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The composition of precipitation and element loads originating from rainwater were examined monthly between 2005 and 2008 at two experimental stations (Őrbottyán in the Danube–Tisza Interfluve region and Nagyhörcsök in the Mezőföld region of Hungary) of the Research Institute for Soil Science and Agricultural Chemistry (RISSAC) of the Hungarian Academy of Sciences. Twenty-five characteristics were analysed: pH, EC, NO 3 -N, NH 4 -N, and concentrations of the main macro- and microelements. The observation represents the dry and wet deposition together. Measurements were carried out by ICP-OES device, with the exception of carbonate, chloride, ammonia and nitrate. The main results can be summarized as follows: – Generally, the lower amounts of monthly precipitation resulted in higher EC, pH; NH 4 -N, Ca, Na and K concentrations. The highest element yields, however, were typical of the wet months. Acidic precipitation (below pH 5) was rich in nitric acid forming NO 3 -N, but poor in NH 4 -N at the Őrbottyán Experimental Station. Emission of the nearby cement works in February and March 2006 caused an order of magnitude higher increase in Ca, Mg, Na and Sr elements as compared to other months, and there was a considerable rise in the NH 4 -N, S, Zn, As, Cr and Pb concentrations of the precipitation (Table 5, 1st half of the year). The pH reached 7.0 at this site. – Depositions were small at the Nagyhörcsök Experimental Station in winter. During the warmer months (May, June and July) the NH 4 -N concentration was 10–20 times higher than the NO 3 -N concentration. The neighbouring fertile and humus rich soils, fertilization, as well as the nearby animal husbandry farm make notable NH 3 emission. In this period the concentration of NH 4 -N and the alkalizing cations Ca and K raised the precipitation’s pH, and the pH increased from January to June. – Aerial deposition varied greatly at both sites, representing the following values in kg·ha -1 ·year -1 unit: NO 3 -N 5–20; NH 4 -N 10–31; total N 30–48; Ca 6–60; K 6–16; S 2–21; Na 4–13; Mg 2–16; P 2–6. The deposition of Zn, Mn, Fe, Cu and B elements at these sites were similar to previous Hungarian and Austrian data. Pb, Ni, Cd and Co depositions, however, were an order of magnitude lower, which demonstrates the positive result of the successful control of heavy metal pollution in Europe since 1990. – Aerial deposition has considerable agronomical and environmental significance. According to the present study, aerial deposition could satisfy 10% K, 15% Mg, 20% P, 30% Ca and N, 40% S element demand of an average 5 t·ha -1 grain and 5 t·ha -1 straw yield of cereals on the chernozem soil of the Nagyhörcsök Station. When using combine harvesting, the straw remains on the site and only the grain is removed, so 25% P, 45% K, 100–300% S and Ca, and several fold of Na-requirement could be covered by the aerial deposition. – Atmospheric deposition may more or less compensate the amount of Mo, Ni and Se built in by grain, while the Zn requirement might be exceeded by about 60%. The deposition of B, Ba, Cu and Sr is several times higher than the amount built in by the grain yield. Aerial fertilization with Cu, Mo, Se and Zn seems to be advantageous, as the site is poor in Zn and Cu, or not satisfactorily supplied with Mo and Se elements. Cd, Hg and Pb loads, however, are environmentally disadvan-tageous, especially on the long-term. The latter harmful heavy metals can also get into waters, on the surface of crops and can cause direct damage to the food chain. – The following minimal – maximal depositions were measured on the two experimental sites: Zn 112–1391; Sr 30–202; Cu 21–153; Fe 42–119; Ba 40–79; Mn 33–62; B 0–33; Pb 2–4; Ni, Cr and Mo 0–6; As 0–4; Hg 0–1.5; Co 0.4–0.7; Cd 0–0.3 g·ha -1 ·year -1 . The pH varied between 4.2 and 7.0 while electrical conductivity ranged between 25 and 1996 μS·cm -1 .
