Degradation and remediation of soils polluted with oil-field wastewater

The changes in the properties of gray forest soils and leached chernozems under the impact of contamination with highly saline oil-field wastewater were studied in a model experiment. It was shown that the soil contamination results in the development of technogenic salinization and alkalization leading to worsening of the major soil properties. The salinization of the soils with oil-field wastewater transformed the soil exchange complex: the cation exchange capacity decreased, and the exchangeable sodium percentage increased to up to 25% of the CEC upon the wastewater infiltration and up to 60% of the CEC upon the continuous soil saturation with the wastewater independently of the soil type. The content of exchangeable magnesium also increased due to the phenomenon of super-equivalent exchange. Despite the saturation of the soil adsorption complex with sodium, no development of the soil alkalization took place in the presence of the high concentration of soluble salts. However, the soil alkalization was observed upon the soil washing from soluble salts. The gypsum application to the washed soils lowered the exchangeable sodium concentration to acceptable values and normalized the soil reaction. The gypsum application without the preliminary washing of the soils from soluble salts was of low efficiency; even after six months, the content of exchangeable sodium remained very high. The subsequent soil washing resulted in the removal of the soluble salts but did not affect the degree of the soil alkalization.     

Engineered in situ bioremediation of soil and groundwater polluted with weathered hydrocarbons

In this work, we present our experience in the engineered in situ biostimulation of a hydrocarbon-polluted subsoil of an old metal-working plant. The site had a long history of fuel, lubricant oil, and diesel spills and leakages that were initially treated by means of physico-chemical techniques. After one year of treatment, weathered hydrocarbons were firmly sorbed in the unsaturated zone, limiting the effectiveness of the physico-chemical methods being applied. Also, low nutrient and dissolved oxygen levels limited natural attenuation yields. Therefore, a bioremediation approach based on the injection of hydrogen peroxide, an oleophilic fertilizer, and a surfactant was applied. Total petroleum hydrocarbons and gas chromatography-mass spectrometry determinations were performed as a chemical means of monitoring the process. Microbial populations, including the presence of hydrocarbon-degrading bacteria, were simultaneously analyzed during the process, using enrichment techniques and confocal laser scanning microscopy observations with fluorescent indicators. Hydrocarbon-degrading bacteria were already present in the polluted subsoil prior to the implementation of this bioremediation technique and increased noticeably during the first 2 months of treatment. Hence, the suitability of the nutrient and oxygen amending approach was confirmed as further demonstrated by chemical determinations.     

The use of liquid chromatography in the study of cadmium speciation in soil solutions from polluted soils

Chromatographic methods were used in an attempt to identify the various species of cadmium in soil solution. Exclusion and reverse-phase chromatography using HPLC showed that cadmium existed in the form of low-molecular weight, highly polar species. Ion-exchange chromatography was used to divide soil solution cadmium into cationic, anionic and neutral species. Cadmium was found to be mainly in the form of inorganic cationic species, including the free ionic form, Cd²⁺, and some as neutral species, possibly organic as well as inorganic, especially in soils of higher pH. Anionic species were relatively unimportant. These results showed general agreement with those of other authors using computer models to predict cadmium speciation in soil solution.     

Evaluating the necessity for thermal treatment in clay-based metal immobilization techniques as an environmentally acceptable sediment remediation process

Purpose

The objective of this research was to apply the same immobilization (stabilization/solidification) clay-based treatments to sediment contaminated with different metals (Pb, Cd, Ni, Zn, Cu, Cr) with different distributions and availabilities in sediment. We also examined the possibility of using clay as an immobilization agent without the application of thermal treatment, in order to reduce the economic cost of this expensive remediation procedure.

Materials and methods

Clay from a canal in Vojvodina, Republic of Serbia, was used as the immobilization agent in a stabilization/solidification treatment to remediate metal-contaminated sediment. Semi-dynamic and toxicity characteristic leaching tests were conducted to assess the effectiveness of the nonthermal and thermal immobilization treatments with clay, and the long-term leaching behavior of these metals was determined using the following parameters: cumulative percentage of metals leached; diffusion coefficients; leachability indices; and toxicity characteristic leaching test concentration.

Results and discussion

Based on these parameters, both clay-based treatments were effective in immobilizing metals in the contaminated sediment. Results suggest that both heating temperature and clay proportion in the sediment–clay mixture impact the degree of metal immobilization.

Conclusions

Clay-based products are potentially good immobilization materials for metal-contaminated sediments, with the distribution of metals in the original sediment not influencing the efficacy of the treatments. Even without the thermal treatment, the metals were effectively immobilized. The leaching of metals was largely inside the regulatory limits and the treated samples can be regarded as nonhazardous materials. This justifies the choice of not applying the more expensive thermal treatment during remediation, especially when treating sediments containing a mixture of pollutants.     

