Humic Polyelectrolytes Facilitate Rapid Microwave Synthesis of Silver Nanoparticles Suitable for Wound-Healing Applications.

This article describes the one-pot microwave synthesis of silver nanoparticles (AgNPs) assisted with natural polyelectrolytes-humic substances (HS). The humic polyelectrolytes served both as chemical reductants for silver ions and as end-capping agents for AgNPs. Three commercially available sodium humates extracted from lignites and leonardite and one sodium fulvate isolated from natural brown water seeped through peat deposits were used in this study. The dynamics of the growth rate of AgNPs was characterised by UV-VIS spectroscopy by measuring the intensity of surface plasmon resonance at 420 nm. Transmission electron microscopy was used to characterise the size and morphology of AgNPs. Dynamic light scattering was used to determine size distributions of the synthesised AgNPs in the solutions. It was established that both conventional and microwave syntheses assisted with the coal humates produced small-size AgNPs in the range from 4 to 14 nm, with the maximum share of particles with sizes of (6 ± 2) nm by TEM estimates. The peat fulvate yielded much larger NPs with sizes from 10 to 50 nm by TEM estimates. DLS measurements revealed multimodal distributions of AgNPs stabilised with HS, which included both single NPs with the sizes from 5 to 15 nm, as well as their dominating aggregates with sizes from 20 to 200 nm and a smaller portion of extra-large aggregates up to 1000 nm. The given aggregates were loosely bound by humic polyelectrolyte, which prevented the coalescence of AgNPs into larger particles, as can be seen in the TEM images. The significant acceleration in the reaction time-a factor of 60 to 70-was achieved with the use of MW irradiation: from 240 min down to 210-240 s. The coal humate stabilised AgNPs showed antimicrobial properties in relation to S. aureus. A conclusion was made regarding the substantial advantages of microwave synthesis in the context of time and scaling up for the large-scale production of AgNP-HS preparations with antimicrobial properties suitable for external wound-healing applications.

Enhanced Antioxidant Activity and Reduced Cytotoxicity of Silver Nanoparticles Stabilized by Different Humic Materials.

The current article describes the biological activity of new biomaterials combining the "green" properties of humic substances (HSs) and silver nanoparticles. The aim is to investigate the antioxidant activity (AOA) of HS matrices (macroligands) and AgNPs stabilized with humic macroligands (HS-AgNPs). The unique chemical feature of HSs makes them very promising ligands (matrices) for AgNP stabilization. HSs have previously been shown to exert many pharmacological effects mediated by their AOA. AgNPs stabilized with HS showed a pronounced ability to bind to reactive oxygen species (ROS) in the test with ABTS. Also, higher AOA was observed for HS-AgNPs as compared to the HS matrices. In vitro cytotoxicity studies have shown that the stabilization of AgNPs with the HS matrices reduces the cytotoxicity of AgNPs. As a result of in vitro experiments with the use of 2,7-dichlorodihydrofluorescein diacetate (DCFDA), it was found that all HS materials tested and the HS-AgNPs did not exhibit prooxidant effects. Moreover, more pronounced AOA was shown for HS-AgNP samples as compared to the original HS matrices. Two putative mechanisms of the pronounced AOA of the tested compositions are proposed: firstly, the pronounced ability of HSs to inactivate ROS and, secondly, the large surface area and surface-to-volume ratio of HS-AgNPs, which facilitate electron transfer and mitigate kinetic barriers to the reduction reaction. As a result, the antioxidant properties of the tested HS-AgNPs might be of particular interest for biomedical applications aimed at inhibiting the growth of bacteria and viruses and the healing of purulent wounds.

Yedoma Permafrost Releases Organic Matter with Lesser Affinity for Cu2+ and Ni2+ as Compared to Peat from the Non-Permafrost Area: Risk of Rising Toxicity of Potentially Toxic Elements in the Arctic Ocean.

