Manganese as an ecological factor in salt marshes

The plant available manganese concentration (Mn²⁺) of salt-marsh sediments was compared to that of acidic and neutral soils. The mean soil-manganese concentration was higher in the top 1 cm of salt-marsh soil than in the neutral soil and comparable to that of the acidic soil (0–5 cm). A peak in the soil-manganese concentration in the upper marsh was observed one week after the spring tide but this effect was not evident in the lower marsh. Despite these differences, there was no correlation between mean manganese concentration and position on the marsh.The response to manganese of salt-marsh halophytes was studied by measuring growth and root elongation in a range of Mn²⁺ concentrations with and without sodium chloride. Although there was a differential response to manganese between salt-marsh species, manganese resistance was not related to position on the marsh. Most of the species investigated were tolerant of Mn²⁺ at concentrations higher than normally recommended for plant growth. Moreover a salt-marsh ecotype of Festuca rubra was found to have a higher manganese resistance than an inland ecotype of the same species.When sodium chloride was included in the growth medium, salt-marsh plants had a greatly increased resistance to manganese associated with a reduced uptake. This effect is reflected in the tissue-manganese concentration which was lower than in Deschampsia flexuosa although both groups of plants were exposed to a similar range of Mn²⁺ concentrations. It is concluded that sodium chloride markedly reduces the phytotoxicity of manganese in salt marshes.Nomenclature following Clapham, Tutin & Warburg (1968). Flora of the British Isles.The work was carried out while one of us (C. E. Singer) was in receipt of an SERC studentship, which is gratefully acknowledged.     

The distribution of sulphur in the muds,water and vegetation of Lake Victoria

Summary The sulphur contents of the muds, water and vegetation at the northern end of Lake Victoria have been determined. Contrary to previous assumptions it was found that the sulphur in the bottom deposits is principally in the form of organic compounds and not as sulphides. Evidence is presented which suggests that the muds are in an aerated condition. The water of the lake contains extremely small amounts of sulphur and receives a negligible quantity of this element from the rain. The soils of the islands in the lake are rocky and well-leached of sulphur except where patches of forest conserve it. Certain peculiarities were noted in the behaviour of the muds and these are to be discussed in a future paper.     

The Iron and Manganese Content of Plants present in the Natural Vegetation of the English Lake District

Estimations of iron and manganese have been made on ninety-sixspecies of plants (including fungi, mosses, ferns, and floweringplants) from a wide range of natural habitats. These plantsnormally contain more of both elements than is usual in cropplants grown on cultivated fields, probably owing to the greateracidity and humus content of the natural soils. The amount presentvaries with the individual species, the plant group, and thetype of habitat. While some species and groups tend to takeup iron or manganese selectively, both the absolute amountsand the ratio of the two elements may vary widely without apparentinjury to the plant. In general, these elements accumulate mostin aquatic plants growing on organic and anaerobic muds. Thelowest amounts are found in species characteristic of flushedbrown earths and in plants from drained acid peats. The fruitingbodies of fungi contain little of either element.     

The effect of catchment geochemistry and geomorphology on the productivity of a tropical African montane lake (Little Connemara Dam No. 3, Rhodesia)

SUMMARY. An extensive limnological study of a tropical African montane lake (Little Connemara Dam No. 3) was undertaken in 1975 to explain the discrepancy between the high nutrient content of the bottom muds and the oligotrophic status of the water column. Little Connemara Dam (No. 3) lies in a small dolerite catchment. The dolerite is strongly jointed allowing considerable water movement and it weathers easily under high rainfall. A number of homes are built in the small catchment.
The results of the study showed that the majority of the nutrients were being flushed into the lake from septic tanks via underground streams. As the dolerite weathers, large amounts of iron and manganese, but little calcium or carbonate, are released. The PO₄-P in the water column is complexed with the Fe and Mn allowing only small concentrations for use by algae. Nitrogen enters the lake mainly as particulate nitrogen but is not significantly converted to soluble combined forms of nitrogen at the low pH values (6.2—6.7) found in the lake. Bioassay experiments indicated that combined forms of nitrogen limited phytoplankton growth.     

