M. Iggy Litaor

Spatial analysis of selected soil attributes across an alpine topographic/snow gradient

The impact of the topographic/snow gradient on soil processes in alpinetundra on Niwot Ridge of the Colorado Front Range (Rocky mts, USA) was assessedusinggeostatistical modeling and a fractal approach. The mean snow depth, whichmeasured between 1984 and 2000, exhibited a smooth spatial continuity acrossthestudy grid area (550 × 400 meter). Soil color variables showed a nestedstructure that was attributed to a confounded effect of various soil-formingfactors on catenary processes. The spatial structure of texture classesexhibited no spatial structure and was explained by data sparsity,cryoturbation, and biological processes that mask the expected long-distancevariations (i.e., 550-m) of the catenary processes. Organic C, pH, bulkdensity,and soil moisture content showed various degrees of spatial continuity, but allindicated that the topographic/snow gradient is not the only dominantsoil-forming factor in this alpine ecosystem. The estimated fractal dimensionDfor the grid landform and the mean snow depth varied between 1.2 and 1.4,indicating that they vary smoothly with long-range variation. The estimatedDofthe soil variables ranged between 1.6 and 1.8, showing a noisy appearance withshort-range variations. These results strongly suggest that most small andmicro-scale variations in the alpine soil environs resulted from the combinedeffect of cryoturbation, biological activity, parent-material and eoliandeposition, whereas the large-scale variations originated as a result of thetopographic/snow gradient.

Evaluation of the ornithogenic influence on the trophic state of East Mediterranean wetland ecosystem using trend analysis

The Great Rift Valley portion of the East African-Eurasian Migratory Flyway is extremely important globally because of the numbers (>500 million) and diversity of seasonal traveling birds. The construction of the Agmon wetland (1.1km(2)) in the Hula Valley, Israel in 1994 and a change in crop type and rotation has attracted increasing number of Eurasian cranes (Grus grus) to winter in the wetland (>40,000 in 2014). The birds are fed in an area of 100ha and roost during the night in the wetland for protection from predators. Feeding practices have yielded an eco-tourism bonanza with over 400,000 visitors annually. However, this practice may have negative impacts on the trophic state of the wetland. We performed trend analyses using monthly means of selected constituents collected from mid-1994 to 2014. The temporal distribution of TN and TP concentrations in the inlets did not change with time. The concentrations of TN and TP in the outlet increased significantly during the earlier monitoring period. Kendall-Theil regression showed that TP concentrations in the outlet increased significantly from a monthly mean of 180μgL(-1) in 2010 to a monthly mean of 260μgL(-1) in 2014. Similarly, the results of chlorophyll a concentrations in the outlet showed a sharp upturn in the latter part of the series from a mean of 66mgL(-1) in 2010 to a mean of 122mgL(-1) in 2014. The concurrent increase of TP and chlorophyll a, the two most important parameters affecting a waterbody trophic index coincided with the observed increase in the number of roosting cranes in the wetland. Hence, we assume that the continued increases in TP concentrations could transform the wetland from a mild eutrophic to a permanent hypereutrophic state. Reducing the number of roosting cranes may prevent this from happening.

The impact of ornithogenic inputs on phosphorous transport from altered wetland soils to waterways in East Mediterranean ecosystem.

Large flocks of Eurasian crane (Grus grus, >35,000) have begun wintering in an altered wetland agro-ecosystem located in Northern Israel, a phenomenon that attracts more than 400,000 eco-tourists a year. A 100-ha plot has been used to feed the cranes in order to protect nearby fields. The objective of this study was to evaluate the influence of this birds feeding practice on the P status of the altered wetland soils and waterways. We installed a series of wells at two depths (40 and 90 cm) between two major waterways in the feeding area and monitored the hydraulic heads and collected groundwater samples for elemental analyses. We collected six soil cores and four sediment samples from the waterways and conducted sequential P extraction. We found significant increase in groundwater soluble reactive P (SRP) (>0.5 mg l(-1)) compared with much lower concentrations (~0.06 mg l(-1)) collected in the period prior to the feeding. We found significant decrease in Fe((II)), Ca, and SO4 concentrations in the shallow groundwater (33, 208, and 213 mg l(-1), respectively) compared with the period prior to the feeding (47, 460, and 370 mg l(-1) respectively). An increase in the more labile P fraction was observed in soils and sediments compared with the period before the feeding. The P input by bird excrement to the feeding area was estimated around 700 kg P per season, while P removal by plant harvesting was estimated around 640 kg Pyr(-1). This finding supports the current eco-tourism practices in the middle of intensive farming area, suggesting little impact on waterways.

