Prolonged simulated acid rain treatment in the subarctic: Effect on the soil respiration rate and microbial biomass   总被引：2，自引：0，他引：2  

P. Vanhala  H. Fritze  S. Neuvonen 《Biology and Fertility of Soils》1996,23(1):7-14

Humus chemistry and respiration rate, ATP, ergosterol, and muramic acid concentration as measures of chemical properties, microbial activity, biomass, and indicators of fungal and bacterial biomass were studied in a long-term acid rain experiment in the far north of Finnish Lapland. The treatments used in this study were dry control, irrigated control (spring water, pH 6), and two levels of simulated acid rain (pH 4 and pH 3). Originally (1985–1988), simulated acid rain was prepared by adding both H₂SO₄ and HNO₃ (1.9:1 by weight). In 1989 the treatments were modified as follows. In subarea 1 the treatments continued unchanged (H₂SO₄+HNO₃ in rain to pH 4 and pH 3), but in subarea 2 only H₂SO₄ was applied. The plots were sampled in 1992. The acid application affected humus chemistry by lowering the pH, cation exchange capacity, and base saturation (due to a decrease in Ca and Mg) in the treatment with H₂SO₄+HNO₃ to pH 4 (total proton load over 8 years 2.92 kmol ha^-1), whereas the microbial variables were not affected at this proton load, and only the respiration rate decreased by 20% in the strongest simulated acid rain treatment (total proton load 14.9 kmol ha^-1). The different ratios of H₂SO₄+HNO₃ in subareas 1 and 2 did not affect the results.  相似文献   

Comparison of the adsorption of maize root mucilage and polygalacturonic acid on montmorillonite homoionic to divalent lead and cadmium   总被引：1，自引：0，他引：1  

J. L. Morel  F. Andreux  L. Habib  A. Guckert 《Biology and Fertility of Soils》1987,5(1):13-17

Summary Root mucilage material (RM) was isolated from maize plants grown in the field, and its affinity to montmorillonite (M) homoionic to Pb²⁺ and Cd²⁺ was compared with that of a commercial polygalacturonic acid (PGA). Adsorption isotherms of the commercial and natural materials on the two clay systems were compared in unbuffered systems at pH 3 and pH 6. Adsorption of PGA occurred only at pH 3, and was higher on M-Pb than on M-Cd. In contrast, the adsorption of RM was higher on M-Cd than on M-Pb. Total amounts of RM adsorbed at pH 3 were about 3 times lower on M-Cd and 20 times lower on M-Pb than the respective amounts of PGA adsorbed at the same pH. Polygalacturonic acid had a high content of relatively well dissociated (pKa = 3.5) carboxylic groups, and adsorbed on the clay surface at pH values lower than its pKa. At pH 6, the dissociation of the acid groups favoured its solubility, and the metal cations were then probably displaced by ion exchange. The lower affinity of RM to the clay materials was related to its average molecular weight, which was lower than that of PGA, and to its water solubility, which was higher than that of PGA. The low pH dependence of the adsorption of RM was related to its lower carboxylic acidity and higher content in hydroxyl and amino groups.  相似文献   

Capacity of fatty acid profiles and substrate utilization patterns to describe differences in soil microbial communities associated with increased salinity or alkalinity at three locations in South Australia   总被引：17，自引：0，他引：17  

C. E. Pankhurst  S. Yu  B. G. Hawke  B. D. Harch 《Biology and Fertility of Soils》2001,33(3):204-217

 Fatty acid methyl ester (FAME) profiles, together with Biolog substrate utilization patterns, were used in conjunction with measurements of other soil chemical and microbiological properties to describe differences in soil microbial communities induced by increased salinity and alkalinity in grass/legume pastures at three sites in SE South Australia. Total ester-linked FAMEs (EL-FAMEs) and phospholipid-linked FAMEs (PL-FAMEs), were also compared for their ability to detect differences between the soil microbial communities. The level of salinity and alkalinity in affected areas of the pastures showed seasonal variation, being greater in summer than in winter. At the time of sampling for the chemical and microbiological measurements (winter) only the affected soil at site 1 was significantly saline. The affected soils at all three sites had lower organic C and total N concentrations than the corresponding non-affected soils. At site 1 microbial biomass, CO₂-C respiration and the rate of cellulose decomposition was also lower in the affected soil compared to the non-affected soil. Biomarker fatty acids present in both the EL- and PL-FAME profiles indicated a lower ratio of fungal to bacterial fatty acids in the saline affected soil at site 1. Analysis of Biolog substrate utilization patterns indicated that the bacterial community in the affected soil at site 1 utilized fewer carbon substrates and had lower functional diversity than the corresponding community in the non-affected soil. In contrast, increased alkalinity, of major importance at sites 2 and 3, had no effect on microbial biomass, the rate of cellulose decomposition or functional diversity but was associated with significant differences in the relative amounts of several fatty acids in the PL-FAME profiles indicative of a shift towards a bacterial dominated community. Despite differences in the number and relative amounts of fatty acids detected, principal component analysis of the EL- and PL-FAME profiles were equally capable of separating the affected and non-affected soils at all three sites. Redundancy analysis of the FAME data showed that organic C, microbial biomass, electrical conductivity and bicarbonate-extractable P were significantly correlated with variation in the EL-FAME profiles, whereas pH, electrical conductivity, NH₄-N, CO₂-C respiration and the microbial quotient were significantly correlated with variation in the PL-FAME profiles. Redundancy analysis of the Biolog data indicated that cation exchange capacity and bicarbonate-extractable K were significantly correlated with the variation in Biolog substrate utilization patterns. Received: 8 March 2000  相似文献   

