Lanthanum/aluminum-modified zeolite adsorbent (La/Al-ZA) was prepared and investigated for their ability to remove phosphorus from wastewater. Various batch adsorption conditions, e.g., pH, ionic strength, temperature, contact time, initial phosphorus concentration, and the dosage of adsorbent were tested. The results showed that the adsorption amount increased with the increase of temperature, contact time, and initial phosphorus concentration and decreased with the increase of adsorbent dosage and initial anion concentration. The adsorption amount first increased with increasing pH from 2.0 to 4.0 and reached a plateau over the pH range from 4.0 to 8.0, then significantly decreased from 8.0 to 12.0, and the suitable adsorption was achieved with the pH range 4–9. The phosphorus removal efficiency decreased slightly from 95.86 to 93.39 and 92.53 %, respectively, in the presence of Cl⁻ and SO₄²⁻ at the lower concentration of 0.1 mmol/L, while they decreased significantly from 95.86 % to the ranges of 85.02–88.80 % and 83.77–87.45 %, respectively, in the presence of Cl⁻ and SO₄²⁻ at higher concentrations ranging from 0.5 to 2.0 mmol/L, and the effects on adsorption of La/Al-ZA follow the order: Cl⁻ > SO₄²⁻. Phosphorus adsorption matched with both Langmuir and Freundlich isotherms. The results presented here supported the potential use of the new La/Al-ZA as a material for the treatment of phosphorus in wastewater.

A comparison of chromium abatement from irrigation water, by the use of two selected plant species, Phragmites australis and Helianthus annuus, planted in chromium-contaminated soil, was studied in the present work. The above plant species were irrigated, in a continuous mode, with 10 mg Crⱽᴵ/L contaminated tap water. More than 90 % of hexavalent chromium was reduced to trivalent chromium, from both plant species, as measured in the drainage water. Moreover, total chromium removal ranged from 54 % (Phragmites) to 70 % (Helianthus). After 90 days, the total chromium content of the contaminated soil dropped from 70 to 32 and 34 mg Cr/kgdᵣy ₛₒᵢₗ, for Helianthus and Phragmites, respectively. Helianthus accumulated higher amount of chromium in the roots (2,730 mg Cr/kgdᵣy ₜᵢₛₛᵤₑ) as compared to 1,800 mg Cr/kgdᵣy ₜᵢₛₛᵤₑ for Phragmites. Most of Crⱽᴵ was reduced to Crᴵᴵᴵ in all plant tissues, with Phragmites showing lower affinity for Crⱽᴵ reduction in the root tissues but higher chromium translocation potential from roots to stems, while Helianthus showed higher chromium translocation from roots to leaves. Toxicity effects, expressed as root growth rate inhibition, indicated that Phragmites were the most tolerant specie to chromium effects. Both plant species showed high potentialities to be used in phytoremediation installations for chromium removal.

A special sequential extraction (SE) procedure for mercury (Hg) was conducted to determine biogeochemical fractions of Hg and their controlling factors in four contaminated soil profiles located in two distinct floodplain ecosystems which differ in their industrial histories and thus in their Hg loads. The first study area is located at the Wupper River (Western Germany) and the soil profiles reveal sum of Hg (Hgₛᵤₘ) concentrations up to 48 ppm. The second study area is located at the Saale River (Eastern Germany) and the soil profiles have Hgₛᵤₘ concentrations up to 4.3 ppm. The majority of Hg was found in fraction IV (FIV, Hg⁰) for both study areas, indicating its anthropogenic origin. Moreover, we have detected Hg in fraction V (FV) and in fraction III (FIII). As Hg in FV is mostly associated with Hg sulfides being formed under reducing conditions, it indicates reduction processes which usually occurred during flooding. Mercury in FIII (organo-chelated Hg) exhibits a moderate mobility and a high methylation potential. Between Hg in FIII and hot-water-extractable carbon (CHWE) as a measure of easy degradable, labile soil organic matter, we found a significant correlation. Sum of Hg seem to have a high affinity to organic carbon (Cₒᵣg). The concentrations of Hg in the mobile and exchangeable fractions FI and FII were low. Moreover, the significant positive correlation between iron (Fe) and Hg in FIV indicate an interaction between Hg and Fe. The majority of the Hg in our soils is considered to be relatively immobile. However, since the formation of more mobile Hg species via oxidation or methylation might occur in floodplain soils, the low Hg concentrations in mobile fractions should not be underestimated due to their high mobility and potential plant availability.