Catastrophic Dieback of Cyperus Papyrus in Response to Geochemical Changes in an East Mediterranean Altered Wetland

Catastrophic vegetation dieback is a common phenomenon that has occurred in many wetland habitats worldwide. Different mechanisms have been proposed to explain these occurrences. We tested two published models proposed as potential mechanisms for the catastrophic dieback of Cyperus papyrus in the Hula Nature Reserve (HNR), Israel. Sulfide toxicity and P limitation models were tested using lysimeters. The sulfide toxicity was tested by redox-suppression simulation, while the P deficiency was evaluated using N/P ratio index. The sulfide toxicity model was not accepted as a viable mechanism because papyrus stands did not show any sign of stress, even when growing with sulfide concentration threefold that reported during the cattail dieback in a nearby wetland or values reported in the literature. The P limitation model was not supported by the N/P index that indicated N limitation rather than P limitation. Next, we tested two alternative mechanisms that link the dieback to N cycles and depletion in the HNR system or to a sequential stressor cascade that caused major N limitation. We concluded that the N deficiency hypothesis is a better explanation for the observed dieback and the current health status of C. papyrus in this East Mediterranean ecosystem.

Phosphorus Sorption Characteristics in Aluminum-based Water Treatment Residuals Reacted with Dairy Wastewater: 1. Isotherms, XRD, and SEM-EDS Analysis

We examined P sorption characteristics in Al-based water treatment residuals (Al-WTR) generated from slightly alkaline surface water and in an organic residual composite (WW-Al/O-WTR), produced by using the Al-WTR to treat organic-rich and high P concentration dairy wastewater. Solids from both residuals were examined using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD), and exposed to P additions of 0 to 4000 mg L in a sorption experiment. The Al-WTR removed ∼97% of the added P, whereas WW-Al/O-WTR removed only 78% of the added P in the addition range of 0 to 100 mg P L. With P additions of ≥100 mg L, the removal rate declined to <38% by Al-WTR and to 16% by WW-Al/O-WTR, possibly implying a change in sorption mechanisms. Analysis by XRD indicated that the major mineral was calcite, with some silica and poorly crystalline Al hydroxides. Analysis by SEM-EDS, which used three-element overlay maps of the residual surfaces, indicated that P was sparsely sorbed on both calcic and Al (hydr)oxide surfaces, along with a few clusters, even at low P concentrations of the treated waters. Ternary clusters of P, Al, and Ca were more abundant on the WW-Al/O-WTR. Carbon distribution suggested that organic substances covered Al surfaces. Sorption of P onto WW-Al/O-WTR may be reversible due to relatively weak Ca-P and Al-P bonds induced by the slight alkaline nature and in the presence of organic moieties, enhancing the WW-Al/O-WTR potential to act as a P source, rather than a P sink, in agricultural applications.

Phosphorus Sorption to Aluminum-based Water Treatment Residuals Reacted with Dairy Wastewater: 2. X-Ray Absorption Spectroscopy

Phosphorus capture from wastewater can decrease water pollution and provide a P-rich fertilizer alternative for use in agricultural production. This study was conducted to elucidate P retention mechanisms in Al-based water treatment residuals (Al-WTR) to gain insight regarding P sorption and the potential for P release from Al-WTR after reaction with dairy wastewater. Synchrotron-based microfocused X-ray fluorescence (micro-XRF) spectrometry, bulk P -edge X-ray absorption near edge structure spectroscopy (XANES), and P -edge micro-XANES spectroscopy were used to determine P distribution and speciation within the Al-WTR materials. Bulk XANES analyses indicated a shift from ∼56 P atom % Ca-associated P in the initial Al-WTR to ∼32% P atom % Ca-associated P after reaction with wastewater; Al-associated P made up the remainder of the P species. According to XANES analyses, adsorption appeared to be the primary P retention mechanism in the Al-WTR materials. However, micro-XANES analyses depicted a more complicated picture of P retention mechanisms, with regions of primarily Al-associated P, regions of primarily Ca-associated P, regions of mixed Al- and Ca-associated P, and distinct apatite- or octocalcium phosphate-like P grains. Synchrotron micro-XRF mapping further suggested that exposure of the aggregate exteriors to wastewater caused P to diffuse into the porous Al-WTR aggregates. Organic P species were not explicitly identified via P -edge XANES despite high organic matter content, suggesting that organic P may have been predominantly associated with mineral surfaces. Although diffusion and sorption to Al may decrease P bioavailability, Ca-associated P may increase P bioavailability from Al-WTR that is reused as a soil amendment.