Skip to main content
SpringerLink
Log in

Phosphorus Environmental Risk Assessment in Wetland Soil

  • Original research article
  • Published:
Wetlands Aims and scope Submit manuscript

Abstract

At the interface between agricultural fields and water bodies there are wetlands constituted by hydromorphic soils. Our hypothesis is that hydromorphic soil acts a P sink and the P buffer capacity increases over time. To test our hypothesis, we apply tools to evaluate the P environmental risk via i) maximum phosphorus adsorption capacity (PMAC); ii) environmental soil phosphorus thresholds (P-threshold); iii) soil phosphorus storage capacity (SPSC) in hydromorphic soil (Histosol) and a non-hydromorphic soil (Cambisol) under application of mineral P. The PMAC was estimated by the Langmuir model in soil samples collected at four depths (0–10, 10–20, 20–40 and 40–60 cm). Soil samples were incubated for 30, 60 and 120 days with mineral P equivalent to 0, 25, 50, 75 and 100% of the PMAC. The P-threshold was determined from the degree of phosphorus saturation (DPS), estimated using PMAC and Fe + Al extracted with Mehlich-1. The SPSC was obtained from the 0–60 cm depth using the DPS%M1(CMAP). The PMAC values ranged from 2321 to 3539 mg kg−1 with higher values in the Histosol compared to the Cambisol. The Histosol presented a P-threshold of 19% DPS (609 mg kg−1), while in the Cambisol it was 24% DPS (582 mg kg−1 of P Mehlich-1). According to the SPSC tool, the soil acted as a source of P when P Mehlich-1 exceeded 887 mg kg−1 in Histosol, while in Cambisol it was 773 mg kg−1. Overall, the P buffering capacity was higher in the Histosol, indicating the importance of preserving wetlands for water quality.

Graphical Abstract

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

Similar content being viewed by others

Data Availability

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

References

  • Abboud FY, Favaretto N, Motta ACV, Barth G, Goularte GD (2018) Phosphorus mobility and degree of saturation in oxisol under no-tillage after long-term dairy liquid manure application. Soil Tillage Res 177:45–53

    Article  Google Scholar 

  • Albuquerque CG, Gavelaki F, Melo VF, Motta ACV, Zarbin AJG, Ferreira CM (2022) Model of inner-sphere adsorption of oxyanions in goethite – why is phosphate adsorption more significant than that of sulfate? Rev Bras Cienc Solo 46:e0210146

    Article  Google Scholar 

  • Alva AK, Larsen S, Bille SW (1980) The influence of rhizosphere in rice crop on resin-extractable phosphate in flooded soils at various levels of phosphate aplications. Plant Soil 56:17–25

    Article  CAS  Google Scholar 

  • Alvares CA, Stape JL, Sentelhas PC, Moraes Gonçalves JL, Sparovek G (2013) Köppen’s climate classification map for Brazil. Meteorol Z 22:711–728

    Article  Google Scholar 

  • Alvarez VVH, Fonseca DM (1990) Definição de doses de fósforo para determinação de capacidade máxima de adsorção de fosfatos e para ensaios de casa de vegetação. Revista Brasileira de Ciência do Solo, Campinas 14:49–55

    Google Scholar 

  • Alvarez VVH, Novais RF, Dias LE, Oliveira JA (2000) Determinação e uso do fósforo remanescente. Boletim Informativo Sociedade Brasileira De Ciência Do Solo 25:27–32

    Google Scholar 

  • Akpan US, Nkanga NA (2017) Phosphate Sorption Capacity, Bonding Energy and Buffering Mechanisms of Wetland Soils in Akwa Ibom State Nigeria. Greener Journal of Agricultural Sciences 7:065–073

    Article  Google Scholar 

  • Bajwa MI (1982) Soil Clay Mineralogies in Relation to Fertility Management: Effect of Clay Mineral Types on Ammonium Fixation under Conditions of Wetland Rice Culture. Agronomy Journal 74:143–144

