Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 43

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  soil acidification
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
This article was prepared on a base of program lectures and studies presented on posters as well as discussions carried out during plenary sessions and at posters. Comparing to 1980, emission and fall of sulfur (IV) oxide (SO₂) in Poland was clearly reduced, about 36%. Very high dynamics of nitrogen oxides immission can invoke an anxiety. In 1975 - 1990 those compounds fall increased about seven times. At present, the amount of nitrogen emitted with ammonia from animal production is significantly higher than that emitted with nitrogen oxides du to energetic raw materials combustion. Anthropogenic causes of soil acidification due to nitrogen fertilization was also calculated. Among analysed anthropogenic factors. SO₂ imission is the largest source of protons in a country scale, it was 52 - 55% of the total acidification contribution. The percentage nitrogen fertilization in soil acidification is 30 - 45% on the average in Poland. Since 1975 to 1992 was observed the decrease nitrogen fertilization in anthropogenic acidification share. At present, the increase of acidification due to nitrogen fertilizers is noted. Soil acidification results were most often identified with mobilizaion/immobilization of nutrients and heavy metals. Deficiencies of magnesium and phosphorus as well as excesses of aluminium and manganese symptoms were most often stated on crops in acidic soils.
6
72%
A model for estimating the precipitation of Cd-, Pb- and As-sulphide in soils at various pH is presented. pH influences not only the solubility of heavy metal-sulphides but also on the distribution of the S atom among sulphide (S²⁻, SH⁻, H₂S) and sulphate (SO₄²⁻) species by the redox potential of the soil solution. The model, based on the Nerst-equation. considers the equilibrium of protolitic processes and complex ion formation. In order to test the model, a long term field experiment polluted with different levels of toxic heavy metals on Hungarian typical soils was performed. Coarse textured soils were treated with Cd. Pb and As salts at pH = 6.8 and 8 and after 6 months and 2 years the heavy metal precipitation was investigated. The Pb ion precipitated at pH = 8.0 and pH = 6.2 while Cd ion at pH = 8. The As ion did not show precipitation effect in any soil according to the majority of arsenate ions at the actual redox potential. Although the solubility of CdS (pK = 26.1) and PbS (pk = 26.6) is similar, the Cd concentration in the solution was higher than that of Pb. The difference between the two ion concentrations is interpreted by the stronger Pb ion adsorption to organic and inorganic soil constituents. It indicated that the adsorbed and complex ion should be considered for the prediction of precipitation.
In Poland 11% of soils feature elevated zinc content or slight zinc contamination. This investigation aimed at estimation of the effect of progressive acidification of slightly zinccontaminated soils on zinc content in plants and translocation of this metal downwards the soil profile. The study involved a two-year lysimetric experiment on lessive soil. The amount of zinc indicating slight soil contamination was introduced into 0.2 m of topsoil, which was subjected to progressive acidification with sulfuric acid solution in the course of the experiment. Zinc content proved to considerably increase in plants (barley straw and maize) only under strong acidification. Soil reaction did not significantly influence the zinc content in soil, both total and assayed in HCl zinc forms, while a considerable increase in easily soluble zinc forms (in CaCl2 solution) occurred on strongly acidified soils. Considering the whole research period, increasing soil acidification did not result in any alterations involving zinc content in Bbr and C horizons of soil profiles (below 30 cm).
Polish agriculture, as distinct from the European one, has struggled with the problem of excessive soil acidification for many years. Thus, in times of strong competition on the agricultural market it is important to look for efficient and also cheap methods to ensure an improvement of acidity of Polish soils. The aim of the present study was to determine if the negative effects of acidification were of a durable nature and if these effects could be removed by single applications of relatively small doses of lime. This aim was achieved based on soil material from a long-term fertilizing experiment situated in Łyczyn, central Poland. This experiment comprises of fertilizing treatments constituting all combinations of basic nutrients used in fertilization N, P, K, Ca in only mineral fertilization system and in the system of mineral fertilization with farmyard manure (FYM). The experiment was carried out on the grey-brown podzolic soil. The chosen experimental objects were not limed since 1960 and the yields grown on these treatments were very low. As a result of a single liming, significant increase of potato, spring barley and rye yield was observed. The soil pH increase resulted in statistically proven growth of available and active phospohrus, which is evidence of the soil reserve phosphorus activation. The study results indicate that it is very easy to disturb the ion balance of sandy soil and thus reduce its productivity in unstable nutrient management conditions. On the other hand, it is possible to restore the productive value of soil with little financial input.