Control techniques and strategies for regional air pollution control from energy and industrial sectors

The technological options currently available to reduce SO₂ and NO_x emissions including abatement technologies and high efficient energy conversion technologies are reviewed. The energy emission model EFOMENV (Energy Flow Optimization Model-Environment) which takes into account all relevant emission reduction measures is used to determine the cost optimized energy pathway, the ranking of reduction measures and the corresponding costs as a function of given reduction levels of SO₂ and/or NO_x emissions for different scenarios in selected Central and Eastern European countries. It is shown that restructuring of the energy system is a major emission reduction option in all countries but with a potential varying greatly from country to country depending mainly on the existing structure and the age of the plants and on the development of the energy demand. The emission reduction costs for SO₂ in Central and Eastern European countries are 50% to 70% lower than in Western countries due to high potential of fuel/technology switching and energy saving measures. Cost efficient measures to reduce CO₂ emissions also lead to a significant decrease of SO₂ and NO_x emissions.     

Technologies for the diagnosis and remediation of Fe deficiency

The objective of this paper is to review the developments in the last few years in two important issues related to Fe deficiency in plants. First, the current knowledge on the possible ways to carry out the diagnosis and prognosis of Fe deficiency in plants is discussed. This includes discussion on the best ways to carry out a meaningful analysis of Fe-containing compounds in different plant parts. We will also discuss other measurement techniques that can permit to assess the Fe nutritional status in plants, including leaf chlorophyll concentrations and others. Second, the new developments in management techniques to control and remediate iron deficiency are discussed. This includes possible improved ways to supply Fe compounds available to plants, both to the soil and to the irrigation water. We also discuss possible ways to supply directly the plant with Fe containing compounds, either to the foliage or to the stem. A particular emphasis is given throughout the paper to fruit tree crops growing in Mediterranean areas.     

The palmate newt triturus helveticus helveticus (Raz.) in flanders (Belgium). Distribution and habitat preferences

The distribution of the breeding sites of Triturus h. helveticus in Flanders is given. The influence of some geographical and ambient factors are analysed (altitude, geology, environment of the breeding site, its type, permanency, area, depth, current, exposure, turbidity, pH, the presence of fish, and pollution).     

Energy use,emissions, and air pollution reduction strategies in Asia

In contrast to Europe and North America, air pollution in Asia is increasing rapidly, resulting in both local air quality problems and higher acidic depositions. In 1989, an east-west group of scientists initiated a multi-institutional research project on Acid Rain and Emissions Reduction in Asia, funded for the past two years by the World Bank and the Asian Development Bank. Phase I, covering 23 countries of Asia, focussed on the development of PC-based software called the Regional Air Pollution INformation and Simulation Model (RAINS-ASIA). A 94-region Regional Energy Scenario Generator was developed to create alternative energy/emission scenarios through the year 2020. A long-range atmospheric transport model was developed to calculate dispersion and deposition of sulfur, based upon emissions from area and large point sources, on a one-degree grid of Asia. The resulting impacts of acidic deposition on a variety of vegetation types were analyzed using the critical loads approach to test different emissions management strategies, including both energy conservation measures and sulfur abatement technologies.     

Alternative technologies for remediation of technogenic barrens in the Kola Subarctic

The efficiency of remediation of technogenic barrens under the reduction of air pollutant emissions from the Severonikel smelter in the Kola Subarctic is determined largely by the soil state and the technology applied. The covering of the contaminated soils with artificially made material based on organomineral substrates and the following liming and fertilization promoted a sharp and long-term reduction of acidity, decrease in the biological availability of heavy metals, increase in the supply with nutrients, and improvement of the life state of willow and birch plantations. The effect of economically more profitable chemo–phytostabilization is short-term; it requires constant maintenance. Under the current production and a high level of soil contamination, repeated measures are required to optimize the soil reaction, supply with nutrients, and to correct the availability of heavy metals in the soils based on the results of continuous monitoring     

Influence of alternative liquid chromatography techniques on the chemical complexity and bioactivity of isolated proanthocyanidin mixtures

