Steamboat Creek, Washoe County, Nevada, is considered the most polluted tributary of the Truckee River, therefore the reduction of nutrients from the creek is an important factor in reducing eutrophication in the lower Truckee River. Restoration of the wetlands along the creek has been proposed as one method to improve water quality by reducing nutrient and sediments from non-point sources. This study was aimed to design a simulation model wetlands water quality model (WWQM) that evaluates nitrogen, phosphorus, and sediments retention from a constructed wetland system. WWQM is divided into four submodels: hydrological, nitrogen, phosphorus, and sediment. WWQM is virtual Visual Basic 6.0 program that calculates hydrologic parameters, nutrients, and sediments based on available data, simple assumptions, knowledge of the wetland system, and literature data. WWQM calibration and performance was evaluated using data sets obtained from the pilot-scale constructed wetland over a period of four and half years. The pilot-scale wetland was constructed to quantify the ability of the proposed wetland system for nutrient and sediment removal. WWQM simulates nutrient and sediments retention reasonably well and agrees with the observed values from the pilot-scale wetland system. The model predicts that wetlands along the creek will remove nitrogen, phosphorus, and sediments by 62, 38, and 84 %, respectively, which would help to reduce eutrophication in the lower Truckee River.

In Europe more than 2,500 lysimeters operated by research institutes and industry (Lanthaler 2005). Originally lysimeters were built for investigations of soil water and solutes, nutrient leaching and pesticide degradation (see e.g. Winton and Weber 1996). Currently lysimeters additionally used as a tool for investigations on biological processes, and structural changes of plants, including root distribution, and enzyme activities etc. (see e.g. Dizer et al. 2002; Schloter et al. 2005).

Spectroscopic (XRD, XPS, ICP-MS and AAS) and microscopic (ESEM) techniques have been used in order to study the chemical effects with emphasis on mercury speciation, during thermal treatment of a mercury contaminated soil. In the untreated soil, mercury was found concentrated in spherical particles, which were successively broken down upon thermal treatment. Hg⁰ and inorganic mercury compounds (presumably HgO(s) and HgSO₄(s)) could be detected. No (CH₃)₂Hg and only traces of CH₃Hg⁺ could be found. The dependence on temperature and heating time indicated that the evaporation of mercury from the soil was partly controlled by diffusion mechanisms. Mercury volatilized in two separate stages during heating; initial elemental vaporization, and subsequent volatilization of the oxide or sulfate phase at higher temperatures (>230°C). By thermal treatment at 470°C and 20 min, a removal of >99% of the mercury could be achieved.

A critical load data base was developed for Europe and Northern Asia using the latest data bases on soils, vegetation, climate and forest growth. Critical loads for acidity and nutrient nitrogen for terrestrial ecosystems were computed with the Simple Mass Balance model. The resulting critical loads are in accordance with critical loads from previous global empirical studies, but have a much higher spatial resolution. Critical loads of acidity are sensitive to both the chemical criterion and the critical limit chosen. Therefore a sensitivity analysis of critical loads was performed by employing different chemical criteria. A critical limit based on an acid neutralizing capacity (ANC) of zero resulted in critical loads that protect ecosystems against toxic concentrations of aluminium and unfavourable Al/Bc ratios, suggesting that ANC could be an alternative to the commonly used Al/Bc ratio. Critical loads of nutrient nitrogen are sensitive to the specified critical nitrate concentration, especially in areas with a high precipitation surplus. If limits of 3-6 mg N l⁻¹ are used for Western Europe instead of the widely used 0.2 mg N l⁻¹, critical loads double on average. In low precipitation areas, the increase is less than 50%. The strong dependence on precipitation surplus is a consequence of the simple modelling approach. Future models should explore other nitrogen parameters (such as nitrogen availability) instead of leaching as the factor influencing vegetation changes in terrestrial ecosystems.

