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Journal of Environmental Management Jan 2022Streamflow patterns are closely linked with the quality of stream water, but they are often dealt separately. Due to this, the effects of change in streamflow patterns...
Streamflow patterns are closely linked with the quality of stream water, but they are often dealt separately. Due to this, the effects of change in streamflow patterns resulting from river regulation and flow diversion on stream water quality remain under-investigated. This study models change in water quality indicators including pollutants (total suspended solids and turbidity), nutrients (total nitrogen and phosphorus), dissolved oxygen, nitrogen (kjeldahl), pH, and salinity caused by the change in streamflow patterns under different scenarios of river regulation, flow diversion, and rainfall. The generalized additive model was used and the Goulburn-Broken catchment, Australia was chosen as the case study. It was found that concentrations of pollutants and nutrients increased by 38% while dissolved oxygen and nitrogen (kjeldahl) decreased by 35% during the period 1990-2018. These changes were associated with an average increase of 20% in low and medium flows, an average decline of 22% in high and overbank flows and a 15% decline in rainfall. Under the scenario of climate change, river regulation and flow diversion, the overbank flow patterns would mimic the effects of low and medium flows on the water quality indicators that would raise the concentration of pollutants, nutrients, and salinity by 19%. Restoration of high flows would decrease these concentrations by 28% relative to current concentrations, however, it would also reduce dissolved oxygen, nitrogen (kjeldahl), and pH. Effects of streamflow patterns on water quality have implications for environmental flow management, thus, this study recommends critical adjustments in low, medium, and high flows for improving water quality.
Topics: Environmental Monitoring; Nitrogen; Phosphorus; Rivers; Water Quality
PubMed: 34717101
DOI: 10.1016/j.jenvman.2021.113991 -
The Science of the Total Environment Nov 2021A good understanding of the nutrient cycle under a regional development strategy is crucial for nutrient management decision-making. Quantitatively assessment of...
A good understanding of the nutrient cycle under a regional development strategy is crucial for nutrient management decision-making. Quantitatively assessment of nutrient flow under the regional coordinated development strategy in mainland China can provide scientific reference for achieving global high-quality coordinated economic and agricultural development. In this study, the characteristics of nitrogen (N) and phosphorus (P) flows of agricultural systems in mainland China from 1998 to 2030 were quantified using nutrient flows in food chain environment and resource (NUFER) model. The results revealed that national N and P surplus intensity were 50.3 and 18.6 kg·hm in 2018, respectively, and there is still space for soil nutrient retention. The national input and output of N and P showed a continuous upward trend over the last two decades. Chemical fertilizer application and livestock rearing are the key points for nutrient management in China's agricultural systems. Under the regional development strategy, considerable geographical variation in N and P surplus intensity was observed across the country. From 1998 to 2013, the regional distribution of N and P surplus intensity was in accordance with regional economic characteristics. Areas with higher N and P surplus intensities were mainly in the eastern and central regions. From 2014 to 2018, equal emphasis on ecology and economy in the Yangtze River Economic Belt allowed development without aggravating the deterioration of the N and P surplus in the region. Over the next 10 years, our simulation predicts that future nutrient footprints tend to decrease, and coordinated governance of regional development and agricultural environment protection are the key to regional sustainable development.
Topics: Agriculture; China; Fertilizers; Nitrogen; Phosphorus
PubMed: 34225161
DOI: 10.1016/j.scitotenv.2021.148655 -
Environmental Monitoring and Assessment Jun 2023Phosphorus (P) inputs are essential for maximizing agronomic potential, yet high P inputs and subsequent P losses can cause eutrophication of water bodies. There is a... (Meta-Analysis)
Meta-Analysis Review
Phosphorus (P) inputs are essential for maximizing agronomic potential, yet high P inputs and subsequent P losses can cause eutrophication of water bodies. There is a need to evaluate P contents in agricultural soils globally both from an agronomic and environmental perspective. This systematic review and meta-analysis estimated the pooled mean levels of P contents of Iran. In this study, data on available and total P contents of Iran's calcareous soils was compiled (main focus on Olsen P) and compared to (i) estimated Iranian background and global agricultural soil P contents, and (ii) agronomic and (iii) environmentally critical Olsen P values. The pooled mean estimate from the meta-analysis indicates that the levels of Olsen P across 425 soil samples (27 studies) were 21.3 mg kg and total P across 190 soil samples (12 studies) 805.5 mg kg. Using 26 mg kg as the agronomic critical Olsen P value above which no increase in crop yield occurs, crops grown on 61% of the soil samples in the investigated region would respond to P fertilizer and 20% of soils are currently in the optimum category (26-45 mg kg Olsen P). The environmentally critical Olsen P value (~ 63 mg kg), defined as the amount above which P leaches from soil rapidly, was exceeded by 11% of soils with a further 4% of soils with elevated eutrophication risk. To maximize crop yields while maintaining a minimal risk of P leaching in Iran's calcareous soils, we suggest an ideal Olsen P of 26 mg kg. The outcomes from this study inform about the P status of Iranian soils and could help update recommendations for P fertilizer applications in calcareous soils globally. The framework presented here could further be adopted to evaluate the P status in other soil types.
