Contributions to the ecology of halophytes: D.N. Sen and K.S. Rajpurohit (Editors), Tasks for Vegetation Science. Vol. 2, Junk,The Hague, 1982, 272 pp., US$69.50, Dfl. 165, ISBN 90-6193-942-9, ISBN 90-6193-897-X (series).

Mature tissue and particulate organic decomposition products of the submersed aquatic plant Myriophyllum heterophyllum Michx were analysed by Curie-point pyrolysis low voltage ionisation mass spectrometry. Decomposition was performed under controlled aerobic and anaerobic conditions at 10°C and 25°C for 180 days. Particulate components were analysed at 0, 2, 4, 10, 24, 48, 90 and 180-day intervals.The composition of the native plant material changed markedly during the decomposition period, as was demonstrated qualitatively and quantitatively by factor analysis of the pyrolysis mass spectrometric data.The particulate residues were characterized by increasing amounts of proteins and N-acetyl aminosugars, especially at the longer decomposition intervals.Decreasing weight loss correlated with an increasing presence of these polymers in or on the decomposing plant structural matter. This process took place faster at the higher decomposition temperatures. The anaerobic processes were more sensitive to temperature than the aerobic processes.     

Ammonia volatilization during aerobic and anaerobic manure decomposition

Ammonia volatilization, nitrogen immobilization, carbon decomposition and formation of volatile fatty acids was investigated in a laboratory incubation experiment with fresh poultry manure, to which increasing amounts of straw were added. Less than 1% of the manure nitrogen was volatilized as ammonia during anaerobic decomposition due to low pH values. In aerobic manure alkaline conditions prevailed and between 9 to 44% of the nitrogen was volatilized as ammonia. The volatilization courses could be described by a parallel first-order model. Increasing straw additions reduced ammonia volatilization during aerobic decomposition. Straw caused no immobilization of nitrogen under anaerobic conditions. In aerobic manure, nitrogen was mainly bound in organic forms whereas in anaerobic manure about two-thirds of the nitrogen was in ammonium form. C/N ratios in the organic matter of anaerobic manure were higher (33.1–87.5) than in the aerobic manure (9.5–18.0).     

Nitrogen fixation in submerged soilsand-energy material media and the aerobic-anaerobic interface

Summary Flooded soils usually consist of a surface aerobic phase a few millimeters thick (in contact with the atmosphere or oxygenated solution) underlain by an anaerobic phase. The objective of this research was to study nitrogen fixation in the aerobic-anaerobic interfacial area in flooded, cellulose enriched media and the utilization of the products of anaerobic decomposition of cellulose by nitrogen-fixing organisms when these products are brought under aerobic conditions by processes such as diffusion, mixing, and drying. The medium used for these studies was basically a sand matrix supplemented with a small amount of soil and mineral nutrients. When columns of medium enriched with cellulose were sectioned after incubation in the dark under flooded conditions, the increase in content of nitrogen per gram medium in the top 2 to 3 mm of the column was as much as 10 to 15 times the increase in nitrogen content of the lower portions of the column. Periodic mixing of flooded media, alternation of shaking in nitrogen and air atmospheres, and alternate flooding and drying all enhanced fixation relative to undisturbed, continuously flooded media incubated in air. Fixation during incubation under a nitrogen atmosphere was less than fixation under air atmospheres. The results of numerous experiments are consistent with the hypothesis that nitrogen fixation is enhanced when the products of anaerobic decomposition of cellulose are brought under aerobic conditions by any of several processes. Portions of a Ph.D. thesis submitted by the senior author. For more details refer to: Magdoff, F. R. Nitrogen fixation in submerged soil-sand-energy material media and the aerobic-anaerobic interface. Unpublished Ph.D. thesis. Cornell University Library. Ithaca, New York, 1969. Agronomy Department Paper No. 868.     