    Article  CAS  Google Scholar 

  • Barbier EB, Acreman M, Knowler D (1997) Valoración económica de los humedales. Guía para decisores y planificadores. Oficina de la Convención de Ramsar, Gland, Suiza, p 150

  • Barbosa J, Poggere G, Mancini M, Silva SHG, Motta ACV, Marques J, Sáe Melo JJG, Curi N (2022) National-scale spatial variations of soil phosphorus retention capacity in Brazil. Physics and Chemistry of the Earth 128:103271

    Article  Google Scholar 

  • Bedrock CN, Cheshire MV, Shand CA (1997) The involvement of iron and aluminum in the bonding of phosphorus to soil humic acid. Communications in Soil Science and Plant Analysis 28(11–12):961–971

    Article  CAS  Google Scholar 

  • Bloom PR (1981) Phosphorus Adsorption by an Aluminum-Peat Complex. Soil Science Society of America Journal 45:267–272

    Article  CAS  Google Scholar 

  • Bortolon L, Ernani PR, Bortolon ESO, Gianello C, Almeida RGO, Welter S, Rogeri DA (2016) Degree of phosphorus saturation threshold in soils from Southern Brazil. Pesquisa Agropecuária Brasileira [s. l.] 51(9):1088–1098

    Article  Google Scholar 

  • BRASIL. Decreto nº 86.146, de 23 de Junho de 1981. Dispõe sobre a criação do Programa Nacional para Aproveitamento de Várzeas Irrigáveis - PROVÁRZEAS NACIONAL. Brasília, 23 de junho de 1981

  • Breeuwsma A, Silva S (1992) Phosphorus fertilization and environmental effects in The Netherlands and the Po Region (Italy). In: Report 57, agricultural research department, the winand staring centre for integrated land, soil, and water research, Wageningen, p 39

  • Diegues ACS (2002) Povos e águas: inventário de áreas úmidas brasileiras. São Paulo, NUPAUB 1:597

    Google Scholar 

  • Dunne EJ, Reddy R, Clark MW (2006) Biogeochemical indices of phosphorus retention and release by wetland soils and adjacent stream sediments. Wetlands 26(4):1026–1041

    Article  Google Scholar 

  • EMBRAPA (2011) Centro Nacional de Pesquisa de Solos. Manual de métodos de análise de solo. 2 rd edn. Rio de Janeiro: Embrapa Solos, p. 230

  • Eriksson AK, Gustafsson JP, Hesterberg D (2015) Phosphorus speciation of clay fractions from long-term fertility experiments in Sweden. Geoderma 241–242:68–74

    Article  Google Scholar 

  • Ferreira DF (2019) SISVAR: A Computer Analysis system to fixed effects split plot type designs. Revista Brasileira De Biometria 37(4):529

    Article  Google Scholar 

  • Gatiboni LC, Nicoloso RS, Mumbach GL, Souza AA, Dall’Orsoletta DJ, Schmitt DE, Smyth TJ (2020) Establishing environmental soil phosphorus thresholds to decrease the risk of losses to water in soils from Rio Grande do Sul, Brazil. Revista Brasileira de Ciência do Solo 44:1–14

    Article  Google Scholar 

  • Gatiboni LC, Smyth TJ, Schmitt DE, Cassol PC, Oliveira CMB (2015) Soil phosphorus thresholds in evaluating risk of environmental transfer to surface waters in Santa Catarina Brazil. Revista Brasileira de Ciência do Solo 39(4):1225–1234

    Article  CAS  Google Scholar 

  • Gerke J (2010) Humic (organic matter)-Al (Fe)-phosphate complexes: an underestimated phosphate form in soils and source of plant-available phosphate. Soil Science 175(9):417–425

    Article  CAS  Google Scholar 

  • Guilherme LRG, Curi N, Silva MLN, Renó NB, Machado RAF (2000) Adsorção de fósforo em solos de várzea do estado de Minas Gerais. Revista Brasileira de Ciência do Solo Viçosa 24:27–34

