Use of Natural 35S to Trace Sulphate Cycling in Small Lakes,Flattops Wilderness Area,Colorado, U.S.A.

Measurements of the cosmogenically-produced ³⁵S, a radioisotope of sulphur (t_1/2 = 87 days), are reported for the Ned Wilson Lake watershed in Colorado. The watershed contains two small lakes and a flowing spring presumed to be representative of local ground water. The watershed is located in the Flattops Wilderness Area and the waters in the system have low alkalinity, making them sensitive to increases in acid and sulphate deposition. Time series of ³⁵S measurements were made during the summers of 1995 and 1996 (July–September) at all three sites. The system is dominated by melting snow and an initial concentration of 16–20 mBq L^-1 was estimated for snowmelt based on a series of snow samples collected in the Rocky Mountains. The two lakes had large initial ³⁵S concentrations in July, indicating that a large fraction of the lake water and sulphate was introduced by meltwater from that year's snowpack. In 1995 and 1996, ³⁵S concentrations decreased more rapidly than could be accounted for by decay, indicating that other processes were affecting ³⁵S concentrations. The most likely explanation is that exchange with sediments or the biota was removing ³⁵S from the lake and replacing it with older sulphate devoid of ³⁵S. In September of 1995 and 1996, ³⁵S concentrations increased, suggesting that atmospheric deposition is important in the sulphate flux of these lakes in late summer. Sulphur-35 concentrations in the spring water were highly variable but never higher than 3.6 mBq L^-1 and averaged 2 mBq L^-1. Using a simple mixing model, it was estimated that 75% of the spring water was derived from precipitation of previous years.     

Deposition and Fate of Lead in a Forested Catchment, Lesni Potok, Central Czech Republic

The deposition of trace elements and their fate in a forest ecosystemhas been monitored at the experimental site, Lesni Potok catchment (LP), with granite bedrock. The catchment is located 30 km ESE from Prague. Annual bulk Pb-deposition flux F_Pb was 3.41 kg km^-2 a^-1 in 1994 and gradually decreased to 0.49 kg km^-2 a^-1 in 2001. The decrease is comparable with those observed in Germany and in the U.S.A. in the 1970s and 1980s. The total sales ban of leaded gasoline in the Czech Republic since January 2001 was accompanied by a pronounced decrease of F_Pb in a single year. The residual Pb-deposition flux is assigned to both the long-range transport of fine-grained vehicular lead aerosol (with a long residence time in the atmosphere) and to theemissions from power plant boilers burning lignite mined in the Czech northwest coal basin. The F_Pb of lead correlates stronglywith those of As, Cd, Cu, Zn and Be, the typical metals in coal fly ash, at two monitored sites. Topsoil horizons contain elevated concentrations of Pb (53–67 mg kg^-1), which are of anthropogenicorigin. Soils in the riparian areas contain increased concentrations of Pb when compared to soils on the hillslope areas. Significant amounts of Pb were found on a stream substrate and Fe-precipitate sampled from the stream. Low concentrations of Pb in bark and bole wood suggest that the uptake of Pb by vegetation is negligible. The very small surface water outputs (average of 0.002 kg km^-2 a^-1) compared to inputs (average of 1.890 kg km^-2 a^-1) from the LP catchment indicate an ongoing accumulation of Pb in a forested landscape.     

Lead Speciation in the Sediments of the Heavily Polluted Western Harbor of Alexandria

The Western Harbor (WH) became under stress in the past decades, following successive increase in population. This study deals with local distribution of total lead and its species in the WH sediments. The lead content was high and there was a relationship between its enrichment and oil dispersed from ships. The lowest total lead value was found in the harbor middle far from direct effects of pollution. A five-step sequential extraction scheme was applied to illustrate the contribution shared by each individual fraction in the total lead concentration in the WH sediments. The exchangeable fraction (F1) was very low. The bound to carbonate fraction (F2), the bound to iron-manganese oxide fraction (F3) and the bound to organic matter—sulfide fraction (F4) ranked fourth, second and third in abundance. Oxygen was the main factor controlling the value of F2. F3 gave a direct relationship with total lead. The high levels of F4 occurred at locations of low salinity and enriched with organic matter. The residual fraction (F5) dominated other lead species, reflecting the sediment composition and the amounts of discharged pollutants.     

