Background environmental pollution of the Eurasian continent

1. The interest to studying pollution of environmental media on the background level has grown in the recent years. There arose a necessity to establish a specialized observational system for conducting observations of changes in the state of the environment, and of ecological consequences of pollution as well as to produce assessments of the current and predicted states. The realized program of background monitoring and first results of integrated background measurements have already been published. The paper presented illustrates time-and-space features of the background pollution of natural environmental media according to data from various background stations.
2. Long-term systematic measurements at the ‘Borovoe’ station (Kazakh SSR) commenced in 1976 have been supplemented with the results of the background pollution studies carried out in Berezinskyi, Caucasian, Central-Chernozem, Sary-Chelek, and Repetek Biosphere Reserves and in locations of the background stations in Hungary and Czechoslovakia. The data from the Hungarian and Czechoslovak stations were obtained during joint expeditions. Details are given in the relevant publications.
3. Ozone. Ozone measurements show the diurnal variation with the day-time maxima from 35 up to 160 μg m^?3. The correlation between day-time and nocturnal concentrations is a good indicator of the anthropogenic effect.
4. Sulphur dioxide and sulphates. The annual variation of sulphur dioxide characterised by winter maximum and summer minimum indicates the direct dependence on the amount of fuel burnt in the given region. Mean values of the sulphur dioxide content in the surface layer of the atmosphere correlates with the extent of the region urbanization and varies within 0.2–12.5 μg m^?3. The value of sulphur dioxide and sulphates correlation in the atmosphere is rather stable and varies within 0.18–0.37 μg m^?3.
5. Heavy metals. The annual cycle of the atmospheric content of lead, cadmium and arsenic is well expressed by winter maximum and summer minimum (which is opposite in case of mercury). As for lead and mercury, their annual variation is more distinct than that of cadmium and arsenic; their time-and-space variation is also more distinct. The content of these metals in the urbanized regions of Europe is 5 times higher than in Asia and the Caucasus. Atmospheric contents of arsenic and cadmium vary insignificantly from region to region. The content of all these metals in other environmental media (soil, water, vegetation) is of insignificant spatial variability. Observations in the Caucasian Biosphere Reserve showed minimum levels of the background atmospheric pollution: lead-16 μg m^?3, mercury-5 ng m^?3, arsenic-3.9 ng m^?3, cadmium-0.5 ng m^?3.
6. Organochloride pesticides. Concentrations of DDT and its metabolites and hexachlorocyclohexane isomers in the environmental media of European background regions are 3 times higher than those in Asia (‘Borovoe’).
7. PAH. Atmospheric content of BaP has a well expressed annual variation with winter maximum; the difference between winter and summer periods reaches the magnitude of an order. Background concentrations in European regions (Hungary, Berzinskyi Biosphere Reserve) are noticeably higher than in Asia; the difference reaches 3–5 times.
8. Comparisons with literature data on the background pollution show that observational materials from the background monitoring stations supplement to a considerable extent, and extent, the current notions on the background pollution and show the effects of the man-made impact on the background regions.

     

Monitoring bio-available marine contaminants with mussels (Mytilus edulis L) in the Netherlands

After discussing the usefulness of mussels (e.g. Mytilus edulis) for investigating contamination in the marine environment, four cases are presented:

1. A survey of Cu bioavailability in and around the Eastern Scheldt during one winter (1974–1975);
2. A surveillance with a six years interval (1974; 1980) of the bioavailability of Zn along the Dutch North Sea coast.
3. A monitoring programme over the period 1972–1980 showing the decrease in bioavailable Hg in the water column of the Ems-Dollard estuary after decreased emissions at Delfzijl.
4. Retrospective monitoring of two PCB's, as a background for the effectiveness of legal restrictions to PCB use.

These four cases are considered a first step in understanding the effects of pollutants in marine ecosystems. In depth physiological, histological and biochemical studies could lay the basis for improved routine biological effect monitoring.     

