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RESEARCH ARTICLE

Nitrogen nutrients in a subtropical river: temporal variation and analysis at different spatial scales

Rodrigo Moncayo-Estrada A D , Carlos Escalera-Gallardo B , Miriam Arroyo-Damián C , Oswaldo Campos-Campos B and José T. Silva-García B
+ Author Affiliations
- Author Affiliations

A Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, Avenida Instituto Politécnico Nacional s/n, Col. Playa de Santa Rita, COFAA, La Paz, BCS, 23096 México.

B Instituto Politécnico Nacional, Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional, Justo Sierra 28, COFAA, Jiquilpan, Michoacán, 59510 México.

C Universidad de la Ciénega del Estado de Michoacán de Ocampo, Las Higueras 3000, Lomas de Universidad, 59103 Jiquilpan, Michoacán, México.

D Corresponding author. Email: rmoncayo@ipn.mx

Marine and Freshwater Research 68(10) 1935-1949 https://doi.org/10.1071/MF16344
Submitted: 28 January 2016  Accepted: 16 January 2017   Published: 30 March 2017

Abstract

Herein we provide a framework for evaluating the spatiotemporal variation of nitrate and ammonium and their relationships with environmental and anthropogenic variables at different scales. Bimonthly samples were collected from 28 sites in the Duero River, Mexico, from May to December 2013. The river flow changed and lost connectivity during the dry season because more water was diverted for irrigation. Four sites had the highest nitrate and ammonium values (7.6 and 22.1 mg L–1 respectively), which were related to direct waste water discharge. The remaining 24 sites were analysed using a multivariate approach. Using hierarchical cluster analysis, seasonal trends were identified with two groupings during July and five in December. Sites were grouped into those with constant discharge and nitrates affected by springs and those with poor water quality (high concentrations of ammonium). Non-metric multidimensional scaling simultaneously revealed the variation in time and space, organised sites into an environmental ammonium gradient and differentiated between seasons according to nitrate levels. Regression tree analysis established a relationship between nutrients and independent variables. At the landscape level, the agricultural area affected nitrate (75%) and urban area affected ammonium (45%); at the basin level, road density influenced both parameters (10.68 km per 25 km2).

Additional keywords: agricultural watershed, Duero River, multivariate analysis, restoration actions, riverine landscape, waste water input.


References

Abell, R., Allan, J. D., and Lehner, B. (2007). Unlocking the potential of protected areas for freshwaters. Biological Conservation 134, 48–63.
Unlocking the potential of protected areas for freshwaters.Crossref | GoogleScholarGoogle Scholar |

Abghari, H., Tabari, H., and Talaee, P. H. (2013). River flow trends in the west of Iran during the past 40 years: impact of precipitation variability. Global and Planetary Change 101, 52–60.
River flow trends in the west of Iran during the past 40 years: impact of precipitation variability.Crossref | GoogleScholarGoogle Scholar |

Ahearn, D. S., Sheibley, R. W., Dahlgren, R. A., Anderson, M., Johnson, J., and Tate, K. W. (2005). Land use and land cover influence on water quality in the last free-flowing river draining the western Sierra Nevada, California. Journal of Hydrology 313, 234–247.
Land use and land cover influence on water quality in the last free-flowing river draining the western Sierra Nevada, California.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXhtFSmtLzN&md5=bfdc01d47d0bae00f2e91a2e1a091d1eCAS |

American Public Health Association (1999). ‘Standard Methods for the Examination of Water and Wastewater’, 20th edn. (APHA: Washington, DC, USA.)

Arheimer, B., and Liden, R. (2000). Nitrogen and phosphorus concentrations from agricultural catchments – influence of spatial and temporal variables. Journal of Hydrology 227, 140–159.
Nitrogen and phosphorus concentrations from agricultural catchments – influence of spatial and temporal variables.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3cXhvVCqu7w%3D&md5=e23f7ad21a3a3fe3130a4f5d16857382CAS |

Ayers, R., and Westcot, D. (1994). Water quality for agriculture. Irrigation and Drainage Paper number 29, Food and Agriculture Organization of the United Nations, Rome, Italy.

Ayyasamy, P., Rajakumar, S., Sathishkumar, M., Swaminathan, K., Shanthi, K., Lakshmanaperumalsamy, P., and Lee, S. (2009). Nitrate removal from synthetic medium and groundwater with aquatic macrophytes. Desalination 242, 286–296.
Nitrate removal from synthetic medium and groundwater with aquatic macrophytes.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXks12msL0%3D&md5=52d23c7e3f487c1230df729ed9c5be77CAS |

Bayram, A., Önsoy, H., Bulut, V. N., and Akinci, G. (2013). Influences of urban wastewaters on the stream water quality: a case study from Gumushane Province, Turkey. Environmental Monitoring and Assessment 185, 1285–1303.
Influences of urban wastewaters on the stream water quality: a case study from Gumushane Province, Turkey.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXntVSksw%3D%3D&md5=e4b96240cfba0487adf3a3e514132815CAS |