Sorption of Cd in Soils: Pedotransfer Functions for the Parameters of the Freundlich Sorption Isotherm

Using a data set derived from 480 soil samples, pedotransfer functions for the coefficient (K) and the exponent (m) of the Freundlich sorption isotherm were developed. The functions were validated with data from 135 independent soil samples. We found high goodness-of-fit for the approaches of the Freundlich coefficient, whereas the efficiency of the models for predicting the independent samples should be improved. For the Freundlich exponent, the mean value of the parameterisation data set (m = 0.88) served as a better predictor than any of the developed functions. These findings contribute to the interpretation stated by previous authors that variation of the Freundlich exponent is of minor importance and therefore negligible in the course of sorption modelling.     

Variability of Flow and Solutes in the Rattaphum Catchment (Songkhla Lake Basin), Thailand

Pesticides can have a number of adverse impacts on crops, soil and water. In this paper, we focus on the physical and hydraulic properties of soils controlling the leaching of pesticides into the shallow groundwater of the Rattaphum Catchment in Thailand. Results from an analysis of soil physical properties, hydraulic conductivity, dye tracer and bromide tests show that the top 10–30 cm of soils in the three agro-ecosystems (vegetables, fruits and rubber) have a high clay and organic carbon content and are relatively impermeable with very low hydraulic conductivity (15–40 cm/day). Most of the dye and bromide were retained in the top clayey layer; the bromide forming a miniature bulge below 30 cm in two profiles which dissipated after 30 days, while the pesticides were mainly confined to the top 10 cm.     

Atmospheric Budget of Non-Seasalt Chlorine in the Kanto District,Japan

To evaluate the influence of anthropogenic emission of HCl on the air quality in the Kanto district of Japan, the atmospheric budgetof non-seasalt Cl (nssCl) was analyzed. The Kanto district, which consists of the Tokyo metropolis and the six surrounding prefectures, is the most densely populated region in Japan. The emission intensity of HCl is extremely high compared with those in other regions and most western countries. In this study, the annual wet and dry depositions of nssClwere estimated on a 0.25 × 0.25° grid over the Kanto district based on the concentration monitoring resultsand meteorological data. The budget analysis was conducted by comparing the estimated deposition with the emission of HCl. As a result, the annual total (wet + dry) deposition of nssCl was estimated to be 32 kt yr^-1, which closely agreed with HCl emission (36 kt yr^-1) from waste incineration in this area. The result suggested that the anthropogenic emission of HCl had a significant influence on the air quality and the deposition of acidity in this area.     

Investigating the Use of Iron Reducing Bacteria for the Removal of Arsenic from Contaminated Soils

Clean-up techniques, which were developed for removing cationic heavy metals from contaminated soils, are inappropriate for the metalloid As, which is a common and highly toxic pollutant. Because arsenic is mainly found associated with the hydrous ferric oxides of the soil, a possible mechanism for the mobilisation of this element is the reductive dissolution of Fe(III) oxyhydroxides. In this paper we investigate the possibility to mobilise arsenic, using the Fe(III)-reducing bacterium Desulfuromonas Palmitatis. The initial experiments were carried out using a crystalline ferric arsenate as model compound, i.e. scorodite (FeAsO₄.2H₂O). D. palmitatis was found able to reduce the trivalent iron of scorodite at a percentage of 80% within 16 days, but arsenic remained in the pentavalent state, and reprecipitated with Fe(II) in the form of low solubility ferrous arsenates. To avoid the precipitation of ferrous arsenates the subsequent experiments with soil were conducted by combining the reducing ability of D. palmitatis with the chelating strength of EDTA (ethylenediamine tetracetic acid), which can form strong aqueous complexes with Fe(II). Approximately 60% of Fe and 75% of As were recovered in the aqueous solution in the presence of EDTA, while in the simple biological treatment no Fe was dissolved and only a 3% of As was mobilised.     

