Special Issue "Nitrogen and Phosphorus in Surface- and Ground-Water: Sources, Mechanisms, Processes, and Pathways"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Water Quality and Contamination".

Deadline for manuscript submissions: closed (31 July 2022) | Viewed by 7010

Special Issue Editors

Prof. Dr. Gurpal S. Toor
E-Mail Website
Guest Editor
Department of Environmental Science and Technology, University of Maryland, College Park, MD 20742, USA
Interests: nitrogen; phosphorus; biogeochemistry; water quality; stable isotopes
Prof. Dr. Zhi Li
E-Mail Website
Guest Editor
College of Natural Resources and Environment, Northwest Agriculture and Forestry University, Yangling 712100, China
Interests: hydrological processes; water quality; tracer techniques; land use change effects
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Special Issue Information

Dear Colleagues,

Nitrogen and phosphorus are two critical nutrients for crop productivity and are largely responsible for ensuring adequate food, fiber, and shelter for the growing human population. Abundant availability and excessive use of nutrients to grow food have led to nutrient surpluses in developed countries and mismanagement of nutrients in developing countries. This has resulted in losses of nutrients from land to water bodies, leading to eutrophication, the onset of harmful algal blooms, and hypoxia in water bodies. This Special Issue aims to invite contributions that explore the sources, processes, mechanisms, and pathways of nitrogen and phosphorus losses from land to surface- and ground-water. Example topics of interest include, but are not limited to:

  • Fate and transport of nitrogen and phosphorus in landscapes perturbed by anthropogenic activities (agriculture, urbanization, deforestation, mining, etc.);
  • Tracking sources of nitrogen and phosphorus in water bodies using isotopes and other techniques;
  • Unraveling mechanistic processes driving nitrogen and phosphorus release and transport from land to water;
  • Pathways (leaching, runoff, sub-surface) of nitrogen and phosphorus loss from landscapes to water bodies;
  • Biogeochemistry of nitrogen and phosphorus in the soil–plant–water–atmosphere continuum.

Prof. Dr. Gurpal S. Toor
Prof. Dr. Zhi Li
Guest Editors

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Keywords

  • nitrogen
  • phosphorus
  • water quality
  • surface water
  • ground-water

Published Papers (7 papers)