Bernhardt, E. S., Band, L. E., Walsh, C. J., and Berke, P. E. (2008). Understanding, managing, and minimizing urban impacts on surface water nitrogen loading. Annals of the New York Academy of Sciences 1134, 61–96.
Understanding, managing, and minimizing urban impacts on surface water nitrogen loading.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXht12lu73E&md5=5019a5d654065bd0452b7119239c1623CAS |

Blann, K. L., Anderson, J. L., Sands, G. R., and Vondracek, B. (2009). Effects of agricultural drainage on aquatic ecosystems: a review. Critical Reviews in Environmental Science and Technology 39, 909–1001.
Effects of agricultural drainage on aquatic ecosystems: a review.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXhsVWhtLzP&md5=10e13b1587e2f2eb483450c052664203CAS |

Brauman, K. A., Daily, G. C., Duarte, T. K. E., and Mooney, H. A. (2007). The nature and value of ecosystem services: an overview highlighting hydrologic services. Annual Review of Environment and Resources 32, 67–98.
The nature and value of ecosystem services: an overview highlighting hydrologic services.Crossref | GoogleScholarGoogle Scholar |

Brodie, J. E., and Mitchell, A. W. (2005). Nutrients in Australian tropical rivers: changes with agricultural development and implications for receiving environments. Marine and Freshwater Research 56, 279–302.
Nutrients in Australian tropical rivers: changes with agricultural development and implications for receiving environments.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXkslSrtrg%3D&md5=517fad777a0d4db88346d2913daba04bCAS |

Capps, K. A., Bentsen, C. N., and Ramírez, A. (2016). Poverty, urbanization, and environmental degradation: urban streams in the developing world. Freshwater Science 35, 429–435.
Poverty, urbanization, and environmental degradation: urban streams in the developing world.Crossref | GoogleScholarGoogle Scholar |

Charrad, M., Ghazzali, N., Boiteau, V., Niknafs, A., and Charrad, M. M. (2014). Package ‘NbClust’. Journal of Statistical Software 61, 1–36.

Chen, D., Lu, J., Shen, Y., Gong, D., and Deng, O. (2011). Spatio-temporal variations of nitrogen in an agricultural watershed in eastern China: catchment export, stream attenuation and discharge. Environmental Pollution 159, 2989–2995.
Spatio-temporal variations of nitrogen in an agricultural watershed in eastern China: catchment export, stream attenuation and discharge.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXhtFehtLjO&md5=62aaf15e8639bb896b67f245ad97d39bCAS |

Chen, D., Dahlgren, R. A., and Lu, J. (2013). A modified load apportionment model for identifying point and diffuse source nutrient inputs to rivers from stream monitoring data. Journal of Hydrology 501, 25–34.
A modified load apportionment model for identifying point and diffuse source nutrient inputs to rivers from stream monitoring data.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXhsVClt73L&md5=a6fbf4c14da1bed713eae7830bd167bdCAS |

Chigor, V. N., Umoh, V. J., Okuofu, C. A., Ameh, J. B., Igbinosa, E. O., and Okoh, A. I. (2012). Water quality assessment: surface water sources used for drinking and irrigation in Zaria, Nigeria are a public health hazard. Environmental Monitoring and Assessment 184, 3389–3400.
Water quality assessment: surface water sources used for drinking and irrigation in Zaria, Nigeria are a public health hazard.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38Xmt1ahs78%3D&md5=dafd8f45cf9c54e322326d30486967e9CAS |

Chung, B., Song, C., Park, B., and Cho, J. (2011). Heavy metals in brown rice (Oryza sativa L.) and soil after long-term irrigation of wastewater discharged from domestic sewage treatment plants. Pedosphere 21, 621–627.
Heavy metals in brown rice (Oryza sativa L.) and soil after long-term irrigation of wastewater discharged from domestic sewage treatment plants.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXhsVGkurbF&md5=08ab7b3d33530fe04eaa3ee176a95a54CAS |

Collos, Y., and Harrison, P. J. (2014). Acclimation and toxicity of high ammonium concentrations to unicellular algae. Marine Pollution Bulletin 80, 8–23.
Acclimation and toxicity of high ammonium concentrations to unicellular algae.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXislKmu7Y%3D&md5=40e2929280d251e610a92958f47f71b3CAS |

Cun, C., and Vilagines, R. (1997). Time series analysis on chlorides, nitrates, ammonium and dissolved oxygen concentrations in the Seine River near Paris. The Science of the Total Environment 208, 59–69.
Time series analysis on chlorides, nitrates, ammonium and dissolved oxygen concentrations in the Seine River near Paris.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1cXhtVChtA%3D%3D&md5=90c0f2e83f27a926bedbcb3dc0d409cbCAS |

