Geochemistry of the Hyperalkaline Gorka Pit Lake (pH?>?13) in the Chrzanow Region, Southern Poland

The Gorka pit lake was formed in an inactive Jurassic limestone quarry after cessation of open-pit dewatering. The main problem of the water quality in this area is linked to a large volume of extremely alkaline leachate disposed in the flooded quarry. The lake is meromictic due to a large density contrast between shallow and deep water layers. Water in the lake is of the Na?CCO₃?COH type, pH is in the range from 11.5 to 13.3, and there are high concentrations of sulfate and several toxic elements (Al, As, Cr, Mo, P, and V). The chemical composition of the extremely alkaline leachate was formed as a result of the groundwater interaction with the industrial red mud wastes containing 5?C10 wt.% of sodium carbonate. There is a trend of increasing concentrations and pH values with depth, mainly due to the in-gassing of atmospheric CO₂ into the surface layer and due to density stratification in the water column. Similar stratification is observed in groundwater wells around the lake. High dissolved concentrations of oxyanionic contaminants such as As, Cr, and V are caused by their high mobility and desorption under extremely alkaline conditions. In spite of reducing conditions at the bottom of the lake, caused by high concentrations of dumped organic matter, sulfate behaves conservatively because sulfate reducing bacteria do not survive in this pH range.     

Biomonitoring and Sourcing Toxic Elements Using Vascular Epiphytes of the Tillandsia Genus in the Mining Region of Taxco de Alarcón,Guerrero, Southern Mexico

Water, Air, &; Soil Pollution - The concentration of As, Pb, Cd, Zn, Fe, Mn, and Cu and the Sr and Pb isotopic compositions were determined in four species of the vascular epiphyte Tillandsia...     

Quantification of Soil Macropores at Different Slope Positions under Alpine Meadow Using Computed Tomography in the Qinghai Lake Watershed,NE Qinghai–Tibet

Eurasian Soil Science - Soil macropores largely control fluid and solute transport and the runoff processes on the slopes. However, the characterization of soil macropores for different slope...     

SE—Structures and Environment: Optimal Control Strategies for Carbon Dioxide Enrichment in Greenhouse Tomato Crops,Part II: Using the Exhaust Gases of Natural Gas Fired Boilers

Optimized control strategies for carbon dioxide (CO₂) enrichment of greenhouse tomato crops using CO₂ from the exhaust gases of boilers burning natural gas are presented. In one group of strategies, the heat produced during CO₂ generation which exceeds the immediate heat requirement of the greenhouse is stored as hot water and used subsequently for heating. The simulations show that, use of optimal control can increase the financial margin of crop value over the combined expenditure on gas used for CO₂ and heating by £2·3 m⁻² (11%) when heat is not stored and by £4·9 m⁻² (24%) when heat is stored, compared with enriching with CO₂ only when heating is required. A 30% increase in gas price reduced the financial margin by 11%, whereas a 30% increase in tomato price increased the margin by 40%. The capacity of the heat store places a limit on the amount of heat that can be stored and consequently on the amount of natural gas that can be burnt and the associated amount of CO₂ produced during the day. The optimum size of heat store is 20×10⁻³ m³ per unit greenhouse area.