Problems of correlation of global and local monitoring of air pollution

1. The Air Polluttion Monitoring System has got a significant development of late, which is in direct relation with a considerable extention and improvement of the observation network in cities and industrial areas, with creation of a new network for assessing regional and global background of the atmosphere pollution, as well as with the wide involvement of meteorologists to monitoring organization.
2. While developing a new global monitoring system, it is necessary to take into account its relationship with the local monitoring within the region of air pollution sources, i.e. at the \lsimpact\rs level. The need in such an account is dictated first of all by the physics of pollutant spreading that states: changes in air pollution over large territories must be in a certain agreement with greater changes in the vicinity of emission sources. Methods applied in the global and local monitoring have also a number of common peculiarities. White organizing regional network for observations of the background pollution of the atmosphere twin stations (one of the pair of stations located outside the city boundaries in a small community, and the other, in the nearest city with the population of 200–400 thousand inhabitants) were established in the U.S.S.R. and in a number of socialist countries in Europe.
3. Implementation of the twin-station principles in the U.S.S.R. has contributed to data interpretation and representativity assessment as well as to correction of the station location. Observation results from the Soviet background stations and those abroad have been compared by now according to a number of indices.
4. The correlation of monitoring systems of various scales tells positively both on mutual improvement and completion of observational methods. The methods of obtaining integral characteristics of air pollution were used for the global monitoring, in particular spectral actinometric observations and chemical analysis of the precipitation composition. Now they find still wider employment. Thus methods of spectral actinometric measurements and data processing were used to estimate the degree of aerosol pollution of a number of industrial centres. The theory of solar radiation spreading and aerosol contents determination in urban atmosphere has also been developed. It is a generalization of an earlier developed theory, used to estimate global atmosphere pollution basing on actinometric data. The organization of precipitation collection and analysis on a network of stations around Leningrad and in Donbass area enables us to compare the admixture content in precipitations falling in industrial and agricultural areas.
5. A considerable increase of possibilities to measure microconcentrations of sulphur dioxide, nitrogen oxides and of a number of other pollutants is connected with the use of solid solvents for sampling. Their use will allow to avoid establishment of special laboratories at background stations and only send samples by post for their analysis in centralized laboratories.

They will also allow to considerably increase precision and accuracy of measurements. The international comparisons of methods of air pollution measurements on the background level allow to judge about the effiency of these methods.     

Planning for implementation of long-term resource monitoring programs

Guidelines for the early stages of developing a monitoring program are presented. Jumping right into a monitoring program based on standard protocols and a number of commonly monitored parameters is an attractive idea, but it is unlikely to lead to an intelligent allocation of time and money. Rather, a number of well-defined planning steps must be followed before monitoring is begun:

1. Objectives for the program should be well defined.
2. The attributes to be monitored in order to meet objectives should be listed.
3. Methods of monitoring these attributes should be developed.
4. A pilot study should be conducted to determine spatial and temporal variability of the attributes being monitored and the cost of sampling.
5. The results of the pilot study should be carefully evaluated to determine whether program objectives can be met for an acceptable cost.
6. Objectives, attributes to be monitored, and methods should be revised in accordance with the results of the pilot study.

     

Approaches to standardization of atmospheric pollution undergoing long-range and transboundary transport

The authors consider some possible ways of regulating three types of atmospheric emission of pollutants:

1. emission of substances causing pollution of the natural environment on the global scale (global pollutants);
2. emission of substances causing pollution on a regional scale, most often including territories of several countries (international pollutants);
3. emission of substances causing negative effects in a relatively limited region, for example within border area of two adjoining countries.

Substances (gaseous, as a rule) of a long life-time in the atmosphere that can contaminate natural media on a global scale irrespective of the place of emission refer to the first class of pollutants that are subject to emission regulation at an international level and to quota establishement for individual countries. They are carbon dioxide, freon, krypton-85. Various approaches to determining permissible emission and to quota establishing are discussed in the paper. The second group includes substances of a limited, yet rather long, life-time whose emission intensity makes a notable contribution to environmental pollution of a large region including territories of several countries. Here it is needed to regulate internationally not the atmospheric emission as it is but pollutant transport over national boundaries (sulphur and nitrogen oxides, pesticides, heavy metals). The third group includes substances of relatively short time of life producing local effects. Emission regulation in such cases should be based upon bilateral agreements with due account of countries' mutual interests.     

