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doi: 10.1002/jpln.200390023pmid: N/A
Antibiotics are highly effective, bioactive substances. As a result of their consumption, excretion, and persistence, they are disseminated mostly via excrements and enter the soils and other environmental compartments. Resulting residual concentrations in soils range from a few μg upto g kg–1 and correspond to those found for pesticides. Numerous antibiotic molecules comprise of a non‐polar core combined with polar functional moieties. Many antibiotics are amphiphilic or amphoteric and ionize. However, physicochemical properties vary widely among compounds from the various structural classes. Existing analytical methods for environmental samples often combine an extraction with acidic buffered solvents and the use of LC‐MS for determination. In soils, adsorption of antibiotics to the organic and mineral exchange sites is mostly due to charge transfer and ion interactions and not to hydrophobic partitioning. Sorption is strongly influenced by the pH of the medium and governs the mobility and transport of the antibiotics. In particular for the strongly adsorbed antibiotics, fast leaching through soils by macropore or preferential transport facilitated by dissolved soil colloids seems to be the major transport process. Antibiotics of numerous classes are photodegraded. However, on soil surfaces this process if of minor influence. Compared to this, biotransformation yields a more effective degradation and inactivation of antibiotics. However, some metabolites still comprise of an antibiotic potency. Degradation of antibiotics is hampered by fixation to the soil matrix; persisting antibiotics were already determined in soils. Effects on soil organisms are very diverse, although all antibiotics are highly bioactive. The absence of effects might in parts be due to a lack of suitable test methods. However, dose and persistence time related effects especially on soil microorganisms are often observed that might cause shifts of the microbial community. Significant effects on soil fauna were only determined for anthelmintics. Due to the antibiotic effect, resistance in soil microorganisms can be provoked by antibiotics. Additionally, the administration of antibiotics mostly causes the formation of resistant microorganisms within the treated body. Hence, resistant microorganisms reach directly the soils with contaminated excrements. When pathogens are resistant or acquire resistance from commensal microorganisms via gene transfer, humans and animals are endangered to suffer from infections that cannot be treated with pharmacotherapy. The uptake into plants even of mobile antibiotics is small. However, effects on plant growth were determined for some species and antibiotics.
Langusch, Jens‐Johann; Borken, Werner; Armbruster, Martin; Dise, Nancy B.; Matzner, Egbert
doi: 10.1002/jpln.200390024pmid: N/A
The leaching of Ca, Mg, and K from canopies is a major pathway of these cations into forest soils. Our aim was to quantify rates of canopy leaching and to identify driving factors at the regional scale using annual fluxes of bulk precipitation and throughfall from 37 coniferous and deciduous forests of North and Central Europe. Total deposition of Ca, Mg, K, and H+ was estimated with Na as an index cation. The median canopy leaching increased in the order: Mg (0.11 kmolc ha–1 a–1) < Ca (0.31 kmolc ha–1 a–1) < K (0.39 kmolc ha–1 a–1). Canopy leaching of Ca and K was positively correlated with the calculated total H+ deposition and H+ buffered in the canopy, whereas canopy leaching of Mg was not. With contrasting effects, fluxes of SO4‐S and NH4‐N in throughfall explained to 64 % (P<0.001) of the Ca canopy leaching. Fluxes of NH4‐N and Ca were negatively correlated, suggesting that buffering of H+ by NH3 deposition reduced canopy leaching of Ca. Amount of bulk precipitation and SO4‐S in throughfall were identified as much weaker driving factors for canopy leaching of K (r2=0.28, P<0.01). Our results show that Ca is the dominant cation in buffering the H+ input in the canopy. At the regional and annual scale, canopy leaching of Mg appears to be unaffected by H+ deposition and H+ buffering in the canopy.
Noguchi, Kyotaro; Ishii, Tadashi; Matsunaga, Toshiro; Kakegawa, Koichi; Hayashi, Hiroaki; Fujiwara, Toru
doi: 10.1002/jpln.200390025pmid: N/A
We examined concentrations of boron (B) and dimerization of rhamnogalacturonan II (RG‐II), a B‐binding polysaccharide, in the cell wall of a low‐B sensitive mutant of Arabidopsis thaliana, bor1‐1, to investigate possible effects of the bor1‐1 mutation on the biochemical form of pectins in the cell wall. In the bor1‐1 mutant, B concentrations in the cell wall from shoots were lower than those in the wild type at low B supply, whereas they were similar at sufficient B supply. The amount of B present as borate ester of the RG‐II dimer (dRG‐II‐B) in the bor1‐1 mutant was lower than that in the wild type at low B supply. In the wild type, about 90 % of RG‐II was present as dRG‐II‐B, both, at low and sufficient B supply. In the bor1‐1 mutant, about 60 % of RG‐II was in its monomeric form (mRG‐II) at low B supply, whereas more than 85 % of it was present as dRG‐II‐B at sufficient B supply. However, similar as the wild type, mRG‐II derived from the bor1‐1 mutant was able to form dRG‐II‐B in vitro in the presence of borate and lead. Sugar composition of cell wall fractions was similar in both genotypes. These results suggest that the polysaccharide composition in the cell wall was not strongly affected by the bor1‐1 mutation. The observed difference in dimerization of RG‐II at low B supply is most likely due to a reduced B concentration in the shoots of the bor1‐1 mutant.
