Microbial activity and biogeochemical cycling in a nutrient-rich meromictic acid pit lake     

Katrin Wendt-Potthoff  Matthias KoschorreckMarta Diez Ercilla  Javier Sánchez España 《Limnologica》2012,42(3):175-188

Microbial activity, abundance and biomass, and biogeochemical cycling of iron, sulphur and carbon were studied in the extremely acidic (pH 2.5-4.3), meromictic, nutrient-rich pit lake Cueva de la Mora in Spain. The goal was to find out (1) if the relatively high nutrient content influenced plankton abundance in the water column and alkalinity-producing microbial processes in the sediments compared to other acid pit lakes, and (2) if sediments in the shallow, mixed and the deep, stagnant parts of the lake exhibited differences in microbial activities and geochemical sediment composition related to meromixis. We hypothesised that redox cycling was more intense in the mixed part and higher amounts of reduced components would accumulate in the stagnant part. Especially phytoplankton biomass, CO₂ production, and sulphate reduction were indeed higher than reported from typical acid pit lakes and were rather within the range of neutral or weakly acidic lakes, which can be attributed to the relatively high nutrient contents of Cueva de la Mora. Even in the monimolimnion, anaerobic processes occurred mainly in the sediments. Sediments from the mixed and stagnant parts of the lake differed markedly in their biogeochemistry. Mixolimnetic sediments showed high iron and sulphate reduction rates, and they appeared to undergo substantial recycling, as supported by reactive Fe, relation between gross sulphate reduction rate and net accumulation of reduced sulphur, and viable counts of iron and sulphur bacteria. Monimolimnetic sediments exhibited lower anaerobic microbial activities, and surprisingly they accumulated more Fe(II) than mixolimnetic sediments, but less reduced sulphur and carbon. This might be explained by a strong separation of the two water bodies, resulting in comparably less input of energy (light) and allochthonous matter into the monimolimnion. Regarding the total extent of alkalinity-generating microbial processes, their net effect is not sufficient to neutralise the lake within decades.  相似文献   

Denaturing gradient gel electrophoresis shows that bacterial communities change with mid-ocean ballast water exchange     

Akiko Tomaru  Masanobu Kawachi  Yasuwo Fukuyo 《Marine pollution bulletin》2010,60(2):299-255

Ships carry ballast water for better stability and to control trim. However, the discharge of ballast water near ports is known to transport invasive species from one coastal area to another. The exchange of ballast water on the high seas is supposed to reduce such invasions of exotic species. In this study, we used denaturing gradient gel electrophoresis (DGGE) to analyze the composition of the bacterial community in ballast water before and after such a mid-ocean exchange, and we also measured total bacterial counts. Our findings confirmed that the ballast water was replaced by the mid-ocean exchange, as indicated by the marked change in the composition of the bacterial community. There was also a significant decrease in bacterial abundance after the mid-ocean exchange. Finally, our findings support the incubation hypothesis, because the composition of the bacterial communities changed over time within the same ballast water.  相似文献   

Microbial load from animal feces at a recreational beach     

Mary E. Wright  Helena M. Solo-Gabriele  Samir Elmir  Lora E. Fleming   《Marine pollution bulletin》2009,58(11):1649-1656

The goal of this study was to quantify the microbial load (enterococci) contributed by the different animals that frequent a beach site. The highest enterococci concentrations were observed in dog feces with average levels of 3.9 × 10⁷ CFU/g; the next highest enterococci levels were observed in birds averaging 3.3 × 10⁵ CFU/g. The lowest measured levels of enterococci were observed in material collected from shrimp fecal mounds (2.0 CFU/g). A comparison of the microbial loads showed that 1 dog fecal event was equivalent to 6940 bird fecal events or 3.2 × 10⁸ shrimp fecal mounds. Comparing animal contributions to previously published numbers for human bather shedding indicates that one adult human swimmer contributes approximately the same microbial load as one bird fecal event. Given the abundance of animals observed on the beach, this study suggests that dogs are the largest contributing animal source of enterococci to the beach site.  相似文献   