Effect of phosphorus and zinc on the growth and phosphorus,zinc, copper,iron and manganese nutrition of rice

Summary A greenhouse experiment was conducted to study the effect of phosphorus and zinc application, in three lowland alluvial rice soils (Haplustalf) on the growth of rice and the concentration of phosphorus, zinc, copper, iron and manganese in shoots and roots. The results showed that application of phosphorus and zinc significantly increased the dry matter yield of shoots, grains and roots. Application of phosphorus caused a decrease in the concentration of zinc, copper, iron and manganese both in shoots and roots. Application of zinc also similarly lowered the concentration of phosphorus, copper and iron, but increased that of manganese in shoots and roots. The decrease in the concentration of the elements in the shoots was not due to dilution effect or to the reduced rate of translocation of the elements from the roots to tops. This has been attributed more to the changes in the availability of the elements in soil resulting from the application of phosphorus and zinc.     

Soil-dependent variability of leaf iron accumulation in transgenic tobacco overexpressing ferritin

Ferritin overexpression in transgenic plants has been recently reported to increase leaf and seed iron content. We investigated the influence of various soil conditions on this increase in leaf iron content. One control transgenic tobacco and two transgenic tobaccos overexpressing ferritin in the plastids or in the cytoplasm, respectively, were grown on five different soils, two of them being amended with sewage sludge. Although a significant increase in leaf iron concentration was measured in transgenics overexpressing ferritin grown on three out of five soils, this increase was not a general rule. On some soils, leaf iron concentration of control plants was as high as in transgenics grown on other soils. In addition, an increased phosphorus concentration in the two sewage sludge amended soils correlated with a high leaf iron concentration in control plants, similar to the one measured in ferritin transformed plants. Indeed, growing plants in vitro with various increasing phosphate concentrations revealed a direct P involvement in iron loading of control plants, at a similar level as overexpressing ferritin plants. Also, with one of the soil tested, not only iron but also manganese, zinc and cadmium, and to a much lesser extent copper, nickel and lead were found more abundantly in ferritin transformed plants than in control plants. These data indicate that the iron fortification of leaves, based on ferritin overexpression, could be limited in its biotechnological application because of its high soil dependence.     

Studies on the manganese uptake of lettuce on steam-sterilised glasshouse soils

Summary During steam sterilisation of glasshouse soils appreciable amounts of easily reducible manganese are converted into exchangeable manganese. The reverse process takes place much more gradually. As a result, manganese toxicity occurs in several crops on newly steamed soils. In the Netherlands, lettuce has been found to be particularly prone to manganese toxicity. An investigation was carried out to obtain more information about the manganese status of steamed glasshouse soils in which lettuce was used as the test crop. The following results were noted.The uptake of exchangeable manganese is easier in the lighter soils than in heavy soils. Application of iron to the soil inhibits manganese uptake by the plant, but the iron must be applied in the form of chelate. The pH has a profound effect on manganese uptake on steamed as well as on unsteamed soils. However, the relationship between the pH and the manganese content of the crop on steamed soils is different from that found on unsteamed soils.The slow rate of oxidation of manganese in steamed glasshouse soil may be explained by the fact that the oxidising bacteria are killed during the steam sterilisation process. The fixation of manganese can be accelerated appreciably by inoculating the steamed soil with manganese-oxidising bacteria.The effect on manganese uptake of five soil desinfection chemicals used in the investigation proved to be very small.The lettuce varieties used in the Netherlands show a wide variation in susceptibility to manganese toxicity. This cannot be explained by different rates of manganese uptake. It is more likely that the varietal differences are based on different levels of resistance to manganese present in the plants.     

Transformation of iron and manganese in rice soils under different moisture regimes and organic matter applications

Summary Transformation of iron and manganese under three different moisture regimes,viz continuous waterlogged (W₁), continuous saturated (W₂) and alternate waterlogged and saturated (W₃) and three levels of organic matterviz 0, 0.5 and 1.0% in all possible combinations was studied in four soils. The results showed that under waterlogged moisture regime there was a sharp increase in the content of water soluble plus exchangeable manganese accompanied by significant decrease in the content of reducible manganese in all the soils excepting the acidic soil which was very poor in active manganese content. The increase in respect of iron in similar form was, however, very small. The increase in the content of water soluble plus exchangeable manganese as well as iron under the continuous saturated and alternate waterlogged and saturated moisture regimes was always much lower as compared to that under the continuous waterlogged condition. Application of organic matter brought about an increase in the content of water soluble plus exchangeable manganese in all the soils excepting the lateritic one irrespective of moisture regimes but did not cause any change in the content of iron and manganese in insoluble complex. The content of water soluble plus exchangeable iron and of insoluble ferrous iron although recorded some increase due to organic matter application, the increase was not so marked in any of the soils.     

