Complete Genome Sequence of Methanobacterium electrotrophus Strain YSL, Isolated from Coastal Riverine Sediments

Methanobacterium electrotrophus strain YSL was isolated from enriched microbial aggregates from a coastal riverine sediment sample from Shandong Province, China. The genome of YSL was sequenced with the PacBio Sequel platform and contained three plasmids in addition to the chromosome. A total of 2,521 protein-coding genes and 58 RNA genes were predicted.

Mercury Bioaccumulation in Benthic Invertebrates: From Riverine Sediments to Higher Trophic Levels

Riverine sediments are important sites of mercury methylation and benthic invertebrates may be indicators of Hg exposure to higher organisms. From 2014 to 2018, sediments and invertebrates were collected along a mercury gradient in the Toce River (Northern Italy) and analyzed for THg and MeHg. Concentrations in invertebrates, separated according to taxon and to Functional Feeding Group, ranged from 20 to 253 µg kg−1 dry weight (d.w.) for THg, increasing from grazers (Leuctra, Baetis, Serratella) to predators (Perla). MeHg ranged from 3 to 88 µg kg−1 d.w. in biota, representing 6–53% of THg, while in sediments it was mostly below LOD (0.7 µg kg−1), accounting for ≤3.8% of THg. The Biota-Sediment Accumulation Factor (BSAF, ranging 0.2–4.6) showed an inverse relation to exposure concentrations (THg in sediments, ranging 0.014–0.403 µg kg−1 d.w.) and to organic carbon. THg in invertebrates (up to 73 µg kg−1 wet weight), i.e., at the basal levels of the aquatic trophic chain, exceeded the European Environmental Quality Standard for biota (20 µg kg−1 w.w.), posing potential risks for top predators. Concentrations in adult insects were close to those in aquatic stages, proving active mercury transfer even to terrestrial food chains.

Polycyclic Aromatic Hydrocarbons in Sediments from Typical Algae, Macrophyte Lake Bay and Adjoining River of Taihu Lake, China: Distribution, Sources, and Risk Assessment

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants in sediments and pose a serious risk for freshwater ecosystems. In this study, sediment samples from 24 sites were collected from the cyanobacterial bloom-occurring, macrophyte-growing lake bay and adjoining river of Taihu Lake. Here, the concentration levels, sources, and risk assessment of 16 priority PAHs in the surface sediments from typical algae, macrophyte lake bay and adjoining river of Taihu Lake, were investigated, and the results were compared with those of previous studies. The total PAH (ΣPAH) concentrations ranged from 4900 to 16,800 ng·g−1 in sediments of the Taihu Lake bay and from 5736.2 to 69,362.8 ng·g−1 in sediments of the adjoining river. The level of PAHs in riverine sediments was significantly higher than those of the Taihu Lake bay, and that of the Dongshan River was significantly higher than that of the Mashan River, while there was no significant difference in the concentrations of PAHs between the cyanobacterial bloom-occurring and macrophyte-growing lake zone. The results indicated petroleum contamination was dominated in the cyanobacterial bloom-occurring, macrophyte-growing lake bay, while PAHs of the riverine sediments derived from petroleum contamination and the combined combustion including wood, coal combustion, and petroleum combustion according to the identification by the molecular diagnostic ratio and principal component analysis (PCA). Sediment risk assessment based on sediment quality guidelines (SQGs) suggested that partial regions of the Taihu Lake bay were subjected to the potential ecological risk of the 3-ring and 5-ring PAHs, and there existed negative effects related to naphthalene pollutant in all survey regions. The adjoining riverine sediments showed a high ecological risk.

Exploring variations of Hexabromocyclododecane concentrations in riverine sediments along the River Medway, UK

Surface riverine sediment samples were collected along the course of the River Medway, UK between Yalding and the mouth of the estuary at 40 different sites. The samples were then...

Impact of mining on geochemical signatures of riverine sediments in adjacent ecosystems

<p>As a result of the open-cast lignite mining in Lusatia (Eastern Germany), large quantities of iron (Fe) and sulphate (SO<sub>4</sub><sup>2-</sup>) are fed into small streams discharging into the Spree river system. The study examined whether the inputs of Fe and SO<sub>4</sub><sup>2-</sup> lead to longitu­dinal and depth-dependent gradients in the riverine sediments downstream the mining region in terms of element composition and mineral formations.</p><p>We sampled the surface (upper 0-3, 3-6 cm) sediment using a gravity corer at 18 sites from the heavily mining impacted Spreewald region downstream 200 km to the Bänke at Lake Müggelsee. We also included sampling sites at a pit water purification system in Vetschau, one neutral mining lake and a reference site without mining impact. Sedi­ments were analysed for total C, N using an element analyser, for various elements (incl. Fe, S, Mn, Al, P, heavy metals) by ICP-OES after digestion with hot aqua regia. A sequential Fe-extraction from fresh sediments and XRD was performed to differenti­ate solid iron forms and other minerals, respectively.  Characteristic sediment signatures are investigated with the help of a Principal Component Analysis (18 sites, 19 parameters).</p><p>We discovered a decreasing sedimentary Fe-content in flow direction from 300 mg g-1 in Vetschau, 130 mg g-1 close to the mining region in Lübbenau down to 30 mg g-1 at Bänke near Lake Müggelsee. In contrast, the S-content increased with decreasing mining impact from 3 mg g-1 in Vetschau up to 35 mg g-1. Minimum Fe- and S-contents are similar to Bautzen reservoir as a non-mining impacted reference location with Fe 28 mg g-1 and S 4 mg g-1. The statistical analysis with the PCA revealed the longitudinal influence of mining products within Spree river. Two major groups emerge from the score plot. First, there are those samples, which are clearly influenced by mining activities. Second, there are samples, which include the reference point and samples more distant from mining, where we expect no or only minor mining impact. This separation becomes even more apparent after taking heavy metals into account. Furthermore, the Fe binding shifts from more easily reducible Fe/amorphous minerals to less easily reducible Fe/more crystalline minerals in flow direction, which probably has consequences for the microbial degradability of organic matter and the strength of the ability of Fe to bind phosphorus.  </p><p>We were able to prove that the sedimentary ele­ment composition and especially the Fe mineral characteristics are influenced by mining activities at least 100 km downstream the Spree river system, probably affecting the phosphorus availability and carbon turnover.</p>