Damotharan, P., Perumal, N. V., Arumugam, M., Perumal, P., Vijayalakshmi, S., and Balasubramanian, T. (2010). Studies on zooplankton ecology from Kodiakkarai (Point Calimere) coastal waters (South East coast of India). Research Journal of Biological Sciences 5, 187–198.
Studies on zooplankton ecology from Kodiakkarai (Point Calimere) coastal waters (South East coast of India).Crossref | GoogleScholarGoogle Scholar |

David, M. B., Drinkwater, L. E., and Mcisaac, G. F. (2010). Sources of nitrate yields in the Mississippi River Basin. Journal of Environmental Quality 39, 1657–1667.
Sources of nitrate yields in the Mississippi River Basin.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXhtFGgtb3L&md5=2cee101a2cab538a53de595a153edc8bCAS |

Davidson, N. C. (2014). How much wetland has the world lost? Long-term and recent trends in global wetland area. Marine and Freshwater Research 65, 934–941.
How much wetland has the world lost? Long-term and recent trends in global wetland area.Crossref | GoogleScholarGoogle Scholar |

de Groot, R. S., Alkemade, R., Braat, L., Hein, L., and Willemen, L. (2010). Challenges in integrating the concept of ecosystem services and values in landscape planning, management and decision making. Ecological Complexity 7, 260–272.
Challenges in integrating the concept of ecosystem services and values in landscape planning, management and decision making.Crossref | GoogleScholarGoogle Scholar |

Dinnes, D. L., Karlen, D. L., Jaynes, D. B., Kaspar, T. C., Hatfield, J. L., Colvin, T. S., and Cambardella, C. A. (2002). Nitrogen management strategies to reduce nitrate leaching in tile-drained Midwestern soils. Agronomy Journal 94, 153–171.
Nitrogen management strategies to reduce nitrate leaching in tile-drained Midwestern soils.Crossref | GoogleScholarGoogle Scholar |

FAO (1993). The state of food and agriculture. FAO Agriculture Series, number 26. Food and Agriculture Organization of the United Nations, Rome, Italy.

Fatema, K., Maznah, W. W., and Isa, M. M. (2014). Spatial and temporal variation of physico-chemical parameters in the Merbok Estuary, Kedah, Malaysia. Tropical Life Sciences Research 25, 1–19.

Foley, J. A., Ramankutty, N., Brauman, K. A., Cassidy, E. S., Gerber, J. S., Johnston, M., Mueller, N. D., O’connell, C., Ray, D. K., and West, P. C. (2011). Solutions for a cultivated planet. Nature 478, 337–342.
Solutions for a cultivated planet.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXhtlSktbjF&md5=6e04a2b4e49344330474aaa04ddfe117CAS |

Frenken, K., and Faurès, J.-M. (1997). Irrigation potential in Africa: a basin approach. FAO Land and Water Bulletin 4, Food and Agriculture Organization of the United Nations, Rome, Italy.

Ganasri, B. P., and Ramesh, H. (2016). Assessment of soil erosion by RUSLE model using remote sensing and GIS – a case study of Nethravathi Basin. Geoscience Frontiers 7, 953–961.
Assessment of soil erosion by RUSLE model using remote sensing and GIS – a case study of Nethravathi Basin.Crossref | GoogleScholarGoogle Scholar |

Grantham, T. E., Figueroa, R., and Prat, N. (2013). Water management in Mediterranean river basins: a comparison of management frameworks, physical impacts, and ecological responses. Hydrobiologia 719, 451–482.
Water management in Mediterranean river basins: a comparison of management frameworks, physical impacts, and ecological responses.Crossref | GoogleScholarGoogle Scholar |

Gregory, K. J. (2006). The human role in changing river channels. Geomorphology 79, 172–191.
The human role in changing river channels.Crossref | GoogleScholarGoogle Scholar |

Gupta, P., Roy, S., and Mahindrakar, A. B. (2012). Treatment of water using water hyacinth, water lettuce and vetiver grass: a review. Resources and Environment 2, 202–215.
Treatment of water using water hyacinth, water lettuce and vetiver grass: a review.Crossref | GoogleScholarGoogle Scholar |

Hanasz, P. (2014). ‘The Problem with Problems of Water Scarcity in South Asia. Global Water Forum.’ (UNESCO: Paris, France).

