Phytoremediation, an approach that uses plants to remediate contaminated soil through degradation, stabilization or accumulation, may provide an efficient solution to some mercury contamination problems. Palojärvi (, Westergaard B. Soil pH was measured directly in a soil solution (10 g dissolved in 25 ml distilled water 1 h prior to measurement). Frostegård Substrates with a mean OD<0 were excluded from further analysis as they do not contribute to the biological information. C.D. The replicates were made from the same cell extract of each soil. (, Rønn Heavy metals are among the quantitatively most important pollutant groups, and are highly persistent in the soil environment. https://doi.org/10.1016/j.envpol.2020.115057. C. K.E. A. L. Biological parameters for soils sampled at three distances from the center of mercury contamination. They are able to do so by developing resistance against the toxic substances through metabolic processes. The observed changes in the different soil microbial populations are probably a combination of both direct and indirect effects of the mercury contamination. In highly polluted areas where mercury has accumulated through industrial or mining activities, natural processes may bury, dilute, or erode the mercury deposits, resulting in declines in concentration. Colony appearance on agar plates each day during a 14-day period expressed in percentage of the total number of CFU. It was lowest in soil C and markedly higher in soil B than in soil A. L.D. 4Y). 3) accounted for 15% of the total light intensity. (, Miller The number of fast-growing protozoa was determined on wells in which protozoa had been detected after 1 week, while the total number was determined on all wells in which protozoa were detected. A.K. (, De Leij These differences can also affect the microbial populations, but they are largely attributable to the mercury contamination and the present study thus reveals the combination of direct and indirect effects of mercury pollution on the soil microbial community. mercury contamination within 50 km of the goldfields, it was not the major cause of mercury pollution further downriver. K. Rasmussen An essential requisite for controlling and monitoring mercury in the environment is to identify its species in different types of soils and sediments, as this will help not only to establish its mobility in the environment and ecosystem and the degree of its toxicity, but also to establish the source of contamination. Physical and chemical parameters for soils sampled at three distances from the center of mercury contamination. Soils were spiked with increasing concentrations of inorganic Hg and left to age for 5 years. it decreased with increasing mercury concentration. J.M. Microbial C was calculated by dividing the difference between the fumigated and unfumigated soil subsamples using an extractability factor kEC=0.33 [15]. A. Only a small part of the total mercury was bioavailable in soil C (0.043%), and the amount of bioavailable mercury in soils A and B was below the detection level (35 ng Hg g dry weight (dw) soil −1). Hg driven co-selection of several ARGs namely intI1, tetA and tetB were observed in the alkaline soil within the tested Hg concentrations. Using amplified ribosomal DNA restriction analysis (ARDRA), the community structure of soil subjected to long-term copper contamination has been demonstrated to differ from that of uncontaminated soil [5]. The number of protozoa was estimated using the most probable number method [18] with the following exceptions: 1 g of soil was diluted in 10 ml PBS and vortexed for 1 min. Mercury may occur in the environment in several forms (fig. The t-test was only performed if ANOVA revealed significant differences (P<0.05). 2003; Hartikainen and Kerko 2009; Sanderson et al. A control experiment was performed using a mutant strain constitutively expressing the lux gene [13] to investigate whether inhibition of light development occurred in soil samples. D.S. A. The effect of the heavy metal in question on the assay also needs to be taken into account since it has been shown that zinc is able to both prevent color formation and cause false-positive readings [34]. The appearance of colonies on agar plates over a 14-day period (Fig. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. Long-lasting effect of mercury contamination on the soil microbiota and its co-selection of antibiotic resistance. Contamination Introduction Mercury (Hg) is one of the most toxic elements and can cause renal and neurotoxicity to humans and wildlife. M. The number of morphotypes, DGGE bands and substrates utilized (well color>0.1) were counted. These anneal to conserved regions of the 16S rDNA of eubacteria, which correspond to position 341–534 in Escherichia coli and contain a G–C clamp. Nielsen (, Brookes The color development rank curves for substrate utilization were similar in all three soils (data not shown). R.A. Industrialization has led to an increase of heavy metal contamination in the soil, including mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr), and arsenic (As), etc. Of the total mercury present, 88% was identified as mercuric sulfide, 0.01% as methyl … Only a small part of the total mercury was bioavailable in soil C (0.043%), and the amount of bioavailable mercury in soils A and B was below the detection level (35 ng Hg g dry weight (dw) soil−1). Switzerland Shooting ranges are known for their elevated contamina-tion in heavy metals from gunshot residues (Knechten-hofer et al. Diaz-Ravina Å. de Waal This report contains information on the availability, performance, and cost of eight technologies for the treatment of mercury in soil, waste, and water. Mercury from vari-ous waste streams (used products, landfi lls, emissions from industrial sources) ends up in the sewage sludge that is used as agricultural fertiliser. Although the highest levels of inorganic mercury in soil are found in forested areas, the highest levels of methylmercury in fish and wildlife tend to occur in more arid regions of the West such as the Great … V. Øvreås Where two measurements were performed, both results are given; where triplicate measurements were performed, the mean±S.E.M. S.M. Search for other works by this author on: Department of Terrestrial Ecology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen Ø, Denmark, Heavy metals toxicity to microbe-mediated ecological processes: A review and potential application to regulatory policies, Effects of heavy metals in soil on microbial processes and population, Toxicity of heavy metals to microorganisms and microbial processes in agricultural soils: A review, Effect of metal-rich sludge amendments on the soil microbial community, Detection of shifts in microbial community structure and diversity in soil caused by copper contamination using amplified ribosomal DNA restriction analysis, Effect of metal-rich sewage sludge application on the bacterial communities of grasslands, Microfungi and microbial activity along a heavy metal gradient, Soil microfungi in an area polluted by heavy metals, Changes in microbial community structure during long-term incubation in two soils experimentally contaminated with metals, Field analysis of mercury in water, sediment and soil using static headspace analysis, Luminescence facilitated detection of bioavailable mercury in natural waters, Effects of dissolved organic carbon and salinity on bioavailability of mercury, Microbial biomass C, N and P in two arctic soils and responses to addition of NPK fertilizer and sugar: Implications for plant nutrient uptake, A direct extraction method to estimate soil microbial C: Calibrating in situ using microbial respiration and, Chloroform fumigation and the release of soil nitrogen: The effects of fumigation time and temperature, The fumigation-extraction method to estimate soil microbial biomass: Calibration of the, Optimizing soil extract and broth media for MPN-enumeration of naked amoebae and heterotrophic flagellates in soil, The use of fluorogenic substrates to measure fungal presence and activity in soil, The use of colony development for the characterization of bacterial communities in soil and on roots, Influence of media on measurement of bacterial populations in the subsurface: Numbers and diversity, Methods for General and Molecular Bacteriology, Profiling of complex microbial populations by denaturing gradient gel electrophoresis analysis of polymerase chain reaction-amplified genes coding for 16S rRNA, Classification and characterization of heterotrophic microbial communities on the basis of patterns of community-level sole-carbon-source utilization, Functional diversity and community structure of microorganisms in uncontaminated and creosote-contaminated soils as determined by sole-carbon-source-utilization, Phenotypic and genotypic adaptation of aerobic heterotrophic sediment bacterial communities to mercury stress, The resistance patterns to metals of bacterial populations in contaminated land, Effects of heavy metal contamination and remediation on soil microbial communities in the vicinity of a zinc smelter, Biomass carbon measurements and substrate utilization patterns of microbial populations from soils amended with cadmium, copper or zinc, The effects of biocidal treatments on metabolism in soil - IV. The greater percentage of fast-growing protozoa in soil B than in soil A is in agreement with the prediction that disturbed ecosystems contain a higher proportion of opportunists [32]. Campbell Moreover, they affect all groups of organisms and ecosystem processes, including microbially mediated processes [1–3]. Triplicate 10 μl samples of appropriate dilutions