Although the climate change effects on plants have been a focus for more than two decades, such effects on aquatic species remain largely unknown. To evaluate the potential effects of elevated CO₂ on growth and nutrient uptake of Eichhornia crassipe Solms (commonly known as water hyacinth, the world's most significant invasive aquatic weed), plants were grown at two CO₂ concentrations (380 and 800 ppm) combined with four nutrient levels (oligo-, meso-, eu-, and hypertrophic) for 2 months. Overall, elevated CO₂ consistently enhanced plant growth at all nutrient levels, indicating more infestations of water hyacinth in future natural eutrophic waters. Moreover, the enhancement extent varied among nutrient availabilities, being more in eu- and hypertrophic levels and less in meso- and oligotrophic levels. Furthermore, the CO₂ enrichment-deduced assimilation was allocated more to plant roots than shoots which would improve the nutrient absorption capacity and mostly transferred to offspring ramets rather than maintained at the mother ramet which would benefit the vegetative reproduction. Finally, under elevated CO₂, although the nitrogen (N) and phosphorus (P) contents of E. crassipe slightly decreased which might mean increased difficulties in preventing its infestation by reducing N and/or P in eutrophic waters, the total N and P accumulation increased suggesting higher bioremediation efficiency of using water hyacinth for water eutrophication.

The investigation was carried out on laboratory scale to assess the feasibility of upflow anaerobic sludge blanket reactor system as a pretreatment for hydrogenated vegetable oil industry wastewater with recourse to energy recovery. The reactor system operated at 35°C, resulted in COD removal efficiency in the range 98.9-80.1% at organic loading varying in the range 1.33-10 kgCOD/m³ day. The specific methane yield varied from 0.295-0.345 m³CH₄/kgCODr. Hydraulic retention time, substrate concentrations, pH, and temperature were also varied to study the influence of operating parameters on reactor performance. The methane content decreased with increase in substrate loading rate, and varied from 53-66.7% under varying operating conditions. Impulse loading studies in terms of hydraulic, organic, and pH though resulted in destabilization of the reactor; however, the reactor rapidly achieved stable performance after steady operation.

In the present work the kinetics of ferric reduction was investigated using dissimilatory ferric- and sulphate-reducing bacterial cultures. The effect of sulphate reduction on Fe(III) reduction was also studied. The study is an attempt to improve the biological reduction rate of Fe(III) as an alternative biotechnological way to the reduction step in steelmaking processing operations. The results obtained show that the reduction of ferric iron and sulphate took place in a successive way and none synergetic effect was detected. The simultaneous action of both metabolic activities did not enhance the process but slowed down the kinetics of ferric reduction. The reduction process of 3 g/L of soluble ferric and 3 g/L of sulphate lasted 25 days. Ferric iron was the first electron acceptor to be reduced in the first 15 days followed by the sulphate reduction in the following 10 days. That result suggests that ferric reduction is a preferential metabolic process over sulphate reduction when both electron acceptors coexist. None improvement in the kinetics was observed using an electron donor concentration in excess. In contrast, the total reduction of ferric ion (3 g/L) with adapted bacterial cultures was achieved in only 36 h. The presence of sulphate had no effect on the ferric reduction. Finally, an improved culture medium for ferric-reducing bacteria is also proposed.

This work presents the results of 4 years long monitoring of concentrations of SO₂ gas and PM₁₀ in the urban area around the copper smelter in Bor. The contents of heavy metals Pb, Cd, Cu, Ni, and As in PM₁₀ were determined and obtained values were compared to the limit values provided in EU Directives. Manifold excess concentrations of all the components in the atmosphere of the urban area of the townsite Bor were registered. Through application of a multi-criteria analysis by using PROMETHEE/GAIA method, the zones were ranked according to the level of pollution.