Houser, J. N., and Richardson, W. B. (2010). Nitrogen and phosphorus in the Upper Mississippi River: transport, processing, and effects on the river ecosystem. Hydrobiologia 640, 71–88.
Nitrogen and phosphorus in the Upper Mississippi River: transport, processing, and effects on the river ecosystem.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXnvFaksw%3D%3D&md5=003c8ec7c340618dca76d7dee8460a65CAS |

Instituto Nacional de Estadística y Geografía (2013). Topografía carta escala 1:50 000. Available at http://www.inegi.org.mx/geo/contenidos/topografia/carta50000.aspx [Verified 15 May 2015]

Jaeger, K. L., Olden, J. D., and Pelland, N. A. (2014). Climate change poised to threaten hydrologic connectivity and endemic fishes in dryland streams. Proceedings of the National Academy of Sciences of the United States of America 111, 13894–13899.
Climate change poised to threaten hydrologic connectivity and endemic fishes in dryland streams.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXhsVartr3L&md5=a89b6e575b8449e29724a830eca181a9CAS |

Johnson, L. B., and Host, G. E. (2010). Recent developments in landscape approaches for the study of aquatic ecosystems. Journal of the North American Benthological Society 29, 41–66.
Recent developments in landscape approaches for the study of aquatic ecosystems.Crossref | GoogleScholarGoogle Scholar |

Johnson, L. B., Richards, C., Host, G. E., and Arthur, J. (1997). Landscape influences on water chemistry in Mid-western stream ecosystems. Freshwater Biology 37, 193–208.
Landscape influences on water chemistry in Mid-western stream ecosystems.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2sXhvVemt7c%3D&md5=794bb39773dcea984fbb2c76a123fe92CAS |

Jones, K. B., Neale, A. C., Nash, M. S., Van Remortel, R. D., Wickham, J. D., Riitters, K. H., and O’neill, R. V. (2001). Predicting nutrient and sediment loadings to streams from landscape metrics: a multiple watershed study from the United States Mid-Atlantic Region. Landscape Ecology 16, 301–312.
Predicting nutrient and sediment loadings to streams from landscape metrics: a multiple watershed study from the United States Mid-Atlantic Region.Crossref | GoogleScholarGoogle Scholar |

Jones, K. B., Neale, A. C., Wade, T. G., Cross, C. L., Wickham, J. D., Nash, M. S., Edmonds, C. M., Riitters, K. H., O’neill, R. V., and Smith, E. R. (2006). Multiscale relationships between landscape characteristics and nitrogen concentrations in streams. In ‘Scaling and Uncertainty Analysis in Ecology’. (Eds J. Wu, K. B. Jones, H. Li, and O. L. Loucks.) pp. 205–224. (Springer: London, UK.)

Kennen, J. G., Sullivan, D. J., May, J. T., Bell, A. H., Beaulieu, K. M., and Rice, D. E. (2012). Temporal changes in aquatic-invertebrate and fish assemblages in streams of the north-central and northeastern US. Ecological Indicators 18, 312–329.
Temporal changes in aquatic-invertebrate and fish assemblages in streams of the north-central and northeastern US.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38XktFWlurs%3D&md5=0978cfbe2b8c3cba836e3e6a872daac8CAS |

Khanizadeh, S. (1994). Breeding strawberries for eastern central Canada. Euphytica 77, 45–49.
Breeding strawberries for eastern central Canada.Crossref | GoogleScholarGoogle Scholar |

Kliment, Z., and Matoušková, M. (2009). Runoff changes in the Šumava Mountains (Black Forest) and the foothill regions: extent of influence by human impact and climate change. Water Resources Management 23, 1813–1834.
Runoff changes in the Šumava Mountains (Black Forest) and the foothill regions: extent of influence by human impact and climate change.Crossref | GoogleScholarGoogle Scholar |

Koschke, L., Fuerst, C., Frank, S., and Makeschin, F. (2012). A multi-criteria approach for an integrated land-cover-based assessment of ecosystem services provision to support landscape planning. Ecological Indicators 21, 54–66.
A multi-criteria approach for an integrated land-cover-based assessment of ecosystem services provision to support landscape planning.Crossref | GoogleScholarGoogle Scholar |

Krause, S., Jacobs, J., Voss, A., Bronstert, A., and Zehe, E. (2008). Assessing the impact of changes in landuse and management practices on the diffuse pollution and retention of nitrate in a riparian floodplain. The Science of the Total Environment 389, 149–164.
Assessing the impact of changes in landuse and management practices on the diffuse pollution and retention of nitrate in a riparian floodplain.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXhtlGmur%2FI&md5=f8521f104c25b3ca4ad69b7b8f12f2b9CAS |

Larned, S. T., Datry, T., Arscott, D. B., and Tockner, K. (2010). Emerging concepts in temporary‐river ecology. Freshwater Biology 55, 717–738.
Emerging concepts in temporary‐river ecology.Crossref | GoogleScholarGoogle Scholar |

Lee, K. E., Goldstein, R. M., and Hanson, P. E. (2001). Relation between fish communities and riparian zone conditions at two spatial scales. Journal of the American Water Resources Association 37, 1465–1473.
Relation between fish communities and riparian zone conditions at two spatial scales.Crossref | GoogleScholarGoogle Scholar |