Gromes, Reiner; Behrens, Sandra; Nagel, Elke
doi: 10.1002/jpln.200390026pmid: N/A
The objective of this study was to test the applicability of different reflectometric test kits for the determination of potential nitrification and the activity of invertase in soil directly in the field. For the investigation of nitrification in the field, the incubation time was reduced because a linear correlation between incubation time and nitrification rates was found. Likewise, a linear correlation between invertase activity and the incubation temperature was observed which allowed for the calculation of temperature‐dependent factors. Activity measurements in the field at lower temperatures in comparison to the standard procedure were corrected by these factors. Ten different soils were investigated for potential nitrification and invertase activity with standard methods in comparison to field tests with reflectometric detection of the reaction products. The results showed that the reflectometric test kits are suitable for the estimation of potential nitrification and invertase activity directly in the field.
Kohler, Martin; Hildebrand, Ernst E.
doi: 10.1002/jpln.200390027pmid: N/A
Ion release in the C horizon of a Skeletic Umbrisol on gneiss bedrock was investigated by percolation experiments at a water status near field capacity and with adjusted CO2 partial pressures in soil air. CO2 partial pressures of 0.001, 0.01, and 0.1 bar with pH‐values of 5.7, 4.9, and 4.5 yielded cation release rates of 3.0, 8.5, and 12.3 kmolc yr–1 ha–1 at a 1 m horizon depth and 800 mm seepage water. Within the pH range of 5.7 to 4.5, the activity of carbonic acid triggers ion release. For the treatment with a CO2 partial pressure of 0.001, the isolation of a weathering rate (0.5 kmolc yr–1 ha–1) was possible because parallel running processes such as the dissolution of solid compounds could be identified by dissolved anions, and exchange processes only modified internal ratios of mobilized basic cations. The weathering rate at a site‐typical CO2 partial pressure of 0.01 bar was about 5–10 times higher than usually assumed in the literature. There are three reasons that may account for this: (1) the consideration of actual carbonic acid activities and (2) specific site features such as the richness of basic minerals and/or the presence of a skeletal fraction with micro voids and fissures providing large internal surfaces. Furthermore, (3) it can not be completely excluded that parallel running exchange processes contribute to ion release.
Friesl, Wolfgang; Lombi, Enzo; Horak, Othmar; Wenzel, Walter W.
doi: 10.1002/jpln.200390028pmid: N/A
The effect of red mud (10 g kg–1), a by‐product of the alumina industry, zeolite (20 g kg–1), a naturally‐occurring hydrous aluminosilicate, and lime (3 g kg–1) on metal lability in soil and uptake by fescue (Festuca rubra L.) (FEST) and amaranthus (Amaranthus hybridus L.) (AMA) was investigated in four different soils from Austria. The soil collection locations were Untertiefenbach (UNT), Weyersdorf (WEY), Reisenberg (REI), and Arnoldstein (ARN). The latter was collected in the vicinity of a former Pb‐Zn smelter and was highly polluted with Pb (12300 mg kg–1), Zn (2713 mg kg–1), and Cd (19.7 mg kg–1) by long‐term deposition. The other soils were spiked with Zn (700 mg kg–1), Cu (250 mg kg–1), Ni (100 mg kg–1), V (100 mg kg–1), and Cd (7 mg kg–1) salts in 1987. The two plant species were cultivated for 15 months. Ammonium nitrate (1 M) extraction was used in a soil : solution ratio of 1:2.5 to assess the influence of the amendments on the labile metal pools. The reduction of metal extractability due to red mud was 70 % (Cd), 89 % (Zn), and 74 % (Ni) in the sandy soil (WEY). Plant uptake in this treatment was reduced by 38 to 87 % (Cd), 50 to 81 % (Zn), and 66 to 87 % (Ni) when compared to the control. Sequential extraction revealed relative enrichments of Fe‐oxide‐associated metal fractions at the expense of exchangeable metal fractions. Red mud was the only amendment that decreased lability in soil and plant uptake of Zn, Cd, and Ni consistently. Possible drawbacks of red mud application (e.g., As and Cr concentration) remain to be evaluated.