Impact of the Use of Reclaimed Water on the Quality of Groundwater Resources in the Jordan Valley,Jordan     

Mustafa Al Kuisi  Taiseer Aljazzar  Thomas Rüde  Armin Margane 《洁净——土壤、空气、水》2008,36(12):1001-1014

The use of reclaimed water and its impact on groundwater quality in the middle and southern parts of the Jordan Valley are investigated. The chemical analyses indicate that nitrate and bacteriological pollution is widespread, and thus, seriously affects groundwater use. During the study, 365 water samples were collected from wells and springs to determine the water chemistry and the extent of nitrate pollution. Three hydrochemical facies are identifed, i. e., (Ca–(Mg)–Na–HCO₃), (Ca–Na–SO₄–Cl) and (Ca–Na–Cl). The change of facies is accompanied by a gradual increase in the groundwater total dissolved solids (TDS), which is mainly controlled by evaporates and carbonates dissolution in the aquifer matrix. Water analyses indicate that the shallow aquifer in the study area is affected by non‐point pollution sources, primarily from natural (manure) and chemical nitrogen (N)‐fertilizers and treated wastewater used for agriculture. The concentration of nitrate in the groundwater ranges from 10 to 355 mg/L. Considerable seasonal fluctuations in groundwater quality are observed as a consequence of agricultural practices and other factors such as annual rainfall distribution and the Zarqa River flow. The noticeable levels of total coliform and Escherichia coli in the northern part of the study area may be attributed to contamination from the urban areas, intensive livestock production, and illegal dumping of sewage. Heavy metal concentrations in all samples were found to be significantly lower than the permissible limits for drinking water standards.  相似文献   

盘锦芦苇湿地土壤微生物初步研究   总被引：7，自引：0，他引：7  

赵先丽  周广胜  周莉  吕国红  贾庆宇  谢艳兵 《气象与环境学报》2007,23(1):30-33

基于盘锦湿地生态系统野外观测站芦苇群落生长季的定位观测资料,分析了芦苇湿地土壤微生物不同层次上的比率变化。结果表明:在0—10,10—20 cm和20—30 cm的3个层次上及微生物总数中土壤的细菌所占比率最大,而且在3个层次上的比率自上至下逐渐增大;其次是放线菌,且在3个层次上的比率逐渐减少;最少的是真菌,在3个层次上相差不大接近为零,在整个微生物中所占比率为最少的。这是由于盘锦芦苇湿地的土壤偏盐碱性,有利于细菌和放线菌繁殖,抑制了真菌的繁殖;而且季节性积水导致通气状况不良也抑制了真菌的生存。在盘锦芦苇湿地土壤微生物垂直梯度的比率中,细菌垂直梯度变化比较明显,基本上是下面2个层次所占比率比表层大一些;放线菌垂直梯度变化明显,一般表层比率最大,下面2层比率较小;真菌垂直梯度上所占的比率没有明显变化,接近为零。  相似文献   

Modelling Phage−Bacteria Interaction in Micro‐Bioreactors     

《洁净——土壤、空气、水》2017,45(8)

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海洋沉积物中现存微生物化学标志物完整极性膜脂研究进展   总被引：3，自引：0，他引：3  

姚鹏  于志刚 《地球科学进展》2010,25(5):474-483

完整极性膜脂作为活的微生物细胞的化学标志物,能够反映海洋沉积物中现存微生物群落结构和生物量等信息.与生物学方法相比,完整极性膜脂分析技术具有无需培养、快速和普适性等特点.综述了海洋沉积物中细菌和古菌的细胞膜完整极性膜脂的组成特点及其在生物地球化学和微生物生态学等研究中的应用,重点评述了在生物地球化学循环中有特殊作用的微生物,如厌氧氨氧化细菌、甲烷氧化古菌、氨氧化古菌、具有四醚膜脂结构的海洋泉古菌等,或者是一些特殊生态系统,如冷泉、海底深部生物圈等研究中完整极性膜脂应用的进展.还简要介绍了完整极性膜脂的分析方法,并对其应用前景进行了展望.  相似文献   

