Tetracycline (TC) antibiotics are one of the class of drugs widely used in clinical practice but also constitute a significant environmental concern. However, the adverse effects of TC on non-target organisms have not been well studied. The aim of this study was to examine the influence of exposure to high levels of TC on thalli of lichens to determine the impact on (1) physiological parameters including integrity of cell membranes, photosynthetic efficiency and viability, (2) oxidative stress response such as membrane lipid peroxidation, and (3) enzymatic antioxidant activities as catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR). Data demonstrated that exposure to tetracycline did not markedly affect the lichen membrane damage as indicated by no change in conductivity. This antibiotic diminished the potential photosystem II efficiency (FV/FM) indicating enhanced susceptibility as evidenced by lower chlorophyll fluorescence and chlorophyll content. The viability of lichens exposed to high concentrations of tetracycline was significantly reduced. The concentrations of thiobarbituric acid reactive substances were markedly elevated with increasing concentrations of antibiotics. At higher TC concentrations, 500 mg/L SOD activity was significantly elevated. In the case of CAT, APX and GR, TC at higher concentrations significantly decreased these enzymic activities. The findings of this study contribute to the knowledge that TC antibiotics exert adverse ecotoxicological effects on lichens at high concentrations and provided a better understanding of the mechanisms underlying toxicity. Data also indicates that lichens may serve as an effective biomonitoring species for TC antibiotic exposure.

Dryland degradation is a global problem, destabilizing ecosystems and disrupting coupled human-natural systems in arid regions. Degradation, caused by livestock grazing, wildfire, vehicles, construction, climate perturbances, and other surface disturbances, open space for invasive plants to establish while damaging soils, biological soil crusts (biocrusts), and vascular plant communities. Due to the scale of invasive plant infestations and the cost of mechanical control, invasive plants are commonly treated with herbicides, but little is known about the consequences of herbicides on biocrust. Biocrusts are communities of biota that aggregate the soil surface and provide ecosystem services, including mitigating soil erosion and fixing nitrogen, making biocrust a promising and emerging tool to counteract degradation. To test biocrust compatibility with standard herbicide treatments, we conducted a organisms (mosses and the lichens Placidium/Clavascidium and Enchylium). We found that response varied based on the herbicide mechanistic family, with the magnitude of response varying for biocrust organisms. Mosses treated with amino acid disrupters (glyphosate and imazapic) had 65-75% less health tissue area than controls after 3 months. Surprisingly, mosses treated with synthetic auxins (2,4-D and aminopyralid) had a similar or slightly greater healthy area. Blue dye and surfactants had no effect on any tested biocrust organism. This greenhouse study suggests that through careful selection of herbicides, biocrust restoration could be simultaneously used with herbicide treatments of invasive plants to improve soil health.

Thin plastic films used for packing food materials are unsafe for consumers and are not readily degradable. Single-use plastic films accumulate in the environment and cause adverse effects in the food chain. In this study, Kappaphycus alvarezii, which has the value-added polymer carrageenan, was used for developing a bioplastic film along with the plasticizer polyethylene glycol (PEG 3000). Different concentrations of seaweed were used (3%, 4% and 5% dry weight), of which 4% had a higher tensile strength than the other concentrations. The physical and mechanical properties of the developed plastic films, such as thickness, tensile strength (TS), water vapor transmission rate (WVTR), oxygen transmission rate (OTR) and color, were tested for packaging applications in the food industry. A higher concentration of seaweed increased the WVTR, and a lower concentration increased the OTR. In addition, the biodegradation of the developed bioplastic was tested using isolated deep-sea microbial consortia to meet environmental standards. A deep-sea marine microbial consortium (Bacillus paralicheniformis G1, Bacillus subtilis G2, Bacillus subtilis Z1, and Enterobacter cloacae subsp. dissolvens Z2) degrades seaweed (Kappaphycus alvarezii)-derived bioplastic under buried soil conditions. The maximum degradation (88%) in the 5% (w/v) bioplastic film was observed within 10 days of incubation.