Finnish Lake Survey: The Role of Catchment Attributes in Determining Nitrogen, Phosphorus, and Organic Carbon Concentrations

This study is based on a Finnish lake survey conducted in 1995, a dataset of 874 statistically selected lakes from the national lake register. The dataset was divided into subgroups to evaluate lake water-catchment relationships in different geographical regions and in lakes of different size. In the three southernmost regions, the coefficients of determination in multiple regression equations varied between 0.40 and 0.53 for total nitrogen (TN) and between 0.37 and 0.53 for total phosphorus (TP); the best interpreters were agricultural land and water area in the catchment. In the two northernmost regions, TN concentrations in lake water were best predicted by the proportion of peatlands in the catchment, the catchment slope, and TP concentrations by lake elevation and latitude. Coefficients of determination in multiple regression equations in these northern regions varied between 0.39 and 0.67 for TN and between 0.41 and 0.52 for TP. For all the subsets formed, the best coefficients of determination explaining TN, TP, and total organic carbon (TOC) were obtained for a subset of large lakes (>10 km²), in which 72–83% of the variation was explained. This was probably due to large heterogeneous catchments of these lakes.     

Regional Assessment of Nutrient and Pesticide Leaching in the Vegetable Production Area of Rattaphum Catchment, Thailand

Regional groundwater vulnerability maps to indicate the impact of leaching of chemicals under different management scenarios were prepared for the Rattaphum Catchment using several leaching models and GIS techniques. The Attenuation Factor (AF) model was used to simulate the leaching potential of several pesticides for selected soils in the catchment under different rates of recharge from irrigation. The LEACHN model was used to simulate the NO₃ ⁻ leaching potential and LEACHP was used to simulate leaching potential of metolachlor under different management scenarios. The results showed that only a small number of pesticides have the potential to contaminate the shallow groundwater. However, the risk of contamination with nutrients is much higher due to the mobility and conservative nature of the NO₃ ⁻. The LEACHP results indicated that the intensive use of agrochemicals in the vegetable growing area, especially during the rainy season when the groundwater is near the surface, increases the risk of pesticide contamination. The results of upscaling from the farm to the catchment scale using soil maps and GIS techniques under various management scenarios and chemical application rates showed that the most effective strategy to reduce chemical leaching is by reducing pesticide application rates and optimizing the application of irrigation water. The identification of potential high risk farms by ranking soils and agricultural practices could be used to formulate management practices that reduce pesticide contamination of the surface and ground water resources in the area.     

Determination of Nitrogen and Sulfur in Plants and Soils Sampled from the Area Near a Fertilizer Plant

The purpose of this study was to investigate NO_x and SO₂-inducednitrogen and sulfur levels accumulated over vegetation and soil in the surrounds of the fertilizer plant in Kütahya, Turkey. Therefore, leaf samples collected from the seven locations adjacent to the plant were morphologically observed (pollution-related injuries and color deformation) and chemically analyzed. Besides, nitrogen and sulfur contents were determined in the soil samples collected from each location. A significant correlation was achieved between locations and different vegetation samples and soil samples. The highest nitrogen level present in the trees was 3.07 ± 0.105% (3rd location, Robinia pseudoacacia), with the highest sulfur level being 5.79 ± 0.085% (3rd location, Salix alba). The highest nitrogen and sulfur levels in soils were 0.31 ± 0.045 and 0.57 ± 0.052% (3rd location), respectively. Furthermore, the highest nitrogen and sulfur levels were 4.69 and 2.20%, respectively,in agricultural plants in the surrounds of the fertilizer plant. A higher level of pollutants was observed in the samples collectedfrom the locations in the direction of the prevailing wind. Also, differences between locations as well as between plant specimens were statistically evaluated.     

Nitrogen Budget of a Spruce Forest Ecosystem After Six-year Addition of Ammonium Sulphate in Southwest Sweden