On the effect of ferrous sulphate on the available manganese in the soil and the uptake of manganese by the plant

Summary Application of iron as ferrous sulphate or chloride to a loam not deficient in manganese had no effect on the yield but increased the uptake of manganese even in barley which grew vigorously.In an experiment with sugar beet on two soils contrasted with regard to their available manganese supply, applications of manganese, iron and nitrogen were tested in all combinations. On the Købelev soil, not deficient in manganese, no increases in yields were obtained on addition of ferrous sulphate while increases in manganese uptake were found for all combinations of treatments except where iron was added in the presence of manganese.On the manganese deficient Faarevejle soil, significantly higher increases in yields of roots were obtained from ferrous sulphate in the presence of nitrogen than in the presence of manganese. The effect of iron in the presence of nitrogen on the yield of tops was also significant. These treatments also gave the highest increases in manganese uptake.The amounts of manganese extractable from the soils by magnesium nitrate over a range of pH 2–8 could be increased considerably by addition of ferrous sulphate.The results support the suggestion that application of ferrous sulphate to some soils has the same effect as an addition of manganese.     

Trace element budget in an African savannah ecosystem

The concentration of selected trace elements (Co, Cu, Fe, Mn, Mo, Se, and Zn) were analysed in soils, grass, bush, and tree samples from the Mole National Park, Ghana. The distribution of the essential nutrients: cobalt, copper, manganese, and selenium is controlled by bedrock geology, whereas iron, molybdenum, and zinc distribution is controlled by soil and hydrological processes. In the soils, iron, manganese, and cobalt are largely fixed in the mineral fraction while most of the copper, molybdenum, and selenium in the soils can be extracted by disodium ethylenediaminetetracetate. Copper, cobalt, and manganese appear to be preferentially concentrated in grass species while molybdenum and selenium are concentrated in browse plants. Variations in uptake exist between wet and dry seasons with all trace elements studied, except iron and manganese, showing a marked increased availability in the wet season and increased concentration in the residual fraction of the mineral and organic soils in the dry season. In the dry season the plant concentration of molybdenum and selenium decreased while copper and zine showed increased concentrations and this may be related to a lower pH of the groundwaters at this time. A budget of metal input and output in the ecosystem at Mole has been computed. From this potential dietary deficiencies in cobalt can be observed, however for other metals soil and plant concentrations are sufficient to prevent straightforward deficiencies while the concentrations of molybdenum and selenium are sufficiently low to be considered safe.     

双峰驼不同生态环境条件下组织中微量元素的分布研究

对砾石和沙质两种不同的荒漠区双峰驼组织中６种微量元素的含量及分布规律进行了研究。结果表明,Ｃｕ、Ｍｎ、Ｆｅ、Ｍｏ的丰度在肝脏最高,Ｓｅ和Ｚｎ则分别在肾脏和肌肉组织中最高。由于砾石荒漠区土壤和牧草中Ｆｅ、Ｃｕ、Ｍｏ含量极显著高于沙质荒漠区（Ｐ〈０．０１）,导致两地双峰驼肝脏和肾脏Ｃｕ含量差异极显著（Ｐ〈０．０１）．同时发现,上述两地区双峰驼组织中Ｍｎ含量显著低于其他反刍动物。     

Origin and composition of settling iron aggregates in oligotrophic Sombre Lake, Signy Island, Antarctica

