the UK context, but surface soils have been reported to experience such high temperatures during summer (c.f. Blackwell et al., 2009). Moreover, to our knowledge, the effects of chloroform fumigation on soil microbial biomass phosphorus leaching have not yet been studied in pre- and post-dried soil samples. This work investigates how the soil microbial biomass responds to fumigation in the presence or absence of soil moisture and impacts on dissolved reactive phosphorus (DRP) leaching. In the above context the basic objectives of our controlled laboratory experiments were to: (1) test the hypothesis that increases in the intensity and duration of soil drying will significantly increase concentrations of DRP in leachates, (2) determine the soil microbial biomass phosphorus contribution to enhanced leaching of DRP following DRW, and (3) examine how the soil microbial biomass responds to chloroform fumigation in pre- and post-drying soil samples—this will help understand how soil drying-rewetting influences phosphorus leaching when biomass is killed before or after drying. Phosphorus leaching from soils occurs in the forms of DRP, dissolved organic P and particulate-bound P (Hooda et al., 1999). This work, however, considers only DRP leaching because this is the most important factor in terms of water quality and eutrophication as noted in the Water Environment 1 .
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Leaching studies utilising monolithic soil lysimeters and lab based leaching experiments were undertaken on soils taken from a recently established dairy unit, that occupies part of the Manuherikia River flood plain within the Alexandra basin of Otago, New Zealand. The research objective was to study the potential for P to move down the vadose zone and into groundwater from common P applications under irrigated and grazed dairy pastures. This was addressed by firstly examining the bioavailability of different organic P forms leached in these gravels, secondly, to determine if low ASC gravel soils coincide with enhanced vertical P loss and thirdly, estimating how long intensive farming of these areas would take to enrich groundwater P.
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Conventional fertilizers formulations such as single super phosphate (SSP), monoammonium phosphate (MAP) and diammonium phosphate (DAP) were devel- oped with the goal of minimizing the production costs per unit of soluble P. The study of SSP, MAP and DAP modiﬁcation to reduce susceptibility to P runoff and leaching has been limited (Hart et al., 2003). SRFs have been employed to reduce direct fertilizer runoff losses. Nutrient leaching from SRFs is reduced through degrada- tion of an organic or inorganic coating around a core of inorganic fertilizer. Quin et al. (2003) describe coating a DAP with a slurry of elemental sulfur which provides a short-term barrier to water. Field trials demonstrated an approximately 40% reduction of P runoff during the ﬁrst runoff event after application. Nash et al. (2003) conducted laboratory dissolution studies comparing SSP and a dry sulfur-coated superphosphate, in which sulfate of ammonia was the binding agent. The authors found that the water- extractable P was greater from the coated superphosphate fertilizer treatments (6.6%) compared to 4.8% from superphosphate treatments. The rapid dissolution of the S-coated superphosphate resulted from the rapid solubili- zation of the sulfate of ammonia in the extraction procedure, and with it removal of the sulfur coat and protection against P dissolution in the granules (Hart et al., 2004).
This situation demonstrates the need for further research concerning the soil and waste management effects on P leaching in acid sandy soils of the North Carolina Coastal Plain. There is a need for more research that describes the extent of P leaching in naturally drained soils; specifically data demonstrating the P concentration in the soil solution of soils with histories of long-term waste application, including relationships between leachate P concentrations and easily quantifiably soil properties. This will assist in quantifying the environmental risks of P leaching as well as determining a need for future research describing P transport in shallow ground water. As previously stated, P desorption from P saturated soils could potentially result in continued P leaching even after elimination of P addition. For example, Schoumans and Groenendijk (2000) and Breeuwsma et al. (1995) have estimated that P leaching could continue for 100 to 200 years given the current P status of soils in the Netherlands. Management
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(Fig. 7b, c) were not significant. In contrast, phosphate-P loads from the loam increased by 230% in the biochar treat- ment compared to the control but due to large variation be- tween replicates, this was not significant either (Fig. 7d). The biochar may have potentially caused this, as the biochar P content was 8.8 g kg − 1 (Table 3), or the applied equivalent of 6 mg P per lysimeter (874 kg P ha −1 ). However, this is unlikely as large P release would have also been noted from the other soils. One hypothesis was that increased erosion due to a structural effect of Mg 2+ ions leached out of the biochar on the clay particles (Dontsova and Norton 2002) could have led to increased losses. However, the leaching data showed no increase in particulate-P which would be expected if this was the explanation. Instead, a combination of desorption of P below the biochar layer and high replicate variability due to the low replicate number (n = 3) likely overshadowed the ef- fect of any P sorption/desorption from the biochar in the loam soil.