Heavy metals are present in a variety of products and can be released to the environment during product life cycles. The concentration of metals in municipal solid waste (MSW) reflects the amount of metals in products and is directly related to the amount of metals transferred to disposal sites. Measured monthly mean concentrations of cadmium, lead, and mercury in the ash from May 1995 through October 2007 at the Essex County, NJ incinerator and from May 2004 through November 2007 at the Warren County, NJ incinerator were used, along with air emissions data for mercury, to estimate the content of these metals in MSW. Estimated mean concentration and 95% confidence limits for cadmium in MSW at the Essex and Warren facilities, respectively, were 17.4 ± 0.1 and 10.1 ± 1.2 ppm. For lead, the corresponding values were 408 ± 41 and 239 ± 42 ppm, and for mercury, they were 2.6 ± 0.2 and 0.9 ± 0.2 ppm. A trend of increasing cadmium concentrations was found at both facilities. No change vs. time was observed in lead concentrations. Mercury concentration was found to be decreasing over time at the Essex facility.

Dredged river sediments and biosolids used as amendments for agricultural purposes can provide a suitable plant growth medium, a topsoil substitute. Nevertheless, trace metal bioaccumulation and risk of plant toxicity remains a concern. We conducted a greenhouse experiment to evaluate the plant growth and trace metal bioaccumulation on sediments and biosolid mixtures. These included dredged sediment from the Peoria Lakes portion of the Illinois River and class A biosolids from the Metropolitan Water Reclamation District of Greater Chicago. Six different mixtures were produced in addition to a standard greenhouse mix serving as a control. Barley (Hordeum vulgare) and snap bean (Phaseolus vulgaris) were grown on the mixtures in the greenhouse. Plants grew in all treatments, except for snap beans that were stunted likely by high salt content in unleached biosolid mixtures. The highest overall biomass production for barley was obtained in the treatment composed of 50% sediment and 50% biosolids. For snap bean, the highest biomass productions were obtained in treatments composed of ≤50% biosolids in the mixture. Trace metals in plant tissue were within ranges considered normal, except for Mo in snap bean, which was at a level considered excessive. However, addition of biosolids to sediments decreased Mo plant uptake. Based on our results, sediments mixed with biosolids make a fertile topsoil and have no inherent chemical or physical properties that would preclude its use as a plant growth medium. Adding sediments to unleached fresh biosolids improved plant growth and diminished trace metal uptake. The suggested optimal ratio of sediments to biosolids would be 80:20 to 70:30 by volume in most situations.

The Han River, which is the largest river in Korea, is the primary source of drinking water for the 20 million people that live in the Seoul metropolitan and surrounding areas. The sediments in the river are highly polluted due to pollutant inputs from upstream tributaries as well as from partially treated municipal wastewaters. To characterize the contamination of the sediments, disturbed and undisturbed sediment samples were periodically collected from eight locations of the mid-to-lower Han River. They were analyzed for pH, water content, total solids, ignition loss (IL), total phosphorous (TP), total Kjehldahl nitrogen (TKN), and chemical oxygen demand (COD). The mean values of pollutant concentrations in disturbed sediment were determined to be 6.9% for IL, 1,700 mg/kg for TP, 3,350 mg/kg for TKN, and 65,710 mg/kg for COD. Pollutant concentrations of undisturbed samples were found to decrease with sediment depth and time due to the removal mechanism. Monitoring of pre- and post-dredging conditions was also performed, and the results show that the pollutant concentrations decreased from those for the pre-dredging condition to 33-57% for TP, 51-64% for TKN, and 30-62% for COD. It is concluded that dredging was an effective means to reduce the internal pollutant source.