Sediment traps were deployed in an oligotrophic, seasonally anoxic maritime Antarctic lake for 15 months. Immediately after the onset of the inflow in spring many iron oxyhydroxide aggregates were collected in the traps. Image analysis, scanning electron microscopy and energy dispersive X-ray analysis were used to examine the aggregates.The aggregates consisted of primary particles that persisted in the aggregates. The mean diameter of the aggregates was constant with depth. The aggregates consisted predominantly of iron, phosphorus and oxygen but calcium was also an important constituent. Significant concentrations of manganese and sodium were also detected. The molar ratio Fe:P remained constant at 4:1 as did the ratio Fe:Ca at 52:1. The concentration of iron, phosphorus and calcium in the aggregates increased with depth, whilst the concentration of manganese decreased with depth in parallel with a gradient of increasing anoxia.The stable water column formed under ice cover and the temporal and spatial data provide evidence that the Fe:P and Fe:Ca ratios are constant and characteristic of the aggregates, whilst the overall composition of the aggregates is more dynamic and dependant on redox conditions and water chemistry.     

EVALUATIONS OF THE AVAILABILITY OF SOURCES OF NITROGEN AND PHOSPHORUS FOR ALGAE1

Techniques are compared for the evaluation of nutrient sources in which the potential nutrients are in contact with algae over their entire culture period versus relatively short-term exposure tests. Different nitrogen and phosphorus compounds were shown to be utilized in darkness as well as in light and were equally available at pH 7 and 9. The availability of relatively insoluble nutrients–iron-phosphorus compounds and teeth for phosphorus, hair for nitrogen iron pyrites for iron, and marble for carbon–indicates that in many cases the equilibrium between soluble and insoluble forms allows algae to compete successfully with insoluble forms for nutrients. Apparently, factors other than mere insolubility prevent algae from obtaining available nitrogen or phosphorus from phosphate rock or lake muds. Live algae or aquatic weeds with adequate or surplus nitrogen or phosphorus were shown to not share their nutrients with nitrogen- or phosphorus-limited algae, whereas the nutrients of killed algae or aquatic weeds were readily used by nutrient-limited algae. The facts–(1) that live algae and aquatic weeds do not share their adequate or surplus nutrients with nutrient-limited algae and (2) that lake muds do not provide readily available nitrogen or phosphorus–indicate that once lake waters are stripped of available nutrients by plant production, further plant production will depend upon nutrients from continuous sources of nutrients, such as wastewater effluents.     

Nutrient metabolism (C,N, P,and Si) in the trophogenic zone of a meromictic lake

The dynamics of seston and dissolved elements in a meromictic lake with high concentrations of manganese and iron in the monimolimnion were studied through an annual cycle. This publication presents results for assimilation, sedimentation and recovery of nutrients (C, N, P, and Si) in the trophogenic zone. Phosphorus deficiency kept the productivity of the diatom dominated phytoplankton at an oligotrophic level. High concentrations of iron in influent streams and redistribution followed by precipitation of iron during periods of partial turnover removed phosphorus from the water. High concentrations of manganese and sulfate did not have the anticipated fertilizing effect, and recovery of nutrients from the depth of the lake was negligible. Mass balance calculations indicate that liberation of phosphorus from the sediments in the trophogenic zone was most important for the maintenance of primary production. 75% of carbon, 80% of nitrogen and 25% of phosphorus assimilated by the phytoplankton was mineralized in the trophogenic zone. Silica was effectively regenerated from the littoral zone during the decline of diatom blooms. Nitrogen and silica retention was 45% of the external load compared to 66% for phosphorus.Dept. of Limnology University of Oslo     

Kinetics and reactions of hydrogen sulphide in solution of flooded rice soils

Summary The sulphide-ion electrode was used to study the kinetics and reactions of free hydrogen sulphide in solution of flooded rice soils. The observed sulphide potential obeyed the Nernst equation over a range of sulphide-ion concentration from 10^-1 to 10^-19 M. Peak H₂S concentrations were lowest in neutral soils high in iron and manganese; moderately high in soils low in iron or high in organic matter; and highest in acid sulphate soil low in iron. Harmful concentrations of H₂S may be present in acid sulphate and acid soils low in iron during the first few weeks after flooding. The concentrations in acid sulphate soils can be drastically lowered by liming. There was thermodynamic evidence for the presence of FeS and ZnS in the solutions of most soils.     