Data were collected simultaneously at different succession stages using a space-for-time substitution, and were analyzed using the quantitative classification method (Twinspan) and the ordination technique (DCA). The community succession analysis of naturally colonized plants on coal gob piles in Shanxi mining areas was as followings: Assoc. Setaria viridis + Amaranthus retroflexus [rightward arrow] Assoc. Tribulus terrester + Setaria viridis [rightward arrow] Assoc. Setaria viridis + Artemisia annua [rightward arrow] Assoc. Bothriochloa ischaemum + Artemisia capillaries [rightward arrow] Assoc. Bothriochloa ischaemum + Artemisia scoparia [rightward arrow] Assoc. Periploca sepium - Artemisia gmelinii [rightward arrow] Assoc. Periploca sepium + Lespedeza daurica - Artemisia gmelinii [rightward arrow] Assoc. Periploca sepium + Vitex negundo var. heterophylla - Bothriochloa ischaemum [rightward arrow] Assoc. Ailanthus altissima - Lespedeza daurica - Artemisia gmelinii [rightward arrow] Assoc. Robinia pseudoacacia - Vitex negundo var. heterophylla - Bothriochloa ischaemum. This established a model of the recovery of natural vegetation on coal gob piles in Shanxi mining areas. The structure, composition and life-forms changed significantly during succession. Six indices of species diversity were used to analyze changes in the richness, evenness and heterogeneity of species during the succession process. As the succession progressed, the richness of plant communities increased significantly, the evenness increased slightly and the heterogeneity increased obviously. The plant development could obviously increase the organic content in the surface layer of coal gob piles. Pioneer species of Setaria viridis, Amaranthus retroflexus, Tribulus terreste, Artemisia gmelinii, Bothriochloa ischaemum, Periploca sepium, Lespedeza daurica, Vitex negundo var. heterophylla, Ailanthus altissima and Robinia pseudoacacia, etc. could colonize successfully and play important roles on the vegetation restoration of coal gob piles.

Persistently high Nitrogen (N) deposition may have caused widespread N saturation in Central Europe's forests. Simple and inexpensive methods are required for estimating the N status. This study suggests that the current N status of forest ecosystems can be estimated by measuring CaCl₂-extractable nitrate concentrations in the soil below the main rooting zone. We tested this possibility using a large number of samples (135 in total) in a nested sampling design in two homogeneous Norway spruce forests in southern Bavaria. This approach was accompanied by a small scale survey with suction cups (N = 54) in one forest. Nitrate concentrations determined by soil extracts varied widely (coefficients of variance 95 and 125%) and were well comparable with those of the simultaneous investigation of seepage water. Site and stand conditions explained only a small portion (<10%) of the total variation. Mineral soil nitrate concentrations were not spatially dependent at the medium and large scales (about 10 m to several km) in both forests. Therefore the reliability of estimates at these scales depends mainly on the sample size. At the small scale (<about 10 m) large variation in nitrate concentrations and a considerable spatial dependency could be observed. Therefore intensive sampling is necessary at short distances in order to estimate the mean adequately. From our results, we deduct possibilities and limitations of nitrate inventories as a tool for regional assessment of the N status of forests.

Developing procedures for assessing the potential environmental fate and transport of nanomaterials is an active endeavor of the environmental technical research community. Insufficient information exists for estimating the likelihood of nanomaterial deposition on natural surfaces in aquatic environments. This work develops a framework for estimating potential metal oxide nanomaterial self-aggregation through the combined application of recent developments in diffuse layer model surface complexation theory with historical Derjaguin–Landau–Verwey–Overbeek (DLVO) procedures. Findings from the work include: 1) the surface, diffuse layer, and/or zeta potentials of nanomaterials in environmental aqueous systems are likely to have an absolute value less than 25 mV, 2) only nanomaterials with a Hamaker constant as large as 1E-19 J (and an absolute surface potential < 25 mV) will likely aggregate in most environmental aquatic media, 3) natural organic matter coatings may render metal oxide nanomaterials less likely to aggregate in aquatic systems, 4) nanomaterials in aqueous suspension will likely have an absolute surface potential less than their micron-sized counterparts of the same composition, and 5) robust diffuse layer model databases of intrinsic surface site reactivity constants with multivalent aqueous environmental ions will need to be developed in order to provide accurate mechanistic estimates of the surface potential of nanoparticles suspended in aqueous environmental systems.