Auditing the quality of effluent discharges

The public and their elected representatives want to see whether they get Value-for-Money from investment in preventing pollution. For many rivers, the achievement of good water quality is a matter of regulating the discharges from wastewater treatment plants. The effective audit of the quality of such discharges is a good basis for measuring progress in controlling pollution. To prove that control is effective, the techniques which underpin the following tasks must be sound and consistent:

- the standards for rivers must be devised so that the environmental objectives are met with the required reliability; the form of the standards will be constrained by the procedures available to monitor compliance;

- the standards worked out for effluents must have the correct mathematical relation with the river targets, and they too must be consistent with the options available for auditing performance;

- the assessment of compliance must be objective; and,

- statistics used to summarise the performance of a region (or a Nation) must be simple, stable, clear, and consistent with the results for individual sites.

     

Harmonization problems in the implemention of the EEC directive on air quality limit values and guide values for sulphur dioxide and suspended particulates

This report deals with the implementation of Article 10 of the Directive on air quality limit values and guide values for sulphur dioxide and suspended particulates (80/779/EEC). For this purpose the Commission, in cooperation with the Member States, has prepared a ‘Common Measurement Programme’ which basically provides for:

1. examination and improvement of the reference measurement methods,
2. examination of the comparability of the measuring procedures and equipment used for monitoring purposes in the Member States,
3. the provision of guidelines and the carrying out of measurements to determine the corresponding stringency of the limit values laid down in Annexes IV and I of the Directive.

     

Ecological principles of World Ocean monitoring

Anthropogenic effect on the World Ocean in the course of exploiting its resources has led to a significant contamination of some ocean areas in the latest decades and to diminution of the natural capacity of marine ecosystems to reproduction and self-regulation. Thus, the most urgent problem of today has become evident: the problem of the World Ocean pollution and its negative ecological effects. Local pollutions and their ecological effects on the World Ocean go on acquiring large-scale regional and even global character since the elements of ocean ecosystems and the ocean properties are interrelated and interconditioned. Looking into pollutant transfer and transformation in the marine environment we can distinguish four subsystems: ocean-land, ocean-atmosphere, and water-bottom sediments interfaces as well as ocean water mass. Ocean-atmosphere and water-floor subsystems require special consideration since their coefficients of pollutant accumulation are much greater than that of the water mass. Besides water exchange, the processes of pollutant transfer in the water mass effect the interference between the solute and suspended matter on the one hand, and water mass-biota interaction on the other. Atmospheric transport and deposition of chemical toxicants are considerable sources of the World Ocean pollution; their share in the total balance of the anthropogenic pollution influx into marine environment is commensurable with the river runoff. The most dangerous, among various pollutants entering the World Ocean, are oil, hydrocarbon chlorides (pesticides, polychloride bifenyls), toxic metals (mercury, cadmium, lead), i.e. globally occurring chemical compounds continuously entering the marine environment and effecting marine organisms and their populations. Still new and new pollutants are being discovered now in the oceans: chloride and polychloride terpenes, nitrosamines, chlordane, etc. The problems of eutrophication and microbiological contamination of the inland seas and ocean coastal zones are becoming still more urgent. Accumulation of aromatic polycyclic carcinogenous hydrocarbons. BaP in particular, is pregnant with unexpected ecological effects. The highest PAH concentrations have been observed in the sea coast areas and in the zones of intensive navigation. Rather high coefficients (10²–10⁴) of BaP accumulation in the sea biota and bottom sediments are marked. Ecological and biological effects of changes in the chemical composition of the ocean make up the chain of interrelated reactions; transformation of natural biogeocenoses, disturbance of the cycle of carbon, nitrogen, sulphur and other elements, reduction of biological productivity and cell genome affection present the most essential effects of these reactions. Stresses in the abiotic component of the ecosystem are expressed through disturbances in the chemical balance, changes in the evaporation from the sea surface, oil aggregate formation (floatable biocenoses), disturbances in reducing reactions of biogenous elements, salinity and temperature variation, and so on. Population-biocenotic effects of the man-made impact, actually important for the level of ecosystem stability, include the following processes of the structural and functional character:

1. alteration of the mean biomass of plankton and benthos populations, in particular in semi-enclosed seas and off-shore ocean areas;
2. alteration of the number of higher taxons-genera or families of the sea organisms, in particular replacement of the dominant populations of mass species, and emergence of hydrobionts new for the marine environment;
3. alteration of the relations between the numbers of some taxonomic groups of hydrobionts and abundant development of indicator species of the sea biota, e.g. BaP and PCB oxidizing microorganisms;
4. disturbances in production/destruction processes of organic substances;
5. energy flux changes in the marine ecosystem.