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Research

Article
Effects of Phosphorus Fertilizer Application Rates on Colloidal Phosphorus Leaching in Purple Soil in Southwest China
Water 2022, 14(15), 2391; https://doi.org/10.3390/w14152391 - 02 Aug 2022
Viewed by 653
Abstract
Phosphorus (P) lost via leaching from agricultural land is of major concern for water resource managers worldwide, and colloidal phosphorus (CP) may have a high contribution, since it is an important mobile form of P in soil and subsurface drainage. The objective of [...] Read more.
Phosphorus (P) lost via leaching from agricultural land is of major concern for water resource managers worldwide, and colloidal phosphorus (CP) may have a high contribution, since it is an important mobile form of P in soil and subsurface drainage. The objective of this study is to relate P fertilization application rates to CP leaching. To eliminate the influence of climate and facilitate the accurate measurement of P contents in different soil layers, we established soil columns to investigate the impacts of fertilizer application rates and timing on P leaching. Therefore, a soil column leaching experiment was undertaken with different P fertilization application rates (0, 20, 40, 100, 200, and 400 mg kg−1) for purple soil in southwest China. P application rates had significant effects on CP and dissolved phosphorus concentrations in the top soils (p < 0.05) (e.g., 0–10 cm in this study), and they further increased P leaching loss by 24–375%. CP was the dominant P form and contributed 31–61% to total phosphorus in the leachate. The concentration of different P forms in leachates decreased significantly over time, and the risk of P leaching loss was greater within two weeks after P application (p < 0.05). The advisable range of P application rate is recommended to be 0–450 kg ha−1 for agricultural practice, and it is also recommended to keep P fertilizer in the soil for more than two weeks. Some countermeasures, related to application rates and timing, should be taken to minimize the buildup of P in the field and reduce the risk of P leaching. Full article
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Article
Alum and Gypsum Amendments Decrease Phosphorus Losses from Soil Monoliths to Overlying Floodwater under Simulated Snowmelt Flooding
Water 2022, 14(4), 559; https://doi.org/10.3390/w14040559 - 12 Feb 2022
Viewed by 627
Abstract
Phosphorus (P) loss from soils poses a threat of eutrophication to downstream waterbodies. Alum (Al2(SO4)3·18H2O) and gypsum (CaSO4·2H2O) are effective in reducing P loss from soils; however, knowledge on their effectiveness [...] Read more.
Phosphorus (P) loss from soils poses a threat of eutrophication to downstream waterbodies. Alum (Al2(SO4)3·18H2O) and gypsum (CaSO4·2H2O) are effective in reducing P loss from soils; however, knowledge on their effectiveness under cold temperatures is limited. This study examined the reduction of P loss from soils with alum and gypsum amendment under simulated snowmelt flooding. Intact soil monoliths (15 cm depth) collected from eight agricultural fields in flood-prone areas of Manitoba, Canada, were surface amended with alum or gypsum, pre-incubated for 2 weeks, then flooded and incubated at 4 °C for 8 weeks. Porewater and floodwater samples collected weekly were analyzed for dissolved reactive P (DRP), dominant cations and anions. An enhanced P release with flooding time was observed in all soils whether amended or unamended; however, alum/gypsum amendment reduced DRP concentrations in porewater and floodwater in general, with alum showing a more consistent effect across soils. The reduction in floodwater DRP concentrations (maximum DRP concentration during flooding) with alum and gypsum ranged from 34–90% and 1–66%, respectively. Based on Visual MINTEQ thermodynamic model predictions, precipitation of P and formation of P-sorbing mineral species with alum and gypsum amendment reduced DRP concentrations at latter stages of flooding. Full article
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Article
Spatial–Temporal Distribution of Phosphorus Fractions and Their Relationship in Water–Sediment Phases in the Tuojiang River, China
Water 2022, 14(1), 27; https://doi.org/10.3390/w14010027 - 23 Dec 2021
Cited by 1 | Viewed by 1061
Abstract
Understanding the distribution and transportation of phosphorus is vital for the sustainable development of aquatic environmental protection and ecological security. The spatial–temporal distribution of phosphorus fractions in water–sediment phases in river systems and their relationships remain unclear in Southwest China. In this study, [...] Read more.
Understanding the distribution and transportation of phosphorus is vital for the sustainable development of aquatic environmental protection and ecological security. The spatial–temporal distribution of phosphorus fractions in water–sediment phases in river systems and their relationships remain unclear in Southwest China. In this study, the spatial and temporal distribution of phosphorus fractions in water–sediment phases in the Tuojiang River, a primary tributary of the Yangtze River which plays important roles in the economy and ecology of the region, and the relationships among the different phosphorus fractions were analyzed. These fractions were soluble reactive phosphorus (SRP), dissolved organic phosphorus (DOP), and total particulate phosphorus (PP) fractions in water, and exchangeable phosphorus (Ex-P), organic phosphorus (Or-P), phosphorus bound by Fe oxides (Fe-P), authigenic phosphorus (Ca-P), detrital phosphorus (De-P), and refractory phosphorus (Res-P) fractions in sediment. The SPR and Fe-P were the dominant phosphorus fractions in the water and sediment, respectively. The TP content was greater in the lower reaches than in the middle and upper reaches. The average abundances of most phosphorus fractions in water–sediment phases showed significant seasonal variations. The Fe-P, Org-P, and TP in sediments were released to the water interface, resulting in the increase of phosphorus in the overlying water. Redundancy analysis (RDA) indicated that the physicochemical properties of water and sediment have a certain influence on the spatial–temporal distribution of the phosphorus fractions. Principal component analysis (PCA) revealed that the main phosphorus source was anthropogenic activities. These results provide primary data regarding phosphorus fractions and contribute to understanding phosphorus cycling and controlling phosphorus pollution in the Tuojiang River. Full article
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Article
Nitrogen Migration and Transformation Mechanism in the Groundwater Level Fluctuation Zone of Typical Medium
Water 2021, 13(24), 3626; https://doi.org/10.3390/w13243626 - 16 Dec 2021
Cited by 1 | Viewed by 878
Abstract
Because of the nitrogen pollution problem in groundwater, the migration conversion mechanism of nitrogen in groundwater level fluctuations was analyzed. Technology and methods through indoor experiments and theoretical analysis were used to study coarse sand, medium sand, and fine sand groundwater level fluctuation [...] Read more.
