Intermittent wastewater loading, a characteristic of aquaculture operations, undermines the usefulness of treatment wetlands designed using the steady state assumption. Being biological systems, the treatment variability of such wetlands must also be addressed during the design phase. A simulation-optimization model suitable for modeling intermittent pollutant releases and identifying optimal area and wastewater loading patterns for aquaculture operations is integrated with a decision-analytic framework to determine wetland area and release pattern under uncertainty and risk. Wetland area and release patterns corresponding to different decision making priorities were obtained by applying the minimax, maximax, Hurwicz and minimax regret criteria. The developed methodology provides a convenient framework for aquaculture operators and wetland design engineers to consider trade-off between the wetland size (an indicator of construction and opportunity costs) and wastewater loadings (an indicator of operation costs) during the design process. The results can also be used to characterize the risk-attitudes of the aquaculture operators and identify the worth of additional studies (i.e., pilot tests) given their risk-preferences.

In 1998, the pond containing the ore wastes from a pyrite mine in Aznalcóllar (SW, Spain) broke open, spilling some 36×10⁵ m³ of acidic waters and 9 × 10⁵ m³ of tailings containing high concentrations of As and heavy metals. The affected area was around 55 km² of predominantly agricultural soils. After the clean-up of the tailings, many remediation actions were undertaken and the use of blocking agents to immobilize the As was one of the most extended measure. The first experiment performed was to determine the most important soil components in As adsorption under acidic conditions. A second experiment was conducted to neutralize the acidity caused by the solution coming from the tailings undergoing oxidation; an adequate liming material (sugar-refinery scum) was selected and the application rates were established. After the remediation measures, the zone was monitored for three years. A detailed study in four experimental plots located in the most polluted sector was carried out to test the influence of iron oxides in the As immobilization. The use of red soils of the area (rich in free-iron oxides Fed) was established as an appropriate material in the remediation of the area.

Heavy metal pollution in sediments derived from the Deûle canal and sampled at different sites not far from a smelting plant has been examined in the present work in order to identify the sources of these metals and to assess the sediment environmental quality. The total concentrations of lead, zinc, cadmium, thallium, indium and tin in the samples were determined using inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Our investigations have revealed that metal pollution is readily apparent in the studied sediments, with metals contents largely exceeding those measured in the background soils: maximum values are obtained for sediments collected near the industrial zone. The chemical forms of Pb, Zn, Cd, Tl, In and Sn in these sediments have also been studied using a sequential extraction method in order to evaluate their possible mobility, bioavailability and toxicity in this aquatic environment. Overall, the averaged fractionation of Pb and Zn is dominated, in a decreasing order, by the easily reducible, oxidizable and carbonate fractions. The importance of oxidizable phase (which is assumed to be composed mainly of organic matter and sulphides) in the Pb and Zn fractionations has been confirmed by the detection of X-ray diffraction peaks ascribed to galena (PbS) and wurtzite (ZnS) in contaminated sediment samples. Anthropogenic Tl, In, and Cd are mainly retained in Fe–Mn oxides/hydroxides, whereas anthropogenic Sn predominates in aluminosilicates/clays. We suspect that elevated percentage levels of Pb, Zn, Cd and In in the reducible fraction constitute a particular potential risk to this aquatic environment in case early diagenetic phenomena (that are observed in the sedimentary material) and physical disturbances (that occur in the water column) both take place strongly in the medium.

Investigation of nine herbaceous species collected around five polluters in northwestern Russia (nickel-copper smelters at Monchegorsk and Nikel, ore-roasting factory at Zapolyarnyy, aluminium smelter in Kandalaksha, and iron pellet plant at Kostomuksha) demonstrated that effects of pollution on plant growth were rarely significant in individual analyses. However, meta-analysis revealed decrease in plant size, in terms of height and leaf length; simultaneous increase in the number of leaves and flowers/inflorescences may compensate for this decline, thus the biomass of aboveground plant parts did not change. This result contrasts numerous experimental studies that generally demonstrate adverse effects of various pollutants on growth and reproduction of herbaceous plants, hinting that the effects detected in short-term experiments are of limited value for predicting performance of plant individuals surviving in polluted ecosystems. Changes in growth and reproduction of plants persisting under chronic pollution are minor presumably due to development of pollution tolerance and adaptation to altered environmental conditions.