Extracts rich in proanthocyanidins, which are implicated in multiple human health benefits, were comparatively separated using alternative separation methods [vacuum or open column liquid chromatography], separation matrices [Toyopearl, Sephadex, or silica gel], and degrees of subfractionation [8 or 12 subfraction series], to evaluate the influence of separation technique on the resolution of the chemical composition and the biological activity of separated proanthocyanidin mixtures in individual subfractions. Bioactivity was assessed using a DNA human topoisomerase II bioassay and structural composition by acid thiolysis (average degree of polymerization, DP) and HPLC-ESI/MS. The amount of parent fraction needed to inhibit 50% of topoisomerase II was 3.38 ng/mL with an average DP of 25.5. A 2(3) factorial analysis revealed that the vacuum and open column strategies for separation, when individually considered, did not yield significantly different results in terms of mass recovery, DP, or bioactivity; however, interactions with other factors such as matrix or subfraction series resulted in distinctive shifts in fraction profiles and biological activity. In general, Sephadex as a matrix permitted elution and separation of discrete, polymerized subfractions with potent inhibition against human topoisomerase II. Sephadex vacuum chromatography, Toyopearl open column chromatography, and Toyopearl vacuum chromatography separation techniques eluted highly polymerized proanthocyanidin mixtures, but the inhibitory bioactivity was attenuated as compared to the parent fraction, whereas Sephadex open column chromatography eluted highly polymerized subfraction mixtures that retained bioactive potential.     

Development of population control strategies for mink Mustela vison, using floating rafts as monitors and trap sites

We describe a raft designed to act both as a monitoring device and as a trap site for American mink, Mustela vison. The raft uses a wet tracking medium to record footprints. It was evaluated during summer in a chalk-stream river catchment in central southern England. The raft detected mink at significantly more sites (55%) than did either owners and managers relying on field observation and trapping (19%), or established biological survey techniques (33%).

The primary value of the raft is seen to be in experimental field research to determine appropriate policies for mink management. In the pilot application described, rafts were used to derive a minimum mink population estimate for the catchment, and to determine the benefit of a commercially available scent attractant for mink. The raft also has immediate value in management to improve several aspects of trapping for mink population control: efficiency, non-target involvement, and post-removal monitoring.     

Woody species diversity in temperate Andean forests: The need for new conservation strategies

Chile has more than half of the temperate forests in the southern hemisphere. These have been included among the most threatened eco-regions in the world, because of the high degree of endemism and presence of monotypic genera. In this study, we develop empirical models to investigate present and future spatial patterns of woody species richness in temperate forests in south-central Chile. Our aims are both to increase understanding of species richness patterns in such forests and to develop recommendations for forest conservation strategies. Our data were obtained at multiple spatial scales, including field sampling, climate, elevation and topography data, and land-cover and spectrally derived variables from satellite sensor imagery. Climatic and land-cover variables most effectively accounted for tree species richness variability, while only weak relationships were found between explanatory variables and shrub species richness. The best models were used to obtain prediction maps of tree species richness for 2050, using data from the Hadley Centre’s HadCM3 model. Current protected areas are located far from the areas of highest tree conservation value and our models suggest this trend will continue. We therefore suggest that current conservation strategies are insufficient, a trend likely to be repeated across many other areas. We propose the current network of protected areas should be increased, prioritizing sites of both current and future importance to increase the effectiveness of the national protected areas system. In this way, target sites for conservation can also be chosen to bring other benefits, such as improved water supply to populated areas.     

The environmental impacts of humans on groundwater in Lebanon

The execution of most large water projects in Lebanon has been continuously postponed, due to political reasons for the period preceding 1975 and to the civil war after that date. The accumulated impacts of mismanagement and shortage in water supplies forced population to drill their private wells and extract groundwater to meet their increasing needs. This uncontrolled action has significantly deteriorated the quality of groundwater, reflected in the increasing salinity of extracted water from coastal aquifers, and in the contamination of many wells and springs by improperly disposed waste water. The overexploitation of the aquifers has led to considerable decline in the discharge of springs and rivers amounting 18.8% between the 1960's and early 80's, irrespective of rainfall fluctuations. This study shows that the water budget in early 1980's has decreased appreciably, relative to 1960's budget. In Mount Lebanon basin the amount of precipitation dropped from 2700 to 2214 m³ yr^?1, the rivers, discharge declined from 1320 to 834 Mm³ yr^?1, and the recharge to groundwater decreased from 733 to 601 Mm³ yr^?1.     

Phyto-dehydration of confined sludge: a sustainable approach for the management of polluted ponds

Purpose

Leaf transpiration drives many of the processes involved in phyto-technologies, and it can represent a useful mechanism to remove water from different kind of storage basins presenting inorganic, organic or microbiological contamination (phyto-dehydration), with the aim to reduce the risk of environmental contamination. In this framework, a mesocosm-scale trial was carried out to test the capacity of different helophyte species to reduce the excess of water in an artificial pond filled with oversaturated sludge.