Lester, R. E., and Wright, W. (2009). Reintroducing wood to streams in agricultural landscapes: changes in velocity profile, stage and erosion rates. River Research and Applications 25, 376–392.
Reintroducing wood to streams in agricultural landscapes: changes in velocity profile, stage and erosion rates.Crossref | GoogleScholarGoogle Scholar |

Maloney, K. O., and Weller, D. E. (2011). Anthropogenic disturbance and streams: land use and land‐use change affect stream ecosystems via multiple pathways. Freshwater Biology 56, 611–626.
Anthropogenic disturbance and streams: land use and land‐use change affect stream ecosystems via multiple pathways.Crossref | GoogleScholarGoogle Scholar |

Meijer, K., Van Der Krogt, W., and Van Beek, E. (2012). A new approach to incorporating environmental flow requirements in water allocation modeling. Water Resources Management 26, 1271–1286.
A new approach to incorporating environmental flow requirements in water allocation modeling.Crossref | GoogleScholarGoogle Scholar |

Méndez-Toribio, M., Zermeño-Hernández, I., and Ibarra-Manríquez, G. (2014). Effect of land use on the structure and diversity of riparian vegetation in the Duero River watershed in Michoacán, Mexico. Plant Ecology 215, 285–296.
Effect of land use on the structure and diversity of riparian vegetation in the Duero River watershed in Michoacán, Mexico.Crossref | GoogleScholarGoogle Scholar |

Mitsch, W. J., Day, J. W., Gilliam, J. W., Groffman, P. M., Hey, D. L., Randall, G. W., and Wang, N. (2001). Reducing nitrogen loading to the Gulf of Mexico from the Mississippi River Basin: strategies to counter a persistent ecological problem: ecotechnology – the use of natural ecosystems to solve environmental problems – should be a part of efforts to shrink the zone of hypoxia in the Gulf of Mexico. Bioscience 51, 373–388.
Reducing nitrogen loading to the Gulf of Mexico from the Mississippi River Basin: strategies to counter a persistent ecological problem: ecotechnology – the use of natural ecosystems to solve environmental problems – should be a part of efforts to shrink the zone of hypoxia in the Gulf of Mexico.Crossref | GoogleScholarGoogle Scholar |

Mitsch, W. J., Day, J. W., Zhang, L., and Lane, R. R. (2005). Nitrate-nitrogen retention in wetlands in the Mississippi River Basin. Ecological Engineering 24, 267–278.
Nitrate-nitrogen retention in wetlands in the Mississippi River Basin.Crossref | GoogleScholarGoogle Scholar |

Molle, F., and Berkoff, J. (2006). ‘Cities versus Agriculture: Revisiting Intersectoral Water Transfers, Potential Gains, and Conflicts.’ (International Water Management Institute: Colombo, Sri Lanka.)

Moncayo-Estrada, R., Lyons, J., Ramirez‐Herrejon, J., Escalera‐Gallardo, C., and Campos‐Campos, O. (2015). Status and trends in biotic integrity in a sub-tropical river drainage: analysis of the fish assemblage over a three decade period. River Research and Applications 31, 808–824.
Status and trends in biotic integrity in a sub-tropical river drainage: analysis of the fish assemblage over a three decade period.Crossref | GoogleScholarGoogle Scholar |

Moss, B. (2008). Water pollution by agriculture. Philosophical Transactions of the Royal Society of London – B. Biological Sciences 363, 659–666.
Water pollution by agriculture.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXisFClsrk%3D&md5=8d7ae93306f338d0912dd842ddcf88c6CAS |

Muro, M., and Jeffrey, P. (2012). Time to talk? How the structure of dialog processes shapes stakeholder learning in participatory water resources management. Ecology and Society 17, art3.
Time to talk? How the structure of dialog processes shapes stakeholder learning in participatory water resources management.Crossref | GoogleScholarGoogle Scholar |

Neal, C., Jarvie, H. P., Neal, M., Love, A. J., Hill, L., and Wickham, H. (2005). Water quality of treated sewage effluent in a rural area of the upper Thames Basin, southern England, and the impacts of such effluents on riverine phosphorus concentrations. Journal of Hydrology 304, 103–117.
Water quality of treated sewage effluent in a rural area of the upper Thames Basin, southern England, and the impacts of such effluents on riverine phosphorus concentrations.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXitVGhsr8%3D&md5=ae438e30aff2fa5f737def50551381eeCAS |

Nel, J. L., Reyers, B., Roux, D. J., Dean, I. N., and Cowling, R. M. (2011). Designing a conservation area network that supports the representation and persistence of freshwater biodiversity. Freshwater Biology 56, 106–124.
Designing a conservation area network that supports the representation and persistence of freshwater biodiversity.Crossref | GoogleScholarGoogle Scholar |

Nijboer, R. C., and Verdonschot, P. F. (2004). Variable selection for modelling effects of eutrophication on stream and river ecosystems. Ecological Modelling 177, 17–39.
Variable selection for modelling effects of eutrophication on stream and river ecosystems.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXlt1ekt7g%3D&md5=ffb9fbf0869f209781dad640ffd713e0CAS |

O’Donoghue, E. J., Hoppe, R. A., Banker, D. E., Ebel, R., Fuglie, K., Korb, P., Livingston, M., Nickerson, C., and Sandretto, C. (2011). The changing organization of US farming. EIB-88, USDA, Washington, DC, USA.