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SAS institute, 2001. The SAS system for Windows. Version 8.2. SAS inst., Cary. N.C. Self-Davis, M.L. and P.A. Moore, 2000. Determining water-soluble P in animal manure. p. 74-76. In G.M. Pierzynski (ed.) Methods of phosphorus analysis for soils, sediments, residuals, and waters. Bull. No. 369. Southern Extension Research Activity-Information Exchange (SERA-IEG-17), Kansas State University, Manhattan, KS.
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The dynamics of soil phosphorus leaching by different types of low molecular weight organic acids. As shown in Table 2, at the beginning of leaching, none of the acids could leach out the soil phosphorus, which might be explained by the adsorption of these four organic acids by the soil. Xu et al. (2007) found that no aluminum was leached out at the beginning of leaching due to the adsorption of salicylic acid by the soil. When the adsorption became saturated, the organic acids manifested a strong facilitation for the migration of aluminum. For citric acid, the soil phosphorus began to be leached out when the volume of the leaching solution reached 310 mL (Table 2). The leached phosphorus increased rapidly to its maxi- mum level (8.4 mg/kg). The leached phosphorus
factor (R) were incorporated into the computer program. The trial values of D and R were taken from the literature values (Almani et al., 2013). By running this program, the theoretical effluent concentrations were determined, and the plot was generated with the theoretical breakthrough curves. The theoretical effluent concentrations were compared with experimental values and the iterations were continued till the theoretical curve match with the experimental values. The transport parameters were obtained by matching the theoretical elution curves (with a set of assumed diffusion coefficients and retardation factors) with the experimental elution curves (i.e. breakthrough curves for leaching).
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For the tooth 12, the annual dose was calculated from the sediment without dosimeter. The very old US age of enamel corresponds probably to a limit of the measurement technique due to the low uranium content in this sample. In contrast, dentin has a parameter p = -0.689 showing a uranium incorporation with a low exponential manner, which tends to rejuvenate age slightly that is most likely between 35 and 40 ka. Indeed, US-ESR age of 40 ± 6 ka calculated for the entire tooth confirms this. In contrast, dentin has a parameter p = -0.689 showing a uranium incorporation with a low exponential manner, which tends to rejuvenate age slightly that is most likely between 35 and 40 ka. Indeed, US-ESR age of 40 ± 6 ka calculated for the entire tooth confirms this. For the tooth 11, the annual dose was also calculated from the sediment without dosimeter. For enamel, the activity of uranium determined by alpha spectrometry (TABLE 2) is equal to the activity of radon determined by gamma spectrometry (TABLE 4). This means that the radon is in equilibrium with its father uranium; therefore enamel behaves as a closed system. In addition, the parameter p, calculated for the enamel, is -1; this confirms that uranium incorporates there according to the EU model. US age of dentin is very old equal to 114 ka, which is abnormal because the two teeth 12 and 11 are in the same layer. Therefore dentin presents significant uranium leaching, having the effect of grow old age. Thus the US age of enamel 49 +8/-7 ka is correct. This is confirmed by the ESR-US age for the entire tooth that gives 45 ± 7 consistent with that of the tooth 12 in the same layer that gives 40 ± 6 ka. It should be noted that the amount of uranium determined by gamma spectrometry is not taken into account in the calculation even if there is a balance between the elements; son and father due to the low percentage of gamma radiation emitted compared to alpha radiation.