A nitrogen (N) budget was constructed for a period of 6 years (1988–1993) in a Norway spruce stand with current deposition of 19 kg N and 22 kg S ha⁻¹ year⁻¹. The stand was fertilized annually by addition of 100 kg N and 114 kg S ha⁻¹ (NS). Above and below ground biomass, litterfall, fine- root litter production, soil solution and net mineralization were measured to estimate pools, fluxes and accumulation of nitrogen. The average needle litterfall in control (C) and NS plots in 1993 was 2.2 and 2.5 ton ha⁻¹ year⁻¹, respectively. The fine root litter production prior to treatment (1987) was 4.4 ton ha⁻¹ year⁻¹ and after treatment (1993) it was 4.5 and 3.9 ton ha⁻¹ year⁻¹ in C and NS plots, respectively. Net N mineralization in the soil profile down to 50 cm was estimated to be 86 and 115 kg ha⁻¹ year⁻¹ in C and NS plots, respectively in 1992. During the treatment period the uptake of N in the needle biomass in C and NS plots was 29 and 77 kg ha⁻¹ year⁻¹, respectively. No N was accumulated in needles of C plot where the NS plots accumulated 34 kg ha⁻¹ year⁻¹. Of the annually added inorganic N to NS plots 47% was accumulated in the above and below ground biomass and 37% in the soil. N fluxes via fine-root litter production in the C plots were much higher (54 kg ha⁻¹ year⁻¹) than that via litterfall (29 kg ha⁻¹ year⁻¹). The corresponding values in the NS plots were 65 and 43 kg ha⁻¹ year⁻¹, respectively. Most of the net N mineralization occurred in the FH layer and upper mineral soil. It is concluded that fine root litter and litterfall play an important role in the cycling of N. Despite a high N uptake the losses of N in litterfall and fine root litter resulted in an incorporation of N in soil organic matter.     

Methane Fluxes from a Wetland using the Flux-Gradient Technique The Measurement of Methane Flux from a Natural Wetland Pond and Adjacent Vegetated Wetlands using a TDL-Based Flux-Gradient Technique

Methane emissions were measured from a bog andlake in the Experimental Lakes Area in Northern Ontario in 1992and 1993, prior to and following flooding. Bog fluxes were smallin 1992 (0.27 mg m^-2 d^-1) but increased 5-fold in 1993 afterflooding. Over the bog, there was a diel cycle of nighttimeemission and daytime uptake in 1992 in contrast to constantemission in 1993. Lake emissions decreased after flooding butwere much greater than bog emissions in both years (average = 7.3 mg m^-2 d^-1). Seasonally, the bog flux was correlated withground temperatures after flooding. In 1992, lake fluxes werecorrelated with air temperature on a daily basis. In contrast,seasonal lake fluxes were correlated with water and sedimenttemperatures in 1992, but only with sediment temperatures in1993. These results are explained with respect to the effects offlooding on lake and bog dynamics.     

An Assessment of Management Practices to Control Nutrient and Pesticide Levels in Vegetable Production Areas in the Rattaphum Catchment, Thailand

The over-use of agrochemicals may have adverse effects on soils along with surface and groundwater. An assessment of alternative management practices to reduce the application of agrochemicals and minimise the pollution of water resources was carried out in the vegetable agro-ecosystem in the Rattaphum Catchment. This paper details the factors that govern the volume of agrochemicals used on high intensity crops in this area, covering the choice of crop and cropping patterns, level of pest and weed infestation and the socio-economic status of farmers such as capital, size of holding and labour availability. Alternative management practices tested included (i) a reduction in the use of pesticides and chemical fertilisers; (ii) the use of bio-insecticides and bio-fertilisers; and (iii) the development of buffer zones near streams to reduce nutrient leaching into surface water systems. The results showed that when compared with bio-insecticides, synthetic insecticides were more effective in controlling major insect pests during chaisim vegetable production and were associated with higher net incomes. The high rate of application of chemical fertilisers in home gardens and commercial farms led to the accumulation of phosphorous and potassium in the top soil, with the traditional method of combining organic and chemical fertilisers producing the highest total nitrogen soil content. A fifty percent reduction in chemical fertilisers in the commercial farms produced the lowest total nitrogen soil content, without any apparent change in crop yield. The three types of tested buffers seem to be effective in reducing runoff and sediment load and were particularly efficient in lowering nutrient leaching to streams; the best results were obtained with an effective length of 2.5 m.     