Grazing-induced changes in plant composition affect litter quality and nutrient cycling in flooding Pampa grasslands

Changes in plant community composition induced by vertebrate grazers have been found to either accelerate or slow C and nutrient cycling in soil. This variation may reflect the differential effects of grazing-promoted (G+) plant species on overall litter quality and decomposition processes. Further, site conditions associated with prior grazing history are expected to influence litter decay and nutrient turnover. We studied how grazing-induced changes in plant life forms and species identity modified the quality of litter inputs to soil, decomposition rate and nutrient release in a flooding Pampa grassland, Argentina. Litter from G+ forbs and grasses (two species each) and grazing-reduced (G−) grasses (two species) was incubated in long-term grazed and ungrazed sites. G+ species, overall, showed higher rates of decomposition and N and P release from litter. However, this pattern was primarily driven by the low-growing, high litter-quality forbs included among G+ species. Forbs decomposed and released nutrients faster than either G+ or G− grasses. While no consistent differences between G+ and G− grasses were observed, patterns of grass litter decay and nutrient release corresponded with interspecific differences in phenology and photosynthetic pathway. Litter decomposition, N release and soil N availability were higher in the grazed site, irrespective of species litter type. Our results contradict the notion that grazing, by reducing more palatable species and promoting less palatable ones, should decrease nutrient cycling from litter. Plant tissue quality and palatability may not unequivocally link patterns of grazing resistance and litter decomposability within a community, especially where grazing causes major shifts in life form composition. Thus, plant functional groups defined by species’ “responses” to grazing may only partially overlap with functional groups based on species “effects” on C and nutrient cycling.     

Invasive forbs differ functionally from native graminoids, but are similar to native forbs

? Exotic plant invasions can alter ecosystem processes, particularly if the invasive species are functionally different from native species. We investigated whether such alterations can be explained by differences in functional traits between native and invasive plants of the same functional group or by differences in functional group affiliation. ? We compared six invasive forbs in Europe with six native forbs and six native graminoids in leaf and whole-plant traits, plasticity in response to nutrient supply and interspecific competition, litter decomposition rate, effects on soil nutrient availability, and allelopathy. All traits were measured in a series of pot experiments, and leaf traits additionally in the field. ? Invasive forbs differed from native forbs for only a few traits; they had less leaf chlorophyll and lower phosphorus (P) uptake from soil, but they tended to have a stronger allelopathic effect. The invasive forbs differed in many traits from the native graminoids, their leaves had lower tissue densities and a shorter life span, their litter decomposed faster and they had a lower nitrogen-use efficiency. ? Our results suggest that invasive forbs have the potential to alter ecosystem properties when invading graminoid-dominated and displacing native graminoids but not when displacing native forbs.     

Plant identity influences decomposition through more than one mechanism

Plant litter decomposition is a critical ecosystem process representing a major pathway for carbon flux, but little is known about how it is affected by changes in plant composition and diversity. Single plant functional groups (graminoids, legumes, non-leguminous forbs) were removed from a grassland in northern Canada to examine the impacts of functional group identity on decomposition. Removals were conducted within two different environmental contexts (fertilization and fungicide application) to examine the context-dependency of these identity effects. We examined two different mechanisms by which the loss of plant functional groups may impact decomposition: effects of the living plant community on the decomposition microenvironment, and changes in the species composition of the decomposing litter, as well as the interaction between these mechanisms. We show that the identity of the plant functional group removed affects decomposition through both mechanisms. Removal of both graminoids and forbs slowed decomposition through changes in the decomposition microenvironment. We found non-additive effects of litter mixing, with both the direction and identity of the functional group responsible depending on year; in 2004 graminoids positively influenced decomposition whereas in 2006 forbs negatively influenced decomposition rate. Although these two mechanisms act independently, their effects may be additive if both mechanisms are considered simultaneously. It is essential to understand the variety of mechanisms through which even a single ecosystem property is affected if we are to predict the future consequences of biodiversity loss.     

Plant community and tissue chemistry responses to fertilizer and litter nutrient manipulations in a temperate grassland

Human-mediated nutrient amendments have widespread effects on plant communities. One of the major consequences has been the loss of species diversity under increased nutrient inputs. The loss of species can be functional group dependent with certain functional groups being more prone to decline than others. We present results from the sixth year of a long-term fertilization and litter manipulation study in an old-field grassland. We measured plant tissue chemistry (C:N ratio) to understand the role of plant physiological responses in the increase or decline of functional groups under nutrient manipulations. Fertilized plots had significantly more total aboveground biomass and live biomass than unfertilized plots, which was largely due to greater productivity by exotic C₃ grasses. We found that both fertilization and litter treatments affected plant species richness. Species richness was lower on plots that were fertilized or had litter intact; species losses were primarily from forbs and non-Poaceae graminoids. C₃ grasses and forbs had lower C:N ratios under fertilization with forbs having marginally greater %N responses to fertilization than grasses. Tissue chemistry in the C₃ grasses also varied depending on tissue type with reproductive tillers having higher C:N ratios than vegetative tillers. Although forbs had greater tissue chemistry responses to fertilization, they did not have a similar positive response in productivity and the number of forb species is decreasing on our experimental plots. Overall, differential nutrient uptake and use among functional groups influenced biomass production and species interactions, favoring exotic C₃ grasses and leading to their dominance. These data suggest functional groups may differ in their responses to anthropogenic nutrient amendments, ultimately influencing plant community composition.     