Analysis of the current knowledge on the ocean environment pollution and its negative effects has enabled to formulate the main directions of the World Ocean ecological monitoring. Investigations of the biogeochemical cycles of pollutants and elements in the marine environment, identification of the effect of pollutants abundant in the ocean on the Earth's climate and hydrochemical regime as well as major geophysical processes in the ocean and atmosphere make up integral parts of the ocean monitoring together with the studies of pollutant impact on the ocean biota which leads to biological regime alterations and affection of the sea organisms genofond.     

Heavy metals regulate physiological and behavioral events by modulating ion channels in neuronal membranes of molluscs

The interaction of heavy metals (HgCl₂, CdCl₂, CuCl₂, PbCl₂ and ZnCl₂) and neurotransmitters (ACh, 5HT and DA) was studied on the excitable membrane of identified neurons of Lymnaea stagnalis and Helix pomatia. It was shown that,

1. The excitability and chemosensitivity of molluscan neurons were modified under the influence of the heavy metals Hg²⁺, Cd²⁺, Cu²⁺, Pb²⁺ and Zn²⁺.
2. Change in excitability to transmitters occurred as a potentiation or depression of the evoked response both in duration of membrane polarization and in frequency of spike activity.
3. The chemosensitivity changes in various ways, namely:
4. excitatory effect was totally eliminated;
5. one component of the effect was depressed.
Different neurons may show different reactions to the same heavy metal.
6. There were differences in the effects of various heavy metals. Hg²⁺ has a more generalized effect than Cd²⁺; Cu²⁺, Pb²⁺ and Zn²⁺ were less effective in a number of neurons. The heavy metal effect was dose dependent, too.
7. Both inward and outward currents, which were evoked by neurotransmitters or voltage induced, were modified in most of the tested neurons. Both an increase and decrease of the membrane permeability occurred in different neurons in response to the same or different heavy metals.
8. The changes can be interpreted as a result of
9. direct effect on specific ionic channels;
10. modification of receptors binding ACh, 5HT, or DA;
11. modification of intracellular processes responsible for the regulation of membrane permeability.

     

Soil sampling and analysis for volatile organic compounds

Concerns over data quality have raised many questions related to sampling soils for volatile organic compounds (VOCs). This paper was prepared in response to some of these questions and concerns expressed by Remedial Project Managers (RPMs) and On-Scene Coordinators (OSCs). The following questions are frequently asked:

1. Is there a specific device suggested for sampling soils for VOCs?
2. Are there significant losses of VOCs when transferring a soil sample from a sampling device (e.g., split spoon) into the sample container?
3. What is the best method for getting the sample from the split spoon (or other device) into the sample container?
4. Are there smaller devices such as subcore samplers available for collecting aliquots from the larger core and efficiently transferring the sample into the sample container?
5. Are certain containers better than others for shipping and storing soil samples for VOC analysis?
6. Are there any reliable preservation procedures for reducing VOC losses from soil samples and for extending holding times?

Guidance is provided for selecting the most effective sampling device for collecting samples from soil matrices. The techniques for sample collection, sample handling, containerizing, shipment, and storage described in this paper reduce VOC losses and generally provide more representative samples for volatile organic analyses (VOA) than techniques in current use. For a discussion on the proper use of sampling equipment the reader should refer to other sources (Acker, 1974; U.S. EPA, 1983; U.S. EPA, 1986a). Soil, as referred to in this report, encompasses the mass (surface and subsurface) of unconsolidated mantle of weathered rock and loose material lying above solid rock. Further, a distinction must be made as to what fraction of the unconsolidated material is soil and what fraction is not. The soil component here is defined as all mineral and naturally occurring organic material that is 2 mm or less in size. This is the size normally used to differentiate between soils (consisting of sands, silts, and clays) and gravels. Although numerous sampling situations may be encountered, this paper focuses on three broad categories of sites that might be sampled for VOCs:

1. Open test pit or trench.
2. Surface soils (<5 ft in depth).
3. Subsurface soils (>5 ft in depth).

     

Non-radiological contaminants from uranium mining and milling at Ranger,Jabiru, Northern Territory,Australia

Protection from the hazards from radioactivity is of prime importance in the management of uranium mine and mill wastes. Such wastes also contain non-radiological contaminants (heavy metals, acids and neutralising agents) which give rise to potential long-term health and environmental hazards and short-term hazards to the aquatic ecosystem, e.g. as a result of release of waste water. This study seeks to identify non-radiological contaminants (elements) transferred to waste water at the Ranger uranium mine/mill complex at Jabiru, which are likely to hazardous to the aquatic environment. The two principal sources of contaminants are:

1. ore and waste rock mobilised from mining; and
2. process reagents used in the milling and mineral extraction process.