Smoldering Combustion (STAR) for the Treatment of Contaminated Soils: Examining Limitations and Defining Success

Smoldering combustion, commercially available as the Self‐sustaining Treatment for Active Remediation (STAR) technology, is an innovative technique that has shown promise for the remediation of contaminant source zones. Smoldering combustion is an exothermic reaction (net energy producing) converting carbon compounds and an oxidant (e.g., oxygen in air) to carbon dioxide, water, and energy. Thus, following ignition, the smoldering combustion reaction can continue in a self‐sustaining manner (i.e., no external energy or added fuel input following ignition) as the heat generated by the reacting contaminants is used to preheat and initiate combustion of contaminants in adjacent areas, propagating a combustion front through the contaminated zone provided a sufficient flux of air is supplied. The STAR technology has applicability across a wide‐range of hydrocarbons in a variety of hydrogeologic settings; however, there are limitations to its use. Impacted soils must be permeable enough to allow a sufficient flux of air to the combustion front and there exists a minimum required concentration of contaminants such that the soils contain sufficient fuel for the reaction to proceed in a self‐sustaining manner. Further limitations, as well as lessons learned and methods to mitigate these limitations, are presented through a series of case studies. In summary, the successful implementation of STAR will result in >99 percent reduction in contaminant concentrations in treated areas, limited residual contaminant mass, reduced groundwater contaminant mass flux which can be addressed through monitored natural attenuation; and an enhanced site exit strategy, reduced lifecycle costs, and reduced risk. ©2016 Wiley Periodicals, Inc.     

Production and Consumption of NO in Forest and Pasture Soils from the Amazon Basin

NO production and the rate constant of NO consumptionin soil samples from Amazonian forest and pasturesites were determined in the laboratory. The purposewas to study NO production and consumption in soilsfrom both types of land use as functions of soiltemperature and soil moisture. NO productionincreased exponentially with soil temperature. Thedegree of increase depended on soil moisture,indicating that the response of NO production to achange in soil temperature is most pronounced at acertain intermediate soil moisture. NO productionpeaked at a soil moisture of 0.10 g g^-1, correspondingto 0.27 and 0.38 water-filled pore space for forestand pasture soils, respectively. The optimum soilmoisture for which maximum NO release was observedwas independent of soil temperature. NO consumptionwas most efficient at high soil temperatures andunder dry soil conditions. NO release wasapproximately 10 times larger for forest than pasturesoil. The difference may be related to the higherNO₃^- content in forest soil.     

The Transit of 35SO4 2- and 3H2O Added In Situ to Soil in a Boreal Coniferous Forest

A solution containing ³⁵SO₄ ^2- and ³H₂O was applied to four plots (5 × 5 m) in a boreal coniferous forest in the Laflamme Lake watershed, Québec, under two contrasting conditions: in summer (plots 1 and 2), and on the snowpack before snowmelt (plots 3 and 4). The transit of both these tracers in the soil solution was then followed through a network of soil lysimeters located at different depths. Four months after the summer application, ³H₂O had infiltrated the whole soil profile at plot 1, while ³⁵SO₄ ^2- was only observed in the LFH and Bhf horizons. A ³⁵SO₄ ^2- budget calculated from mid-August to November indicated that 89 and 10.6% of the added ³⁵SO₄ ^2- was retained within the LFH and the Bhf layers, respectively. Fifteen months later, the added ³⁵SO₄ ^2- was distributed in the following proportions within the soil horizons: LFH (73.7%), Bhf (11.8%) and Bf (12.8%), for a total retention rate of 98.3%. The superficial penetration of ³H₂O at plot 2 was indicative of a major lateral water movement that prevented the calculation of a ³⁵SO₄ ^2- budget. This situation also was observed at plot 4 during snowmelt. At plot 3, ³H₂O moved freely through the soil profile and a significant fraction of the added ³⁵SO₄ ^2- reached the B horizons, where it was presumably adsorbed on aluminum (Al) and ferric (Fe) oxides. The ³⁵SO₄ ^2- budget for plot 3 from March to November indicated that 87% of the added ³⁵SO₄ ^2- was retained within the soil profile, with most being retained in the B horizons (LFH = 33.1%, Bhf = 33.1%, Bf = 20.8%). The contrasting retention patterns of ³⁵SO₄ ^2- within the soil profile following the summer addition and snowmelt likely was caused by the contrastingsoil temperatures and soil solution residence times within the differentsoil layers. The persistence of ³⁵SO₄ ^2- in the soil solution of the entire profile long after the initial tracer infiltration, and the relative temporal stability of specific activity of SO₄ ^2-, point to the establishment of an isotopic equilibrium between the added ³⁵SO₄ and the active S-containing reservoirs within a given soil horizon. Overall, the results clearly illustrate the very strong potential for ³⁵SO₄ ^2- retention and recycling in forest soils.     