Decomposition of humic acids by incubation in a soil water-extract under various conditions of oxygen availability

Summary Decomposition of humic acids suspended in a soil water-extract under various conditions of oxygen availability (aerobic, anaerobic, alternating aerobic/anaerobic) led to the formation of fulvic acids, lower molecular weight compounds, and humin, a more complex mixture of insoluble compounds. The transformation of humic acids and formation of new humic compounds were higher under aerobic conditions than under either anaerobic or alternating aerobic/anaerobic ones.Although subjected to decomposition under greatly differing conditions of oxygen availability, the residual humic acids showed essentially the same types of chemical alterations, an increase of functional groups containing oxygen and a decrease of hydrolysable ternary and quarternary fractions.     

The faunal role in the degradation of the common intertidal salt marsh plant <Emphasis Type="Italic">Scirpus maritimus</Emphasis>

The aim of this work was to evaluate the role of different environmental conditions (oxic and anoxic), and the presence of macrofauna and/or meiofauna during the different steps of Scirpus maritimus L. decomposition/mineralization under controlled laboratory conditions. The results showed no significant differences between the anaerobic and the aerobic degradation of plant material, under the presence of bacteria or meiofauna. Nevertheless, under anoxic conditions sediment mineralization was enhanced, with an increase concentration of phosphorus and ammonium in the water phase. Concerning the presence of fauna, results show that, although bacterial activity was responsible for 70% of the S. maritimus leaves degradation, the presence of macrofauna together with meiofauna enhanced the leaves mineralization up to 90%. Moreover, the presence of macrofauna together with meiofauna significantly affected the decomposition of phosphorus and of nitrogen, as well as the leaves lesser labile structural parts, by increasing the mineralization of plant carbon, and raised the nutrient turnover within the system.The present study reinforces the functional link between fauna levels on the nutrient dynamics in salt marshes ecosystems, namely at the vegetation detritus/water column interface. Handling editor: S. M. Thomaz     

Linking nitrogen partitioning and species abundance to invasion resistance in the Great Basin

Resource partitioning has been suggested as an important mechanism of invasion resistance. The relative importance of resource partitioning for invasion resistance, however, may depend on how species abundance is distributed in the plant community. This study had two objectives. First, we quantified the degree to which one resource, nitrogen (N), is partitioned by time, depth and chemical form among coexisting species from different functional groups by injecting ¹⁵N into soils around the study species three times during the growing season, at two soil depths and as two chemical forms. A watering treatment also was applied to evaluate the impact of soil water content on N partitioning. Second, we examined the degree to which native functional groups contributed to invasion resistance by seeding a non-native annual grass into plots where bunchgrasses, perennial forbs or annual forbs had been removed. Bunchgrasses and forbs differed in timing, depth and chemical form of N capture, and these patterns of N partitioning were not affected by soil water content. However, when we incorporated abundance (biomass) with these relative measures of N capture to determine N sequestration by the community there was no evidence suggesting that functional groups partitioned different soil N pools. Instead, dominant bunchgrasses acquired the most N from all soil N pools. Consistent with these findings we also found that bunchgrasses were the only functional group that inhibited annual grass establishment. At natural levels of species abundance, N partitioning may facilitate coexistence but may not necessarily contribute to N sequestration and invasion resistance by the plant community. This suggests that a general mechanism of invasion resistance may not be expected across systems. Instead, the key mechanism of invasion resistance within a system may depend on trait variation among coexisting species and on how species abundance is distributed in the system.     

