Temporal and spatial biomonitoring of atmospheric heavy metal pollution using moss bags in Xichang

Plants as effective bioindicators for heavy metal pollution monitoring

This study investigated the bioindicator potential of Amaranthus retroflexus L., Plantago lanceolata L., Rumex acetosa L., and Trifolium pratense L. including the use of Lolium multiflorum L. as a reference species, for heavy metal pollution monitoring, in particular Zinc (Zn), Cadmium (Cd), Nickel (Ni), and Lead (Pb). Controlled heavy metal contamination was applied through irrigation with metal nitrate solutions two levels of contamination (low and high). The study also focused on analyzing heavy metals concentration in plant tissues and related physiological responses. Distinct physiological responses to heavy metal stress were observed among the investigated species, highlighting unique variations in their reactions. Hydrogen peroxide, malondialdehyde content, and enzymatic activities emerged as reliable indicators of plant stress induced by heavy metal solutions. P. lanceolata displayed elevated Zn concentrations in both roots and leaves (3271 ± 337 and 4956 ± 82 mg kg-1). For Pb, L. multiflorum and P. lanceolata showed highest root concentrations (2964 ± 937 and 1605 ± 289 mg kg-1), while R. acetosa had higher leaf concentration (1957 ± 147 mg kg-1). For Ni, L. multiflorum had the highest root concentration (1148 ± 93 mg kg-1), and P. lanceolata exhibited the highest leaf concentration (2492 ± 28 mg kg-1). P. lanceolata consistently demonstrated the highest Cd concentrations in both roots (126 ± 21 mg kg-1) and leaves (163 ± 12 mg kg-1). These results provide valuable insights for selecting effective bioindicator species to establish control strategies for heavy metal pollution.

Ecotoxicological assessments of atmospheric biomonitors exposed to urban pollution in a Brazilian metropolis

Subcellular metal distribution assessments are the most adequate biomonitoring approach to evaluate metal toxicity, instead of total metal assessments This study aimed to assess subcellular metal distributions and associations to the main metal exposure biomarker, metallothionein (MT), in two bromeliad species (Tillandsia usneoides and Tillandsia stricta) exposed established in industrial, urban, and port areas in the metropolitan region of Rio de Janeiro, southeastern Brazil, through an active biomonitoring approach conducted one year. Metals and metalloids in three subcellular fractions (insoluble, thermolabile and thermostable) obtained from the MT purification process were determined by inductively coupled plasma mass spectrometry (ICP-MS). Lower MT concentrations were observed both during the dry sampling periods, associated to the crassulacean acid metabolism (CAM) and during the COVID-19 pandemic, due to reduced urban mobility, decreasing pollutant emissions. The percentage of non-bioavailable metals detected in the insoluble fraction increased throughout the sampling period for both species. Several metals (Cr, Co, Cu, Cd, Mn, Ni, Se, and Zn), most associated with vehicle emissions, the main pollutant source in urban centers, were detected in the thermostable fraction and are, thus, associated with MT through the MT-metal detoxification route. Insoluble metal concentrations were higher in T. stricta, indicating that this species seems less susceptible to cellular metal exposure damage. A potential protective effect of Se and Fe was detected against Pb, suggested by a strong negative correlation, which may be attributed to antioxidant roles and similar uptake routes, respectively.

Moss as a passive biomonitoring tool for the atmospheric deposition and spatial distribution pattern of toxic metals in an industrial city

Anthropogenic pollution impacts human and environmental health, climate change, and air quality. Karabük, an industrial area from the Black Sea Region in northern Türkiye, is vulnerable to environmental pollution, particularly soil and air. In this research on methodological aspects, we analyzed the concentrations of six potential toxic metals in the atmospheric deposition of the city using the passive method of moss biomonitoring. The ground-growing terrestrial moss, Hypnum cupressiforme Hedw., was collected during the dry season of August 2023 at 20 urban points. The concentrations of Cr, Cu, Cd, Ni, Pb, and Co were determined in mosses by the ICP-MS method. Descriptive statistical analysis was employed to evaluate the status and variance in the spatial distribution of the studied metals, and multivariate analysis, Pearson correlation, and cluster analysis were used to investigate the associations of elements and discuss the most probable sources of these elements in the study area. Cd and Co showed positive and significant inter-element correlations (r > 0.938), representing an anthropogenic association mostly present in the air particles emitted from several metal plants. The results showed substantial impacts from local industry, manufactured activity, and soil dust emissions. Steel and iron smelter plants and cement factories are the biggest emitters of trace metals in the Karabük area and the primary sources of Cr, Cd, Ni, and Co deposition.