Rapid expansion of natural gas drilling in Sublette County, WY (1999-present), has raised concerns about the potential ecological effects of enhanced atmospheric nitrogen (N) deposition to the Wind River Range (WRR) including the Class I Bridger Wilderness. We sampled annual throughfall (TF) N deposition and lichen thalli N concentrations under forest canopies in four different drainages of the WRR. Measurements of TF N deposition and N concentrations in lichen thalli were highest at plots closest to drilling operations (<30 km). N concentrations in lichens decreased exponentially with distance from drilling activity. Highest TF N deposition, 4.1 kg ha -1 year-1, coincided with clear evidence of damage to lichen thalli. This deposition value is above estimated preindustrial deposition conditions (0.9 kg N ha-1 year-1) and regional critical loads (a deposition value below which ecosystem harm is prevented) of N deposition for sensitive ecosystem components. N concentrations in Usnea lapponica were strongly correlated (r = 0.96) with TF N deposition, demonstrating that elemental analysis of lichen material can be used to estimate TF N deposition. N concentrations below 1.35 % in U. lapponica and 1.12 % in Letharia vulpina were associated with estimated background conditions of 0.9 kg N ha-1 year-1. Additional lichen sampling in the Bridger Wilderness is recommended to further quantify and monitor spatial patterns of N deposition and to define areas of elevated N deposition. © 2013 Springer Science+Business Media Dordrecht (outside the USA).

In this study, arsenate removal by apricot stone-based activated carbon (IAC) modified with iron (oxy-hydr)oxides was carried out. For this purpose, hybrid adsorbents based on Fe²⁺-loaded activated carbon (IAC–Fe(II)) and Fe³⁺-loaded activated carbon (IAC–Fe(III)) were synthesized by precipitation method. A three-level, three-factor Box–Behnken experimental design combined with response surface methodology (RSM) was employed to find the optimum combination of process parameters for maximizing the As(V) adsorption capacity of activated carbon-based iron-containing hybrid adsorbent. Three important operation parameters, namely, initial pH of solution (3.0–7.0), temperature (25–65 °C), and initial As(V) concentration (0.5–8.5 mg L⁻¹), were chosen as the independent variables, while the As(V) adsorption capacities of hybrid adsorbents were designated as dependent variables. Lack of fit test showed that the quadratic model provided the best fit to experimental data for both adsorbents with the highest coefficients of determination (R ²), adjusted R ², and p-values for lack of fit. The standardized effects of the independent variables and their interactions were tested by analysis of variance and Pareto chart. The model F-values (F IAC–Fₑ₍II₎=330.39 and F IAC–Fₑ₍III₎=36.19) and R ² values (R ² IAC–Fₑ₍II₎=0.9977 and R ² IAC–Fₑ₍III₎=0.9789) of second-order polynomial regression equations indicated the significance of the regression models. Optimum process conditions for As(V) adsorption onto IAC–Fe(II) were 63.68 °C, pH 3.10, and 8.4 mg L⁻¹ initial arsenic concentration, while 25.22 °C, pH 3.07, and 8.28 mg L⁻¹ initial As(V) concentration were found to be optimum conditions for IAC–Fe(III).

Quality of the essential commodity, water, is being compromised by contaminants originating from anthropogenic sources, industrial activities, agriculture, etc. Water scarcity and severe droughts in many regions of the world also represent a significant challenge to availability of this resource. Domestic rainwater harvesting, which involves collection and storage of water from rooftops and diverse surfaces, is successfully implemented worldwide as a sustainable water supplement. This review focuses on chemical and microbial qualities of domestic rainwater harvesting, with a particular focus on sources of chemical pollution and major pathogens associated with the water source. Incidences of disease linked to consumption and utilization of harvested rainwater are also discussed. In addition, various procedures and methods used for disinfection and treatment of harvested rainwater, such as implementation of filter systems (activated carbon, slow sand filtration, etc.), heat treatment, and chlorination, among others, are also presented.

A study was undertaken using urban soils in Detroit, MI and reference materials (cerussite, anglesite, pyromorphite, apatite, goethite, calcite, pyrolusite, and peat) to determine which geochemical forms of Pb measured by sequential extraction analysis are bioaccessible. The results suggest that the water soluble (Pb-fulvic acid complexes), exchangeable, and part of the carbonateoccluded fractions are bioaccessible. The Fe oxideoccluded, Mn oxide-occluded, and higher molecular weight component of the organically bound fraction are not bioaccessible. Sequential extraction predicts the presence of detectable levels of bioaccessible Pb in the rhizosphere when the summed total is ≥90 mg kg-1 and labile Pb is ≥30 mg kg-1. Cerussite (paint-Pb) and anglesite (auto-Pb), recovered mainly in the carbonateoccluded fraction, may cause an overestimation of calcite-Pb. Pyromorphite and apatite Pb (bone) may cause an overestimation of Fe oxide-occluded Pb. © Springer Science+Business Media Dordrecht 2013.