    Article  CAS  Google Scholar 

  • Guppy CN, Menzies NW, Moody PW, Blamey FPC (2005) Competitive sorption reactions between phosphorus and organic matter in soil: a review. Australian Journal of Soil Research 43:189–202

    Article  CAS  Google Scholar 

  • Hargrove WL, Thomas GW (1982) Conditional formation constants for aluminumorganic matter complexes. Canadian Journal of Soil Science 62:571–575

    Article  CAS  Google Scholar 

  • Hernández J, Meurer EJ (1998) Adsorção de fósforo e sua relação com formas de ferro em dez solos do Uruguai. Revista Brasileira de Ciência do Solo 22:223–230

    Article  Google Scholar 

  • Hue NV, Craddock CR, Adams F (1986) Effect of organic acids on aluminium toxicity in subsoils. Soil Science Society of America Journal 50:28–34

    Article  CAS  Google Scholar 

  • Janardhanan L, Daroub S (2010) Phosphorus sorption in organic soils in South Florida. Soil Sci Soc Am J 74:1597–1606

    Article  CAS  Google Scholar 

  • Juo ASR, Fox RL (1977) Phosphate sorption capacity of some benchmark soils in West Africa. Soil Science 124:370–376

    Article  CAS  Google Scholar 

  • Kay P, Edwards AC, Foulger M (2009) A review of the efficacy of contemporary agricultural stewardship measures for ameliorating water pollution problems of key concern to the UK water industry. Agricultural Systems 99:67–75

    Article  Google Scholar 

  • Larsen JE, Warren GF, Langston R (1959) Effect of iron, aluminum and humic acid on phosphorus fixation by organic soils. Soil Science Society of America Proceedings 23:438–440

    Article  CAS  Google Scholar 

  • Litaor M, Reichmann O, Belzer M, Auerswald K, Nishri A, Shenker M (2003) Spatial Analysis of Phosphorus Sorption Capacity in a Semiarid Altered Wetland. Journal of Environmental Quality 32:335–343

    Article  CAS  PubMed  Google Scholar 

  • Maack R (2012) Geografia Física do estado do Paraná. 4 ed. Curitiba: Imprensa Oficial, p 526

  • Mcdowell RW, Sharpley AN, Brookes PC, Poulton PR (2001) Relationship between soil test phosphorus and phosphorus release to solution. Soil Science 166:137–149

    Article  CAS  Google Scholar 

  • Mcdowell RW, Sharpley AN, Withers P (2002) Indicator to Predict the Movement of Phosphorus from Soil to Subsurface Flow. Environmental Science & Technology 36:1505–1509

    Article  CAS  Google Scholar 

  • Mckeague JA (1978) Manual on Soil Sampling and Methods of Analysis, 2nd edn. Canadian Society of Soil Science, Ottawa, p 212

    Google Scholar 

  • Mehra OP, Jackson ML (1960) Iron oxide removal from soils and clay by a dithionite-citrate system buffered with sodium bicarbonate. Clays Clay Mine 7:317–327

    Google Scholar 

  • Mesquita Filho MV, Torrent J (1993) Phosphate sorption as related to mineralogy of a hydrosequence of soils from the Cerrado region (Brazil). Geoderma 58:107–123

    Article  Google Scholar 

  • Mitsch WJ, Gosselink JG (1993) Wetlands. 2nd ed. John Wiley and Sons, New York, p 722

  • Mng’ong’o M, Munishi L, Blake W, Ndakidemi P, Comber S, Hutchinson T (2021) Characterization of soil phosphate status, sorption and saturation in paddy wetlands in usangu basin-Tanzania. Chemosphere 278:130466

    Article  PubMed  Google Scholar 

  • Mukherjee A, Nair V, Clark M (2009) Reddy K (2009) Development of Indices to Predict Phosphorus Release from Wetland Soils. Journal of Environmental Quality 38:878–886

    Article  CAS  PubMed  Google Scholar 

  • Nair V (2014) Soil phosphorus saturation ratio for risk assessment in land use systems. Front Environ Sci 2:1–4