Physiological changes and defense mechanisms induced by cadmium stress in maize   总被引：2，自引：0，他引：2  

Magda Pl  Eszter Horvth  Tibor Janda  Emil Pldi  Gabriella Szalai 《植物养料与土壤学杂志》2006,169(2):239-246

Heavy metals such as cadmium (Cd) enter the ecosystem chiefly as the result of human activities. Nowadays the heavy‐metal pollution of the soil is causing ever greater problems, exacerbated by the fact that the heavy metals accumulated in plants may, either directly or indirectly, find their way into animals and human beings. Maize is one of the world's most important crops, ranking third after wheat and rice, so the changes induced by one of the most toxic heavy metals, Cd, in maize plants is a cause of some concern. This review discusses not only the toxic symptoms caused by Cd stress, but also the tolerance mechanisms activated in the plants. Cadmium induces a number of physiological changes, such as growth inhibition, changes in the water and ion metabolism, the inhibition of photosynthesis, changes in enzyme activities, and the formation of free radicals. The synthesis and compartmentalization of phytochelatins is induced shortly after the initiation of Cd stress, while other defense mechanisms also play an important role.  相似文献   

Responses of phosphatases and arylsulfatase in soils to liming and tillage systems   总被引：1，自引：0，他引：1  

Mine Ekenler  M. A. Tabatabai 《植物养料与土壤学杂志》2003,166(3):281-290

This study was carried out to investigate the long‐term influence of lime application and tillage systems (no‐till, ridge‐till, and chisel plow) on the activities of phosphatases and arylsulfatase in soils at four research sites in Iowa, USA. The activities of the following enzymes were studied: acid and alkaline phosphatases, phosphodiesterase, and arylsulfatase at their optimal pH values. With the exception of acid phosphatase, which was significantly (P < 0.001) but negatively correlated with soil pH (r ranged from –0.65** to –0.98***), the activities of other enzymes were significantly (P < 0.001) and positively correlated with soil pH, with r values ranging from 0.65** to 0.99*** for alkaline phosphatase, from 0.79*** to 0.97*** for phosphodiesterase, and from 0.66*** to 0.97*** for arylsulfatase. The Δ activity/Δ pH values were calculated to determine the sensitivity of each enzyme to changes in soil pH. Acid phosphatase was the most sensitive and arylsulfatase the least sensitive to changes in soil pH. Activities of the enzymes were greater in the 0 – 5 cm depth samples than those in 0 – 15 cm samples under no‐till treatment. With the exception of acid phosphatase, enzyme activities were mostly significantly (P < 0.001) and positively correlated with microbial biomass C (C_mic), with r values ranging from 0.28 (not significant) to 0.83*** and with microbial biomass N (N_mic), with r values ranging from 0.31 (not significant) to 0.94***. Liming and tillage systems significantly affected the activities of some enzymes but not others, as was evident from the specific activity values (g of p‐nitrophenol released kg^–1 C_org h^–1).  相似文献   

不同环境胁迫对根系分泌有机酸的影响研究进展   总被引：10，自引：1，他引：10  

赵宽  周葆华  马万征  羊礼敏 《土壤》2016,48(2):235-240

综述了根系分泌有机酸种类、组成含量、来源、分析检测方法、影响因素及其作用。根系分泌有机酸是植物应对环境胁迫的一种适应性响应机制,在许多环境胁迫下诸如养分胁迫、水分胁迫和重金属胁迫条件下,植物通过根系释放有机酸到根际土壤中,不仅可以改变土壤的理化性质及微生物活性,还会影响土壤-植物界面的许多生理生化过程。通过深入研究不同环境胁迫对根系分泌有机酸的影响及机制,有助于更深层次地研究植物在逆境胁迫下的适应性机制。  相似文献   