Near-infrared diffuse reflectance sensing (NIRS) of soils has been the object of considerable interest and research in the last few years. This has been motivated by the prospect that this method seems to provide a cheap, convenient alternative to conventional, time-consuming methods for the measurement of a wide range of soil parameters. In particular, various authors have advocated that NIRS could be used to measure rapidly and non-destructively the concentration of trace metals in surface soils. Correlation analyses between NIRS spectra and trace metal concentration have yielded inconclusive results to date, suggesting that trace metal concentration may belong to a class of “tertiary” soil parameters, linked to NIRS spectra through “surrogate”, or indirect, correlations, involving some other primary or secondary parameter like clay or organic matter content, to which NIRS spectra are very sensitive. To assess the validity of this surrogate correlation hypothesis in the case of trace metals, experiments were carried out with soil samples varying only in the amount of trace metals they contain. Field-aged Hudson and Arkport soil pots spiked with Cu and Zn, freshly spiked samples of the same soils, and samples of a metalliferous peat soil from Western New York naturally rich in Cd and Zn were subjected to NIRS under laboratory conditions. Detailed analysis indicates that the NIR spectrum is sensitive to sample handling, including the orientation of the samples in the NIRS instrument, but that, at the same time, there is no discernable effect of the presence of trace metals on any part of the NIR spectrum. These results provide strong experimental support to the hypothesis of “surrogate” correlation for trace metals, and indicate that trace metals, even in severely contaminated soils, should not interfere with the NIR sensing of primary or secondary parameters, like organic matter content. Further work is needed to determine if this feature of NIR spectra extends to other soil chemical parameters.

Stable isotope analyses were performed on gas samples collected within two instrumented biocovers, with the goal of evaluating CH₄ oxidation efficiencies (f ₀). In each of the biocovers, gas probes were installed at four locations and at several depths. One of the biocovers was fed with biogas directly from the waste mass, whereas the other was fed through a gas distribution system that allowed monitoring of biogas fluxes. While the f ₀ values obtained at a depth of 0.1 m were low (between 0.0% and 25.2%) for profiles with poor aeration, they were high for profiles with better aeration, reaching 89.7%. Several interrelated factors affecting aeration seem to be influencing f ₀, including the degree of water saturation, the magnitude of the biogas flux and the temperature within the substrate. Low f ₀ values do not mean necessarily that little CH₄ was oxidized. In fact, in certain cases where the CH₄ loading was high, the absolute amount of CH₄ oxidized was quite high and comparable to the rate of CH₄ oxidation for cases with low CH₄ loading and high f ₀. For the experimental biocover for which the CH₄ loading was known, the oxidation efficiency obtained using stable isotopes (f ₀ = 55.67% for samples taken inside flux chambers) was compared to the value obtained by mass balance (f ₀ = 70.0%). Several factors can explain this discrepancy, including the high sensitivity of f ₀ to slight changes in the isotopic fractionation factor for bacterial oxidation, α ox, uncertainties related to mass flow metre readings and to the static chamber method.

The environmental and economic consequences of nitrogen (N) lost in rice-based systems in Vietnam is important but has not been extensively studied. The objective of this study was to quantify the amount of N lost in major cropping systems in the Red River Delta. An experiment was conducted in the Red River Delta of Vietnam, on five different crops including rose, daisy, cabbage, chili, and a rice-rice-maize rotation during 2004 and 2005. Core soil samples were taken periodically in 20-cm increments to a depth of 1 m and analyzed for nitrate-nitrogen and ammonium-nitrogen. The results indicate appreciable leaching losses on N in high-rainfall and irrigation conditions, especially when fertilizer application was not well synchronized with crop N demand. Highest annual leaching losses of N were recorded in flowers with 185-190 mm of percolation and 173-193 kg N ha⁻¹, followed by vegetable (cabbage and chili) with 120-122 mm of percolation and 112-115 kg N ha⁻¹, while it was lowest in rice with about 50 kg N ha⁻¹. We developed a simple N transport model that combined water and N movement through the soil profile. In most cases, the model accurately predicted the seasonal dynamics of N as well as N flow between soil layers and the amounts of N lost from the soil profile. The simulated results of N leaching with soil “puddling” conditions illustrate the advantage of an impermeable or hardpan layer in increasing water and nutrient use efficiencies in these soils. These model results also showed that it is possible to accurately estimate N losses with only a few parameters and helped us identify the risks of N leaching.