Pollution of the Arctic Ocean by potentially toxic elements (PTEs) is a current environmental problem. Humic acids (HAs) play an important role in the regulation of PTE mobility in soil and water. The permafrost thaw releases ancient organic matter (OM) with a specific molecular composition into the Arctic watersheds. This could affect the mobility of PTEs in the region. In our study, we isolated HAs from two types of permafrost deposits: the Yedoma ice complex, which contains pristine buried OM, and the alas formed in the course of multiple thaw-refreezing cycles with the most altered OM. We also used peat from the non-permafrost region as the recent environmental endmember for the evolution of Arctic OM. The HAs were characterized using 13C NMR and elemental analysis. Adsorption experiments were conducted to assess the affinity of HAs for binding Cu2+ and Ni2+. It was found that Yedoma HAs were enriched with aliphatic and N-containing structures as compared to the much more aromatic and oxidized alas and peat HAs. The adsorption experiments have revealed that the peat and alas HAs have a higher affinity for binding both ions as compared to the Yedoma HAs. The obtained data suggest that a substantial release of the OM from the Yedoma deposits due to a rapid thaw of the permafrost might increase the mobility of PTEs and their toxicity in the Arctic Ocean because of much lesser "neutralization potential".

Diet and Blood Concentrations of Essential and Non-Essential Elements among Rural Residents in Arctic Russia.

Nutrition is an essential factor for human health. Earlier research has suggested that Arctic residents are vulnerable to environmental toxic exposures through traditional foods. Although Russia is the largest Arctic country, the evidence on the topic from the Russian part of the Arctic is scarce. We studied associations between blood concentrations of essential and non-essential elements and traditional food consumption in 297 adults from seven rural settlements in the Nenets Autonomous Area, Northwest Russia. Blood arsenic concentration was positively associated with consumption of rainbow smelt, pink salmon, Arctic char and navaga fish. Frequent consumption of northern pike was associated with increased concentration of blood mercury. Blood mercury and arsenic concentrations were significantly associated with blood selenium. We also observed positive associations between blood lead levels and the frequency of goose consumption. Moreover, subjects who reported to be hunters had higher blood levels of lead, suggesting contamination of goose meat with fragments of shotgun shells. Blood cobalt and manganese concentrations were inversely associated with serum ferritin levels. Positive associations between blood levels of manganese and lead were observed. Moreover, blood lead concentrations were significantly associated with cadmium, mercury, copper, and zinc. Our results corroborate earlier findings on the traditional foods as source of non-essential elements for the Arctic residents. Observed correlations between the levels of lead and other elements warrant further research and may have potential implications for the studies on the associations between essential elements and health outcomes.

Combining citizen and conventional science for microplastics monitoring in the White Sea basin (Russian Arctic).

The study presents the results of the field expedition in the Russian Arctic held by a group of NGO members, scientists and volunteers in summer-autumn 2020 in the Arkhangelsk Region (Russia). The survey showed microplastics presence in 7 out of 13 remote and sparsely inhabited locations in lakes, rivers and coastal areas of the White Sea basin, with microplastic particle average concentration 1.14 part/m3, that is in agreement with other recent regional studies. Mostly PE, PET and PVC were found. A simple, cheap and easy-to-use microplastics monitoring protocol was developed and tested to be used by volunteers in remote Arctic communities. Video-lectures and tutorials are available online in an open-aсcess mode. 200 volunteers from polar communities are trained in microplastic sampling and litter separation, learning about microplastic pollution, including local residents, schoolchildren and students.

Essential and non-essential elements in biological samples of inhabitants residing in Nenets Autonomous Okrug of the Russian Arctic.