OECD (2016). ‘Sustainable Business Models for Water Supply and Sanitation in Small Towns and Rural Settlements in Kazakhstan.’ (Organization for Economic Co-operation and Development, Studies on Water: Paris, France.)

Olaniran, A. O., Naicker, K., and Pillay, B. (2014). Assessment of physico-chemical qualities and heavy metal concentrations of Umgeni and Umdloti Rivers in Durban, South Africa. Environmental Monitoring and Assessment 186, 2629–2639.
Assessment of physico-chemical qualities and heavy metal concentrations of Umgeni and Umdloti Rivers in Durban, South Africa.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXhvFOgsrbK&md5=e8f4165a9c2e6bc865f42dade4bfac0aCAS |

Ouattara, N. K., Garcia-Armisen, T., Anzil, A., Brion, N., and Servais, P. (2014). Impact of wastewater release on the faecal contamination of a small urban river: the Zenne River in Brussels (Belgium). Water, Air, and Soil Pollution 225, 2043.
Impact of wastewater release on the faecal contamination of a small urban river: the Zenne River in Brussels (Belgium).Crossref | GoogleScholarGoogle Scholar |

Parkyn, S. (2004). Review of riparian buffer zone effectiveness. MAF Technical Paper number 2004/05, Ministry of Agriculture and Forestry, Wellington, New Zealand.

Pärn, J., Pinay, G., and Mander, Ü. (2012). Indicators of nutrients transport from agricultural catchments under temperate climate: a review. Ecological Indicators 22, 4–15.
Indicators of nutrients transport from agricultural catchments under temperate climate: a review.Crossref | GoogleScholarGoogle Scholar |

Peña, F. (2012). Social problems with the agricultural use of urban wastewater. In ‘Water Resources in Mexico’. (Ed. U. S. Oswald.) pp. 145–154. (Springer: Berlin, Germany.)

Peresin, D., Vieceli, N. C., Bortolin, T. A., Bavaresco, G., and Schneider, V. E. (2015). Potential for attenuation of a stream in a subtropical region – Rio Grande do Sul-Brazil. Scientia cum Industria 3, 1–7.
Potential for attenuation of a stream in a subtropical region – Rio Grande do Sul-Brazil.Crossref | GoogleScholarGoogle Scholar |

Pescod, M. (1992). Wastewater treatment and use in agriculture. Irrigation and Drainage Paper number 47, Food and Agriculture Organization of the United Nations, Rome, Italy.

Petrovna-Tomilina, E., Ivanovna-Glotova, I., and Petrovna-Kuzmenko, I. (2013). Development of integration processes in the traditional sectors of agriculture. Middle East Journal of Scientific Research 13, 178–182.

Pimentel, J. L., and Velázquez, M. A. (2009). Construyendo la problemática de la gestión de las aguas superficiales y subterráneas de la cuenca del río Duero, Michoacán (México). Artículos y Ensayos de Sociología Rural 6, 48–55.

Poff, N. L., Richter, B. D., Arthington, A. H., Bunn, S. E., Naiman, R. J., Kendy, E., Acreman, M., Apse, C., Bledsoe, B. P., and Freeman, M. C. (2010). The ecological limits of hydrologic alteration (ELOHA): a new framework for developing regional environmental flow standards. Freshwater Biology 55, 147–170.
The ecological limits of hydrologic alteration (ELOHA): a new framework for developing regional environmental flow standards.Crossref | GoogleScholarGoogle Scholar |

Priego, Á. G., Morales, H., and Enríquez, C. (2004). Paisajes físico-geográficos de la cuenca Lerma-Chapala. Gaceta Ecológica 71, 11–22.

Pritts, M., Heidenreich, C., Mcdermott, L., and Miller, J. (2015). Berry soil and nutrient management – a guide for educators and growers. Northeast SARE, USDA. Available at http://www.sare.org/Learning-Center/SARE-Project-Products/Northeast-SARE-Project-Products/Berry-Soil-and-Nutrient-Management [Verified 4 July 2015].