Plant age affects its elemental uptake and biomass accumulation, which is important for the application of plants in phytoextraction. In this research, we evaluated the effects of plant age on arsenic accumulation by arsenic hyperaccumulator Pteris vittata after growing in an arsenic-contaminated soil for 8 weeks. The study used a completely randomized design consisting of four plant ages (2, 4, 10 and 16 months) with four replications each. While the fronds of the 2 month old plants contained 36% more arsenic than those of the 4 and 16 month old plants, they were lower in roots. After 8 weeks of growth, the final frond biomass increased by 39, 6.9, 2.0 and 1.1 times compared to the initial frond biomass, from youngest to oldest, respectively. Higher phosphorus and iron accumulation in the roots of older plants may have affected the plant's efficiency to bioconcentrate and transfer arsenic from the roots to the fronds. Greater metabolic activity and higher rate of biomass production lead to higher As accumulation and removal by young plants. This research demonstrated that the use of young plants can be an effective strategy to reduce the time to remediate an As-contaminated site.

Highly organic soils, and in particular ombrotrophic bogs, have been often used to reconstruct climate changes and heavy metal contaminations. Ombrotrophic peat bogs, in fact, are domed peatlands in which the surface layers are hydrologically isolated from the influence of local groundwaters and surface waters, and are supplied only by atmospheric depositions. In the present work, the attention of Authors has been focused on Pb, Cu, and Zn, coming mainly from anthropogenic activities, and ¹³⁷Cs, released mostly during the Chernobyl disaster. Practically, an undisturbed peat profile was cored in 2005 from a Swiss ombrotrophic bog and analysed using energy-dispersive miniprobe multielement analyzer X-ray fluorescence and Low Background γ-ray spectrometry in order to investigate and quantify the impact of human activities (e.g., industry, traffic, combustion of fossil fuels, “environmental disasters”) in causing Pb, Cu, Zn, and ¹³⁷Cs contaminations during the centuries. Obtained data show that highly organic soils in general, and ombrotrophic bogs in particular, reflect the anthropogenic inputs in heavy metal and radionuclide contaminations. In fact, these environments allowed to follow the depositional history of Pb, Cu, and Zn, both underlining a general increasing of their production since the Industrial Revolution, and remarking past single impacting events such as the introduction of leaded gasoline and of particular agricultural practices. Further, although ¹³⁷Cs showed a main peak corresponding to the Chernobyl disaster, confirming the role of bogs as archive of human activity, data revealed a certain mobility of this radionuclide along the profile. Thus, highly organic soils can be considered as both “witness” of the impact of human activity during centuries and indicator of the health of our planet.

A quasi steady state respiration test based on Fick's law with a correction term for advective flux, for estimating petroleum hydrocarbon degradation rates, was evaluated in a full-scale (3,000 m³) biopile study. A contaminated clayey sand soil with an average TPH content of 1,421 ± 260 mg kg-¹ soil was treated in a biopile with a fixed venting and heating system. Temperature in the biopile ranged from 12.1 to 36.6°C and soil water content from 15.2 to 35.8 m³ H₂O m-³ soil. Oxygen concentrations in the biopile showed a rapid decrease with depth, before venting and reached constant atmospheric concentration during venting. Measured oxygen consumption in the biopile ranged from -0.04 to -0.68 mol O₂ m-³ soil day-¹. Average oxygen consumption rates calculated with the quasi-steady-state method were significantly (P < 0.05) lower then the oxygen consumption rates calculated with the transient method. It was suggested that the oxygen diffusion was underestimated by the diffusivity models used and that further research is needed to determine relative effective diffusion coefficients in biopiles. Although both respiration testing and petroleum hydrocarbon concentration showed a decrease of oxygen consumption in time, the estimated degradation rate was low compared to the actual decrease in petroleum hydrocarbon concentration. Additional work will have to be done to acquire a more precise knowledge of the relationship between respirometrically determined degradation rates and the actual change in petroleum hydrocarbon concentration in the soil.