Exposure of Arctic residents to environmental pollutants is an emerging public health problem receiving little global attention. The objective of this study was to assess whole blood concentrations of nine selected essential (Co, Cu, Mn, Se, Zn) and non-essential (As, Cd, Hg, Pb) elements among Nenets and non-Nenets adult residents of the Nenets Autonomous Okrug (NAO) living in seven coastal and inland settlements. Urine was collected in two settlements for assessment of iodine status. Altogether 297 whole blood and 68 urine samples were analysed by inductively coupled mass spectrometry and the accuracy of the measurements was assessed by use of human whole blood and urine quality control materials. Several essential and non-essential showed significant variations in whole blood concentrations characterized by gender, population group and locality. Cd levels among non-Nenets non-smokers (0.19 µg/L) indicated a dietary intake at a natural global background level. Hg concentrations in whole blood show that not more than 10% of women in the fertile age had a Hg intake above the EFAS's recommendation. The Pb concentrations were in the range of, or partly exceeding reference values for increased risk of nephrotoxicity, and there is a need for a continued effort to reduce Pb exposure among the population groups in NAO. With high prevalence of obesity among the Nenets and non-Nenets population, a high prevalence of Fe-deficiency among menstruating women (<50 years) (37.2%) and a lower I status than recommended by WHO, these nutritional dependent components deserve further attention.

Concentrations of Persistent Organic Pollutants in Women's Serum in the European Arctic Russia.

Persistent organic pollutants (POPs) are heterogeneous carbon-based compounds that can seriously affect human health. The aim of this study was to measure serum concentrations of POPs in women residing in the Euro-Arctic Region of Russia. A total of 204 women from seven rural settlements of the Nenets Autonomous Okrug (NAO) took part in the study. We measured serum concentrations of 11 polychlorinated biphenyls (PCBs) and 17 organochlorine pesticides (OCPs) across the study sites and among Nenets and non-Nenets residents. Measurement of POPs was performed using an Agilent 7890A gas chromatograph equipped with an Agilent 7000 series MS/MS triple quadrupole system. The concentrations of all POPs were low and similar to findings from other Arctic countries. However, significant geographic differences between the settlements were observed with exceptionally high concentrations of PCBs in Varnek located on Vaygach Island. Both ΣDDT (p = 0.011) and ΣPCB (p = 0.038) concentrations were significantly lower in Nenets. Our main findings suggest that the serum concentrations of the legacy POPs in women in the Euro-Arctic Region of Russia are low and similar to those in other Arctic countries. Significant variations between settlements, and between Nenets and non-Nenets residents, were found. Arctic biomonitoring research in Russia should include studies on the associations between nutrition and concentrations of POPs.

Iodine Status of Women and Infants in Russia: A Systematic Review.

This systematic review presents a critical synthesis of the available information on the iodine status among women and infants in Russia. Literature search was performed in accordance with PRISMA guidelines using PubMed, Scopus Web of Science databases as well as eLIBRARY-the Russian national source. Altogether, 277 papers were identified and 19 of them were eligible for the review. The data on median urinary iodine concentration (UIC) in women and infants from 25 Russian regions were presented. A substantial variability in UIC across the country with no clear geographical pattern was observed. Despite substantial heterogeneity in research methodology and data presentation the results suggest that the iodine status among pregnant women and infants in Russia is below the recommended levels. Our findings demonstrate that iodine deficiency is a re-emerging public health problem in Russia. Urgent public health measures on national, regional and individual levels are warranted.

Iodine and bromine in fish consumed by indigenous peoples of the Russian Arctic.

Fish muscle may constitute one of the main sources of iodine (I) for the indigenous peoples of the Russian Arctic, although limited information is available about its content in commonly consumed fish species. In the current study, bromine (Br), I, the essential elements (copper, selenium and zinc) and other non-essential elements - specifically mercury, arsenic (As), cadmium, lead and nickel - have been quantified in 10 fish species consumed by people living in the Nenets and Chukotka Regions. Fish muscle was analysed by ICP-MS after nitric acid or tetramethylammonium hydroxide digestion. Certified reference materials were employed and concentrations are reported as geometric means (GMs). Atlantic cod (6.32 mg/kg) and navaga (0.934 mg/kg) contained substantially higher amounts of I than all other fish species, while broad whitefish had the lowest (0.033 mg/kg). By comparison, navaga contained more Br (14.5 mg/kg) than the other fish species, ranging 7.45 mg/kg in Atlantic cod to 2.39 mg/kg in northern pike. A significant inter-fish association between As and I in freshwater and marine fish was observed, suggesting common sources and perhaps parallel absorption patterns. Only Atlantic cod and, to lesser extent, navaga constituted significant dietary sources of I.