The Classical and other long-term experiments at Rothamsted Experimental Station illustrate the causes and effects of soil acidification. One hundred and fifty years of precipitation measurements show how atmospheric deposition has increased, causing acidification of grassland and woodland soils. Where applied, ammonium fertilisers cause very rapid acidification unless their effects are offset by the application of lime. Acidification causes the mobilisation and removal by leaching of base cations to be replaced by aluminium, manganese or iron, the reduction of base saturation and, in the long-term, the reduction of cation exchange capacity by the weathering of clay minerals. Mobilised toxic metals are taken up by vegetation growing on the acidified soils. Some plots of the Park Grass Experiment have acidified to sufficiently to cause the release of aluminium to be taken up in hay in amounts toxic to cattle - a Chemical Time Bomb.
Celem pracy było określenie aktualnych, przyrodniczych i antropogenicznych przyczyn zakwaszenia gleb użytkowanych rolniczo w Polsce. Zarządzanie odczynem ma istotne znaczenie w przemianach mineralnych składników pokarmowych roślin w glebach, a zwłaszcza ich mobilizacji/immobilizacjii i związanym z tym obiegiem pierwiastków w środowisku, a przez to produkcyjnością ekosystemów rolniczych. Po omówieniu przyrodniczych przyczyn zakwaszenia dokonano ilościowej oceny ładunku protonu w oparciu o dane z Roczników Głównego Urzędu Statystycznego dotyczące średniego zużycia nawozów mineralnych NPK i wapna nawozowego oraz emisji i depozycji gazowych zanieczyszczeń powietrza (SO2, NOx iNH3). W oparciu o te dane obliczono wielkość ładunku protonu wyrażonego w(kmol H+·ha-1). Biorąc pod uwagę fakt, że 1 mol CaO wapna nawozowego neutralizuje 2 mole protonu, obliczono zdolność neutralizacyjną dawek nawozów wapniowych stosowanych w ostatnim dwudziestoleciu. Dokonano też bilansu ładunków protonu (H+) pochodzenia antropogenicznego, który posłużył do oceny presji zakwaszania antropogenicznego agroekosystemów w ostatnich 20 latach. Zakwaszenie gleb użytkowanych rolniczo związane jest w ostatnich latach przede wszystkim z: drastycznym zmniejszeniem zużycia wapna nawozowego: z 182,8 w roku 1990 do 36,8 kg CaO·ha-1 w roku 2011, zwiększonym udziałem azotu w nawożeniu NPK, gdzie stosunek N : P : K w roku 1990 wynosił 1 : 0,59 : 0,79, a w 2011 1 : 0,37 : 0,42. Pomimo znaczącego obniżenia emisji gazowych kwasotwórczych zanieczyszczeń powietrza, głównie SO2 i NOx oraz NH3, czynniki te nadal potęgują presję zakwaszenia gleb.
In the two-year pot experiment on spring rape, spring barley, white mustard, and oats, the influence of sulphur fertilisation and liming on the content of available forms of phosphorus, potassium, and magnesium in soil was evaluated. The results received indicate that in conditions of strong acidification and lack of available sulphur, the uptake of Mg, and especially P and K used in fertilisers by the plants is limited. This is reflected in the increase in the soils richness in the available forms of these elements. The effectiveness of fertilisation with P, K, and Mg increased significantly in sites fertilised with sulphur and limed.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.