were spread on 10% LB agar plates supplemented with fungicide (25 μg natamycin ml−1). Elemental mercury can readily volatilize and enter the atmosphere, where it can combine with other materials and settle. This paper has been recommended for acceptance by Yong Sik Ok. Current address: South Australian Research and Development Institute, Urrbrae, SA 5064, Australia. The results of the three bacterial community analyses – colony morphology typing, DGGE, and sole carbon source utilization – were analyzed in a similar way. Colony morphotypes were ordered according to their relative abundance (y axis), the most common on the left. Gillman F.L. Mercury in the food chain is a universally recognized health hazard. Mercury contamination in soil, tailing and plants on agricultural fields near closed gold mine Journal of Degraded and Mining Lands Management 1029 The soils were air dried for one week and passed through a 2-mm sieve prior to laboratory analyses to obtain soil fertility profile. Colony morphotype abundance curves. E. tendency to swarm [22]. (, Muyzer The polymerase was added after a hotstart procedure (94°C in 5 min). A.M. Mercury is a toxic element found throughout the environment. III R.G. ARG co-selection is strongly correlated with microbiota shift and soil chemistry. To our knowledge, there have been no previous investigations of the effect of mercury on the soil protozoan population. When a soil is contaminated with heavy metals it is difficult to be remediated. The data for population size and the number of bands, morphotypes and substrates utilized were analyzed by ANOVA (SAS 6.12 for Windows). All morphological examinations were made on three replicate samples of each soil. S. Comparisons were performed by image analysis using Quantity One 4.0.1 for Macintosh (Bio-Rad) on digital gel images obtained with the Gel Doc 1000 system (Bio-Rad). A nutrient-rich medium (TSA) was used to enhance expression of the differences between colonies [21]. After gel electrophoresis (2% w/v agarose gel) of 5 μl subsamples of the PCR product, the amount of amplified DNA was calculated by comparing band intensities to a standard curve based on intensities from a Low DNA Mass™ Ladder (Gibco BRL). Antibiotic resistance genes (ARGs) in the environment are an exposure risk to humans and animals and is emerging as a global public health concern. A poisonous chain Studies revealed widespread contamination in river sediments, in many of the fish, and in people living beside the river. DGGE profiles of amplified 16S rDNA fragments from soil A (lanes labelled A), soil B (lanes labelled B) and soil C (lanes labelled C). (, Derry Soil C could nevertheless be separated from the two other soils by PCA. A.V. Mercury Contamination - Past, Present, and Future . Bååth The last resort antibiotic vancomycin resistance gene, vanB and quinolone resistance gene, qnrS were not detected. It has been identified as a priority T.J. The t-test was only performed if ANOVA revealed significant differences (P<0.05). Phelps The principal component analysis (PCA) of colony morphology typing (Fig. The slurry was then centrifuged for 10 min at 1000×g, and the supernatant was transferred to a new tube. S. This extract was diluted to obtain a cell density (estimated by direct counting after staining with Acridine Orange) of approximately 4×105 cells ml−1. Soils vary in type and consistency; mercury commonly is found very close to the surface. Since this was not corrected for, the possibility remains that separation of the soils by the PCA could be attributable to these differences. mercury sensitivity and the quality and amount of available food. The total mercury content of the soil samples was negatively correlated to the distance from the center of contamination . Numbers (mean±S.E.M.) natural component of the soil (Roulet et al ., 1998). © 2020 Elsevier Ltd. All rights reserved. This does not imply that the soil microbial community maintains its functional capacity when exposed to mercury, however. K. Substrate utilization profiles have previously been reported both to differ between metal-rich sludge-amended soil and control soil [29,30] and not to differ [4]. This paper presents growth chamber experiments that tested the ability of plant species to stabilize mercury in soil. Acceptable limits for mercury in soil were determined at a site with mercury contamination after measuring the soil concentration of total mercury, the species of mercury, and the intestinal absorption of mercuric sulfide by mice. J.W.M. Hence, in the present study the community became gradually more dominated by r-strategists as the mercury concentration increased. Rangger More specific, the structure of the culturable and total microbial communities was altered including a reduced bacterial diversity. Duplicate soil samples (about 5 g) were used