Halbfaß, Stefan; Grunewald, Karsten
doi: 10.1002/jpln.200390029pmid: N/A
In den Oberböden zweier kleiner landwirtschaftlich genutzter Einzugsgebiete wurde die räumliche Variabilität der Gehalte an Gesamtphosphor (Pt) in Abhängigkeit von der Reliefposition und der Nutzung untersucht. Bei mittleren Pt‐Gehalten von 982 mg kg–1 lagen 80 % der Werte zwischen 560 und 1530 mg kg–1. Die jeweils höchsten Gehalte wurden auf der Hangkuppe und am Hangfuß gefunden, hingegen an den Mittelhängen stets niedrigere Gehalte. Auf den Hangpositionen wurde die räumliche Variabilität durch die Relief‐ und Bodeneigenschaften verursacht, auf dem Maßstab der Einzugsgebiete vor allem durch die Bewirtschaftungsmethoden. Diese Unterschiede müssen für die Modellierung des diffusen P‐Eintrages in die Oberflächengewässer berücksichtigt werden.
Rennert, Thilo; Mansfeldt, Tim
doi: 10.1002/jpln.200390030pmid: N/A
Dissolved organic matter (DOM) in soils is partially adsorbed when passing through a soil profile. In most adsorption studies, water soluble organic matter extracted by water or dilute salt solutions is used instead of real DOM gained in situ by lysimeters or ceramic suction cups. We investigated the adsorption of DOM gained in situ from three compartments (forest floor leachate and soil solution from 20 cm (Bg horizon) and 60 cm depth (2Bg horizon)) on the corresponding clay and fine silt fractions (< 6.3 μm, separated together from the bulk soil) of the horizons Ah, Bg, and 2Bg of a forested Stagnic Gleysol by batch experiments. An aliquot of each clay and fine silt fraction was treated with H2O2 to destroy soil organic matter. Before and after the experiments, the solutions were characterized by ultra‐violet and fluorescence spectroscopy and analyzed for sulfate, chloride, nitrate, and fluoride. The highest affinity for DOM was found for the Ah samples, and the affinity decreased in the sequence Ah > Bg > 2Bg. Dissolved organic matter in the 2Bg horizon can be regarded as slightly reactive, because adsorption was low. Desorption of DOM from the subsoil samples was reflected more realistically with a non‐linear regression approach than with initial mass isotherms. The results show that the extent of DOM adsorption especially in subsoils is controlled by the composition and by the origin of the DOM used as adsorptive rather than by the mineralogical composition of the soil or by contents of soil organic matter. We recommend to use DOM gained in situ when investigating the fate of DOM in subsoils.
doi: 10.1002/jpln.200390031pmid: N/A
The long‐term measurement of soil redox potential (EH) by permanently installed Pt electrodes may be restricted by electrode breakdown (electrode rupture and resin leakage) and contamination, especially under wet and strongly reducing soil conditions. The EH of a slightly alkaline (pH 7.1 to 7.3) Calcaric Gleysol developed from marine sediment in the dyked marsh of Schleswig‐Holstein, Northern Germany, was monitored weekly during a 4‐year period using permanently installed Pt electrodes. Measurements were performed in fivefold at 10, 30, 60, 100, and 150 cm. Furthermore, water table level was recorded. Sulfide occurred in 150 cm as a heritage of the previous marine environment. Mean water table level was 84 cm below the soil surface but was characterized by both short‐term and seasonally strong fluctuations. Levels of water table ranged from 33 to >200 cm below soil surface. In consistence with water table level, the EH continually decreased with soil depth. Mean redox conditions were oxidizing at 10 (550 mV) and 30 cm (430 mV), weakly reducing at 60 cm (230 mV), and moderately reducing at 100 (120 mV) and 150 cm depth (–80 mV). Soil hydrology differed markedly during the study as expressed by periods of water saturation for each depth. This was reflected by Pt electrodes response, since period of water saturation and EH were significantly negatively correlated as calculated for each year and depth (rs = –0.971; n = 20; P < 0.01). The 60‐cm depth was most frequently influenced by water table fluctuations, showed the largest EH range (920 mV) and the most distinct seasonal pattern in EH. Good function of the electrodes in this depth can be concluded even after long time of installation in soil. Although established in a sulfide‐bearing environment, three of five electrodes at 150 cm showed a substantial increase (+500 mV) in EH during summer of the third and fourth years of investigation, which had low water tables. It is not clear whether the non‐response of two electrodes was due to electrode contamination or spatial variation in EH. When operating in reducing systems, this problem can be circumvented by installing a large number of electrodes or by a regular replacement of electrodes. Using properly constructed and permanently installed Pt electrodes, soil EH can be monitored for extended periods under wet and reducing soil conditions.
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