomass. Bivalves and snails paired together would reduce periphyton, phytoplankton, and zooplankton compared to communities with paired bivalve species. Finally, nutrient enrichment would increase the survival or biomass of paired bivalves and snails. Single, paired, and three co‐occurring invasive mollusks did not affect algae or zooplankton abundance. Banded mystery snails reduced nutrient concentrations in high‐nutrient conditions more than other invasive species, but the reduced nutrients did not affect algal abundance. Paired invasive species did not affect the survival or biomass of other invasive species. Nutrient enrichment increased the biomass of zebra mussels and mystery snails, but not Asian clams. Additionally, zebra mussel reproduction increased in the high‐nutrient treatment when banded mystery snails were present, but not when all three species were together. We conclude that human‐induced trophic states might determine the effects that single and multiple invasive species have in freshwater environments. [ABSTRACT FROM AUTHOR]

This study presents the principles and methods used in set target water quality values of total phosphorus (TP) in three major rivers of South Korea, such as Nakdong, Geum, and Yeongsan/Seomjin River. The QUALKO model (modified QUAL2E) was applied to establish the target water quality. According to the findings, while determining total maximum daily load (TMDL) targets, the intended use of water, current water quality, load density, and future pollutant elimination plans should be considered. If a watershed fails to meet the target quality standard, then the appropriate plan for the area should be established. In areas where small amounts of pollutants are released, development should be allowed within the limits of compliance with the water quality standards, targeting both development and water quality protection, which is the basic concept of TMDLs. Heavily polluted areas tend to continue releasing large amounts of pollutants, whereas others release only small amounts. The TMDL system is designed to address the problem by encouraging heavily polluted areas to reduce pollutant emission while allowing others to release some for development. The recommendations of this paper provide a reference to the development of a methodology for determining TP water quality considering TMDL. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the reduction of phosphorus from rice mill wastewater by using free floating aquatic plants. Four free floating aquatic plants were used for this study, namely water hyacinth, water lettuce, salvinia, and duckweed. The aquatic plants reduced the total phosphorus (TP) content up to 80% and chemical oxygen demand (COD) up to 75% within 15 days. The maximum efficiency of TP and COD reduction was observed with water lettuce followed by water hyacinth, duckweed, and salvinia. The study also aims to predict phosphorus removal by three modeling techniques, for example, linear regression (LR), artificial neural network (ANN), and M5P. Prediction has been done considering hydraulic retention time (HRT), hydraulic loading rate (HLR), and initial concentration of phosphorus (Cin) as input variables whereas the reduction rate of TP (R) has been considered as a predicted variable. ANN shows promising results as compared to M5P tree and LR modeling. The model accuracy is analyzed using three statistical evaluation parameters which are coefficient of determination (R2), root mean square error (RMSE), and means absolute error (MAE). [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Complex flow patterns and hydraulic characteristics could reduce the utilization efficiency of constructed wetland (CW), and consequently, its pollutant removal performance. Thus, it is of great importance to explore the internal flow patterns of CWs. Isotopic molecules exist naturally in CWs and have special properties under liquid conditions; using hydrogen and oxygen isotope technology cannot only reduce secondary pollution but also reflect the hydraulic characteristics of CWs. In the present study, the annual variation of isotopic composition in field-scale CW was investigated to evaluate the long-term feasibility of stable isotopic technology characterizing hydraulic flow patterns. The relationship between nutrients concentration distribution and flow pattern variation in CW under different seasons was discussed as well. Results demonstrated that isotope 18O/16O distribution could be used to determine the internal flow pattern of CW throughout the year, except for preferential flow area of CWs in winter, since more hydraulic retention time is needed to ensure the change of water isotopes due to the small evaporation in winter. Lower ammonia nitrogen concentration was observed in the stagnant area, while the total phosphorus concentration of the stagnant area increased during winter. And more attention should be paid to aquatic plants during the CW design, since it has significant influence on the hydraulic flow patterns of CW. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]

