The Interaction of Static and Alternating Electric Fields with Biological Systems

A discussion is presented regarding the presence of natural and man-made electric fields in our environment. It is seen that biological objects readily come into contact with such fields. The interaction of some biological objects with electric fields is presented as well as original experimentation in this area. One experiment discussed deals with the influence of a 245 V/in (96.5 V/cm) electric field on the glucose concentration (as measured by per cent transmission) of human red blood cells. The data presented show an influence by the field. The second experiment discussed deals with the behavioral manifestations of electric fields on rats. An approach-avoidance procedure is utilized. The data presented shows an avoidance response at a high electric field intensity (4.5 kV/in) (1.77 kV/cm). Practical applications of this area of study are also presented.     

观赏草在美国园林中的应用

在美国,观赏草越来越受到风景园林师和园丁的青睐。这些容易生长的植物不仅维护简单,而且适应较大范围的设计用途:可以与其他植物配置,也可以单独成景,或丛植,或作为地被,或作为屏障和边界。观赏草能很好地融合草地和自然种植,而且也适宜盆栽。观赏草丰富了园林的叶色,增加了园林的季相。     

The Distribution of Antimony and Arsenic in Waters of the Dúbrava Abandoned Mine Site, Slovak Republic

The abandoned Dúbrava Mine, situated in the northern part of the Nízke Tatry Mts in the middle of Slovakia, was the most significant producer of antimony (Sb) in the former Czechoslovakia. Mine drainage from adits (containing up to 9,300 μg/L of Sb), mine waste dumps, and the leachate from mine tailings contribute Sb and arsenic (As) into nearby Palud?anka Creek and groundwater. Some drinking water resources have been closed due to excessive Sb concentrations; the concentration of Sb in one household well (126 μg/L) far exceeds the Sb drinking water limit of 5 μg/L. Although Sb is attenuated by dilution and adsorption on ferric iron in stream sediment in the Palud?anka Creek, Sb concentrations increase downstream of the mine tailings and then remain almost constant, leading to concentrations of 128 μg/L at the northern boundary of the study area. The dissolved As concentrations in the mine drainage are much lower than Sb, ranging from 4 to 62 μg/L. Flow and transport modeling confirmed the observed contamination pattern and the major role of the mine adits. Results of this study indicate serious Sb contamination, which could be mitigated by treatment of the adit discharges.     

Distribution and mobility of arsenic in the Río Dulce alluvial aquifers in Santiago del Estero Province, Argentina

Factors controlling arsenic (As) mobilization in the aquifers of the Río Dulce alluvial cone were investigated. Groundwater analyses show severe As contamination (average concentration of 743 mug/L) from geogenic sources, but spatial variability of As concentration is considerable. Sequential leaching of sediment samples from unsaturated zone using de-ionised water, bicarbonate, acetate, and oxalate extracted As to different extents. Sediment oxalate extraction showed that Al and Mn oxide and hydroxides are more abundant than Fe oxides and hydroxides, in spite of similar total Fe, Mn, and Al concentrations in the sediment. Speciation calculations performed for saturated zone samples indicated that Fe and Al oxides and hydroxides are stable in groundwater, suggesting that As adsorption processes may be to some extent controlled by the presence of Fe and Al mineral phases. Principal Component Analysis (PCA) showed that As is related to F, V, Mo, B, Si, most likely due to their common origin in volcanic ash. This suggests the volcanic ash as the probable source of groundwater As. Locally, elevated pH values linked to carbonate dissolution, cation exchange, and dissolution of silicates promote release of adsorbed As. Another factor contributing to the release of As locally may be the input of organic matter from excessive irrigation. The conceptual model of As release includes: i) As influx from dissolution of volcanic glass in volcanic ash, ii) adsorption of As on the surface of Fe and Al mineral phases in relatively low pH zones, and iii) high mobility of As in high pH zones. Future work should be focused on the determination of mineralogical forms of As in volcanic ash and on detailed investigation on factors controlling As mobility.     

Correction to: An Overview of Priority Pollutants in Selected Coal Mine Discharges in Europe

Mine Water and the Environment - Correct values for radium have been rewritten in Table 1 and Table 2. Correct radium units in Figure 2(c) are Bq/L (Becquerel per liter). The same applies to...     