Assessment of Air Pollution in Ulaanbaatar Using the Moss Bag Technique

Active moss biomonitoring, the so-called moss bag technique, widely applied in many countries, for the first time, was applied to assess the air quality in Ulaanbaatar (Mongolia). Moss bags with Sphagnum girgensohnii Russow were exposed in triplicate in three different periods: December-February, March-May, and December-May at 13 governmental air quality monitoring stations located in the vicinity of thermal power plants and residential areas. The plant tissue content of Al, Ba, Co, Cd, Cr, Cu, Fe, Mn, P, Pb, Sr, S, V, As, and Zn was determined using inductively coupled plasma-optical emission spectrometry, and a direct mercury analyzer was used to determine the Hg content. The samples in residential areas and near thermal power plants that were exposed for 3 months in winter and for 6 months (winter to spring) were characterized by the highest accumulation of the elements. In the moss bags exposed during spring, maximum accumulation of the determined elements was noted in residential areas and near main roads. Regardless of the exposure time and duration, the highest accumulation of Al, Fe, and V was determined at Dambadarjaa air quality station located near a highway and of Hg near the Amgalan power plant. Significant differences in element accumulation between seasons were observed, thus, the accumulation of Al, Ba, As, Co, Cr, Fe, Pb, V, and Zn was higher in spring, while P and S had higher content in the moss samples exposed during winter. The accumulation of elements over the 6-month exposure period was 1.1-6.7 times higher than that of the 3-month periods. Thus, the 6-month exposure can be considered a reliable deployment period as it ensures an adequate signal in terms of enrichment of pollutants. Factor analysis was applied to highlight the association of elements and to link them with possible sources of emission. Three factors were determined, the first one included Al, As, Ba, Co, Cr, Fe, Mn, Pb, Sr, and V and was identified as a geogenic-anthropogenic, the second (Cu, P, and S) and third (Cd and Zn) factors suggested anthropogenic origin. The Relative accumulation factor and enrichment factor were calculated to evaluate the level of air pollution and possible element sources. Considerable contributors to air pollution were Zn, Fe, As, V, Cr, and Al, which may originate from airborne soil particles of crustal matter or transport, as well as coal combustion for heating and cooking.

Significance of moss pretreatments in active biomonitoring surveys

The present study examines the impact of pretreatment procedures on the metal concentrations in bags that are to be exposed. We examine Mn, Fe, Cu, Zn, Cd, and Pb amounts in Sphagnum fallax and Dicranum polysetum mosses using atomic absorption spectrometry. The concentration of Hg was also determined using a mercury analyzer. Two sample preparation ways were tested (with and without rinsing) and their influence was evaluated by determining the coefficient of variation (CV). Chlorophyll content was also determined in mosses collected from three habitats (deep woodland, forest road, and wood lot). The results indicate, that the concentration of elements deposited in mosses depends on the species and the habitat where they were collected (ANOVA, p < 0.001). Rinsing of mosses reduces the CV for Mn, Fe, Cu, and Zn and uniform the material prior to exposure (CV for the majority of metals <10%). Selected correlations were found for element concentrations with chlorophyll content. Photosynthetic activity of mosses decreased by about 80% during their one-month storage in the laboratory. Due to the varying concentration of metals in the collected samples, proper, and standardized preparation of mosses before exposure, they can be effectively used in active biomonitoring.