Ranalli, A. J., and Macalady, D. L. (2010). The importance of the riparian zone and in-stream processes in nitrate attenuation in undisturbed and agricultural watersheds – a review of the scientific literature. Journal of Hydrology 389, 406–415.
The importance of the riparian zone and in-stream processes in nitrate attenuation in undisturbed and agricultural watersheds – a review of the scientific literature.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXpsVCnsrw%3D&md5=2fc2eded6f44e1276a2dd4d4651969bbCAS |

Rap, E., Wester, P., Pérez, P., Mollinga, P., and Bolding, A. (2004). The politics of creating commitment: irrigation reforms and the reconstitution of the hydraulic bureaucracy in Mexico. In ‘The Politics of Irrigation Reform: Contested Policy Formulation and Implementation in Asia, Africa and Latin America’. (Eds P. P. Mollinga and A. Bolding.) pp. 57–94. (Ashgate Publishers: London, UK.)

Reid, I., and Frostick, L. E. (2011). Channel form, flows and sediments of endogenous ephemeral rivers in deserts. In ‘Arid Zone Geomorphology: Process, Form and Change in Drylands’, 3rd edn. (Ed. D. S. G. Thomas.) pp. 301–332. (Wiley: New York, NY, USA.)

Reimann, C., Filzmoser, P., Garrett, R., and Dutter, R. (2011). ‘Statistical Data Analysis Explained: Applied Environmental Statistics with R.’ (Wiley: New York, NY, USA.)

Rosegrant, M. W., Ringler, C., McKinney, D. C., Cai, X., Keller, A., and Donoso, G. (2000). Integrated economic‐hydrologic water modeling at the basin scale: the Maipo River basin. Agricultural Economics 24, 33–46.
Integrated economic‐hydrologic water modeling at the basin scale: the Maipo River basin.Crossref | GoogleScholarGoogle Scholar |

Rost, S., Gerten, D., Bondeau, A., Lucht, W., Rohwer, J., and Schaphoff, S. (2008). Agricultural green and blue water consumption and its influence on the global water system. Water Resources Research 44, W09405.
Agricultural green and blue water consumption and its influence on the global water system.Crossref | GoogleScholarGoogle Scholar |

Saunders, D., Meeuwig, J., and Vincent, A. (2002). Freshwater protected areas: strategies for conservation. Conservation Biology 16, 30–41.
Freshwater protected areas: strategies for conservation.Crossref | GoogleScholarGoogle Scholar |

Sawyer, J. (2014). Nitrogen fertilization rates for corn production. In Integrated Crop Management News, 872. Available at http://lib.dr.iastate.edu/cropnews/872 [Verified 14 February 2017].

Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación (2013). Diversificarán producción de berries con la integración de pequeños productores. (SAGARPA.) Available at http://www.sagarpa.gob.mx/saladeprensa/2012/Paginas/2013B477.aspx [Verified 4 July 2015].

Secretaría de Medio Ambiente y Recursos Naturales (2009). Programa hídrico visión 2030 del Estado de Michoacán de Ocampo. (SEMARNAT.) Available at http://lasa.ciga.unam.mx/monitoreo/images/biblioteca/38%20programa_hidrico_vision_2030michoacan.pdf [Verified 15 August 2015].

Sigua, G. C., and Tweedale, W. A. (2003). Watershed scale assessment of nitrogen and phosphorus loadings in the Indian River Lagoon basin, Florida. Journal of Environmental Management 67, 363–372.
Watershed scale assessment of nitrogen and phosphorus loadings in the Indian River Lagoon basin, Florida.Crossref | GoogleScholarGoogle Scholar |

Silva, J. T., Moncayo-Estrada, R., Ochoa, S., Estrada, F., Cruz-Cárdenas, G., Escalera, C., Villalpando, F., Nava, J., Ramos, A., and López, M. (2013). Calidad química del agua subterránea y superficial en la cuenca del río Duero, Michoacán. Tecnología y Ciencias del Agua 4, 127–141.

Suen, J.-P. (2011). Determining the ecological flow regime for existing reservoir operation. Water Resources Management 25, 817–835.
Determining the ecological flow regime for existing reservoir operation.Crossref | GoogleScholarGoogle Scholar |

Suhardiman, D., and Giordano, M. (2014). Is there an alternative for irrigation reform? World Development 57, 91–100.
Is there an alternative for irrigation reform?Crossref | GoogleScholarGoogle Scholar |

Suthar, S., Sharma, J., Chabukdhara, M., and Nema, A. K. (2010). Water quality assessment of river Hindon at Ghaziabad, India: impact of industrial and urban wastewater. Environmental Monitoring and Assessment 165, 103–112.
Water quality assessment of river Hindon at Ghaziabad, India: impact of industrial and urban wastewater.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXls1Cks7c%3D&md5=072e4556fafcc4b66c8d61eaffdcf907CAS |

Talmage, P. J., Perry, J. A., and Goldstein, R. M. (2002). Relation of instream habitat and physical conditions to fish communities of agricultural streams in the northern Midwest. North American Journal of Fisheries Management 22, 825–833.
Relation of instream habitat and physical conditions to fish communities of agricultural streams in the northern Midwest.Crossref | GoogleScholarGoogle Scholar |