    Article  Google Scholar 

  • Nair VD, Clark M, Reddy KR (2015) Evaluation of Legacy Phosphorus Storage and Release from Wetland Soils. J Environmental Quality 44(6):1956–1964

    Article  CAS  Google Scholar 

  • Nair VD, Harris EG (2004) A capacity factor as an alternative to soil test phosphorus in phosphorus risk assessment. New Zealand Journal of Agricultural Research 47:491–497

    Article  CAS  Google Scholar 

  • Nair VD, Portier KM, Graetz DA, Walker ML (2004) An Environmental Threshold for Degree of Phosphorus Saturation in Sandy Soils. Journal of Environmental Quality 33:107–113

    Article  CAS  PubMed  Google Scholar 

  • Nair VD, Reddy KR (2013) Phosphorus sorption and desorption in wetland soils. In: Delaune R, Reddy KR, Richardson CJ, Megonigal P. Methods in Biogeochemistry of Wetlands. Madison: Soil Science Society of America Publication, 667–678

  • Novak JM, Watts DW (2006) Phosphorus sorption by sediments in a southeastern Coastal Plain in-stream wetland. Journal of Environmental Quality 35:1975–1982

    Article  CAS  PubMed  Google Scholar 

  • Ohno T, Hoskins B, Erich M (2007) Soil organic matter effects on plant available and water-soluble phosphorus. Biology and Fertility of Soils 43:683–690

    Article  CAS  Google Scholar 

  • Olsen SR, Watanabe FS (1957) A method to determine a phosphorus adsorption maximum of soil as measured by the Langmuir isotherm. Soil Science Society of American Proceedings, Madison 21:144–149

    Article  CAS  Google Scholar 

  • PARANÁ. Lei Nº 18295 de 10/11/2014. Súmula Instituição, nos termos do art. 24 da Constituição Federal, do Programa de Regularização Ambiental das propriedades e imóveis rurais, criado pela Lei Federal nº 12.651, de 25 de maio de 2012. Palácio do Governo, em 10 de novembro de 2014

  • PARANÁ (2008) Resolução Conjunta IBAMA/SEMA/IAP N° 005, de 28 de março de 2008. Casa Civil Governadoria do Poder Executivo do Estado do Paraná. Curitiba, PR

  • Pautler MC, Sims JT (2000) Relationships Between Soil Test Phosphorus, Soluble Phosphorus, and Phosphorus Saturation in Delaware Soils. Soil Science Society of America Journal [s. l.] 64(2):765

    Article  CAS  Google Scholar 

  • Pavan MA, Bloch, MF, Zempulski HC, Miyazawa M, Zocoler DC (1992) Manual de análise química de solo e controle de qualidade. Londrina. IAPAR, circular 76:38

  • Penn CJ, Mullins GL, Zelazny LW (2005) Mineralogy in relation to phosphorus sorption and dissolved phosphorus losses in runoff. Soil Science Society of America Journal 69:1532–1540

    Article  CAS  Google Scholar 

  • Raij BV, Andrade JC, Cantarella H, Quaggio JA (2001) Análise química para avaliação da fertilidade de solos tropicais. Instituto Agronômico de Campinas (IAC), Campinas

    Google Scholar 

  • Raij BV, Quaggio JA, Silva NM (1986) Extraction of phosphorus, potassium, calcium, and magnesium from soils by an ion-exchange resin procedure. Communications in Soil Science and Plant Analysis 17(5):547–566

    Article  Google Scholar 

  • R CORE TEAM (2020) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. https://www.R-project.org/. Accessed 16 May 2024

  • Ranno SK, Silva LS, Gatiboni LC, Rhoden AC (2007) Capacidade de adsorção de fósforo em solos de várzea do Estado do Rio Grande do Sul. Revista Brasileira de Ciência do Solo 31(1):21–28

    Article  Google Scholar 

  • Reddy KR, Flaig E, Graetz DA (1996) Phosphorus storage capacity of uplands, wetlands and streams of the Lake Okeechobee Watershed Florida. Agriculture, Ecosystems & Environment 59(3):203–216