Evaluation of Extraction Methods for Plant-Available Soil Cadmium to Wheat by Several Extraction Methods in Cadmium-Polluted Paddy Field     

Toshiyuki Ibaraki  Kazuhiro Kadoshige  Masaharu Murakami 《Soil Science and Plant Nutrition》2005,51(6):893-898

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Soil sensitivity due to acid and heavy metal deposition in East Central Europe     

A. M. Rautengarten  J. L. Schnoor  S. Anderberg  K. Olendrzynski  W. M. Stigliani 《Water, air, and soil pollution》1995,85(2):737-742

Simultaneous soil acidification and deposition of heavy metals is a major concern for forest and agricultural soils of the Black Triangle region of East Central Europe including southern former East Germany, northern Bohemia of the Czech Republic, and southern Poland. The objective of this project was to develop historical and future projections of acid and heavy metal deposition to soils (As, Cd, Pb, Zn) and to produce a preliminary map of soil sensitivity to cadmium pollution and uptake by crops. Ultimately, we wish to assess the relative hazard and recovery times of soils to metals deposition in the region. Emission and deposition data bases obtained from several models developed at IIASA were linked using the Geographical Information System ARC/INFO to produce soil maps of sensitivity to cadmium mobility based on metals deposition, soil type, soil texture, organic matter content, and acid deposition. RAINS 6.1 (Alcamo et al., 1990) was utilized to produce maps of acid deposition for EMEP grids (150 km x 150 km). The largest amount of acid load is deposited in southern East Germany. Sulfur deposition in that area was 10–12 gS/m²/yr in 1990, and S+N deposition exceeded 8000 eq/ha/yr. But the hot spot for metals deposition is further to the east, in the Silesia area of southern Poland. The TRACE2 trajectory model of Alcamo, Bartnicki, and Olendrzynski (1992) was used to estimate cumulative metals deposition since 1955 with scenarios to 2010. Pb has improved over Europe since 1970 when depositions in the Ruhr River Valley of West Germany exceeded 60 mg/m²/yr. But cadmium deposition in southern Poland (Katowice and Krakow) has now accumulated to 60–70 mg/m² by atmospheric deposition alone. During base case simulations from 1955–87, approximately 1.8 mg/kg Pb and 0.12 mg/kg Cd have been added to the mixed plow-layer of 30 cm. If these emissions continue indefinitely, the accumulation of metals will become problematic for agriculture and the food chain.  相似文献   

Enzyme activities and microbial community structure in semiarid agricultural soils   总被引：15，自引：0，他引：15  

Acosta-Martínez  V.  Zobeck  T. M.  Gill  T. E.  Kennedy  A. C. 《Biology and Fertility of Soils》2003,38(4):216-227

This study investigated the effect of management on -glucosidase, -glucosaminidase, alkaline phosphatase, and arylsulfatase activities and the microbial community structure in semiarid soils from West Texas, USA. Surface samples (0–5 cm) were taken from a fine sandy loam, sandy clay loam, and loam that were under continuous cotton ( Gossypium hirsutum L.) or in cotton rotated with peanut ( Arachis hypogaea L.), sorghum ( Sorghum bicolor L.), rye ( Secale cereale) or wheat ( Triticum aestivum L.), and had different water management (irrigated or dryland), and tillage (conservation or conventional). The enzyme activities were higher in the loam and sandy clay loam than in the fine sandy loam. Soil pH was not affected by management, but the soil organic C and total N contents were generally affected by the different crop rotations and tillage practices studied. The trends of the enzyme activities as affected by management depended on the soil, but in general crop rotations and conservation tillage increased the enzyme activities in comparison to continuous cotton and conventional tillage. The soil enzyme activities were significantly correlated with the soil organic C ( r -values up to 0.90, P< 0.001), and were correlated among each other ( r -values up to 0.90, P <0.001). There were differences in the fatty acid methyl ester profiles between the fine sandy loam and the sandy clay loam and loam, and they reflected the differences in the enzyme activities found among the soils. For example, a 15:0 ranged from 1.61±0.25% in cotton-peanut/irrigated/no-till in the fine sandy loam to 3.86±0.48% in cotton-sorghum/dryland/conservation tillage in the sandy clay loam. There were no differences due to management within the same soil.Trade names and company names are included for the benefit of the reader and do not infer any endorsement or preferential treatment of the product by USDA-ARS  相似文献   

Soil acidity limits colonisation by Aporrectodea trapezoides, an exotic earthworm     

Kwong-Yin Chan  John Ashley Mead 《Pedobiologia》2003,47(3):225-229

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