Topics: Soil; Phosphorus; Iran; Fertilizers; Environmental Monitoring
PubMed: 37318653
DOI: 10.1007/s10661-023-11412-5 -
Journal of Environmental Management Dec 2022The slope-gully system, the erosion unit on the Loess Plateau, suffers from severe soil erosion and loss of soil nutrients. Restoring vegetation can effectively reduce...
The slope-gully system, the erosion unit on the Loess Plateau, suffers from severe soil erosion and loss of soil nutrients. Restoring vegetation can effectively reduce soil erosion, thereby reducing the loss of nitrogen and phosphorus. In the Loess Plateau, owing to the shortage of water resources and the adverse effects of over-revegetation, the restoration of vegetation in large areas is limited. To efficiently prevent the loss of soil nutrients and reduce non-point source pollution, vegetation patterns need to be reasonably restored. However, it is currently not clear as to how this can be achieved. Different slope-gully systems were established in this study, including pattern A (no vegetation), pattern B (up-slope vegetation), pattern C (middle-slope vegetation), and pattern D (down-slope vegetation). Then, the effects of vegetation patterns on soil total nitrogen (TN) and soil total phosphorus (TP) losses associated with runoff and sediment processes was quantitatively evaluated through the simulated rainfall. The results showed that (1) vegetation pattern markedly affected the yields of runoff, sediment, soil nitrogen, and soil phosphorus, resulting in the following order: pattern A > pattern B > pattern C > pattern D. (2) The correlation between TN and runoff was higher than that between TN and sediment; conversely, TP was more strongly correlated with sediment than with runoff. (3) Nitrogen loss with runoff was the main source of TN (58.76-90.74%), while phosphorus loss with sediment was the main source of TP (48.51-89.30%). Compared with other vegetation patterns, the down-slope can more effectively reduce the yields of runoff and sediment, thereby reducing the loss of TN and TP. Therefore, it was suggested that the lower part of the slope should be considered when revegetating.
Topics: Phosphorus; Soil; Nitrogen; Environmental Monitoring; China
PubMed: 36179476
DOI: 10.1016/j.jenvman.2022.116288 -
International Journal of Environmental... Nov 2022In order to understand the potential effects of atmospheric nitrogen and phosphorus deposition on the water quality of the Middle Route Project of the South-to-North...
In order to understand the potential effects of atmospheric nitrogen and phosphorus deposition on the water quality of the Middle Route Project of the South-to-North Water Diversion Project, samples of dry and wet deposition of atmospheric nitrogen and phosphorus, meteorological factors, and water quality factors were analyzed out to investigate in the Middle Route Project of the South-to-North Water Diversion in Henan Province from October 2018 to October 2020. The variation characteristics of atmospheric nitrogen and phosphorus deposition with time in the Henan section of the main canal are revealed, and the influence of atmospheric dry and wet deposition on the water quality of the middle line is discussed. It was found that the total nitrogen (TN) sedimentation flux has obvious seasonal variation, which was consistent with the variation trend of rainfall, and increased with the increase of rainfall. Nitrogen and phosphorus deposition was significantly correlated with water factors. The effects of meteorological factors and nitrogen and phosphorus deposition on water quality variation reached 18%. The contribution rate and ecological impact of atmospheric nitrogen and phosphorus deposition on water pollution of main channels will be increasing, which needs to be paid enough attention to.