In recent years, sudden water pollution accidents in China’s rivers have become more frequent, resulting in considerable effects on environmental safety. Therefore, it is necessary to simulate and predict pollution accidents. Simulation and prediction provide strong support for emergency disposal and disaster reduction. This paper describes a new two-dimensional water quantity and the quality model that incorporates a digital elevation model into the geographic information system. The model is used to simulate sudden water pollution accidents in the main stream of the Yangtze River and Jialing River in the Chongqing section of the Three Gorges Reservoir area. The sectional velocity distribution and concentration change of total phosphorus are then analyzed under four hydrological situations. The results show that the proposed model accurately simulates and predicts the concentration change and migration process of total phosphorus under sudden water pollution accidents. The speed of migration and diffusion of pollutants is found to be greatest in the flood season, followed by the water storage period, drawdown season, and dry season, in that order. The selection of an appropriate water scheduling scheme can reduce the peak concentration of river pollutants. This study enables the impact of pollutants on the ecological environment of river water to be alleviated, and provides a scientific basis for the emergency response to sudden water pollution accidents in the Three Gorges Reservoir area. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Alfalfa (Medicago sativa L.) is an important forage legume in arid areas, but limited water resources and low fertilizer utilization have restricted its agricultural development. Meanwhile, studies on the effects of integrated water and phosphorus on production performance and water‐use efficiency and phosphorus‐use efficiency of alfalfa, especially on hay yield, phosphorus accumulation, and total phosphorus uptake are rarely reported under drip irrigation. The treatments were a factorial combination of three irrigation rates (5,250, 6,000, and 6,750 m3/ha per year) and four P rates (0, 50, 100, and 150 kg/ha per year) and consisted of 12 treatments for water and P management, arranged in a randomized complete block design with three replicates. Total hay yield and water‐use efficiency and phosphorus‐use efficiency of alfalfa in P2 treatment were significantly greater than those in the P1 and P3 treatments (p <.05), and the total hay yield of alfalfa with phosphorus application increased by 7.43%–29.87% compared with that in the nonphosphorus (P0) treatment under the same irrigation amount. The total phosphorus and available phosphorus concentrations in the 0–20 cm soil layer were greater than those in the 20–40 cm and 40–60 cm soil layers compared with those in the P0 treatment. Correlation analyses showed that total hay yield was significantly positively correlated with total phosphorus uptake and water‐use efficiency (p <.01). The accumulated phosphorus concentration was significantly positively correlated with total phosphorus and available phosphorus concentration (p <.01) and was positively correlated with the phosphorus‐use efficiency (p <.05). The membership function method was used to evaluate all the indicators, and the three treatments that had the greatest influence on the production performance of alfalfa were, in order, W2P2 > W3P2 > W1P2. Therefore, an irrigation rate of 6,000 m3/ha and a phosphorus application rate of 100 kg/ha per year should be considered as the best management for both high yield and water‐use efficiency and phosphorus‐use efficiency of alfalfa. [ABSTRACT FROM AUTHOR]