The potential for climatic factors as well as soil–plant–climate interactions to change as a result of rising levels of atmospheric CO₂ concentration is an issue of increasing international environmental concern. Agricultural and forest practices and managements may be important contributors to mitigating elevated atmospheric CO₂ concentrations. A computer model was developed using the Structural Thinking and Experiential Learning Laboratory with Animation (STELLA) software for soil CO₂ emissions from a short-rotation woody crop as affected by soil water and temperature regimes, root and microbial respiration, and surficial processes such as rainfall, irrigation, and evapotranspiration. The resulting model was validated with good agreement between the model predictions and the experimental measurements prior to its applications. Two scenarios were then chosen to estimate both diurnal and annual soil CO₂ emissions from a 1-ha mature cottonwood plantation as affected by soil temperature, soil (i.e., root and microbial) respiration, and irrigation. The simulation resulted in typical diurnal soil respiration and CO₂ emission patterns, with increases from morning to early afternoon and decreases from early afternoon to midnight. This pattern was driven by diurnal soil temperature variations, indicating that soil temperature was the main influence on soil respiration and CO₂ efflux into the atmosphere. Our simulations further revealed that the average seasonal soil respiration rate in summer was 1.6 times larger than in winter, whereas the average seasonal CO₂ emission rate in summer was 1.77 times larger than in winter. Characteristic annual variation patterns for soil respiration and CO₂ emission also were modeled, with both increasing from January 1 through June 30 followed by steady declines from September 1 through December 31. These results suggest that the STELLA model developed is a useful tool for estimating soil CO₂ emission from a short-rotation woody crop plantation.

While copper is known to be neurotoxic, effects on behavior and especially on group behavior have received much less attention. Yet such behavioral effects can have important ecological consequences. This study determined whether shoaling behavior could be used as an indicator of acute copper toxicity and as an endpoint in studying acclimation in the least killifish (Heterandria formosa). For acute toxicity, least killifish were exposed to 0, 25, 50, or 100 μg/L of Cu for a 2-h duration and then tested for changes in shoaling behavior. The occurrence of copper acclimation was tested by pre-exposing fish to either 0 or 15 μg/L of Cu for a 7-day duration, then exposing them to 25, 50, or 100 μg/L of Cu to assess whether the two pre-exposure groups differed in their behavioral responses to high Cu levels. Behavioral responses were tested in a subdivided aquarium, with one side containing a group of conspecific fish and the other side the focal fish whose behavior was recorded for 3 min. Shoaling was based on the proximity of the focal fish to the divider separating it from the group of conspecific fish. Acute copper exposure resulted in significant decreases in both the time to first shoaling and in the total amount of time spent shoaling. Experiments assessing the occurrence of copper acclimation using shoaling as the toxicity endpoint did not detect a difference between the pre-exposure groups. Overall, this study demonstrated that acute copper exposure can alter shoaling behavior. However, least killifish shoaling behavior appears to be relatively insensitive as an endpoint to assess copper acclimation. © 2013 Springer Science+Business Media Dordrecht.

A pilot-scale anaerobic bioreactor with high levels of microbial sulfate reduction, known to be capable of removing cationic metals from a metal- and acid-contaminated waste stream, was utilized to determine if the system would be effective in removing metals in the form of oxyanions such as arsenate and chromate. The system removed 90 % to >99 % of the arsenic and between 86 % and 94 % of the chromium from a waste stream containing 5 mg/L of each. Cadmium, copper, iron, lead, and zinc also were removed. An equilibrium geochemistry computer modeling code, MINTEQAK, modified from MINTEQA2, was used for the chemical modeling of processes in the bioreactor. Experimental evidence on the chemical and biological reduction of arsenic and chromium and fluorescent diffraction analysis of precipitates support the following hypotheses: the primary removal process for chromium was the reduction of Cr(VI) to Cr(III) by sulfides, followed by precipitation of chromium hydroxide [Cr(OH) 3(s)]; removal of arsenic was by direct microbial enzymatic reduction of As(V) to As(III) followed by precipitation of arsenic sulfides (As 2S3 or AsS). Experimental evidence and modeling with MINTEQAK confirmed that 90 % to 95 % of the removal of arsenic and chromium occurred in the first quarter volume of the bioreactor. Additional removal of arsenic and chromium occurred in the remaining volume of the bioreactor. The use of a sulfate reduction-based anaerobic treatment system was effective for metal-laden wastewater with elevated concentrations of arsenic and chromium. © 2013 Springer Science+Business Media Dordrecht.