These substances may or may not already be present in the natural environment but may lead to deleterious effects on the aquatic environment if increased above threshold levels. Rhenium, derived from the ore body, was found to be significantly enriched in waste water from Ranger, indicating its suitability as an indicator element for water originating from the mining and milling process, but only uranium, likewise derived from the ore, and magnesium, manganese and sulfur (as sulfate) from the milling process were found to be significant environmental contaminants.     

Improving the effectiveness of planning EIA (PEIA) in China: Integrating planning and assessment during the preparation of Shenzhen's Master Urban Plan

The enactment and implementation of the 2003 EIA Law in China institutionalised the role of plan environmental impact assessment (PEIA). While the philosophy, methodology and mechanisms of PEIA have gradually permeated through the various levels of government with a positive effect on the process and outcome of urban planning, only a few cities in China have so far carried out PEIA as a Strategic Environmental Assessment (SEA)-type procedure. One such case is the southern city of Shenzhen. During the past three decades, Shenzhen has grown from a small town to a large and booming city as China has successfully and rapidly developed its economy by adopting the “reform and open door” policy. In response to the challenges arising from the generally divergent processes of rapid urbanisation, economic transformation and environment protection, Shenzhen has incrementally adopted the SEA concept in developing the city's Master Urban Plan. As such, this paper reviews the effectiveness of PEIA in three ways:

• •as a tool and process for achieving more sustainable and strategic planning;
• •to determine the level of integration of SEA within the planning system; and,
• •its effectiveness vis-à-vis implementation.

The implementation of PEIA within Shenzhen's Master Urban Plan offers important insights into the emergence of innovative practices in undertaking PEIA as well as theoretical contributions to the field, especially in exploring the relationship between PEIA and SEA and highlighting the central role of local governing institutions in SEA development.     

Improving the effectiveness of planning EIA (PEIA) in China: Integrating planning and assessment during the preparation of Shenzhen's Master Urban Plan

The enactment and implementation of the 2003 EIA Law in China institutionalised the role of plan environmental impact assessment (PEIA). While the philosophy, methodology and mechanisms of PEIA have gradually permeated through the various levels of government with a positive effect on the process and outcome of urban planning, only a few cities in China have so far carried out PEIA as a Strategic Environmental Assessment (SEA)-type procedure. One such case is the southern city of Shenzhen. During the past three decades, Shenzhen has grown from a small town to a large and booming city as China has successfully and rapidly developed its economy by adopting the “reform and open door” policy. In response to the challenges arising from the generally divergent processes of rapid urbanisation, economic transformation and environment protection, Shenzhen has incrementally adopted the SEA concept in developing the city's Master Urban Plan. As such, this paper reviews the effectiveness of PEIA in three ways:

• • 

  as a tool and process for achieving more sustainable and strategic planning;

• • 

  to determine the level of integration of SEA within the planning system; and,

• • 

  its effectiveness vis-à-vis implementation.

The implementation of PEIA within Shenzhen's Master Urban Plan offers important insights into the emergence of innovative practices in undertaking PEIA as well as theoretical contributions to the field, especially in exploring the relationship between PEIA and SEA and highlighting the central role of local governing institutions in SEA development.     

Confronting reality in strategic environmental assessment in Slovenia — Costs and benefits

We enlarge on the viewpoint published in the Environmental Impact Assessment Review in 2012 — A viewpoint on the approval context of strategic environmental assessments. Additional alerts concerning the procedural ineffectiveness of the strategic environmental assessment (SEA) process from the cost–benefit point of view are advanced. The major contribution to the long lasting, costly SEA processes, comes from ultraistic treatment of Natura 2000.The case study deals with a plan for constructing a traffic bypass around Škofljica, a town near Ljubljana. Based on their conclusions the authors propose that the following elements of the SEA procedure should be improved and optimised:

• –CBA for SEA should become a regular component when measuring its effectiveness.
• –Concretisation of expected SEA inputs to the plan should clarify its role at the earliest stage of the process.
• –SEA should contribute interactively to the optimisation of alternatives; cost–benefit analysis of the SEA process could support this process.
• –Nature protection interest should be confronted and balanced with wider development interests as formulated in the plan and should not be applied in absolute terms (e.g. Natura 2000).

