Predicting organic matter, nitrogen, and phosphorus concentrations in runoff from peat extraction sites using partial least squares regression

Organic matter and nutrient export from drained peatlands is affected by complex hydrological and biogeochemical interactions. Here, partial least squares regression (PLSR) was used to relate various soil and catchment characteristics to variations in chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) concentrations in runoff. Peat core samples and water quality data were collected from 15 peat extraction sites in Finland. PLSR models constructed by cross-validation and variable selection routines predicted 92, 88, and 95% of the variation in mean COD, TN, and TP concentration in runoff, respectively. The results showed that variations in COD were mainly related to net production (temperature and water-extractable dissolved organic carbon (DOC)), hydrology (topographical relief), and solubility of dissolved organic matter (peat sulfur (S) and calcium (Ca) concentrations). Negative correlations for peat S and runoff COD indicated that acidity from oxidation of organic S stored in peat may be an important mechanism suppressing organic matter leaching. Moreover, runoff COD was associated with peat aluminum (Al), P, and sodium (Na) concentrations. Hydrological controls on TN and COD were similar (i.e., related to topography), whereas degree of humification, bulk density, and water-extractable COD and Al provided additional explanations for TN concentration. Variations in runoff TP concentration were attributed to erosion of particulate P, as indicated by a positive correlation with suspended sediment concentration (SSC), and factors associated with metal-humic complexation and P adsorption (peat Al, water-extractable P, and water-extractable iron (Fe)).

[1]  B. Kløve,et al.  Characteristics of nitrogen and phosphorus loads in peat mining wastewater. , 2001, Water research.

[2]  S. Wold,et al.  The Collinearity Problem in Linear Regression. The Partial Least Squares (PLS) Approach to Generalized Inverses , 1984 .

[3]  J. Vuorenmaa.  Long-term changes of acidifying deposition in Finland (1973-2000). , 2004, Environmental pollution.

[4]  K. R. Reddy,et al.  NITROGEN AND PHOSPHORUS FLUXES FROM A FLOODED ORGANIC SOIL , 1983 .

[5]  J. Canadell,et al.  Peatlands and the carbon cycle: from local processes to global implications - a synthesis , 2008 .

[6]  E. Tipping,et al.  Al(III) and Fe(III) binding by humic substances in freshwaters, and implications for trace metal speciation. , 2002 .

[7]  P. Belleau,et al.  Effects of drainage of a forested peatland on water quality and quantity , 1999 .

[8]  B. Kløve.  Erosion and sediment delivery from peat mines , 1998 .

[9]  Don Monteith,et al.  Alternative explanations for rising dissolved organic carbon export from organic soils , 2006 .

[10]  J. L. Gaunt,et al.  Soluble organic nitrogen in agricultural soils , 2000, Biology and Fertility of Soils.

[11]  J. Stoddard,et al.  Dissolved organic carbon trends resulting from changes in atmospheric deposition chemistry , 2007, Nature.

[12]  B. Kløve,et al.  Erosion and delivery of deposited peat sediment , 2008 .

[13]  J. S. Robinson,et al.  Phosphorus dynamics in the ditch system of a restored peat wetland , 2009 .

[14]  P. Kortelainen,et al.  Content of Total Organic Carbon in Finnish Lakes and Its Relationship to Catchment Characteristics , 1993 .

[15]  B. Kløve,et al.  Effect of soil properties on peat erosion and suspended sediment delivery in drained peatlands , 2014 .

[16]  T. Ellis,et al.  Atmospheric nitrogen deposition promotes carbon loss from peat bogs , 2006, Proceedings of the National Academy of Sciences.

[17]  B. Emmett,et al.  Evidence that Soil Carbon Pool Determines Susceptibility of Semi-Natural Ecosystems to Elevated Nitrogen Leaching , 2006, Ecosystems.

[18]  D. Vitt,et al.  Water and peat chemistry comparisons of natural and post-harvested peatlands across Canada and their relevance to peatland restoration , 1996 .

[19]  S. Wold,et al.  PLS-regression: a basic tool of chemometrics , 2001 .

[20]  W. H. Patrick,et al.  Phosphate Release and Sorption by Soils and Sediments: Effect of Aerobic and Anaerobic Conditions , 1974, Science.

[21]  J. Holden,et al.  Artificial drainage of peatlands: hydrological and hydrochemical process and wetland restoration , 2004 .

[22]  Stuart N. Lane,et al.  Influence of drought‐induced acidification on the mobility of dissolved organic carbon in peat soils , 2005 .

[23]  P. Kortelainen,et al.  Controls on the export of C, N, P and Fe from undisturbed boreal catchments, Finland , 2006, Aquatic Sciences.

[24]  P. Huttunen,et al.  Long-term effects of forestry managements on water quality and loading in brooks , 1999 .

[25]  Claudia Beleites,et al.  Variance reduction in estimating classification error using sparse datasets , 2005 .