to determine the water content and loss on ignition by weighing the samples fresh, dried (80°C overnight) and ashed (550°C for 3 h). The results suggest that mercury can drive co-selection of ARGs in contaminated non-agricultural soils over five years of aging which is linked to soil microbiota shift and metal chemistry in the soil. Microbial N was calculated in the same manner using an extractability factor kEN=0.5 [16,17]. Soil contamination can affect people both directly and indirectly, through the consumption of contaminated plants and animals. F. The soils differed in other ways than the mercury concentration, e.g. For bacterial counts (CFU), 1 g of soil was diluted in 10 ml phosphate-buffered saline (PBS; autoclaved solution of 1.44 g l−1 Na2HPO4.2H2O, 0.24 g l−1 KH2PO4, 8.00 g l−1 NaCl and 0.20 g l−1 KCl in distilled water) and vortexed at maximum velocity for 1 min. D.S. The bacterial colonies were grouped into classes according to the day of appearance on agar plates using a modification of a previously described method [20]. T.V. These findings based on genetic analysis are in concert with the present findings based on morphological differentiation of the isolates. Any residual mercury impacts left in soil above the residential standard will A combined approach was necessary to obtain a more detailed picture of the community, however. I.K. Shifts in the structure of the culturable bacterial community caused by long-term heavy metals contamination have also been detected by analyzing isolates using amplified ribosomal DNA restriction analysis (ARDRA) [5]. Soil contamination or soil pollution as part of land degradation is caused by the presence of xenobiotics (human-made) chemicals or other alteration in the natural soil environment. S.P. Microbial biomass was measured with the chloroform fumigation-extraction method, whereby a fumigated and an unfumigated soil subsample are analyzed for organic carbon (C) and nitrogen (N) [14]. The total mercury content of the soil samples was negatively correlated to the distance from the center of contamination (Table 1). T. (, Palumbo M. 4X). 3), and inter-replicate similarity was around 70% (Fig. The effect of heavy metals on the number of culturable bacteria is uncertain as the findings differ between studies [2]. S.C. The average day of appearance decreased significantly from 3.8 in soil A, to 3.0 in soil B and 2.8 in soil C, i.e. Scarborough Mercury soil contamination is an important environmental problem that needs the development of sustainable and efficient decontamination strategies. Reeslev Powlson The PCR products were loaded on a polyacrylamide gel (7.5% v/v acrylamide/Bis (37:5:1) in 0.5×TAE buffer (4.84 g l−1 Tris-base, 11.42 ml l−1 acetic acid and 20 ml l−1 0.5 M EDTA at pH 8.0)) with a 40–65% denaturing gradient (100% denaturant=7 M urea and 40% v/v deionized formamide) and a 0% denaturing stacking gel on top containing the wells. The gel was destained in distilled water for 1/2 h prior to exposure to UV transillumination using Gel Doc 1000 (Bio-Rad) equipment. Thus even though mercury contamination resulted in an increase in the number of mercury-resistant bacteria, microbial biomass could not be maintained, probably due to the reduced primary production and resultant lower input of energy to the soil microbial community. The PCA of the substrate utilization pattern also separated soil C from soils A and B along PC 1 (Fig. L.D. In many relatively pristine areas, however, mercury concentrations have actually increased because atmospheric deposition has increased. (, Torsvik (, Rasmussen The plates were incubated at 12°C in the dark and inspected for protozoa after 1 and 3 weeks. 1). Kelly The high mercury tolerance of the culturable bacterial population in the mercury-contaminated soil is in agreement with previous studies showing that the occurrence of mercury-resistant bacteria in sediment [27] and soil [28] is related to the mercury concentration. M. Protozoa detected after 1 week of incubation. In addition, some industrial wastes and Mercury can co-select for antibiotic resistance genes in soil. Similar investigations should be performed with other heavy metals to determine whether they also influence the substrate utilization assay. T. Müller In order to minimize the effects of different inoculation densities, the plates were read when the average well color density (AWCD) on a plate was 0.5±0.1. Schmidt Although only few studies have investigated the effects of pollutants on the overall genetic structure and diversity of the whole bacterial community, the findings indicate that exposure to heavy metals alters the bacterial community's genetic structure and diversity. New tube these processes can either be transformation of the soil microbial populations probably. 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