Hierarchical responses of plant stoichiometry to phosphorus addition in an alpine meadow Community北大核心CSCD

Aims Terrestrial carbon (C), nitrogen (N), phosphorus (P) stoichiometry will reflect the effects of adjustment to local growth conditions as well as species' replacements. However, it remains unclear about the hierarchical responses of plant C:N:P to P addition at levels of species and functional groups in the N-limited alpine meadow. Methods A field experiment of P enrichment was conducted in an alpine meadow on the Qinghai-Xizang Plateau during 2009-2013. The stoichiometric patterns of four functional groups (grass, sedge, legume and forb) and five representative species, Elymus nutans (grass), Kobresia humilis (sedge), Oxytropis ochrocephala (legume), Taraxacum lugubre (rosette forb), Geranium pylzowianum (upright forb) were investigated in 2013, and the effects of P addition on species dominance and plant biomass were also analyzed. Important findings Both plant nutrition content and C:N:P varied significantly after five years' P addition, and the responses were consistent at species-And functional group (exemplar species excluded)-levels in the alpine meadow. P addition had neutral effect on C concentrations of grasses, sedges and forbs at both species-And functional group (exemplar species excluded)-levels. P fertilization increased plant P concentrations and thus decreased C:P and N:P of the four functional groups (exemplar species excluded) and the corresponding species. N concentrations significantly decreased and C:N increased in grasses and sedges after P addition, and the species-level responses were consistent with the functional group (exemplar species excluded) level. P addition significantly increased N contents and decreased C:N in Oxytropis ochrocephala, but had neutral effect on N contents and C:N at the functional group (exemplar species excluded) level of the legumes. While N contents and C:N in forbs responded to P addition differently at species and functional group (exemplar species excluded) levels. In the N-limited alpine meadow, species dominance of grasses increased gradually after P addition due to the increased N and P use efficiencies, while the biomass proportion of forbs decreased because of the lowered nutrition use efficiency. © 2018 Editorial Office of Chinese Journal of Plant Ecology. All rights reserved.     

Litter quality and nutrient cycling affected by grazing-induced species replacements along a precipitation gradient

One of the potential mechanisms for the impact of herbivores on nutrient cycling is the effect of selective grazing on litter quality through changes in species composition. However, the scarce evidence collected on this mechanism is controversial and seemingly influenced by site-specific variables. In this paper, we explored the consequences of grazing-induced changes in species composition on litter quality and nitrogen cycling with a regional perspective. Along a 900-mm of mean annual rainfall gradient, we selected species promoted and diminished by grazing from three natural rangelands of Argentina, analyzed their litter quality, and determined their decomposition and nutrient release kinetics under common greenhouse conditions. Litter quality and decomposition rates were strongly associated with plant response to grazing. However, the magnitude and direction of these differences depended on the ecosystem considered. In the wettest site, the species promoted by grazing (forbs) had higher nitrogen and phosphorus contents, faster decomposition rates, and higher release of nitrogen to the soil than species diminished by grazing (C₃ and C₄ grasses). In the intermediate and dry sites, species promoted by grazing had lower nitrogen and phosphorus contents, and slower decomposition rates than those diminished by grazing (C₃ grasses in both cases). Decomposition of the entire group of species was not correlated with mean annual rainfall, but when litter of the species diminished by grazing was analyzed, it was negatively correlated with precipitation. Nitrogen was immobilized more often than mineralized, even after one year of incubation. Immobilization was negatively correlated with precipitation. All these results indicate that grazing may significantly alter nutrient cycling by affecting litter quality through changes in species composition. These effects seem to be larger when species replacements induced by grazing either involve functional groups, as it was the case in our wettest site, or change root to shoot ratios. Therefore, the functional groups involved in the replacement of species as well as shifts between belowground and aboveground allocation should play a key role in grazing-induced changes on nitrogen cycling.     

去除干扰对内蒙古典型草原植物叶片功能属性的影响

以内蒙古典型草原为研究对象,选取放牧和割草、去除放牧、去除放牧和割草样地进行群落调查和叶片属性测量,比较分析各样地土壤性质、群落生产力及主要物种的比叶面积(SLA,Specific Leaf Area)、叶片干物质含量(LDMC,Leaf Dry Matter Content)、叶片氮含量(LNC,Leaf Nitrogen Concentration)在个体、功能群和群落水平对去除干扰的响应。结果表明,1)去除干扰处理在短期对土壤特性和群落生产力的影响不显著;2)多数物种在放牧和割草样地SLA较低,说明典型草原多数物种的SLA表现为放牧逃避;3)不同功能群植物叶片属性对去除干扰的响应不一致,去除放牧后,多年生杂类草的SLA和LDMC不受影响,但LNC变小;多年生禾草的SLA增加,而LDMC和LNC无显著变化。一年生植物在去除放牧和割草后,LNC显著增加。去除割草后,多年生禾草SLA减小,而多年生杂类草SLA、LNC增加,LDMC减小;4)在群落水平,放牧和割草样地由于较占优势的多年生禾草SLA较低,群落比叶面积最低,在去除放牧和割草样地,群落叶片氮含量显著增加;5)在内蒙古典型草原,LDMC能够很好地将多年生禾草和多年生杂类草区分,SLA在个体、功能群和群落水平均比LDMC敏感。     