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SEM images of Co concentrate and matte are shown in Fig. 2. Figure 2(a) shows particles of Co concentrate with ir- regular shapes and various sizes. Similar to the Co concen- trate, matte in Fig. 2(b) consists of particles with irregular shapes and various sizes. Particle size distribution measure- ments are illustrated in Fig. 3. Although the Co concentrate and matte were crushed and ground in the same way, they indicated a slightly different particle size distribution. The particle size of Co concentrate is distributed between 0.5 µm and 500 µm with the most probable size being 60 µm. In the case of matte, particle size ranges between 0.7 µm and 600 µm with dominant particle sizes around 70 µm. Because the difference in particle size of the concentrate, the matte 1 and 2 is not large, the effect of particle size on the leaching of concentrate and matte would not be significant. If any, the Co concentrate would have an advantage in leaching efficiency
In the case of copper, the greatest amount was released using bioleaching at a temperature of 24ºC. After 6 days of the process, 8760 mg of the metal was released from 1 kg of waste. In the case of the chemical leaching with weak sul- furic acid at a temperature of 24ºC, 7652 mg of copper were released after 6 days. In the case of nickel, the largest release was achieved with the use of bioleaching at a temperature of 24ºC. After 9 days of the process, 1800 mg of nickel were released from 1 kg of waste. In the case of chemi- cal process at a temperature of 24ºC after 6 days, 1710 mg were released. Zinc had the worst leach- ing effectiveness. The best results were reached with bioleaching at a temperature of 24ºC, where 696 mg of zinc were released from 1kg of waste.
This research project investigated the use of a range of industry by-products as neutralising agents for treating acid sulfate soils in an effort to locate a cost effective alternative to commercial liming agents. To achieve this, relevant legislation was researched to determine performance criteria to be met by neutralising agents in treating acid sulfate soils. Three trial products were selected; two recycled concrete products and one concrete washout material. A leaching column experiment was carried out to test the effectiveness of these products as neutralising agents in treating an acid sulfate soil sample. A site specific cost analysis was conducted to determine the relative costs of using these products compared to using a commercial liming agent. The results showed that one recycled concrete product and the concrete washout material were effective as neutralising agents. However only the concrete washout material was comparable cost-wise with a commercial liming agent in treating onsite acid sulfate soils.
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exothermal reaction, which means that the reaction creates heat, since with increasing the temperature of exothermal reaction, the solubility decreases. The time has little effect on the leaching efficiency of chromium. Leaching time, as shown in Fig 1 curve, was unstable. The leaching efficiency of chromium decreases when the time was increased until arrive 45 C o the leaching efficiency will increase. This is because of consumption of the
ent saline-sodic problems (Feizi 1993). Roudasht district with the area of about 50 000 ha, which is located about 65 km east of Isfahan (32°29'N, 52°10'E), is one of the salt-affected zones of the Isfahan province (Houshmand et al. 2005). In this district, shallow saline groundwater with the depth of about 2–4 m below soil surface and salinity of about 13 dS/m, low annual precipitation about less than 100 mm per year, high evapotranspiration and the use of saline drainage water for irrigation, caused several problems for soil and agricultural production, especially for wheat (Feizi 1993). To recommend the appropriate management practice for leaching of salts from these soils and to study the effects of different leaching levels on actual leaching and the ease of attainment of steady-state mass balance of salt, wheat as a typical crop and a typical soil of the area were selected and pot experiments were conducted in a greenhouse at the Isfahan University of Technology. Treatments with three irrigation water salinities of 4, 9 and 12 dS/m and four leaching levels of 3, 20, 29 and 37% were applied, using a factorial design with seven replications for each treatment. It should be noted that the salinity of irrigation water used commonly in the study area is about 4 to 10 dS/m, because farmers mix saline drainage water with river water and use it for irrigation. The charac- teristics of irrigation water used in this study are shown in Table 1. Total of 84 plastic pots (each pot with 32 cm diameter and 42 cm depth) were used. Each of them was filled with 14 kg of typical soil of the Roudasht district wheat farms, having silty clay loam texture (EC e = 13.2 dS/m, pH = 7.22, ρ b = 1.34 g/cm 3 and SAR = 11.31). The soil samples
