Spatial Analysis of Phosphorus Sorption Capacity in a Semiarid Altered Wetland

Abstract

The observed increase in phosphorus (P) loading into the Jordan River could increase eutrophication processes in Lake Kinneret, the only freshwater lake in Israel, which provides 25% of the country's drinking water. The P may originate from the peat soils of the highly altered Hula Valley's semiarid wetland ecosystem through which the Jordan River runs. The objectives of this research were to ascertain the sorption capacity of these soils and to identify areas with high potential for P release from soils to ground water. We extracted 80 soil samples collected across the valley with ammonium oxalate and determined the ratio of extractable P to Fe and Al, from which we derived the degree of phosphorus saturation (DPS). A relatively low DPS (<15%) was observed in Histosols compared with the high DPS (>30%) observed in many of the hydromorphic organo-mineral soils. We used a sequential Gaussian simulation technique to assess the spatial pattern of the DPS and found that the Histosols have a low probability (<10%) of exceeding the widely used environmental DPS threshold of 25%. The areas characterized by mineral soils, such as hydromorphic Vertisols and various marl redoximorphic soils, have a high probability (>60%) of exceeding the threshold value. The ability to predict the concentrations of dissolved P in ground water based on DPS values was somewhat impaired because of the preferential flow characteristics in this altered wetland.

Incorporation of spectral data into multivariate geostatistical models to map soil phosphorus variability in a Florida wetland

“…Commonly, univariate geospatial methods are used to model the distribution and variation of soil properties in wetland ecosystems. For example, Newman et al (1997) predicted soil NH 4 -nitrogen, soluble reactive phosphorus, total phosphorus (TP), and total nitrogen (TN) in a subtropical wetland in Florida; DeBusk et al (2001) predicted TP in Water Conservation Area-2A (WCA-2A), Everglades; Litaor et al (2003) predicted soil phosphorus, iron, aluminum, calcium and degree of phosphorus saturation in a semiarid wetland; and Bruland and Richardson (2005) predicted soil organic matter and sand content in four paired created/restored and natural wetland sites in the Coastal Plain of North Carolina. Since anthropogenically-induced phosphorus inputs stimulate microbial, periphyton and macrophyte growth in naturally oligotrophic wetlands, it is critical to describe spatial patterns of soil phosphorus to better understand processes of phosphorus retention, availability and release.…”

Mitigation of Diffuse Phosphorus Pollution during Rewetting of Fen Peat Soils: A Trans-European Case Study

“…These data indicated a minor risk of P leaching losses if the threshold of 25% for mineral soils was assumed (Breeuwsma and Silva 1992;Schoumans and Groenendijk 2000). An extensive study of DPS distribution in the Hula Valley demonstrated a strong correlation between the sorption maxima (S max ) derived from evaluations of adsorption isotherms by the Langmuir equation and the DPS, indicating that DPS could be applied both to mineral and organic soils at the catchment scale (Litaor et al 2003). In that study, the DPS values were much lower in Histosols (6.5±5) than in redoximorphic Gley soils from marl (28±18) and Vertisols (78±28).…”

“…In that study, the DPS values were much lower in Histosols (6.5±5) than in redoximorphic Gley soils from marl (28±18) and Vertisols (78±28). Spatial analysis with a sequential Gaussian simulation technique further indicated that the Histosols had a much lower risk (<10%) of exceeding the commonly used threshold of 25% DPS than redoximorphic Gley soils from marl and Vertisols (>60% probability) (Litaor et al 2003). However, it is doubtful if the thresholds developed for assessments of P leaching risks in sandy acid soils could be applied for the problem of fen peat rewetting.…”

“…There are some indications in the literature (Martin et al 1997;Robinson et al 1998;Renger et al 2002;Litaor et al 2003;Meissner et al 2003), that the restoration of Histosols and wetlands for environmental protection may result in significant P mobilisation and risk of accelerated eutrophication. This can be explained by the following hypothetic sequence of processes: (1) the mineralization of organically bound P during drying, aeration and oxidation of peat plus input of mineral and organic P fertiliser in periods of intensive agricultural led to P enrichment in the soil; (2) much of this P was retained by adsorption to Al, Fe, and Mn oxides and hydroxides under neutral to slightly acidic conditions;…”

Ecosystem service trade-offs in wetland management: drainage and rehabilitation of the Hula, Israel

“…Consequently, there was an increase in suspended material and nitrate loadings into the Sea of Galilee from the Hula Basin via the Jordan River (Litaor et al 2003), with peat being listed as a major source of pollution in the first Sea of Galilee master plan (Salik 1975). Due to water shortages, the water supplied to the Hula Nature Reserve was wastewater from fishponds (Paz 1975).…”