This work describes recent research carried out in an extremely acidic (pH 0.61–0.82) and hypersaline (e.g., 134 g/L SO₄ ²⁻, 74 g/L Fe, 7.5 g/L Al, 3 g/L Mg, 2 g/L Cu, 1 g/L Zn) leachate which seeps from a pyrite pile in San Telmo mine (Huelva, SW Spain) and forms evaporative pools of ultra-concentrated water in which attractive crystals of Zn-rich melanterite (FeᴵᴵSO₄ 7H₂O) are formed. Geochemical modeling with the Pitzer method indicates that the acidic brine was near saturation with respect to melanterite (SIMₑₗ = 0 ± 0.2). The microbiological investigation has revealed a surprisingly high biomass (1.4 × 10⁶ cells mL⁻¹) and an exotic ecosystem composed of acidophilic, Fe-oxidizing archaea (mainly Ferroplasma spp., representing 52% of the microbial population), and minor numbers of acidophilic bacteria (including Leptospirillum spp. (3.2%), Acidithiobacillus spp. (1.6%), and Alphaproteobacteria (2.8%)). The microbial production of Feᴵᴵᴵ allows the oxidative dissolution of pyrite and other sulphides, which results in additional inputs of Feᴵᴵ, SO₄ ²⁻ and acidity to the system. The surfaces of the pyrite crystals show a typical etch-pitted texture, as well as blobs of elemental sulphur, which are both compatible with this indirect, microbially mediated oxidation mechanism. The composition of the acidic leachate seems to result from the combination of several processes which include: (1) formation of melanterite within the pile during relatively dry seasons, (2) subsequent dissolution of melanterite during rainy episodes, (3) microbial oxidation of Feᴵᴵ, (4) sulphide oxidation mediated by Feᴵᴵᴵ, (5) dissolution of chlorite and other aluminosilicates present in the pile, and (6) cooling and/or evaporation of seepage from the pile and consequent melanterite precipitation.

In contaminated water reservoirs, the sorption and binding of radionuclides to solids (SR) determines their bioavailability and transport and thus human and ecosystem exposure. In this work, the influence of organic matter (OM) on binding of the radionuclides ⁹⁰Sr, ¹³⁷Cs, sum of ²³⁵U, ²³⁸U, and sum of ²³⁹Pu, ²⁴⁰Pu to solids are investigated, using experimental data derived from ecological monitoring of radioactive waste deposits in South Ural (Russia). OM in several surface water reservoirs mainly consists of humic substance (HS) which forms humates and fulvates with radionuclides and binds to solids via different mechanisms, such as coordinating bond or covalent bond. These processes are strongly dependent on the phase of HS, which can be colloidal or soluble high-molecular compounds. Based on the spatial distribution of radionuclides, SR and OM in waste deposits, we assumed a specific influence of humic acids (HA) on the binding of radionuclides to SR, and quantified it with invariant values of a modified partitioning coefficient. The mathematical form of this invariant value emphasizes a significant impact of the local mass of HA (mHA/V) and local surface area of SR (s = Ssorb/V) per volume V on the processes involved in binding radionuclides to SR. These processes may retard radionuclide migration into groundwater.

Xenobiotic compounds are widely used in several industries; hence they frequently appear in industrial wastewaters. It is a well-known fact that even the discharge of conventionally treated wastewater may have adverse effects on the receiving water environment. Turkey, a developing EU applicant country, has many industrial sectors producing large amounts of xenobiotic-containing wastewaters. The problem is only enlarged by the lack of monitoring of these substances due to the deficiencies associated with their analysis and detection. Thus, studies in Turkey are based on the use of some collective parameters as a substitute for the xenobiotic itself. Biological, physicochemical, and integrated treatment technologies have been investigated for the removal and/or minimization of the possible adverse effects of xenobiotics in industrial wastewaters. In this respect, this paper provides an overview of the studies conducted on xenobiotic-containing wastewaters from specific industries in Turkey. Although the studies add invaluable information to the scientific background on the subject, new research on the exact biochemical mechanisms of xenobiotic biodegradation will further extend our understanding for improving treatment.