In the field experiments carried out in 2000 and 2001 at the Nagyhörcsök Experimental Station on calcareous chernozem soil contaminated with heavy metals the results show that the application of 40 t/ha Balinka brown coal did not decrease the uptake of essential elements by the maize, barley and rape test plants, and did not decrease the fertility of soil. There was no change or sometimes a slight increase in the investigated tissues of the plants due to the effect of coal application. This is advantageous in Zn deficient soils, but on similar soils strongly polluted with Zn the Balinka brown coal cannot be used as an effective remediator. The coal treatment drastically decreased the Se toxicity of the soil, the maxi-mum yield could even be obtained on the strongly Se-polluted plots. The development of plant stands in the coal treated plots improved considerably, perhaps due to the better moisture regime conditions of the soil. The Sr and Cd content in plant tissues decreased in several cases due to brown coal application. The most dangerous contaminant, the Cd concentration in the plants dropped to half or even 1/3, as a result of coal treatment. The results of the two-year experiments showed that the 40 t/ha rate of Balinka brown coal can be used successfully and economically in the in situ remediation of Cd, Se and Sr contaminated soils. This rate does not influence the original fertility parameters of the soil, but can be applied with advantages both in extremely light- or heavy textured soils in case of moderate contamination. However, further investigations are needed to find out the effects of Balinka-type brown coal application on other soil types, plants and other polluting elements.
A pot experiment was designed to study the variability of some inside and outside mycorrhizosphere characteristics of barley (Hordeum vulgare L.) and the potential transfer of Cd, Ni and Pb in a metal-contaminated calcareous chernozem soil. Substrates of the pots were taken from a long-term field experiment site at Nagyhörcsök, Hungary, where the cadmium (Cd), nickel (Ni) and lead (Pb) were spiked as single salt application at four levels (0, 30, 90 and 270 mg kg−1 dry soil) 12 years prior to this study. Beside the biomass production and element content of plants, the total catabolic enzyme activity measured by fluorescein diacetate analysis (FDA) and the colonization parameters of arbuscular mycorrhizal fungi (AMF); the infection intensity (M%) and the arbusculum richness (A%) were determined. After 12 years, the indigenous mycorrhiza fungi in the soils might be adapted to the contaminated environments, as a function of metals and their applied doses. Stress-defense strategies of the fungal-plant symbiosis, such as the better functioning of the AMF by enhanced arbusculum richness or by the improved phosphore-mobilization capacity was found mainly at the middle (90 mg kg−1) doses of metals. Increasing quantity of Cd above the maximum permitted concentration in the soil could enhance the biomass production of barley roots and reduce the Cd translocation towards the shoots. Outside rhizosphere parameters as the FDA enzymatic activity were stronger influenced by the long-term metal stress, than the inside mycorrhiza colonization, showing the protecting effect of the symbiosis both for the macro- and microsymbionts. Mycorrhizosphere conditions are part of the common plant-microbe strategies and plant-defending mechanisms that can result in a better stress-alleviation at chronic metal-exposures.
Abstract
An equipment and procedure were developed to determine the CaO content of bauxite by X-ray fluorescence method using scintillation techniques and a tritium/Ti exciting source. The time needed for the whole sample preparation procedure and measurement is less than 10 min. The range of concentration where analysis is feasible by the equipment, is from 0.3% upwards.