An Overview of Priority Pollutants in Selected Coal Mine Discharges in Europe

Coal mine discharges in several European countries were investigated as part of the European Commission’s MANAGER project. The emphasis of the project was identification of priority pollutants and potential remedial approaches. The main identified priority pollutants were sulphate (all countries) and iron (all countries except Greece). High concentrations of chloride (particularly in Germany and Poland) were associated with discharge of saline mine waters linked to the presence of fossil sea water; these mine waters also had high boron concentrations, in contrast to chloride-rich waters in UK that are linked to recent sea water inflow. Concentrations of trace metals vary among countries, but radium is an important contaminant in barium-rich waters with low sulphate concentrations, essentially in Poland. Concentrations of trace metals and metalloids were generally low because of their relative scarcity in coal strata and adsorption onto ferric oxides and hydroxides, but they still often exceeded the environmental quality thresholds.

     

MODFLOW-USG: the New Possibilities in Mine Hydrogeology Modelling (or What is Not Written in the Manuals)

Geological heterogeneity associated with layers, open mine voids, tectonic faults and fractures can all make modelling difficult, particularly for mine dewatering. This heterogeneity is difficult to represent with the traditional MODFLOW structured grid. A new version of MODFLOW, called MODFLOW-USG (for UnStructured Grid), supports a wide variety of structured and unstructured grid types (Panday et al. in MODFLOW-USG version 1: an unstructured grid version of MODFLOW for simulating groundwater flow and tightly coupled processes using a control volume finite-difference formulation. USGS, Reston, 2013) that provide flexibility for modelling difficult geologic structures. This communication compares aspects of MODFLOW and MODFLOW-USG, and uses the Gbely lignite deposit as an example of a situation for which MODFLOW-USG could be applied.     

Modified Multi-phase Stability Diagrams: An AMD Case Study at a Site in Northumberland, UK

The weathering of sulphide minerals within spoil heaps causes the release of sulphate and environmentally hazardous metal ions. Newly-formed species can subsequently precipitate as highly soluble, secondary sulphate minerals, which, in turn, might be flushed by dilute recharge water or eventually transformed into more stable minerals. These processes determine which components are retained in the spoil as immobile solid phases and which (and when) others are released into the wider aquatic environment. To elucidate this sequence of mineral formation and transformation, we studied mineral-fluid equilibria in a major abandoned coal mine spoil heap at the former Shillbottle Colliery, Northumberland, UK. The investigations focussed on stability of iron minerals produced during the acid mine drainage process. The multi-component Phreeplot-calculated pE/pH diagrams reveal that many post-mining secondary minerals may co-exist, in contrast to what is indicated by the more commonly used charts. Being able to visualize the mutual stability of these minerals under specific chemical and physical conditions might aid understanding of formation and transformation mechanisms.     

Mechanisms of arsenic enrichment in geothermal and petroleum reservoirs fluids in Mexico

The lack of chemical similarity between thermal fluids in geothermal and petroleum reservoirs in Mexico indicates a distinct origin for arsenic in both types of reservoirs. Deep fluids from geothermal reservoirs along the Transmexican Volcanic Belt (TMVB) are characterized by elevated arsenic concentrations, within a range between 1 and 100 mg L^?1 at a depth from 600 to 3000 m b.s.l. Based on hierarchical cluster analysis (HCA), arsenic is linked to typical geothermal species like lithium, silica, and boron. The lack of correlation between arsenic and salinity reflects the importance of secondary water-rock interaction processes. The predominance of arsenic compared to Fe- and Cu-concentrations, and the occurrence of secondary minerals (sulfides and clay minerals) in temperature-dependent hydrothermal zones, supports this hypothesis. Neither magmatic fluids input, nor As mineralization is a prerequisite for As enrichment in Mexican geothermal fluids. In contrast, petroleum reservoir waters from sedimentary basins in SE-Mexico show maximum As concentrations of 2 mg L^?1, at depths from 2900 to 6100 m b.s.l. The linear chloride–arsenic correlation indicates that evaporated seawater represents the major source for aqueous arsenic in oil reservoirs, and only minor arsenic proportions are derived from interaction with carbonate host rock. Speciation modeling suggests the lack of arsenic solubility control in both geothermal and petroleum reservoirs, but precipitation/co-precipitation of As with secondary sulfides could occur in petroleum reservoirs with high iron concentrations. Geothermal fluids from magmatic-type reservoirs (Los Azufres and Los Humeros at the TMVB and Las Tres Vírgenes with a granodioritic basement) show relative constant arsenic concentrations through varying temperature conditions, which indicates that temperatures above 230–250 °C provide optimal and stable conditions for arsenic mobility. In contrast, temperature conditions for sedimentary-type reservoirs are irrelevant for water-rock interaction processes, as suggested by low arsenic aqueous concentration for both Cerro Prieto geothermal fluids (high temperature – sedimentary type) and oil field formation water (low temperature – sedimentary type).