    Article  CAS  Google Scholar 

  • Reddy KR, Kadlec RH, Flaig E, Gale PM (1999) Phosphorus retention in streams and wetlands: a review. Critical Reviews in Environmental Science and Technology 29:83–146

    Article  CAS  Google Scholar 

  • Reddy KR, Orlando AD, Leonard JS, Moshe A (1995) Phosphorus dynamics in selected wetlands and streams of the lake Okeechobee Basin. Ecological Engineering 5:183–207

    Article  Google Scholar 

  • Rhoades JD (1996) Salinity: Electrical conductivity and total dissolved solids. In: Sparks DL, Page AL, Helmeke PA, Leoppert RH, Soltanpour PN, Tabatabai MA, Johnston CT, Sumner ME (Eds.). Methods of soil analysis. Part 3. SSSA Book Ser. 5. SSSA, Madison, WI, p.417–435

  • Richardson CJ (1985) Mechanisms controlling phosphorus retention capacity in freshwater wetlands. Science 228:1424–1427

    Article  CAS  PubMed  Google Scholar 

  • Richardson CJ, Marshall PE (1986) Processes controlling movement, storage, and export of phosphorus in a fen peatland. Ecological Monographs 56:279–302

    Article  Google Scholar 

  • Roderjan CV, Galvão F, Kuniyoshi YS, Hatschbach GG (2002) As unidades fitogeográficas do estado do Paraná Brasil. Ciência e Ambiente Santa Maria 24:75–92

    Google Scholar 

  • Sanyal SK, De Datta SK (1991) Chemistry of Phosphorus Transformations in Soil. Advances in Soil Science 6:1–120

    Google Scholar 

  • Sekhon BS, Bhumbla DK, Sencindiver J, Mcdonald LM (2014) Using soil survey data for series-level environmental phosphorus risk assessment. Environmental Earth Sciences 72:2345–2356

    Article  CAS  Google Scholar 

  • Sharpley A (1995) Dependence of runoff phosphorus on extractable soil phosphorus. Journal of Environmental Quality 24:920–926

    Article  CAS  Google Scholar 

  • Sharpley A, Wang X (2014) Managing agricultural phosphorus for water quality: Lessons from the USA and China. Journal of Environmental Sciences 16:1770–1782

    Article  Google Scholar 

  • Simonete MA, Ernani PR, Teixeira-Gandra CFA, Moro L (2018) Phosphorus adsorption in lowlands of Santa Catarina cultivated with rice and its relation with soil properties. Revista Ciência Agronômica 49:566–573

    Article  Google Scholar 

  • Sims JT (1993) Environmental Soil Testing for Phosphorus. Journal of Production Agriculture 6:501–507

    Article  Google Scholar 

  • Smith VH, Tilman GD, Nekola JC (1999) Eutrophication: impacts of excess nutrient inputs on freshwater, marine, and terrestrial ecosystems. Environmental Pollution 100:179–196

    Article  CAS  PubMed  Google Scholar 

  • Sposito G (2008) The surface chemistry of soils, 2nd edn. Oxford. University Press, New York

    Google Scholar 

  • Stevenson FJ (1986) Cycles of Soil: C, N, P, S, Micronutrients. John Wiley and Sons, New York

    Google Scholar 

  • Valadares SV, Alvarez VH, Santos WO, Paes JLAG, Lins CB, Novais RF (2017) Sensitivity of soil P availability tests to ca-P in oxisols. Communications in Soil Science and Plant Analysis 48(15):1834–1842

    Article  CAS  Google Scholar 

  • Van Der Zee SEATM, Fokkink LGJ, Van Riemsdijk WH (1987) A new technique for assessment of reversibly adsorbed phosphate. Soil Science Society of America Journal [s. l] 51(3):599–604

    Article  Google Scholar 

  • Verhoeven JTA, Arheimer B, Yin C, Hefting MM (2006) Regional and global concerns over wetlands and water quality. Trends in Ecology & Evolution 21(2):96–103