Bacterial calcification as a possible trigger for francolite precipitation under sulfidic conditions     

Nicolas Tribovillard  Philippe RécourtAlain Trentesaux 《Comptes Rendus Geoscience》2010,342(1):27-35

Francolite (carbonate-fluor-apatite) is known to form in sediments where intense organic-matter decay occurs, but under oxic-to-suboxic conditions, because the alkalinity rise accompanying bacterial sulfate reduction (anoxic conditions) increases francolite solubility, hence preventing its supersaturation and precipitation. However, lagoonal, organic matter-rich, cryptalgal carbonates of Jurassic age located in the French Jura Mountains contain francolite that formed during early diagenesis, under anoxic-sulfidic and highly alkaline conditions. To explain this paradoxical situation, we propose the following “chain of reactions”: the presence of abundant biomass in the sediment would supply the “raw material” to the reactional system, i.e., the initial P budget, released through organic decay. The development of cryptalgal, bacterial mats at the sediment–water interface would have limited exchanges between the water column and the pore space, hampering pore water renewal and favoring the early onset of sulfate-reducing reactions. The onset of sulfate reduction would increase pore water alkalinity, potentially preventing francolite precipitation. In addition, the presence of sulfide ions would induce organic matter sulfurization, resulting in a relative pH rise. Alkalinity and pH rises would trigger the development of conditions leading to carbonate supersaturation, inducing bacterial-structure calcification. The sudden fall in alkalinity induced by early calcification would allow francolite precipitation, despite sulfidic conditions.  相似文献   

Lab tests on the biodegradation of chemically dispersed oil should consider the rapid dilution that occurs at sea     

Kenneth Lee  Tim Nedwed  Roger C. Prince  David Palandro 《Marine pollution bulletin》2013

Most crude oils spread on open water to an average thickness as low as 0.1 mm. The application of dispersants enhances the transport of oil as small droplets into the water column, and when combined with the turbulence of 1 m waves will quickly entrain oil into the top 1 m of the water column, where it rapidly dilutes to concentrations less than 100 ppm. In less than 24 h, the dispersed oil is expected to mix into the top 10 m of the water column and be diluted to concentrations well below 10 ppm, with dilution continuing as time proceeds. Over the multiple weeks that biodegradation takes place, dispersed oil concentrations are expected to be below 1 ppm. Measurements from spills and wave basin studies support these calculations. Published laboratory studies focused on the quantification of contaminant biodegradation rates have used concentrations orders of magnitude greater than this, as it was necessary to ensure the concentrations of hydrocarbons and other chemicals were higher than the detection limits of chemical analysis. However, current analytical methods can quantify individual alkanes and PAHs (and their alkyl homologues) at ppb and ppm levels. To simulate marine biodegradation of dispersed oil at dilute concentrations commonly encountered in the field, laboratory studies should be conducted at similarly low hydrocarbon concentrations.  相似文献   

Toxicological effects induced by the nanomaterials fullerene and nanosilver in the polychaeta Laeonereis acuta (Nereididae) and in the bacteria communities living at their surface     

《Marine environmental research》2013

Fullerene (nC₆₀) and nanosilver (nAg) are nanomaterials with bactericide properties. The increments in their use raise questions about their potential environmental impacts, including estuarine ones. The polychaete Laeonereis acuta (Nereididae) secretes mucus that is colonized by bacteria communities. We analyzed the antioxidant and oxidative damage responses of anterior, middle and posterior region of L. acuta and bacteria communities after nC₆₀ or nAg exposure during 24 h. Molecular analysis showed a prevalence of Vibrio genera in the communities. Bacteria biomass was lowered in worms exposed to 1.0 mg/L of nAg. nC₆₀ reduced total antioxidant capacity of bacteria from worms exposed to 0.1 mg/L. Worms anterior region presented lower antioxidant capacity after exposure to 1.0 mg nC₆₀/L, and the same was observed in the posterior region of worms exposed to 1.0 mg nAg/L. Lipid peroxidation was reduced in the anterior region of worms exposed to nC₆₀ and the opposite was observed in the posterior region.  相似文献