     

Chemical speciation in waters influenced by lead–zinc metallurgical industry

The Lead–Zinc Company region, Kardjali city, Bulgaria, is known to be highly polluted with heavy metals from its pyrometallurgical activities. The polluted levels and the chemical speciation in surface natural waters in the region as well as in the wastewaters of the factory were investigated in January 2008 by application of monitoring studies, thermodynamic modeling, and interpretation in terms of the “softness–hardness” factor. It was found that the levels of trace metals pollution of surface waters were lower than the legislation limits for the regions with Pb and Zn production. The wastewater treatment facilities of the company were found to operate properly, and the quality of the cleaned waters in station Kar4 was comparable to the other surface waters studied (e.g., station Kar5). The trace metals were divided into three groups: (1) Fe^3?+? and Al^3?+?, being “hard” acids, existed in all the studied waters as hydroxy species Fe(OH) $_{2}^{+}$ , AlOH^2?+?, and Al(OH) $_{2}^{+}$ , followed by the phosphate species AlPO $_{4}^{0}$ and Al₂(OH)₂PO $_{4}^{+}$ ; (2) Mn^2?+?, Zn^2?+?, and Cd^2?+? being “soft” acids with crystal field stabilization energy (CFSE) = 0 were present in natural waters mainly as free Me^2?+? ions. Small concentrations of their MeSO $_{4}^{0}$ , MeCO $_{3}^{0}$ species, and of MeCl $_{2}^{0}$ (Me = Zn, Cd) species were also calculated. In the wastewaters, two more species [Me(SO $_{4})_{2}^{2-}$ and Me(SO $_{4})_{3}^{4-}$ ] of the softer Zn and Cd metals were also calculated; (3) Cu^2?+? and Pb^2?+?, as “soft” acids with CFSE $\ne $ 0 preferentially coordinated with softer CO $_{3}^{2-}$ ions and in natural waters existed mainly as MeCO $_{3}^{0}$ and PbHCO $_{3}^{+}$ , followed by free Me^2?+?ions and MeOH^?+?. In the wastewaters, MeSO $_{4}^{0}$ and Pb(SO $_{4})_{2}^{2-}$ species increased at the expense of the free Me^2?+? ions. The highest self-cleaning capability of natural waters was found with respect to Al and Fe, followed by Mn and Cd. The lowest corresponded to Pb, Cu, and Zn.     

Understanding and eliminating iron interference in colorimetric nitrate and nitrite analysis

Across many environments, nitrate ( $\mbox{NO}_{3}^-$ ) is an important form of N available for microorganisms and photosynthetic organisms. Accurate $\mbox{NO}_{3}^-$ measurements are important for examining N cycling and retention in terrestrial and aquatic ecosystems, but a common method of $\mbox{NO}_{3}^-$ analysis can underestimate $\mbox{NO}_{3}^-$ concentrations when soluble iron is present (iron > 10 mg L^???1). The basic method is robust, using copperized cadmium to reduce $\mbox{NO}_{3}^-$ and then diazotizing the resulting $\mbox{NO}_{2}^-$ in a two-step process to form an easily measured colored product. We show that iron interference is unique to using an NH₄Cl and ethylenediaminetetraacetic acid (EDTA) buffer. We hypothesize that interference is through iron-catalyzed reduction of the intermediate color product, a diazonium ion. We examine three historical buffers as alternatives to NH₄Cl/EDTA and recommend replacement of EDTA with diethylenetriaminepentaacetic acid, which chelates metals much like EDTA, but unlike EDTA, it does not cause interference in the presence of iron.     