    Article  Google Scholar 

  • Vepraskas MJ, Caldwell PV (2008) Interpreting morphological features in wetland soils with a hydrologic model. Catena 73:153–165

    Article  Google Scholar 

  • Villapando RR, Graetz DA (2001) Phosphorus Sorption and Desorption Properties of the Spodic Horizon from Selected Florida Spodosols. Soil Science Society of America Journal 65:331–339

    Article  CAS  Google Scholar 

  • Wang X, Hu Y, Tang Y, Yang P, Feng X, Xu W, Zhu M (2017) Phosphate and phytate adsorption and precipitation on ferrihydrite surfaces. Environmental Science: Nano Journal 4:2193–2204

    CAS  Google Scholar 

  • Wang L, Liang T (2014) Effects of exogenous rare earth elements on phosphorus adsorption and desorption in different types of soils. Chemosphere 103:148–155

    Article  CAS  PubMed  Google Scholar 

  • Wang X, Phillips BL, Boily J-F, Hu Y, Hu Z, Yang P, Feng X, Xu W, Zhu M (2019) Phosphate Sorption Speciation and Precipitation Mechanisms on Amorphous Aluminum Hydroxide. Soil Systems 3:20

    Article  Google Scholar 

  • Xu G, Ren Y, Yue M, Lv Y, Chen X, Hui H (2022) Phosphorus sorption capacity in soils from freshwater restored coastal wetlands increased with restoration age. Geoderma 422:115926

    Article  CAS  Google Scholar 

  • Xu T, Weng B, Yan D, Wang K, Li X, Bi W, Li M, Cheng X, Liu Y (2019) Wetlands of international importance: Status, threats, and future protection. International Journal of Environmental Research and Public Health, 16(10):1818

  • Yang X, Chen X, Yang X (2019) Effect of organic matter on phosphorus adsorption and desorption in a black soil from Northeast China. Soil and Tillage Research 187:85–91

    Article  Google Scholar 

Download references

Acknowledgements

The authors are grateful to the National Council for Scientific and Technological Development (CNPq/Brazil) and Coordination for the Improvement of Higher Education Personnel (CAPES/Brazil) for the financial support (grants and scholarships).

Funding

The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.

Author information

Authors and Affiliations

  1. DSEA-UFPR - Department of Soil Science and Agricultural Engineering, Federal University of Paraná, Curitiba, Paraná, Brazil

    Ana Paula Marés Mikosik, Nerilde Favaretto, Antonio Carlos Vargas Motta, Vander de Freitas Melo, Fabiane Machado Vezzani, Jairo Calderari de Oliveira Júnior & Verediana Fernanda Cherobim

Authors
  1. Ana Paula Marés Mikosik
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Nerilde Favaretto
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Antonio Carlos Vargas Motta
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Vander de Freitas Melo
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Fabiane Machado Vezzani
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Jairo Calderari de Oliveira Júnior
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Verediana Fernanda Cherobim
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

All authors contributed to the study conception and design. Field sampling by Ana Paula Marés Mikosik, Nerilde Favaretto, Verediana Fernanda Cherobim, Antonio Carlos Vargas Motta e Jairo Calderari de Oliveira Júnior. Material preparation and laboratories analyses by Ana Paula Marés Mikosik and Verediana Fernanda Cherobim. Date analyses by Ana Paula Marés Mikosik, Nerilde Favaretto, Antonio Carlos Vargas Motta, Vander de Freitas Melo, Fabiane Machado Vezzani. The first draft of the manuscript was written by Ana Paula Marés Mikosik and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Ana Paula Marés Mikosik.

Ethics declarations

Competing Interests

The authors have no relevant financial or non-financial interests to disclose.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Mikosik, A.P.M., Favaretto, N., Motta, A.C.V. et al. Phosphorus Environmental Risk Assessment in Wetland Soil. Wetlands 44, 58 (2024). https://doi.org/10.1007/s13157-024-01812-9

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1007/s13157-024-01812-9

Keywords

Search

Navigation