[26]  D. F. Grigal,et al.  Nitrogen mineralization, nitrification and denitrification in upland and wetland ecosystems , 1991, Oecologia.

[27]  B. Kløve,et al.  Retention of Sediment and Nutrient Loads with Peak Runoff Control , 2009 .

[28]  Ji‐Hyung Park,et al.  Controls on the dynamics of dissolved organic matter in soils: a review. , 2000 .

[29]  David L. Jones,et al.  Experimental evaluation of methods to quantify dissolved organic nitrogen (DON) and dissolved organic carbon (DOC) in soil , 2006 .

[30]  K. R. Reddy,et al.  Water table effects on histosol drainage water carbon, nitrogen, and phosphorus , 1997 .

[31]  B. Kløve,et al.  Managing runoff, water quality and erosion in peatland forestry by peak runoff control , 2010 .

[32]  D. Monteith,et al.  Export of organic carbon from peat soils , 2001, Nature.

[33]  C. Richardson,et al.  Mechanisms Controlling Phosphorus Retention Capacity in Freshwater Wetlands , 1985, Science.

[34]  Dwayne R. Edwards,et al.  Relating Extractable Soil Phosphorus to Phosphorus Losses in Runoff , 1996 .

[35]  Steven J. Eisenreich,et al.  Export of dissolved organic carbon and acidity from peatlands , 1989 .

[36]  J. Gerke,et al.  Adsorption of Orthophosphate to Humic‐Fe‐Complexes and to Amorphous Fe‐Oxide , 1992 .

[37]  S. D. Jong.  SIMPLS: an alternative approach to partial least squares regression , 1993 .

[38]  P. Bloom.  Phosphorus Adsorption by an Aluminum-Peat Complex , 1981 .

[39]  R. Crawford,et al.  Effects of various physiochemical factors on microbial activity in peatlands: aerobic biodegradative processes , 1983 .

[40]  H. Jensen,et al.  Phosphorus mobilization in rewetted peat and sand at variable flow rate and redox regimes , 2012 .

[41]  Karen Updegraff,et al.  CARBON, NITROGEN, AND PHOSPHORUS MINERALIZATION IN NORTHERN WETLANDS , 1998 .

[42]  E. Davidson,et al.  Temperature sensitivity of soil carbon decomposition and feedbacks to climate change , 2006, Nature.

[43]  P. Kortelainen,et al.  Leaching of nitrogen from forested catchments in Finland , 1997 .

[44]  B. Emmett,et al.  Does elevated nitrogen deposition or ecosystem recovery from acidification drive increased dissolved organic carbon loss from upland soil? A review of evidence from field nitrogen addition experiments , 2008 .

[45]  R. Ferrier,et al.  The role of catchment characteristics in determining surface water nitrogen in four upland regions in the UK , 2007 .

[46]  P. Dillon,et al.  Effect of landscape form on export of dissolved organic carbon, iron, and phosphorus from forested stream catchments , 1997 .

[47]  Ammonium release from a blanket peatland into headwater stream systems. , 2012, Environmental pollution.

[48]  R. Bourbonniere,et al.  Dissolved organic carbon export from a cutover and restored peatland , 2008 .

[49]  R. Rees,et al.  Filtration increases the correlation between water extractable organic carbon and soil microbial activity , 2005 .

[50]  E. Tipping,et al.  The distribution of humic substances between the solid and aqueous phases of acid organic soils; a description based on humic heterogeneity and charge-dependent sorption equilibria , 1991 .

[51]  B. Kowalski,et al.  Partial least-squares regression: a tutorial , 1986 .

[52]  C. Agnew,et al.  Sulphur leaching from headwater catchments in an eroded peatland, South Pennines, U.K. , 2008, The Science of the total environment.

[53]  T. Moore,et al.  SOME CONTROLS ON THE RELEASE OF DISSOLVED ORGANIC CARBON BY PLANT TISSUES AND SOILS , 2001 .

[54]  L. Carrascal,et al.  Partial least squares regression as an alternative to current regression methods used in ecology , 2009 .

[55]  B. G. Lockaby,et al.  Effects of forest management on biogeochemical functions in southern forested wetlands , 1994, Wetlands.

[56]  W. H. Patrick,et al.  Effect of alternate aerobic and anaerobic conditions on redox potential, organic matter decomposition and nitrogen loss in a flooded soil , 1975 .

[57]  D. J. Dowrick,et al.  Export of dissolved organic carbon from peatlands under elevated carbon dioxide levels , 2004, Nature.

[58]  Tahir Mehmood,et al.  A review of variable selection methods in Partial Least Squares Regression , 2012 .

[59]  E. Tipping,et al.  Humic substances in acid organic soils: modelling their release to the soil solution in terms of humic charge , 1990 .

[60]  N. Hobbs.  Mire morphology and the properties and behaviour of some British and foreign peats , 1986, Quarterly Journal of Engineering Geology.