Determination of redox potential of sulfidic groundwater in unconsolidated sediments by long-term continuous in situ potentiometric measurements

This study was undertaken to investigate the redox potential (Eh) of sulfidic groundwater in unconsolidated sediments. The Eh was determined by long-term (several days to several weeks) continuous in situ potentiometric measurements using a platinum (Pt) electrode. The Eh values measured in two monitoring campaigns were ?259 and ?202 mV, respectively. Chemical analysis of groundwater showed that the redox species in the groundwater were sulfide (S^2???) and iron, respectively. The saturation indices calculated from the chemical analysis results indicated that FeS_(am) and mainly mackinawite were close to equilibrium in the analyzed waters. Comparison of the measured Eh values with those calculated using different redox couples revealed that the Eh values measured in the first monitoring campaign were nearly equal to those calculated using HS^???/SO $_{4}{^{2-}}$ , S^2???/SO $_{4}{^{2-}}$ , FeS $_{(\text{am})}$ /SO $_{4}{^{2-}}$ , and mackinawite/SO $_{4}{^{2-}}$ redox couples; on the other hand, the Eh values measured in the second monitoring campaign were almost consistent with those measured using the FeS₂/SO $_{4}{^{2-}}$ redox couple. The good fit between the measured Eh values and the theoretical calculated Eh values suggests that the sulfur system is related to the Eh value of sulfidic groundwater in unconsolidated sediments.     

Chemical speciation in mining affected waters: the case study of Asarel-Medet mine

The inorganic chemical species in Maresh and Luda Yana rivers affected by the Cu– Mo Asarel-Medet mine, Bulgaria were determined during a low-flow and a high-flow period. The mining activities, the weathering and the oxidation processes strongly influenced the physicochemical processes in the whole water system. The main pollution source was a small lake receiving the acid effluents of the mining activities. High levels of SO₄ ^2???, Cu, Mg, Al, Mn and Fe were determined at the mining polluted and affected stations. Cu^2?+? and CuCO₃ ⁰ species (1:1) were present in the reference waters and Cu^2?+? and CuSO₄ ⁰ species (1:1) in the polluted and affected waters; Cu^2?+? species was dominating downstream. Me^2?+? followed by $\rm{MeSO}_{4}^{\kern3pt{0}}$ (Me = Mn, Zn, Cd and Pb), $\rm{PbCO}_{3}^{\kern3pt{0}}$ and $\rm{PbHCO}_{3}^{\kern3pt{+}}$ species as well as $\rm{Fe(OH)}_{2}^{\kern3pt{+}}$ , $\rm{Al(OH)}_{4}^{\kern3pt{-}}$ , $\rm{Al(OH)}_{2}^{\kern3pt{+}}$ , $\rm{Al(OH)}_{3}^{\kern3pt{0}}$ were prevailing in the system. $\rm{MeSO}_{4}^{\kern3pt{+}}$ and $\rm{Me(SO}_{4})_{2}^{\kern3pt{-}}$ (Me = Fe, Al), $\rm{Me(SO}_{4})_{2}^{\kern3pt{2-}}$ (Me = Zn, Cd and Pb), $\rm{Me(SO}_{4})_{3}^{\kern3pt{4-}}$ (Me = Zn, Cd) and $\rm{Cd(SO}_{4})_{4}^{\kern3pt{6-}}$ species polluted and affected waters. The major elements K and Na were mainly Me^?+? species, whereas Ca and Mg were Me^2?+? and $\rm{MeSO}_{4}^{\kern3pt{0}}$ species in different ratios. The concentration of concentration of $\rm{NO}_{2}^{\kern3pt{-}}$ , $\rm{NO}_{3}^{\kern3pt{-}}$ and $\rm{NH}_{4}^{\kern3pt{+}}$ species as well as complex phosphorous species such as H₂ $\rm{PO}_{4}^{\kern3pt{-}}$ , $\rm{FeHPO}_{4}^{\kern3pt{+}}$ , $\rm{HPO}_{4}^{\kern4pt{2-}}$ , $\rm{CaPO}_{4}^{\kern3pt{-}}$ , $\rm{CaHPO}_{4}^{\kern3pt{0}}$ and $\rm{MgHPO}_{4}^{\kern3pt{0}}$ were also calculated. The trace element concentrations decreased downstream due to dilution, sorption processes and precipitation, but the percentage of free metal species, which are more toxic, increased. An exception was iron and aluminum of which the dominant hydroxy colloidal and sulphate species were easily incorporated into the suspended phase.