The quality, productivity and sustainability of soil as well as other terrestrial ecosystem renewable components is determined by the ability to accumulate organic matter. The aim of work is to evaluate the long-term effect of reduced tillage and its combinations with practices for soil improvement on soil organic carbon and macronutrients in different soil layers. The research was carried out in 2016-2017 at the Joniskelis Experimental Station of LRCAF on a clay loam. The following tillage systems were investigated: deep ploughing (DP) shallow ploughing (SP), ploughless tillage (PT), ploughless tillage with lime sludge (PT+LS), ploughless tillage with green manure (PT+GM) and mulch without autumn tillage (NT+WM). The content of SOC, total N, P and K were measured in the soil samples, collected from 0-10, 10-20 and 20-30 cm layers. Compared to DP, the applied reduced tillage systems have led to an increase SOC and Ntot content in the 0-10 cm layer, but these decreased in deeper layers. Total and plant available P, plant available K also increased in the 0-10 cm layer due to additional improvement measures. The stratification of SOC and macronutrients was the least under DP. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Polonorum. Formatio Circumiectus is the property of Wydawnictwo Uniwersytetu Rolniczego im. Hugona Kollataja w Krakowie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A traditional rapid infiltration basin (RIB) has been compared to a modified RIB constructed with manufactured biosorption‐activated media (BAM) to evaluate nitrate removal from wastewater effluent. The RIBs are used for reclaimed and excess stormwater disposal. In this work, a mixture of clay, tire crumb, and sand (CTS) was selected to serve as the BAM material (Bold and Gold™ CTS media). Each RIB was constructed with two feet of either sand or BAM, covering more than 43,600 square feet of surface area. Over an eight‐month period, loadings to the BAM RIB and traditional RIB each approximated 5.4 million gallons (MG) per acre. Water samples collected from lysimeters installed below the 2 foot of sand or BAM materials were analyzed for nutrients. Results suggest that under the conditions of the study BAM removed approximately 31% more nitrate–nitrites and total phosphorus than the traditional RIB. Additionally, BAM removed approximately 18% more total nitrogen than the traditional. Practitioner points: Biosorption‐activated media (BAM) removed nitrate–nitrites from reclaimed water more effectively than sand in rapid infiltration basins.BAM could serve as an alternative media for nutrient removal from water prior to release to the environment.Total nitrogen removal was most influenced by NOx removal, with a few removals influenced by TKN.Nutrients could not be effectively removed using BAM or sand from reclaimed water at threshold concentrations below two parts per million. [ABSTRACT FROM AUTHOR]

Background: Rice paddy wetlands may serve as a nutrient source or sink in agricultural ecosystems. However, the pattern of nutrient loss on a watershed scale is not clear. A year-round on-site observation study based on 6-h intervals was conducted. Rainfall, temperature, runoff nutrient concentrations, and adjacent stream water samples were automatically monitored to uncover the temporal changes in the runoff losses of the predominant nutrient proxies (total N and total P) from a typical rice-planting area (120 ha) in the Yangtze river delta region of China. Results: A high total N concentration in the rice-planting area was observed during the rice-planting season; however, significant fluctuation in the total P was evident throughout the year. The Δtotal N (drainage minus stream) parameter showed negative values with a mean of −0.25 mg L−1, while Δtotal P showed positive values with a mean of 0.06 mg L−1. The annual average N and P runoff from paddy field were 11.6 kg ha−1 and 1.5 kg ha−1, respectively. The window phases for the total N loss were mainly concentrated in the rice-growing season. However, the window phase for the total P loss was more dispersive throughout the year. No apparent relationships were found between rainfall and N and P concentrations by self-organizing map analysis. Conclusions: The high-resolution monitoring, in this study, suggested that nutrient loss loading rather than nutrient concentration was strongly related to surface runoff Therefore, fertilization before high-intensity rainfall should be avoided to mitigate the nutrient runoff losses and maintain the rice wetland eco-function. [ABSTRACT FROM AUTHOR]

Lake sediments are subjected to intensive anthropogenic activities such as dumping of industrial waste water and leakage of P fertilisation from agricultural lands. There has a great body of research focusing on examining phosphorus fractions, which provide fundamental data that facilitate understanding the risk of P-induced eutrophication. Here, we have extracted the data of P fractions from 484 sediment samples residing in 48 lakes mainly in EU, China and USA. NH4Cl-P and total phosphorus (TP) displayed a well linear relationship, but not applicable to all lakes. Six groups were categorised as per the slope and intercept by using the clustering analysis. Specific measures were recommended to curb P release risk by considering the characteristics of each group. For instance, TP controlling is deemed as a priority in group with steep linear dependence of NH4Cl-P on TP. A significant correlation was determined between TP and NaOH-P (r2 = 0.63). Among other findings, larger lake area significantly contributes to lower all P pools. Deeper depth could only pronouncedly influence the BD-P, HCl-P. Additionally, we found lakes in Germany have pronounced higher averaged P pools than other regions. Furthermore, this paper creates awareness of the present status of lake eutrophication for researchers and policy-makers. [ABSTRACT FROM AUTHOR]