An experimental test of the effect of plant functional group diversity on arthropod diversity

Characteristics used to categorize plant species into functional groups for their effects on ecosystem functioning may also be relevant to higher trophic levels. In addition, plant and consumer diversity should be positively related because more diverse plant communities offer a greater variety of resources for the consumers. Thus, the functional group composition and richness of a plant community may affect the composition and diversity of the herbivores and even higher trophic levels associated with that community. We tested this hypothesis by sampling arthropods with a vacuum sampler (34 531 individuals of 494 species) from an experiment in which we manipulated plant functional group richness and composition. Plant manipulations included all combinations of three functional groups (forbs, C₃ graminoids, and C₄ graminoids) removed zero, one, or two at a time from grassland plots at Cedar Creek Natural History Area, MN. Although total arthropod species richness was unrelated to plant functional group richness or composition, the species richness of some arthropod orders was affected by plant functional group composition. Two plant characteristics explained most of the effects of plant functional groups on arthropod species richness. Nutritional quality, a characteristic related to ecosystem functioning, and taxonomic diversity, a characteristic not used to designate plant functional groups, seemed to affect arthropod species richness both directly and indirectly. Thus, plant functional groups designated for their effects on ecosystem processes will only be partially relevant to consumer diversity and abundance.     

Comparison of aerobic and anaerobic degradation of municipal solid waste in bioreactor landfills

Two landfill bioreactors were operated under aerobic and anaerobic conditions in a thermo-insulated room at a constant temperature of 32 °C. Reactors were filled with 19.5 kg of shredded synthetic solid waste prepared according to the average municipal solid waste compositions determined in Istanbul and operated under wet-tomb management strategy by using leachate recirculation. Aerobic conditions in the reactor were developed by using an air compressor. The results of experiments indicated that aerobic reactor had higher organic, nitrogen, phosphorus and alkali metal removal efficiencies than the anaerobic one. Furthermore, stabilization time considerably decreased when using aerobic processes with leachate recirculation compared to the anaerobic system with the same recirculation scheme.     

Utilization of nitrate abolishes the “Custers effect” in Dekkera bruxellensis and determines a different pattern of fermentation products

Nitrate is one of the most abundant nitrogen sources in nature. Several yeast species have been shown to be able to assimilate nitrate and nitrite, but the metabolic pathway has been studied in very few of them. Dekkera bruxellensis can use nitrate as sole nitrogen source and this metabolic characteristic can render D. bruxellensis able to overcome S. cerevisiae populations in industrial bioethanol fermentations. In order to better characterize how nitrate utilization affects carbon metabolism and the yields of the fermentation products, we investigated this trait in defined media under well-controlled aerobic and anaerobic conditions. Our experiments showed that in D. bruxellensis, utilization of nitrate determines a different pattern of fermentation products. Acetic acid, instead of ethanol, became in fact the main product of glucose metabolism under aerobic conditions. We have also demonstrated that under anaerobic conditions, nitrate assimilation abolishes the “Custers effect”, in this way improving its fermentative metabolism. This can offer a new strategy, besides aeration, to sustain growth and ethanol production for the employment of this yeast in industrial processes.     

Plant diversity effects on soil heterotrophic activity in experimental grassland ecosystems