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Abstract: In this study, the impact of pulp density (PD) on indirect bioleaching of the sphalerite ore has been resolved over a time of 20 days using adapted Leptospirillum ferriphilum. The strain was segregated from the Chitradurga mine sector in Ingaldhal (Karnataka, India) and was exposed to molecular strategies before bioleaching experiments. The bioleaching process was done at fixed parameters of initial pH, rpm, and temperature at 3.0, 150, and 28 ± 2°C, respectively, and differing PD 1–5% (w/v) in orbital shake flask. At 1% and 5% PD, the bioleaching efficiency of zinc from the ore was 87.85% and 60.1%, respectively, while that of iron from the ore was 92.74% and 65.7%. The results showed that efficiency of bioleaching was unequivocally impacted by PD and maximized at low PD. Rate kinetic study through the first-order kinetics indicated that the maximized rate constant values of bioleaching were obtained at experiments with lower PD. The Michaelis–Menten (M-M) type equation was utilized to anticipate the connection between metal leaching rate and PD as the constraining substrate. From the observed data, the estimations of the M-M kinetic parameters k m and V max were found to be 2.729 mgL -1 and 1.0172 mgh -1 L 1 , respectively, for leaching of zinc, and
Deviational Analysis: Analysis of extracted zinc concentration from the experiment and derived model revealed deviations of the predicted model values from the actual experimental results. This is attributed to the fact that the surface properties of the sphalerite and the physiochemical interactions between the ore and the leaching solution which were found to have played vital roles during the process were not considered during the model formulation. This resulted to the introduction of correction factor, to bring the predicted model of extracted zinc concentration to those of the corresponding experimental values. Deviation (Dn) of model-predicted extracted zinc concentration from that of the experiment is given by
The aim of this study is to review the literature on the methods of low-rank coal enrichment by using microor- ganisms and their metabolites. Effective bio-beneficiation technologies for low-rank coals in the future are also suggested throughout this paper. An extensive literature review highlights recent advances in bio-beneficiation technologies for low rank coals. This paper presents the state of the art in the field of the bio-beneficiation technology – carbon leaching with the aid of microorganisms, especially fungi. The knowledge of the low-rank coals leaching is an important step to meet the carbon eco-requirements and improve the economics of mining companies. There are several reasons to investigate microbial activities towards coal. This paper presents the current state of knowledge concerning bioleaching of coal. Thus, in view of the increasing importance of hard coal as a raw material and energy source, it seems hopeful to study the potential of microorganisms to modify the low-rank coal structure.
Spodumene naturally exists as an insoluble monoclinic aluminium silicate, referred to as α- spodumene (Brown 2016). The molecular arrangement of α-spodumene consists of a sixfold tetrahedra of silicon atoms, centralised around aluminium and lithium ions (Botto 1985, Salakjani et al. 2016) (Figure 4A). It has been found that due to the highly siliceous nature of the mineral, numerous difficulties arise when trying to extract valuable constituents (Meshram et al. 2014, Kuang et al. 2018). Currently the most efficient extraction techniques utilise an energy intensive calcination step prior to leaching. The calcination of α-spodumene promotes a physical transformation to occur resulting in a reactive polymorph forming known as β-spodumene. When calcination occurs the sixfold coordination of the silicon atoms become five membered rings of (Si, Al) O 4 (Botto 1985, Salakjani et al. 2016) (Figure
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(WSP:TP) were determined in the feces. Digestibility coefficients for phosphorus and phytate ranged from 0.11 (corn) to 0.46 (wheat) and 0.94 (oat) to 1.00 (corn and low-phytate barley), respectively. There was very little phytate phosphorus excreted in the feces regardless of the type of cereal grain fed (< 6% of total phosphorus) and phytate degradation was not related to the level of endogenous phytase in the diet. There was a negative relationship between the fecal WSP:TP ratio and the concentration of phosphate monoesters in the feces. In summary, our results indicate that the majority of the phosphorus in the feces of pigs fed cereal grains is present in the form of inorganic phosphate and only trace amounts of phytate are excreted intact. The amount of phytate in the excreta was not related to the amount of phytate or endogenous phytase in the grain. Further research should be conducted with diets more typical of those used in commercial swine production to confirm these findings, as the high inorganic phosphate content and WSP:TP ratio in manure from swine could increase the potential for off-site phosphorus losses when swine feces are applied on agricultural lands.
Fluoride is regarded as one of the most important environmental micro pollutant responsible for soil and groundwater pollution causing dental and skeletal fulorosis [1,2,3]. The risk for human health and the environment can largely be determined by the concentration of fluoride that occurs in groundwater and the rate by which fluoride migrates to groundwater as both these processes can strongly be influenced by the interaction of dissolved fluoride with the soil solid phase via adsorption and desorption  and cation-anion exchange. Thus it is important to study its migration and leaching. The study become more important in saline soils, as above pH 7.0, most of the inorganic fluoride salts are either complexed with Fe and Al show maximum solubility or remain in soluble ionic form in soil water .