Effect of algal growth on the availability of phosphorus,iron and manganese in rice soils

Summary Laboratory experiments were conducted to study the effect of algal growth on the change of (I) pH, (II) available phosphorus and (III) solubility of iron and manganese content in five waterlogged alluvial rice soils of West Bengal, India. The results showed that the algal growth initially caused an increase in the soil pH, which later declined to the original value in some of the soils. The available phosphorus content decreased upto 90 days of their growth and began to increase towards the later period of incubation. The drastic fall of water soluble plus exchaneable manganese content of the soils due to algal growth was accompanied by similar increase in reducible manganese content. No appreciable change in water soluble plus exchangeable ferrous iron content was encountered but theN-NH₄OAC(pH 3) extractable iron due to algal growth progressively decreased with the progress of the incubation period.     

Influence of soil waterlogging on subsequent plant growth and trace metal content

Summary The uptake of trace metals by two plant species (French bean and maize) has been measured on two soils subjected to various waterlogging regimes. Uptake of both manganese and iron was increased due to soil waterlogging, although reoxidation of the soil affected iron more than manganese. Zinc and copper uptake was influenced by a species factor; French bean (Phaseolus vulgaris) showed preferential uptake of zinc, whereas maize (Zea mays) took up copper preferentially. Uptake of cobalt by both species was increased due to waterlogging, following the pattern of manganese.The abilities of these species to take up trace metals from soil followed the pattern predicted by selective extraction of soil for manganese, iron and cobalt, but not for zinc and copper.     

Morphology,distribution and significance of the manganese-accumulating microorganism metallogenium in lakes

The manganese-accumulating microorganism Metallogenium is very common in the deep water and on the sediment surface in lakes of the Oslo district, southern Norway. Metallogenium accumulates manganese in its star-shaped coenobia; other trace metals are also greatly concentrated. The taxonomic position of the organism is uncertain. Sections of coenobia suggests that the encrusted parts are not enclosing living structures.In lake Nordbytjern, the occurrence of Metallogenium coincides with periods of turbulence in the lake. By sinking, the population accumulates close to the chemocline, becoming heavily encrusted. Plankton traps indicate that Metallogenium adds to the downward transport and accumulation of manganese and iron in the lake.     

Effect of artificial destratification on iron,manganese, and zinc in the water,sediments, and two species of benthic macroinvertebrates in an Oklahoma lake

Ham's Lake was destratified in the summers of 1977 and 1978 by pumping surface water to the bottom. However, an arm was prevented from mixing by a submerged dam of a former farm pond and remained stratified. The concentration of manganese in the water increased to over 5 000 µg 1^–1 in the hypolimnion of the anoxic arm in summer. Soluble manganese averaged 28% of total concentration. Total iron concentrations were relatively high in the water and sorbed iron values were extremely low in the sediments. Soluble iron averaged 12% of total concentration. Zinc values were low in the water and sediments. Chaoborus punctipennis and Chironomus riparius concentrated iron and zinc and discriminated against manganese. Concentration factors were unaffected by mixing.     

Manganese and iron interactions on their uptake and distribution in soybean (Glycine max (L.) Merr.)

Summary The uptake and distribution of iron and manganese were studied in a manganese-sensitive soybean cultivar (‘Bragg’) grown over a range of supply levels of these nutrients in solution culture. At high (90 and 275 μM) manganese levels, increasing the iron concentration in solution from 2 to 100 μM partially overcame the effects of manganese toxicity. Interactions between manganese and iron occurred for dry matter yields, rate of Mn absorption by the roots, and the proportions of manganese and iron transported to the tops. No interaction was observed for the rate of root absorption of iron. The percentage distribution of manganese in the plant top increased with increasing iron, despite a reduced rate of Mn uptake. On the other hand, iron uptake was independent of solution Mn concentration and increased with increasing solution Fe. Also more iron was retained in the roots at high Mn and/or Fe levels in solution. Concentrations of manganese and iron in roots, stems and individual leaves were affected independently by the manganese and iron supplyi.e. without any interaction occurring between the two elements. In general, the concentration in a plant part was related directly to the solution concentration. Symptoms resembling iron deficiency correlated poorly with leaf Fe concentrations whereas high levels of manganese were found in leaves displaying Mn toxicity symptoms.