Topics: Water Quality; Phosphorus; Nitrogen; Environmental Monitoring; Water Pollution; China
PubMed: 36361219
DOI: 10.3390/ijerph192114346 -
Environmental Research Apr 2022The loss of soil organic phosphorus can easily cause water eutrophication. In order to effectively reduce the loss of soil organic phosphorus, this manuscript...
The loss of soil organic phosphorus can easily cause water eutrophication. In order to effectively reduce the loss of soil organic phosphorus, this manuscript investigated the adsorption of soil organic phosphorus by lanthanum modified biochar (BC), traditional adsorbent gypsum (GY) and zeolite (ZE) by taking phytic acid as the representative. The adsorption isotherm model and kinetic models were used to fit the phosphorus absorption characteristics of the adsorbents. The effects of initial pH and temperature on the adsorption capacity were discussed, and the adsorption mechanism of each adsorbent was explained by means of FTIR and XRD. The results showed that the adsorption capacity of phytate phosphorus followed the trend of BCTS > GYTS > ZETS > TS (soil), and the maximum phosphorus adsorption capacity obtained from Langmuir isotherm for treatment with BCTS was 2.836 mg g, and the treatment had the strongest affinity for phytate phosphorus and also the ability to store phosphorus. The adsorption process fits well with Langmuir isotherm equation and pseudo-second-order kinetic equation, and the adsorption behavior of phytate phosphorus was mainly controlled by the chemisorption of monolayer. When the concentration of phytate phosphorus was 100 mg L, percentage of modified biochar added to the soil was 3% and the pH was 6, the adsorption capacity reached the maximum, and the maximum adsorption capacity was 2.000 mg g. The results of FTIR and XRD characterization showed that complexation was the main adsorption mechanism. In this study, the combination of modified biochar and soil phytate phosphorus can provide a good theoretical basis for reducing the loss of soil organic phosphorus.
Topics: Adsorption; Charcoal; Hydrogen-Ion Concentration; Kinetics; Phosphorus; Soil; Water Pollutants, Chemical
PubMed: 34863688
DOI: 10.1016/j.envres.2021.112455 -
Environmental Monitoring and Assessment Apr 2023It is critical to understand the risk of element pollution in soils by evaluating their background levels. Phosphorus (P) content in agricultural soils needs to be...
It is critical to understand the risk of element pollution in soils by evaluating their background levels. Phosphorus (P) content in agricultural soils needs to be assessed from agronomic and environmental standpoints. The current study intended to calculate the background levels of available and total P in soils. To achieve this goal, 50 sites without human activities were selected. Soils were sampled from the surface and subsurface of each site (100 soil samples). The available P forms in soils were extracted using the water-extractable P (WEP), calcium chloride-extractable P (CCEP), and Olsen-extractable P (OEP) methods. The first two extractants are being used to evaluate P leaching from soils, while the last one is being used as an agronomic indicator. The methods used to calculate background levels were the iterative 2-δ technique (2-δ) and the calculated distribution function (CDF). Results showed that the upper limits of background levels using 2-δ method were 1.45, 0.92, 8.12, and 424.4 mg kg for WEP, CCEP, OEP, and total P, respectively. Also, the upper limits of background levels using CDF method were 1.42, 1.15, 12.09, and 447.6 mg kg, for WEP, CCEP, OEP, and total P, respectively. It can be concluded that using these background levels, which for the first time were calculated for P, would enable us to have an accurate examination of P excess as a result of human activities.
Topics: Humans; Soil; Phosphorus; Environmental Monitoring; Agriculture; Water
PubMed: 37081194
DOI: 10.1007/s10661-023-11175-z -
Environmental Monitoring and Assessment Nov 2021It is imperative to have a practical indicator for assessing the potential for phosphorus movement from soil to surface waters causing environmental pollution. The...