The loss of plant species from terrestrial ecosystems may cause changes in soil decomposer communities and in decomposition of organic material with potential further consequences for other ecosystem processes. This was tested in experimental communities of 1, 2, 4, 8, 32 plant species and of 1, 2 or 3 functional groups (grasses, legumes and non-leguminous forbs). As plant species richness was reduced from the highest species richness to monocultures, mean aboveground plant biomass decreased by 150%, but microbial biomass (measured by substrate induced respiration) decreased by only 15% (P = 0.05). Irrespective of plant species richness, the absence of legumes (across diversity levels) caused microbial biomass to decrease by 15% (P = 0.02). No effect of plant species richness or composition was detected on the microbial metabolic quotient (qCO₂) and no plant species richness effect was found on feeding activity of the mesofauna (assessed with a bait-lamina-test). Decomposition of cellulose and birchwood sticks was also not affected by plant species richness, but when legumes were absent, cellulose samples were decomposed more slowly (16% in 1996, 27% in 1997, P = 0.006). A significant decrease in earthworm population density of 63% and in total earthworm biomass by 84% was the single most prominent response to the reduction of plant species richness, largely due to a 50% reduction in biomass of the dominant `anecic' earthworms. Voles (Arvicola terrestris L.) also had a clear preference for high-diversity plots. Soil moisture during the growing season was unaffected by plant species richness or the number of functional groups present. In contrast, soil temperature was 2 K higher in monocultures compared with the most diverse mixtures on a bright day at peak season. We conclude that the lower abundance and activity of decomposers with reduced plant species richness was related to altered substrate quantity, a signal which is not reflected in rates of decomposition of standard test material. The presence of nitrogen fixers seemed to be the most important component of the plant diversity manipulation for soil heterotrophs. The reduction in plant biomass due to the simulated loss of plant species had more pronounced effects on voles and earthworms than on microbes, suggesting that higher trophic levels are more strongly affected than lower trophic levels.     

The Role of Nitrogen Deposition in Widespread Plant Community Change Across Semi-natural Habitats

Experimental studies have shown that deposition of reactive nitrogen is an important driver of plant community change, however, most of these experiments are of short duration with unrealistic treatments, and conducted in regions with elevated ambient deposition. Studies of spatial gradients of pollution can complement experimental data and indicate whether the potential impacts demonstrated by experiments are actually occurring in the ‘real world’. However, targeted surveys exist for only a very few habitats and are not readily comparable. In a coordinated campaign, we determined the species richness and plant community composition of five widespread, semi-natural habitats across Great Britain in sites stratified along gradients of climate and pollution, and related these ecological parameters to major drivers of biodiversity, including climate, pollution deposition, and local edaphic factors. In every habitat, we found reduced species richness and changed species composition associated with higher nitrogen deposition, with remarkable consistency in relative species loss across ecosystem types. Whereas the diversity of mosses, lichens, forbs, and graminoids declines with N deposition in different habitats, the cover of graminoids generally increases. Considered alongside previous experimental studies and survey work, our results provide a compelling argument that nitrogen deposition is a widespread and pervasive threat to terrestrial ecosystems.     

青藏高原高寒沼泽湿地在退化梯度上植物群落组成的改变对湿地水分状况的影响

对青藏高原东缘玛曲高寒沼泽湿地分属于15科的47种主要植物进行光合测定, 结合对不同退化类型植物群落的样方调查, 分析了各种植物之间以及不同功能群之间的净光合速率、气孔导度、蒸腾速率和水分利用效率等光合参数的差异。结果表明: 1)玛曲高寒湿地的主要物种在净光合速率、气孔导度、蒸腾速率和水分利用效率4个光合特性参数上的差异显著, 表明各植物种以各自独特的方式适应高寒湿地环境; 在功能群水平上, 各功能群之间的差异亦显著。光合速率从大到小依次为禾草>莎草>豆科和其他双子叶类杂草, 水分利用效率则是莎草>禾草>豆科和其他双子叶类杂草; 2)湿地退化导致其群落组成发生明显改变, 其中最明显的特点是双子叶类杂草的比例大大增加; 而双子叶类杂草普遍较低的水分利用效率将会增大土壤水分通过光合作用的蒸腾散失, 在大气降水对水分补充变化不大的条件下, 这将会进一步加剧群落生境的干旱化, 不利于退化湿地的恢复和附近湿地的保护。研究结果表明, 在湿地保护和退化湿地恢复过程中, 典型湿地土著物种的保存和补充具有重要意义。     

Microbial destruction of cyanide wastes in gold mining: process review

Microbial destruction of cyanide and its related compounds is one of the most important biotechnologies to emerge in the last two decades for treating process and tailings solutions at precious metals mining operations. Hundreds of plant and microbial species (bacteria, fungi and algae) can detoxify cyanide quickly to environmentally acceptable levels and into less harmful by-products. Full-scale bacterial processes have been used effectively for many years in commercial applications in North America. Several species of bacteria can convert cyanide under both aerobic and anaerobic conditions using it as a primary source of nitrogen and carbon. Other organisms are capable of oxidizing the cyanide related compounds of thiocyanate and ammonia under varying conditions of pH, temperature, nutrient levels, oxygen, and metal concentrations. This paper presents an overview of the destruction of cyanide in mining related solutions by microbial processes.