North Pacific Baleen Whales as a Potential Source of Persistent Organic Pollutants (POPs) in the Diet of the Indigenous Peoples of the Eastern Arctic Coasts.

Among marine mammals, gray and bowhead whales contain large amounts of fat and thereby constitute crucial dietary components of the traditional diet of indigenous peoples of the Eastern Arctic. Despite the high nutritional and cultural value of gray and bowhead whales, there is a risk of persistent organic pollutant (POP) intake by indigenous individuals who use marine mammals as their main source of fat. POPs are lipophilic pollutants and are known to accumulate and magnify along the marine food web. Consumption of foods contaminated by POPs can perturb the endocrine, reproductive, and immune systems, and can potentially cause cancer. Moderate to relatively high concentrations of POPs have indeed been reported in the edible tissues of gray and bowhead whales consumed by indigenous peoples of the North Pacific Ocean. Even though their consumption is potentially harmful, there is no regular monitoring of eco-toxicants in the foods consumed by the indigenous peoples of the Eastern Arctic. In our view, the routine analyses of consumable parts of whales and of comparable nutritional items need to be included in the Russian Arctic Biomonitoring Programme.

Concentration dataset for 4 essential and 5 non-essential elements in fish collected in Arctic and sub-Arctic territories of the Nenets Autonomous and Arkhangelsk regions of Russia.

The raw concentration data for the research article entitled "Essential and non-essential trace elements in fish consumed by indigenous peoples of the European Russian Arctic" (Sobolev et al., 2019) [1] are herein presented. Fifteen fish species were collected in the Nenets Autonomous and Arkhangelsk Regions of the Russian Federation and were analysed for 9 elements (As, Cd, Co, Cu, Hg, Ni, Pb, Se and Zn). The sampling sites were located in the European parts of the Russian Arctic and sub-Arctic territories. Within these territories, Nenets indigenous peoples commonly catch and consume local fish. Based on questionnaire data, local fish sources constituted ∼ 90% of the total fish consumed by endemic individuals living in these regions. The data summarized in this publication fill a gap in knowledge.

Essential and non-essential trace elements in fish consumed by indigenous peoples of the European Russian Arctic.

In present study, the analyses of essential [copper (Cu), cobalt (Co), selenium (Se) and zinc (Zn)] and non-essential elements [mercury (Hg), lead (Pb), cadmium (Cd) and arsenic (As)] in 7 fish species consumed by the indigenous people of the European Russia Arctic were conducted. The Nenets Autonomous Region, which is located in the north-eastern part of European Russia, was chosen as a Region of interest. Within it, the Nenets indigenous group (n = 6000) constitutes approximately 10% of the total population. Nearly all of the Nenets live a traditional life with fish caught in the local waters as a subsistence resource. We found that northern pike contained twice the amount of Hg compared with roach, and 3-4 times more than other fish species commonly consumed in the Russian Arctic (namely, Arctic char, pink salmon, navaga, humpback whitefish and inconnu). Fish Hg concentrations were relatively low, but comparable to those reported in other investigations that illustrate a decreasing south-to-north trend in fish Hg concentrations. In the current study, northern pike is the only species for which Hg bioaccumulated significantly. In all fish species, both Cd and Pb were present in considerably lower concentrations than Hg. The total As concentrations observed are similar to those previously published, and it is assumed to be present primarily in non-toxic organic forms. All fish tissues were rich in the essential elements Se, Cu and Zn and, dependent on the amount fish consumed, may contribute significantly to the nutritional intake by indigenous Arctic peoples. We observed large significant differences in the molar Se/Hg ratios, which ranged from 2.3 for northern pike to 71.1 for pink salmon. Values of the latter <1 may increase the toxic potential of Hg, while those >1 appear to enhance the protection against Hg toxicity.