It is imperative to have a practical indicator for assessing the potential for phosphorus movement from soil to surface waters causing environmental pollution. The present study was undertaken with two groups of acidic soils from the terai and red and laterite agro-climatic zone of eastern India to estimate their phosphorus threshold values and establish a simple model with the clay content as the principal variable. The mean phosphorus adsorption maximum and phosphorus buffering capacity were higher in lateritic than terai soil. The change-point soil test values at which water soluble phosphorus enhanced abruptly ranged from 32 to 68 mg kg and 28 to 63 mg kg with Bray-1 and Mehlich-1 method, respectively, for the soils of the terai zone. Similarly, it varied from 47 to 90 mg kg and 44 to 89 mg kg, respectively, for the lateritic soils. Application of phosphatic fertilizers should not be allowed beyond the threshold level, which was considered 75% of the change-point soil test value to avoid the risk of the soil becoming a source of phosphorus pollution for surface water bodies. The simplified models of phosphorus threshold level (mg kg) developed with either of the extractants were "4.75 × clay content (%) - 30" and "6.00 × clay content (%) - 75" for terai and lateritic soil, respectively. These models can be extended to the soils with similar mineralogy but varying in clay content for sustainable phosphorus management without limiting crop production.
Topics: Environmental Monitoring; Fertilizers; Phosphorus; Soil; Soil Pollutants
PubMed: 34779945
DOI: 10.1007/s10661-021-09608-8 -
The Science of the Total Environment Nov 2021Ecological stoichiometry is an efficient tool for exploring the balance and cycling of coupled elements (e.g., carbon [C], nitrogen [N], and phosphorus [P]). Therefore,...
Ecological stoichiometry is an efficient tool for exploring the balance and cycling of coupled elements (e.g., carbon [C], nitrogen [N], and phosphorus [P]). Therefore, C:N:P ratios are essential input parameters in most ecological models of productivity or C cycling. However, previous C:N:P ratios estimated using the species arithmetic means exhibit high uncertainty when used as direct model parameters. In this study, we comprehensively calculated C:N:P ratios from organs to ecosystems for 66 typical natural ecosystems in China (e.g., forests, grasslands, and deserts) using the community biomass-weighted mean (CWM), with the consistently measured element data of 3229 site-species combination. The C:N:P ratios were 427:19:1, 885:13:1, 9549:33:1, and 797:18:1 in the leaves, branches, trunks, and roots of terrestrial ecosystems, respectively. Furthermore, the ratios were 91:4:1, 919:17:1, 1121:25:1, and 55:4:1 in ecosystems, plant communities, litter, and soils, respectively. Significant differences were observed in C:N:P ratios among different ecosystem types and biomes, with generally higher ratios in forests. Moreover, the latitudinal patterns of C:N ratios exhibited no obvious trends, whereas both C:P and N:P ratios decreased significantly with increasing latitude, especially in forests. Environmental conditions explained 15.4-86.6% of the spatial variation of C:N:P ratios from organs to ecosystems. In summary, this study systematically demonstrates the variations in biome-scale C:N:P stoichiometry in terrestrial ecosystems, as well as their influencing factors, using the CWM. More importantly, this study provides a systematic dataset of C:N:P ratios from plot to biome scale that can be used to improve relevant ecological models.
Topics: China; Ecosystem; Forests; Nitrogen; Phosphorus
PubMed: 34246133
DOI: 10.1016/j.scitotenv.2021.148849 -
Water Research Aug 2022The framework, model and methods of Nürnberg were applied and evaluated in Lough Neagh and 19 other lakes in order to establish inflow phosphorus concentrations that...
The framework, model and methods of Nürnberg were applied and evaluated in Lough Neagh and 19 other lakes in order to establish inflow phosphorus concentrations that support target lake values. Supporting concentrations, in the absence of an internal load, were derived and the effect of uncertainty in the model retention coefficient was relatively small, ±11-20 % in Lough Neagh and an average (n = 17) of ±9.7 % in the other lakes. There was further support for the model and methods from an independent estimate of the net internal load in Lough Neagh (13 % difference) and from another model in the other lakes (Supporting concentrations, which should be lower, were by an average of 11 mg P m). In the framework, steady state with the phosphorus load is assumed, but, based on a generic lake model, is not likely if the hydraulic residence time>0.5-0.8 yr and should lead to a decrease in phosphorus retention, which was found during three periods in Lough Neagh. Based on a compilation of internal load recovery times from 23 lakes in the literature, it could take between 8 and 20 years for lakes with an internal load to approach their targets.
Topics: Environmental Monitoring; Eutrophication; Lakes; Nitrogen; Phosphorus
PubMed: 35872519
DOI: 10.1016/j.watres.2022.118858