Moss-bag technique as an approach to monitor elemental concentration indoors

The moss-bag technique has been used for many decades to monitor outdoor pollution. More recently, however, the method has been used to monitor indoor air pollution (IAP), as humans spend the majority of their time indoors. The purpose of the research conducted was to evaluate indoor air pollution using active moss biomonitoring. Pleurozium schreberi moss bags were exposed for two seasons (summer and winter), hanging over tile stoves and coal stoves. The selected elements: Al, Cu, Cd, Co, Pb, Zn, V, Ba, Cr, Fe, Mn, Sr, P, Ni, and S were determined by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and, for Hg, by a direct mercury analyzer. The study found the exposure season affected the concentrations of selected elements in 62.5% of cases, and their source was identified. The average concentrations of Co, Ba, Cr, and Sr were higher, and statistically significant, in winter, after a 12-week exposure period of the mosses, regardless of the type of heating or cooking stove owned. The higher phosphorus concentrations obtained in summer indicate physiological stress caused by unfavorable winter exposure conditions. In the future, the number of species used to assess indoor air pollution should be increased and the range of pollutants expanded, along with the identification of their sources, taking residents' lifestyles into account.

Unravelling Heavy Metal Dynamics in Soil and Honey: A Case Study from Maramureș Region, Romania

The study examined soil and honey samples from the Maramureș region, assessing potentially toxic elements and their concentrations. The highest concentrations were found for (Cu), (Zn), (Pb), (Cr), (Ni), (Cd), (Co), and (As), while (Hg) remained below the detection limit. Samples near anthropogenic sources displayed elevated metal levels, with the Aurul settling pond and Herja mine being major contamination sources. Copper concentrations exceeded the legal limits in areas near these sources. Zinc concentrations were highest near mining areas, and Pb and Cd levels surpassed the legal limits near beehives producing acacia honey. Nickel and Co levels were generally within limits but elevated near the Herja mine. The study highlighted the role of anthropogenic activities in heavy metal pollution. In the second part, honey samples were analyzed for heavy metal concentrations, with variations across types and locations. Positive correlations were identified between certain elements in honey, influenced by factors like location and pollution sources. The research emphasized the need for pollution control measures to ensure honey safety. The bioaccumulation factor analysis indicated a sequential metal transfer from soil to honey. The study's comprehensive approach sheds light on toxic element contamination in honey, addressing pollution sources and pathways.

Nitrogen fixation associated with two cohabiting moss species expresses different patterns under Cu and Zn contamination

Nitrogen (N2) fixation by moss-associated cyanobacteria is an important N source in pristine ecosystems. Previous studies have shown that moss-associated N2 fixation is sensitive to anthropogenic N pollution. However, we still lack understanding of the effects of other factors derived from anthropogenic sources, such as heavy metal pollution on N2 fixation. To test this, we collected two dominant mosses (Pleurozium schreberi and Spaghnum palustre) from a temperate bog in Denmark and assessed their N2 fixation responses to simulated heavy metal pollution by adding 5 levels (plus a control) of copper (Cu, 0-0.05 mg g dw-1) and zinc (Zn, 0-0.1 mg g dw-1). Metal concentrations in both mosses increased linearly with Cu and Zn addition, but N2 fixation activity associated with S. palustre was to a greater extent negatively affected by both Cu and Zn additions than that associated with P. schreberi. Copper additions even promoted N2 fixation in P. schreberi. Hence, the heavy metal sensitivity of N2-fixing cyanobacteria is dependent on the host moss-species, and the vulnerability of ecosystems towards heavy metal pollution could vary depending on the dominant moss species.

Research progress on the content and distribution of rare earth elements in rivers and lakes in China

This study reviewed the content and distribution of rare earth elements (REE) in rivers and lakes in China based on the online literature. The sequence distribution of REE presented the decreasing trends in the order: of Ce > La > Nd > Pr > Sm > Gb > Dy>Er > Yb > Eu > Lu > Ho > Tb > Tm in rivers water. Pearl River and the Jiulong River constitute a significant sediments REE reservoir with an average value mean of 229.6 mg/kg and 266.86 mg/kg, respectively; both have higher concentrations than the global river average (174.8 mg/kg) and higher than the local soil background (Chinese soil background). The Liaohe River is one of China's most polluted rivers, with REE distribution ranging from 106.61 to 174.71 g/L (average 144.59 g/L in water). The total concentrations of dissolved REE in rivers near REE mining areas in China are higher than in other rivers. Increasing anthropogenic inputs to natural systems may permanently alter the natural signatures of REE. The distribution characteristics of REE in Chinese lakes (sediments) varied greatly, and the mean enrichment factor (EF) was sorted as follows: Ce > La > Nd > Pr > Sm > Gd > Dy>Er > Yb > Eu > Ho > Tb > Tm > Lu, where Ce was the most abundant followed by La, Nd, and Pr, and these four elements account for 85.39 % of the total concentration of REE. The REE in the sediments obtained from Poyang Lake and Dongting Lake had an average concentration respectively of 254.0 μg/g and 197.95 μg/g; both are considerably higher than the average upper continental crust (146.4 μg/g) and higher than in other lakes in China and around the world. The distribution and accumulation of LREE in most lake sediments result from the joint action of human activities and natural processes. It concluded that mining tailings were the primary cause of REE pollution in sediments, and industrial and agricultural activities are mainly responsible for water contamination.