Mercuric ions (Hg²⁺) and methylmercury are major, human-generated, toxic contaminants present in fish and our waterways. Bacteria provide a means of bioremediation by taking up these compounds and reducing them to volatile, non-toxic, elemental mercury (Hg°). Three types of mercury/methylmercury transporters have previously been identified: MerC, MerF and MerT. Each of these sets of homologues has distinct topologies. MerF proteins are characterized by a 2-transmembrane α-helical segment (TMS) topology; most MerTs have three TMSs, and MerCs have four TMSs. This report shows that MerT and MerF proteins are related by common descent and are similar in sequence throughout their first two TMSs. One of the MerF proteins is internally duplicated, generating a protein with four TMSs, while several MerT homologues bear a C-terminal extracytoplasmic Hg²⁺-binding MerP domain. MerPs are homologous to heavy metal-binding domains present in copper chaperone proteins, at the N-termini of mercuric reductases and in from one to six copies in heavy metal transporting P-type ATPases. Phylogenetic analyses reveal that mercuric ion transporters have been horizontally transferred with high frequency between bacteria. Some MerTs function with MerP receptors while others do not, and the MerP-dependent MerTs cluster separately from the MerP-independent MerTs on a phylogenetic tree. MerTs possessing a MerP appear to have co-evolved with their cognate receptors. Conserved sequence and motif analyses serve to define the mercuric transporter family fingerprints and allow prediction of specific subfunctions. This report provides the first detailed bioinformatic description of two apparently unrelated families of Hg²⁺ uptake transporters. We propose that all members of these two families function by a simple channel-type mechanism to allow influx of Hg²⁺ in response to the membrane potential in preparation for reduction and detoxification. This information should facilitate the exploitation of these transporters for purposes of microbial and phytobioremediation.

We tested the efficacy of matrix based fertilizer formulations (MBF) that reduce NH₄, total phosphorus (TP), total reactive phosphorus (TRP) and dissolved reactive phosphorus (DRP) in leachate. The MBF formulations cover a range of inorganic N and P in compounds that are relatively loosely bound (MBF1) to more moderately bound (MBF2) and more tightly bound compounds (MBF3) mixed with Al(SO₄)₃ H₂O and/or Fe₂(SO₄)₃ and with the high ionic exchange compounds starch, chitosan and lignin. Glomus interadicies, a species of arbuscular mycorrhizal fungal spores that will form mycorrhizae in high nutrient environments, was added to the MBF formulations to increase plant nutrient uptake. When N and P are released from the inorganic chemicals containing N and P the matrix based fertilizers likely bind these nutrients to the Al(SO₄)₃ H₂O and/or Fe₂(SO₄)₃ starch–chitosan–lignin matrix. We tested the efficacy of the MBFs to reduce N and P leaching compared to Osmocote® 14-14-14, a slow release fertilizer (SRF) in sand filled columns in a greenhouse study. SRF with and without Al and Fe leached 78–84% more NH₄, 58–78% more TP, 20–30% more TRP and 61–77% more than MBF formulations 1, 2, and 3 in a total of 2.0 liters of leachate after 71 days. The concentration and amount of NO₃ leached among SRF and MBF formulations 1 and 2 did not differ. The SRF treatment leached 34% less NO₃, than MBF3. Total plant weight did not differ among fertilizer treatments. Arbuscular mycorrhizal infection did not differ among plants receiving SRF and MBF formulations 1, 2 and 3. Although further greenhouse and field testing are called for, results of this initial investigation warrant further investigation of MBFs.

Buffer capacity analysis of open atmospheric gas-liquid systems containing main acidic and basic atmospheric pollutants was carried out. Usually the buffer capacity is considered as a function of pH as an independent variable. In this work the buffer capacity is analysed including the dependence of pH on the composition of a system. Such an approach allows finding an important, from the viewpoint of atmospheric water acidification, relationship between the gas phase composition and the buffer capacity. It was found that buffer capacity of the open gas-liquid systems may be very high and it may cause the liquid phase pH to remain at low levels. The buffer capacity of the analysed systems is most strongly affected by the simultaneous presence of ammonia and strong acids in the gas phase. The higher concentrations of strong acid gases the lower NH₃ concentration is sufficient to achieve high buffer capacity. In the presence of strong acid gases, calcium ions affect both the buffer capacity and the liquid phase pH only at low NH₃ concentrations. High buffer capacity of open gas-liquid systems may be one of the reasons why the reduction in emissions of acidic gas pollutants has little effect on decrease in atmospheric water acidity.