A Simplified Model for Predicting the Pollution Exchange Coefficient of Small Tidal Embayments

In recent years there has been a significant increase in the development and application of ever more sophisticated multi-dimensional models for solving the hydrodynamic and constituent transport equations which govern the flushing of pollution. However, advanced numerical modelling techniques can sometimes be augmented by alternative mathematical approaches which use simplified analytical solutions to predict the dispersion of contaminants. In the present article, a novel analytical tidal prism model is described for predicting the pollution flushing characteristics of small tidal embayments. The model relates the water quality response of the basin to the external forcing effects of the tide, the initial pollutant loading and the freshwater inflow rate. In general, the pollution flushing not only depends upon the geometry of the embayment and the tidal range but also on the proportion of effluent water which leaves the basin on an ebb tide, mixes with the surrounding coastal water and returns on subsequent flood tides. This effect has been taken into account in the mathematical model by the inclusion of a ‘pollution-return’ parameter. The analytical approach offers a viable and computationally inexpensive alternative to conventional multi-dimensional pollutant transport simulations and, more importantly, provides an increased understanding of the flushing characteristics of semi-enclosed tidal basins. The efficiency of the tidal flushing can be expressed in terms of the pollution exchange coefficient which measures the proportion of water exchanged with the sea each tidal cycle. To demonstrate the accuracy of the proposed mathematical formulation, analytical water quality predictions are compared against experimental pollution data from a 1:400 scale laboratory model of a generic square harbour. The results demonstrate that the analytical approach provides a simple and robust method of determining the water quality response of well-mixed tidal embayments.     

Planning Water Resources Management in Small Islands. The Case of Kalymnos,Greece

Kalymnos is one of the largest islands of the Dodecanese, a rather dense island complex situated at the southeast corner of Europe. The development potential of the area is large. A serious restrictive factor, though, is fresh water availability. The latter has declined in the last few years, due to increase in population and in per capita water demand. As a result, the already stressed groundwater resources have been overexploited, and salinization of many coastal aquifers has already taken place. Since water import from other areas is not a sustainable solution, optimization of the management of local water resources is necessary. This paper deals with both sides of the water balance of Kalymnos. First an estimate of the evolution of water demand is discussed. The use of a GIS tool, in order to estimate renewable water resources at the hydrologic basin scale, is presented next. Conjunctive use of surface and ground water resources, including traditional rainwater collection, is proposed. Water resources development in the hydrologic basin of Vathy, which is one of the largest of the island, is discussed in more detail.     

Restoration of a Small High Mountain Lake after Recent Tourist Impact: The Importance of Limnological Monitoring and Palaeolimnology

The natural Park of Peñalara consists of a small mountainousarea near Madrid and includes a series of water bodies (fromsmall mountain lakes to temporary ponds and peat bogs), the mostknown of them being the so-called `Laguna Grande dePeñalara'. Due to growing numbers of visitors theenvironmental conditions of this lake started to decline in theearly 1970s because of: (1) the start of severe soil erosionprocesses; (2) the increase of nutrient load; and (3) theintroduction of a non-native fish species. Since the area wasprotected in 1990, several conservation and restoration projectsincluded in an integrated management plan have been developed. Here we summarise some of the results of these efforts: (1) controlled access of livestock and visitors to the area; (2) palaeolimnology studies aimed at inferring recent changes in thewatershed; and (3) monitoring of the limnological features of thesystem. Restoration of this lake and its watershed is intendedto serve as a model for the management of other severely alteredhigh mountain lakes.     

Using Design-Expert to Optimize the Properties of a Polyethersulfone Ultrafiltration Membrane Through the Incorporation of NH2-MIL-53(Fe) and PVP for Maximum Cr(VI) Removal and Flux

Journal of Polymers and the Environment - In this study, an NH2-MIL-53(Fe) functionalized membrane was fabricated for Cr(VI) removal from contaminated groundwater. Design-Expert was employed to...