Pelagic and estuarine birds as sentinels of metal(loid)s in the South Atlantic Ocean: Ecological niches as main factors acting on bioaccumulation

Activities related to the offshore exploration and production of oil and natural gas provide economic development and an essential energy source. However, besides the risk of petroleum hydrocarbon contamination, these activities can also be sources of metals and metalloids for marine organism contamination. In this research, we evaluated the potential use of two pelagic (black-browed albatross Thalassarche melanophris and yellow-nosed albatross T. chlororhynchos) and one estuarine bird species (neotropical cormorant Nannopterum brasilianus) as sentinels of contamination of As, Cd, Cr, Cu, Pb, Mn, Mo, Zn, Ni, Ba, V, and Hg in an area under influence of oil and gas activities. The analyses were carried out in samples collected from 2015 to 2022 from 97 individuals. A factor alert; an adaptation from the contamination factor is proposed to identify individuals with high concentrations that possibly suffered contamination by anthropogenic origin. Grouping all species, the metal(loid)s with the highest concentrations were in decreasing order: Zn > Cu > Mn > Hg > As > Cd > Mo > V > Cr > Ba > Ni > Pb. Similar concentrations were observed for V, Mn, Cr and Pb among the three species. Pelagic birds showed higher levels of concentrations for Hg, As and Cd. Based on the correlations and multivariate analysis performed, the results indicate that the ecological niche factor has greater relevance in the bioaccumulation of these elements compared to the habitat. Although some individuals showed high concentrations in part of the trace elements, suggesting exposure to anthropic sources, the direct influence of oil production and exploration activities was not observed, suggesting that activities on the continent are the primary contamination source. The results of this work highlight the role of seabirds as sentinels for metal(loid)s, contributing to the knowledge of the occurrence of contaminants in the South Atlantic Ocean.

Heavy Metals in Honey Collected from Contaminated Locations: A Case of Lithuania

Honey, as a bioindicator, can be used to determine the level of pollution in the environment with selected pollutants, including heavy metals. Twelve locations were selected for experimental studies near the main sources of pollution: industrial sites, landfills, railways, and highways. The honey samples were burned to ash, and the heavy metals in ashes were determined using aqua regia digestion in the microwave digestion system. The concentration of heavy metals (Cd, Cr, Cu, Pb, and Ni) was determined using a Buck Scientific model 210 VGP atomic absorption spectrophotometer with a graphite furnace atomizer and an acetylene-air flame. These median amounts of heavy metals were found in the analyzed honey samples: 0.0030 mg/kg for Cd, 0.0179 mg/kg for Pb, 0.0317 mg/kg for Cr, 0.0999 mg/kg for Cu, and 0.0332 mg/kg for Ni. The obtained results were compared with honey samples research conducted in other countries. It is difficult to compare the level of heavy metal results found in honey from different countries, as the type of honey, soil composition, rainfall, air temperature, the plants from which it was harvested, its vegetation and flowering duration, and the degree of anthropogenic pollution in the area differ. The heavy metal content tested in honey was found to be low, except for the Pb content in one sample of honey, and did not pose a risk to human health. A statistical analysis including average, median, standard deviation, confidence intervals, and Spearman coefficients was performed for the evaluation of the relationships between the heavy metal quantities and the determination of the impact of pollution sources (transport and industry). The correlation analysis showed a strong negative correlation coefficient between heavy metals and distance (r = −0.593 to −0.204).