Despite the importance of soil and surface waters freezing in permafrost landscapes, the behaviour of dissolved organic carbon (DOC), nutrients and metals during periodic freeze-thaw cycles (FTC) remains poorly known. The on-going climate warming is likely to increase the frequency of FTC in continental aquatic settings, which could modify the chemical composition of waters. In this study, we conducted 9 repetitive cycles of overnight freezing (similar to 20 degrees C) and 5 h thawing (4 degrees C) in the laboratory using representative 0.22 mu m-filtered waters from NE European permafrost peatland: leachates of vegetation and soil, and natural surface waters (depression, thermokarst lake and river). Only minor (10%). The leachates and the depression water were enriched in trace elements, whereas the thermokarst lake and the river demonstrated a decrease in concentration of Fe (similar to 39 and similar to 94%, respectively), Al (similar to 9 and similar to 85%), and Mn (similar to 10 and similar to 79%) during FTC. Overall, the observations demonstrated an increase in aliphatic low molecular weight organic matter (OM), and the precipitation of Fe, Al hydroxides and organo-mineral particles. Therefore, enhanced of frequency of FTC can favour the release of metals and toxicants from acidic OM-rich surface waters and maintain stable OM-metalscolloids in large lakes and rivers, thus regulating aquatic transport of DOC and metals from soils to the Arctic Ocean. (C) 2021 Elsevier Ltd. All rights reserved.

Forty soil and lichen samples and sixteen soil horizon samples were collected in the mining and surrounding areas of the Yamal-Nenets autonomous region (Russian Arctic). The positive matrix factorization (PMF) model was used for the source identification of PAHs. The results of the source identification showed that the mining activity was the major source of PAHs in the area, and that the mining influenced the surrounding natural area. The 5+6-ring PAHs were most abundant in the mining area. The lichen/soil (LAS) results showed that 2+3-ring and 4-ring PAHs could be transported by air and accumulated more in lichens than in the soil, while 5+6-ring PAHs accumulated more in the soil. Strong relationships between the quotient of soil/lichen (Q(SL)) and Log K-OA and Log P-L and between the quotient of lichen/histic horizon soil and K-OW were observed. In addition, hydrogeological conditions influenced the downward transport of PAHs. Particularly surprising is the discovery of the high levels of 5 + 6 rings in the permafrost table (the bottom of the active layer). One hypothesis is given that the global climate change may lead to further depth of active layer so that PAHs may migrate to the deeper permafrost. In the impact area of mining activities, the soil inventory for 5+6-ring PAHs was estimated at 0.14 +/- 0.017 tons on average. (C) 2019 Elsevier Ltd. All rights reserved.

Questions Is the macrolichen Usnea antarctica a nurse' species to Antarctic flora? Are positive plantplant interactions more frequent than negative interactions in Antarctic ecosystems? Are microclimatic modifications by cushions of U.antarctica responsible for the nurse effect? Location Two sites in Antarctica: King George Island, South Shetland (62 degrees 11S, 58 degrees 56W; 62 degrees 11S, 58 degrees 59W). Methods We evaluated the association of plant species with U.antarctica cushions by recording species growing in equivalent areas within and outside U.antarctica cushions. Additionally, we performed transplant experiments with Deschampsia antarctica individuals to assess if U.antarctica cushions enhance plant survival. In both study sites we monitored temperature, moisture and nutrient status of soil outside and within the cushions to provide insights into potential mechanisms underlying possible interactions between U.antarctica and other plant species. Results Eight out of 13 species were positively associated with cushions of the widespread lichen U.antarctica, while only one species (U.aurantiaco-atra) showed a negative association with U.antarctica. Survival of Deschampsia was enhanced when growing associated with U.antarctica cushions. Our results indicate that cushions ameliorated the extreme conditions of Antarctic islands through increased temperature and soil moisture, decreased radiation and evaporative water loss and increased nutrient availability. Conclusions The nurse effect of U.antarctica is verified. Cushions of this macrolichen may be a key component in structuring the Antarctic landscape and maintaining local species richness, and their presence might influence range expansion of other species.