Materials and methods

The sludge derives from the digestion of pig slurries, presents high levels of zinc and copper and for most of the year is covered by a water layer of about 20 cm due to rainfalls. This layout (water layer over the sludge) was reproduced inside the mesocosms, where four helophyte species (Phragmites australis and a mix of Carex acutiformis, Iris pseudacorus and Juncus effusus) were planted on floating frames. Plant growth and functionality were monitored for one year, along with their water consumption capacity; the vegetation impact on sludge chemistry, sludge microbial community and sludge greenhouse gases emission/uptake were also evaluated. The sensitivity of the phyto-dehydration system to the reduction of water level occurring during summer in the pond was investigated reducing the water input to the mesocosms.

Results and discussion

P. australis and C. acutiformis successfully established in the mesocosms, while a significant mortality was recorded for I. psudacorus and J. effusus. Once established, plants were able to grow in the mesocosms, and no metal toxicity effect was observed on photosynthesis rates that were comparable with values reported for natural stands of the species. Plants significantly increased (from 24 to 63%, depending on the species) the amount of water lost by the mesocosms and counteracted the reduction of sludge organic carbon that could lead to a mobilization of the heavy metals bound to organic matter: furthermore, plants decreased the rates of mesocosm greenhouse gas emission and reduced the sludge pathogen (Enterobacteriaceae) occurrence. Water limitations reversibly reduced the water consumption and CO₂ uptake capacity of the mesocosms.

Conclusions

The results of this study demonstrated that the water balance of a sludge/water system can be effectively modified through the phyto-dehydration approach, increasing significantly the amount of water lost. Although the low tolerance of two species to the sludge/water environment after plantation needs to be further investigated, this phyto-technology can represent a promising approach to manage the excess of water in polluted ponds.

     

The evaluation of key sites for breeding waders in lowland Scotland

This study considers the selection of sites based on the densities of breeding waders that would be considered to be distributed widely across common habitats in Scotland: so-called ‘wider countryside’ species. Five methods to provide a hierarchical classification of sites are assessed. Fifty percent of the populations of redshank (Tringa totanus) and snipe (Gallinago gallinago) occur on just 2 and 4.5% of Scottish lowlands, respectively, yet neither are suitably protected by conservation measures and both would benefit from a carefully targeted approach to their conservation. Three species, lapwing (Vanellus vanellus), curlew (Numenius arquata) and oystercatcher (Haematopus ostralegus) are more appropriately considered to be dispersed species. We propose that, if the density of a breeding wader on a site exceeds the threshold level predicted for the top 1% of Scottish lowland for that species, and if the area of the site exceeds 1 km² then that site be considered to be a key site for farmland waders. The minimum density (in pairs km⁻²) must exceed 16.8 for lapwing, 10.1 for oystercatcher, 6.1 for snipe, 7.5 for curlew or 3.6 for redshank.     

Mobility of Cd and Zn in polluted and unpolluted Spodosols

Leaching of Cd and Zn in polluted acid, well‐drained soils is a critical pathway for groundwater pollution. Models predicting future groundwater contamination with these metals have rarely been validated at the field scale. Spodosol profiles (pH 3.2–4.5) were sampled in an unpolluted (reference) field and in a field contaminated with Cd and Zn through atmospheric deposition near a zinc smelter. Average metal concentrations in the upper horizons were 0.2 mg Cd kg^?1 and 9 mg Zn kg^?1 in the unpolluted field, and 0.8 mg Cd kg^?1 and 71 mg Zn kg^?1 in the contaminated field. Isotopic dilution was used to measure the labile concentration of Cd and Zn, and the metal transport was modelled using measured sorption parameters that describe the distribution between the labile metal pool (instead of the total metal pool) and the solution phase obtained by centrifugation. Solutions were also collected by wick samplers in two polluted and one unpolluted profile at a depth of 70 cm. Concentrations in these solutions were in the order of 15 µg Cd litre^?1 and 0.8 mg Zn litre^?1 for the polluted profiles, and 1 µg Cd litre^?1 and 0.04 mg Zn litre^?1 for the unpolluted profile. The concentrations in these solutions agreed well with those in soil solutions obtained by centrifugation, which supported the use of the local equilibrium assumption (LEA). Present‐day Cd profiles in the polluted field were calculated with the LEA, based on the emission history of the nearby smelter and taking spatial variability into account. Observed and predicted depth profiles agreed reasonably well, but total Cd concentrations in the topsoil were generally underestimated by the model. This may be attributed to the presence of non‐labile Cd in the atmospheric deposition, which was not accounted for in the retrospective modelling. The large concentrations of non‐labile Zn in the topsoil of the polluted field were also indicative that metals in the atmospheric deposition were (partly) in a sparingly soluble form, and that release of these non‐labile metals is a slow process. The presence of non‐labile metals should be taken into account when evaluating metal mobility or predicting their transport.