Thieu, V., Garnier, J., and Billen, G. (2010). Assessing the effect of nutrient mitigation measures in the watersheds of the Southern Bight of the North Sea. The Science of the Total Environment 408, 1245–1255.
Assessing the effect of nutrient mitigation measures in the watersheds of the Southern Bight of the North Sea.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXhtValuro%3D&md5=83098aebfb528439ff62b869efb18cfeCAS |

Thoms, M., and Sheldon, F. (2000). Water resource development and hydrological change in a large dryland river: the Barwon–Darling River, Australia. Journal of Hydrology 228, 10–21.
Water resource development and hydrological change in a large dryland river: the Barwon–Darling River, Australia.Crossref | GoogleScholarGoogle Scholar |

van Asselen, S., Verburg, P. H., Vermaat, J. E., and Janse, J. H. (2013). Drivers of wetland conversion: a global meta-analysis. PLoS One 8, e81292.
Drivers of wetland conversion: a global meta-analysis.Crossref | GoogleScholarGoogle Scholar |

Van Metre, P. C., Frey, J. W., Musgrove, M., Nakagaki, N., Qi, S., Mahler, B. J., Wieczorek, M. E., and Button, D. T. (2016). High nitrate concentrations in some Midwest United States streams in 2013 after the 2012 drought. Journal of Environmental Quality 45, 1696–1704.
High nitrate concentrations in some Midwest United States streams in 2013 after the 2012 drought.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2sXhs1Oqtr0%3D&md5=bd4606473c32d18cd78557e6d74f1bd2CAS |

Vargas, S., Monsalvo-Velázquez, G., and Wester, P. (2000). Cambios socioeconomicos y diferenciación productiva en los distritos de riego en la cuenca Lerma-Chapala, México. In ‘Asignación, Productividad y Manejo de Recursos Hídricos en Cuencas’. (Eds C. A. Scott, P. Wester and B. M. Pimentel.) pp. 77–92. (International Water Management Institute: Colombo, Sri Lanka).

Wagener, T., Sivapalan, M., Troch, P. A., Mcglynn, B. L., Harman, C. J., Gupta, H. V., Kumar, P., Rao, P. S. C., Basu, N. B., and Wilson, J. S. (2010). The future of hydrology: an evolving science for a changing world. Water Resources Research 46, W05301.
The future of hydrology: an evolving science for a changing world.Crossref | GoogleScholarGoogle Scholar |

Wan, H., Mulla, D. J., and Galzki, J. C. (2014). Using LiDAR and geographic information system data to identify optimal sites in southern Minnesota for constructed wetlands to intercept nonpoint source nitrogen. Journal of Soil and Water Conservation 69, 115A–120A.
Using LiDAR and geographic information system data to identify optimal sites in southern Minnesota for constructed wetlands to intercept nonpoint source nitrogen.Crossref | GoogleScholarGoogle Scholar |

Wang, L., Min, M., Li, Y., Chen, P., Chen, Y., Liu, Y., Wang, Y., and Ruan, R. (2010). Cultivation of green algae Chlorella sp. in different wastewaters from municipal wastewater treatment plant. Applied Biochemistry and Biotechnology 162, 1174–1186.
Cultivation of green algae Chlorella sp. in different wastewaters from municipal wastewater treatment plant.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXhtVOhu7%2FI&md5=23107bf2b4d76175fb68bf05594ab439CAS |

Wu, Y., and Chen, J. (2013). Investigating the effects of point source and nonpoint source pollution on the water quality of the East River (Dongjiang) in South China. Ecological Indicators 32, 294–304.
Investigating the effects of point source and nonpoint source pollution on the water quality of the East River (Dongjiang) in South China.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXnsVGjsLw%3D&md5=5889fb4dbac3d1576518a83b83485654CAS |

Zhang, Q., Xu, C.-Y., Tao, H., Jiang, T., and Chen, Y. D. (2010). Climate changes and their impacts on water resources in the arid regions: a case study of the Tarim River basin, China. Stochastic Environmental Research and Risk Assessment 24, 349–358.
Climate changes and their impacts on water resources in the arid regions: a case study of the Tarim River basin, China.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXitFKhsLc%3D&md5=59b33887ee16653c5cf1f4075e3cafdcCAS |

Zhu, Z., Nordin, R., and Mazumder, A. (2008). Soil and vegetation as the determinants of lake nitrogen concentrations in forested watersheds in British Columbia, Canada. Ecological Indicators 8, 431–441.
Soil and vegetation as the determinants of lake nitrogen concentrations in forested watersheds in British Columbia, Canada.Crossref | GoogleScholarGoogle Scholar |

Zuur, A. F., Ieno, E. N., and Elphick, C. S. (2010). A protocol for data exploration to avoid common statistical problems. Methods in Ecology and Evolution 1, 3–14.
A protocol for data exploration to avoid common statistical problems.Crossref | GoogleScholarGoogle Scholar |