Because of the nitrogen pollution problem in groundwater, the migration conversion mechanism of nitrogen in groundwater level fluctuations was analyzed. Technology and methods through indoor experiments and theoretical analysis were used to study coarse sand, medium sand, and fine sand groundwater level fluctuation in the aeration zone and saturated zone under the situation of nitrogen distribution characteristics, revealing groundwater level fluctuation with the nitrogen migration mechanism. The experimental results showed that the variation range of the nitrate-nitrogen (NO3−N) concentration with the water level is medium sand > fine sand > coarse sand. The ammonium nitrogen (NH4+−N) concentration showed a downward trend after water level fluctuations, and there were more apparent fluctuations in coarse sand and medium sand. The nitrite nitrogen (NO2−N) in coarse sand and medium sand first increased the water level and then gradually reached a balance. The sampling points below the water level in fine sand showed a downward trend with fluctuation of the water level, and then gradually reached equilibrium. The results provide a scientific basis for the remediation and treatment of soil and groundwater pollution. Full article
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Article
After the Storm: Fate and Leaching of Particulate Nitrogen (PN) in the Fluvial Network and the Influence of Watershed Sources and Moisture Conditions
Water 2021, 13(22), 3182; https://doi.org/10.3390/w13223182 - 11 Nov 2021
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Abstract
Large storms can erode, transport, and deposit substantial amounts of particulate nitrogen (PN) in the fluvial network. The fate of this input and its consequence for water quality is poorly understood. This study investigated the transformation and leaching of PN using a 56-day [...] Read more.
Large storms can erode, transport, and deposit substantial amounts of particulate nitrogen (PN) in the fluvial network. The fate of this input and its consequence for water quality is poorly understood. This study investigated the transformation and leaching of PN using a 56-day incubation experiment with five PN sources: forest floor humus, upland mineral A horizon, stream bank, storm deposits, and stream bed. Experiments were subjected to two moisture regimes: continuously moist and dry–wet cycles. Sediment and porewater samples were collected through the incubation and analyzed for N and C species, as well as the quantification of nitrifying and denitrifying genes (amoA, nirS, nirK). C- and N-rich watershed sources experienced decomposition, mineralization, and nitrification and released large amounts of dissolved N, but the amount of N released varied depending on the PN source and moisture regime. Drying and rewetting stimulated nitrification and suppressed denitrification in most PN sources. Storm deposits released large amounts of porewater N regardless of the moisture conditions, indicating that they could readily act as N sources under a variety of conditions. The inputs, processing, and leaching of large, storm-driven PN inputs become increasingly important as the frequency and intensity of large storms is predicted to increase with global climate change. Full article
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Article
Effect of Biochar Amendment in Woodchip Denitrifying Bioreactors for Nitrate and Phosphate Removal in Tile Drainage Flow
Water 2021, 13(20), 2883; https://doi.org/10.3390/w13202883 - 14 Oct 2021
Viewed by 633
Abstract
Biochar has received increased attention in environmental applications in recent years. Therefore, three pilot-scale denitrifying bioreactors, one filled with woodchips only and the other two enriched with 10% and 20% by volume of biochar from deciduous wood, were tested under field conditions for [...] Read more.
Biochar has received increased attention in environmental applications in recent years. Therefore, three pilot-scale denitrifying bioreactors, one filled with woodchips only and the other two enriched with 10% and 20% by volume of biochar from deciduous wood, were tested under field conditions for the removal of nitrate (NO3-N) and phosphate (PO4-P) from tile drainage water in Lithuania over a 3-year period. The experiment showed the possibility to improve NO3-N removal by incorporating 20% biochar into woodchips. Compared to the woodchips only and woodchips amended with 10% biochar, the NO3-N removal effect was particularly higher at temperatures below 10.0 °C. The results also revealed that woodchips alone can be a suitable medium for PO4-P removal, while the amendment of biochar to woodchips (regardless of 10% or 20%) can lead to large releases of PO4-P and other elements. Due to the potential adverse effects, the use of biochar in woodchip bioreactors has proven to be very limited and complicated. The experiment highlighted the need to determine the retention capacity of biochar for relevant substances depending on the feedstock and its physical and chemical properties before using it in denitrifying bioreactors. Full article
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Article
Evidence of Phosphate Mining and Agriculture Influence on Concentrations, Forms, and Ratios of Nitrogen and Phosphorus in a Florida River
Water 2021, 13(8), 1064; https://doi.org/10.3390/w13081064 - 13 Apr 2021
Cited by 2 | Viewed by 1186
Abstract
Florida has a long history of phosphate-mining, but less is known about how mining affects nutrient exports to coastal waters. Here, we investigated the transport of inorganic and organic forms of nitrogen (N) and phosphorus (P) over 23 sampling events during a wet [...] Read more.
Florida has a long history of phosphate-mining, but less is known about how mining affects nutrient exports to coastal waters. Here, we investigated the transport of inorganic and organic forms of nitrogen (N) and phosphorus (P) over 23 sampling events during a wet season (June–September) in primary tributaries and mainstem of Alafia River that drains into the Tampa Bay Estuary. Results showed that a tributary draining the largest phosphate-mining area (South Prong) had less flashy peaks, and nutrients were more evenly exported relative to an adjacent tributary (North Prong), highlighting the effectiveness of the mining reclamation on stream hydrology. Tributaries draining > 10% phosphate-mining area had significantly higher specific conductance (SC), pH, dissolved reactive P (DRP), and total P (TP) than tributaries without phosphate-mining. Further, mean SC, pH, and particulate reactive P were positively correlated with the percent phosphate-mining area. As phosphate-mining occurred in the upper part of the watershed, the SC, pH, DRP, and TP concentrations increased downstream along the mainstem. For example, the upper watershed contributed 91% of TP compared to 59% water discharge to the Alafia River. In contrast to P, the highest concentrations of total N (TN), especially nitrate + nitrite (NOx–N) occurred in agricultural tributaries, where the mean NOx–N was positively correlated with the percent agricultural land. Dissolved organic N was dominant in all streamwaters and showed minor variability across sites. As a result of N depletion and P enrichment, the phosphate-mining tributaries had significantly lower molar ratios of TN:TP and NOx–N:DRP than other tributaries. Bi-weekly monitoring data showed consistent increases in SC and DRP and a decrease in NOx–N at the South Prong tributary (highest phosphate-mining area) throughout the wet season, and different responses of dissolved inorganic nutrients (negative) and particulate nutrients (positive) to water discharge. We conclude that (1) watersheds with active and reclaimed phosphate-mining and agriculture lands are important sources of streamwater P and N, respectively, and (2) elevated P inputs from the phosphate-mining areas altered the N:P ratios in streamwaters of the Alafia River. Full article
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