Phytoremediation is an approach designed to extract excessive heavy metals from contaminated soils through plant uptake. Cadmium (Cd) is among the elements most toxic to living organisms. Health hazards associated with the lethal intake of Cd include renal (kidney) damage, anaemia, hypertension and liver damage. A greenhouse experiment was carried out with Indian mustard (Brassica juncea) grown on artificially spiked soil (100 μg Cd g−1) with EDTA (2 mmol kg−1 in 5 split doses), FYM, vermicompost (VC) and microbial inoculants (MI) such as Azotobacter sp. and Pseudomonas sp. The growth of Brassica juncea L. was better in soil amended with FYM or VC as compared to unamended Cd-polluted soil. Growth was slightly suppressed in EDTA-treated soil, whereas it was better after treatment with MI. The application of FYM and VC increased the dry matter yield of Indian mustard either alone or in combination with microbial inoculants, while that of EDTA caused a significant decrease in the biomass of Indian mustard. The application of microbial inoculants increased the dry matter yield of both the roots and shoots, but not significantly, because MI shows greater sensitivity towards cadmium. The maximum cadmium concentration was observed in the EDTA +MI treatment, but Cd uptake was maximum in the VC + MI treatment. The Cd concentration in the shoots increased by 120% in CdEDTA over the Cd100 treatment, followed by CdVC (65%) and CdFYM (42%) in the absence of microbial inoculants. The corresponding values in the presence of MI were 107, 51 and 37%, respectively. A similar trend was also observed in the roots in the order CdEDTA+M > CdVC+M > CdFYM+M>Cd100+M.MI caused an increase in Cd content of 5.5% in the roots and 4.1% in the shoots in the CdEDTA+M treatment compared with the CdEDTA treatment. FYM, VC and EDTA also increased Cd uptake significantly both in the shoots and roots with and without microbial inoculants.The results indicated that Vermicompost in combination with microbial inoculants is the best treatment for the phytoremediation of Cd-contaminated soil by Indian mustard, as revealed by the Cd uptake values in the shoots: CdVC+M (2265.7 μg/pot) followed by CdEDTA+M (2251.2 μg/pot), CdFYM+M (1485.7 μg/pot) and Cd100+M (993.1 μg/pot).
Potato and beetroot were grown on soils previously treated with heavy metal salts. Each particular microelement had a high concentration in both potato and beetroot [cadmium (Cd) 3.7 and 55.4, lead (Pb) 8.1 and 3.0, and mercury (Hg) 5.8 and 6.8 mg/kg dry matter, respectively]. In a metabolic balance trial 16 New Zealand White rabbits were fed 50 grams of basal diet and potato or beetroot ad libitum. The apparent digestibility of major nutrients and the accumulation of the microelements in different organs were investigated. Both potato and beetroot samples of high Pb and Hg content had the significantly (p < 0.05) lowest digestibility of organic matter and nitrogen-free extract. The Cd ingested from both potato and beetroot accumulated in the kidneys and liver (2.85 and 1.48 as well as 0.459 and 0.265 mg/kg, respectively). All the microelements (Cd, Pb and Hg) accumulated in the testicles (0.196, 0.32 and 0.199 mg/kg, respectively), reducing the rate of spermatogenesis. The tissue retention ofheavy metals depends not only on the element itself, but also upon the ‘carrier’ feedstuff.
Carrots were grown on soils polluted by heavy metal salts. Each particular microelement reached a high concentration [molybdenum (Mo) 39.00, cadmium (Cd) 2.30, lead (Pb) 4.01, mercury (Hg) 30.00, and selenium (Se) 36.20 mg/kg dry matter] in the carrot. In a metabolic balance trial conducted with 15 male and 15 female New Zealand White rabbits, the control animals (n = 5) were fed ad libitum with concentrate as basal diet, while the other rabbits received the basal diet and carrots containing the particular microelement. Blood samples were taken to determine the activity of serum enzymes. To investigate the metabolism of Mo, Cd, Pb, Hg and Se, samples were taken from the heart, liver, lungs, kidneys, spleen, ovaries/testicles, entire digestive tract, adipose tissue, femur, hair, faeces and urine. Carrot had significantly higher digestibility for all nutrients than the rabbit concentrate. Carrot samples of high Pb content had the lowest digestibility of crude protein. The microelements differed in their rate of accumulation in the organs examined: Mo and Cd accumulated in the kidneys, Pb in the kidneys, liver, bones and lungs, Hg in the kidneys and liver, while Se in the liver, kidneys and heart. The proportions of microelements eliminated from the body either via the faeces and urine (Mo 80.18% and Se 47.41%) or via the faeces (Cd 37.86%, Pb 66.39%, Hg 64.65%) were determined. Pathohistological examination revealed that the rate of spermatogenesis was reduced in the Mo, Cd, Pb and Hg groups compared to the control. Lead, Cd and Hg intake resulted in a considerable decrease in gamma-glutamyltransferase (GGT) and in an increase of alkaline phosphatase (ALP) activity because of damages to the kidneys and bones. All experimental treatments decreased the activity of cholinesterase (CHE) because of lesions in the liver.
