Városi szennyvíziszap-terhelés hatásának vizsgálatatenyészedény-kísérletben V.

Translated title of the contribution: Effect of communal sewage sludge in a pot experiment V.

Imre Kádár, Balázs Morvai

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The effect of communal sewage sludge on the total (estimated after digestion with cc. HNO 3 + cc. H 2O 2) and NH 4-acetate + EDTA-soluble element contents of four types of soils [acidic (Nyírlugos) and calcareous (Orbottyán) sand and acidic (Gyöngyös) and calcareous (Nagyhörcsök) clay] was examined in a pot experiment. The data of soil analysis were compared with the Ba, B, Pb, Mo, Sn, Co and As contents of the grain and straw yield of the test plant, spring barley, in order to demonstrate the concentration of these elements in the soil-plant system. For each soil, levels of 0, 2.5, 5, 10 and 20 g sludge/kg soil were tested, in terms of air-dry matter. The maximum application level was equivalent to the ploughing in of 60 t/ha air-dry matter in the field, representing a mass ratio of approx. 2%. The 5 treatments × 4 soils × 4 replications gave a total of 80 pots (10-litre plastic buckets with holes in the base). The main conclusions were as follows: - The original "total" Ba, Pb, B, Sn, Co and As contents estimated by digestion with cc. HNO 3 + cc. H 2O 2rose substantially as the soil texture became heavier. The "total" Mo content was not modified by the soil texture. The NH 4-acetate + EDTA-soluble fraction was 4-5 times greater in heavier soils in the case of Ba and Pb, while the concentrations of B, Mo and Co were an order of magnitude greater on heavier soil than on sandy soil. - The quantities of Ba, Pb, B and Mo introduced into the soil with sewage sludge treatment was clearly detectable as an increase in the "total" contents, while only 50-60% of the Sn could be detected. In the case of Ba contamination the NH 4-acetate + EDTA-soluble fraction was drastically reduced in the treated soils. It was possible to detect 30-50% of the applied Pb, B, Mo and As quantities, or their accumulation could be observed as a rise in the soluble element content of the treated soils. - The NH 4-acetate + EDTA-soluble fraction was around 25-30% of the "total" contents in the case of Pb, Mo and Co, 10-15% for Ba and B and 2-3% for As. The chemical solubility of the elements thus exhibited differences of an order of magnitude. - Barium and boron were mainly accumulated in the by-products, while molybdenum was evenly distributed between the grain and straw, with approximately equal concentrations. Sewage sludge application reduced not only the chemical solubility of Ba in the soil, but also its availability to plants. The Ba concentration in the seed yield of spring barley dropped to a third on treated soil compared to the control. The sludge contained 35% organic matter and 4.6% calcium, so in addition to an enormous addition of organic matter, the Ca-Ba cation antagonism may also have been responsible for the inhibition of Ba uptake. - The solubility of Pb, Sn, Co and As in the soil and their availability to plants were low, in line with data in the literature, so they represented little danger to the soil-plant-animal food chain, as they had little mobility in the soil-plant system. Spring barley did not become contaminated with the microelements investigated, and remained suitable for human and animal consumption. It should be noted that although the maximum rate of sludge application was an order of magnitude higher than the authorised annual Zn, Cu, Cr and Cd rates for all three years of the experiment, the yield of spring barley was 3-5 times higher than the control in the 3rd year, and no yield depression was recorded. - The "total" rise in concentration due to sludge application, expressed in terms of the transfer coefficient (Tcoeff.) or bioconcentration factor (BCF), was negative for barium, indicative of dilution. For Pb, Sn, Co and As it was below the detection limit. In the case of B the value was 0.3 in the seed and 7.7 in the by-products, while for Mo it was 6.5 in the seed and 8.2 in the by-products. The elements B and Mo can easily enter plant organs with mass flow, and their accumulation was clearly characterized by the BCF or Tcoeff. values.

Translated title of the contributionEffect of communal sewage sludge in a pot experiment V.
Original languageHungarian
Pages (from-to)343-358
Number of pages16
JournalAgrokemia es Talajtan
Volume58
Issue number2
DOIs
Publication statusPublished - Dec 1 2009

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Soil Science

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