Search results for "Biogeochemical cycle"
showing 10 items of 101 documents
Contrasting Effects of Environmental Concentrations of Sulfonamides on Microbial Heterotrophic Activities in Freshwater Sediments
2021
The sulfonamide antibiotics sulfamethoxazole (SMX) and sulfamethazine (SMZ) are regularly detected in surface sediments of contaminated hydrosystems, with maximum concentrations that can reach tens of μg kg–1 in stream and river sediments. Little is known about the resulting effects on the exposed benthic organisms. Here we investigated the functional response of stream sediment microbial communities exposed for 4 weeks to two levels of environmentally relevant concentrations of SMX and SMZ, tested individually. To this end, we developed a laboratory channel experiment where natural stream sediments were immersed in water contaminated with nominal environmental concentrations of 500 and 5,0…
Between a rock and a soft place: the role of viruses in lithification of modern microbial mats.
2021
10 pages; International audience; Stromatolites are geobiological systems formed by complex microbial communities, and fossilized stromatolites provide a record of some of the oldest life on Earth. Microbial mats are precursors of extant stromatolites; however, the mechanisms of transition from mat to stromatolite are controversial and are still not well understood. To fully recognize the profound impact that these ecosystems have had on the evolution of the biosphere requires an understanding of modern lithification mechanisms and how they relate to the geological record. We propose here viral mechanisms in carbonate precipitation, leading to stromatolite formation, whereby viruses directl…
Functional Metabolic Diversity of Bacterioplankton in Maritime Antarctic Lakes
2021
A summer survey was conducted on the bacterioplankton communities of seven lakes from Byers Peninsula (Maritime Antarctica), differing in trophic and morphological characteristics. Predictions of the metabolic capabilities of these communities were performed with FAPROTAX using 16S rRNA sequencing data. The versatility for metabolizing carbon sources was also assessed in three of the lakes using Biolog Ecoplates. Relevant differences among lakes and within lake depths were observed. A total of 23 metabolic activities associated to the main biogeochemical cycles were foreseen, namely, carbon (11), nitrogen (4), sulfur (5), iron (2), and hydrogen (1). The aerobic metabolisms dominated, althou…
Stochastic 0-dimensional Biogeochemical Flux Model: Effect of temperature fluctuations on the dynamics of the biogeochemical properties in a marine e…
2021
Abstract We present a new stochastic model, based on a 0-dimensional version of the well known biogeochemical flux model (BFM), which allows to take into account the temperature random fluctuations present in natural systems and therefore to describe more realistically the dynamics of real marine ecosystems. The study presents a detailed analysis of the effects of randomly varying temperature on the lower trophic levels of the food web and ocean biogeochemical processes. More in detail, the temperature is described as a stochastic process driven by an additive self-correlated Gaussian noise. Varying both correlation time and intensity of the noise source, the predominance of different plank…
Biogeochemical decoupling: how, where and when?
2018
Research has dealt with coupling of chemical element cycles and feedback in recent years. Sometimes, this biogeochemical coupling is reversed through abiotic or biotic (including man-made) processes. It is then called biogeochemical decoupling and is a disconnection between two chemical elements whereby transformations of one affect cycling of the other, and results in asynchronical behavior of chemical elements. It appears to be more important and widespread than earlier reports suggest, and gives rise to important changes in element stoichiometry of resources. These changes in turn modify organismal stoichiometry that, if great enough, can affect biodiversity and food webs, thus altering …
Ecological and human health risks appraisal of metal(loid)s in agricultural soils: a review
2019
Agriculture is one of the major human activities that changed the landforms, water resources and the biogeochemical cycles. Pollution of agricultural soilsby metal(loid)s is a serious and global hazard but worldwide studies related to metal(loid)s pollution in agricultural soils are very limited. To fulfil this gap, metal(loid)s content in agricultural soils from 2001 to 2019 all over the world was reviewed. Multivariate statistical techniques, contamination indices and human health risk assessment were determined for the metal(loid)s. Among the analysed metal(loid)s, the average contents of Zn, Cu, Pb, Cr, Cd, As and Ni exceeded the Canadian, and China soil guidelines limits. The results o…
Soil Science Challenges in a New Era: A Transdisciplinary Overview of Relevant Topics
2020
Transdisciplinary approaches that provide holistic views are essential to properly understand soil processes and the importance of soil to society and will be crucial in the future to integrate distinct disciplines into soil studies. A myriad of challenges faces soil science at the beginning of the 2020s. The main aim of this overview is to assess past achievements and current challenges regarding soil threats such as ero-sion and soil contamination related to different United Nations sustainable development goals (SDGs) including (1) sustainable food production, (2) ensure healthy lives and reduce environmental risks (SDG3), (3) ensure water availability (SDG6), and (4) enhanced soil carbo…
Inclusion of a suite of weathering tracers in the cGENIE Earth system model-muffin release v.0.9.23
2021
Abstract. The metals strontium (Sr), lithium (Li), osmium (Os) and calcium (Ca), together with their isotopes, are important tracers of weathering and volcanism – primary processes which shape the long-term cycling of carbon and other biogeochemically important elements at the Earth's surface. Traditionally, because of their long residence times in the ocean, isotopic shifts in these four elements observed in the geologic record are almost exclusively interpreted with the aid of isotope-mixing, tracer-specific box models. However, such models may lack a mechanistic description of the links between the cycling of the four metals to other geochemically relevant elements, particularly carbon, …
Trace element bias in the use of CO2 vents as analogues for low pH environments: Implications for contamination levels in acidified oceans
2013
Abstract Research into the effects of ocean acidification on marine ecosystems has increasingly focused on natural CO 2 vents, although their intrinsic environmental complexity means observations from these areas may not relate exclusively to pH gradients. In order to assess trace element levels and distribution in the Levante Bay (Vulcano Island, NE Sicily, Italy) and its suitability for studying biological effects of pH decline, Ba, Fe and trace elements (As, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, V and Zn) in sediment were analysed from 7 transects. Where present, Cymodocea nodosa leaves and epiphytes were also analysed. At the spatial scale of the bay, trace element concentrations in sedim…
The Role of Fire in Achieving the Sustainable Development Goals of the United Nations
2019
The Sustainable Development Goals (SDGs) of the United Nations do not mention Fire as a key factor in achieving an environmentally-friendly human society. This paper reviews the key aspects of the impact of fire that make it necessary to update the SDGs. Upon reviewing the scientific literature, it was found that fire has been part of the Earth System for the last 400 million years, and that it is part of biogeochemical cycles. From a geological perspective, fire shaped the current Earth System. Humans have used fire in the last million years as hunter-gatherers, and the last Pleistocene period evolved with the presence of fire. Since the Neolithic revolution, humankind spread the use of fi…