Limestone liners to protect groundwater quality against organic wastewater seepage

Crushed limestone was tested as a sealing liner for organic wastewater storage facilities. This material was compacted in laboratory columns and exposed in quadruplet to three levels of wastewater total solids (TS of 0.6, 1.3 and 2.6%). A fourth set of quadruple columns was used to monitor the total nitrogen (TN) loading rate using 1.3% TS wastewater. The crushed limestone cores measured 310 mm in depth by 98 mm in diameter and were exposed to a typical wastewater depth of 290 mm. Wastewater TS and ambient temperatures had a marked effect on seepage and TN loading rates. If the wastewater contains at least 1.3% TS, the seepage and N loading rate can be limited to 2 × 10^-8 m s^-1 and 200 mgN m^-2 d^-1, respectively. Ambient temperatures below 5 °C caused the TN loading rate to increase 7 fold, while those above 5 °C favoured nitrifying and denitrifying activity, thereby reducing seepage TN.     

Indole acetic acid production by Rhizobium: Effect of 2-ketoglutaric acid

I ndole acetic acid (IAA) production from tryptophan by cell suspensions of Rhizobium trifolii, R. leguminosarum, R. phaseoli and R. lupini was studied in the presence or in the absence of 2-ketoglutaric acid. In R. lupini, production of IAA was strongly enhanced by the ketoacid, but in fast growing rhizobia it was less enhanced or unaffected. On the other hand, glutamic acid inhibits IAA production by R. meliloti, but stimulates IAA production in both R. leguminosarum and R. phaseoli. A hypothesis is proposed to explain these results.     

Electrochemical Degradation of a Real Pharmaceutical Effluent

In this work, the electrochemical treatment of an effluent from the pharmaceutical industry with boron-doped diamond electrodes was investigated. The electrolyses were carried out in a discontinuous operation mode under galvanostatic conditions, using a bench-scale plant equipped with a single-compartment electrochemical flow cell. The effect of operating conditions, such as current density (from 25.7 to 179.4?mA?cm²) and flow rate (from 104.8 to 564.7?cm³?min^?1), at residence times between 0 and 570?min, was studied. Design of experiments was used for optimizing the process. The global contribution of operative parameters and evolution of the residence time in TOC removal was studied, and a time of 77?min was obtained in order to evaluate the highest influence of the operative parameters. For this time, ANOVA test reported significance for four of the five involved variables. The current density was found to have a considerable positive effect on TOC removal, whereas the flow rate was found to have a moderate negative effect on target variable.     

Comparison of two approaches for assessing solonetzic process in the virgin and human-transformed soils of the dry steppe zone

Two approaches to diagnose the development of secondary solonetzic process in the reclaimed solonetzes and solonetzic soils of the dry steppe zone were compared. For this purpose, the kinetics of swelling of crushed soil and the physicochemical characteristics of the soils were studied in the same samples. Both approaches gave similar results for the soils with the absence of the solonetzic process and for the soils in which this process was clearly manifested. To assess the risk of the development of the solonetzic process in the soils where its morphological manifestations are absent, the determination of the swelling kinetics and the calculation of the B index of the physicochemical conditions may be used.     

Riverine Flux of Metals from Historically Mined Orefields in England and Wales

Water, Air, &; Soil Pollution - The flux of metals at the tidal limits of major rivers are an important metric of freshwater contaminant transfer to marine habitats, reported in Northeast...     

The capacity of soil particles for spontaneous formation of macroaggregates after a wetting-drying cycle

The capacity of soil particles for spontaneous formation of aggregates >0.25 mm was studied in a laboratory experiment. The particles from soil aggregates (3-1 mm) (initially aggregated particles, APs) and initially free particles (FPs) of <0.25 mm in size were isolated from the soddy-podzolic and chernozemic soils under fallow and from the arable soddy-podzolic soil. The aggregates of 3-1 mm were ground and passed through a 0.25-mm sieve. Then, the aggregates and free particles were poured with water and dried, and the content of the formed aggregates and their water stability were determined; in the samples from the arable soddy-podzolic soil, the organic carbon content was also determined in the newly formed aggregates. The FPs from the untilled soils formed almost no aggregates. At the same time, the APs from these soils manifested the ability for the spontaneous formation of aggregates, including water-stable aggregates. In the arable soddy-podzolic soil, on the contrary, both FPs and APs demonstrated the capacity for spontaneous self-organization into aggregates. The water stability of the self-organized aggregates from the arable soil was similar regardless of their source (APs or FPs). It was supposed that the ability of the FPs from the arable soil to form macroaggregates reflects the mechanical degradation of the aggregates in the soil: tillage results in the degradation of the aggregates, and the particles capable of spontaneously aggregation temporarily fall in the fraction of <0.25 mm. The water-stable aggregates produced from the APs or FPs of the arable soil contained more organic carbon (1.89%) in comparison with the water-stable aggregates separated from the initial 3- to 1-mm aggregates of this soil (1.31%).     

Effect of nitrogen fertilizer on the concentrations of oil and protein in canola (brassica napus) seed

The oil and protein concentration response of canola (Brassica napus L.) to application of nitrogen (N), applied as urea (46%), was measured in 210 field plots done in 1994 and 1995 in south‐western Australia (WA). The canola was grown on a range of soil types deficient in N for maximum seed production. The sites were sown in late May to early June. The concentration of oil in the canola seed decreased concomitantly with an increase in protein. In all experiments, in both years, there was no relationship between the seed yield and the resultant oil or protein concentration. The addition of the oil plus protein concentration in the canola seed was an approximately constant 62% in the both years.     

The Path of Carbon in Photosynthesis. XXV. Plant and Algal Growth Responses to Glycopyranosides

Substituted glycopyranosides were applied to various plant species as foliar and root treatments, with and without nutrient supplements, and growth was compared to untreated or nutrient controls. When formulated with specific fertilizers, particularly available nitrogen, methyl and ethyl glycopyranosides significantly enhanced the overall growth of vascular plants compared to controls provided with the same nutrients. In contrast, vascular plants treated with alkylglycopyranosides without nutrients showed growth equivalent to that of untreated controls. Nitrogen-supplemented alkylglycopyranosides provided as foliar applications of 100 mM, or as root treatments between 35 and 50 mM, consistently enhanced root and shoot productivity. In addition to the vascular plant species tested, the brown alga Laminaria saccharina exhibited significant growth enhancement over nutrient controls when treated with alkylglycopyranosides supplemented with nutrients, especially under low irradiance. Overall, these results indicate that growth of photosynthetic organisms is enhanced by exogenous alkylglycopyranosides supplemented with nitrogen and micronutrients, but not by alkylglycopyranosides alone.