Control priority based on source-specific DALYs of PM2.5-bound heavy metals by PMF-PSCF-IsoSource model in urban and suburban Beijing.

To determine the priority control sources, an approach was proposed to evaluate the source-specific contribution to health risks from inhaling PM2.5-bound heavy metals (PBHMs). A total of 482 daily PM2.5 samples were collected from urban and suburban areas of Beijing, China, between 2018 and 2019. In addition to the PMF-PSCF model, a Pb isotopic IsoSource model was built for more reliable source apportionment. By using the comprehensive indicator of disability-adjusted life years (DALYs), carcinogenic and noncarcinogenic health risks could be compared on a unified scale. The study found that the annual average concentrations of the total PBHMs were significantly higher in suburban areas than in urban areas, with significantly higher concentrations during the heating season than during the nonheating season. Comprehensive dust accounted for the largest contribution to the concentration of PBHMs, while coal combustion contributed the most to the DALYs associated with PBHMs. These results suggest that prioritizing the control of coal combustion could effectively reduce the disease burden associated with PBHMs, leading to notable public health benefits.

Herbaceous ornamental plants with conspicuous aesthetic traits contribute to plant invasion risk in subtropical urban parks.

Global ornamental horticulture is a major pathway for plant invasions, while urban parks are key areas for introducing non-native ornamental plants. To react appropriately to the challenges (e.g., biological invasion issues) and opportunities (e.g., urban ecosystem services) of herbaceous ornamentals in urban parks, we conducted a comprehensive invasive risk assessment in 363 urban parks in Chongqing, a subtropical city in China. The results found more than 1/3 of the 119 non-native species recorded in urban parks had a high invasion risk, and more than five species had potential invasion risk in 96.29% of the study area, indicating herbaceous ornamentals in urban parks are potentially a pool of invasive species that deserves attention. Moreover, humans have chosen herbaceous ornamentals with more aesthetic characteristics in urban parks, where exotic species were more prominent than native species in floral traits, such as more conspicuous flowers and longer flowering periods. The findings can inform urban plant management, provide an integrated approach to assessing herbaceous ornamentals' invasion risk, and offer insights into understanding the filtering effects of human aesthetic preferences.

Reaction Mechanism of 3,4-Dinitrofuroxan Formation from Glyoxime: Dehydrogenation and Cyclization of Oxime.

The reaction pathway of the formation of 3,4-dinitrofuroxan from glyoxime is theoretically investigated under experimental conditions with 25 % nitric acid and dinitrogentetroxide reagents to clarify the mechanism of formation of a furoxan ring by glyoxime. The geometric configurations of minima and transition-state species are optimized at the (U)B3LYP/6-311++G** level. The CCSD(T) and CASSCF(10e,8o)/CASSCF(9e,8o) single-point energy corrections at the same level are performed on top of the optimized geometries. A subsequent dynamic correlation by using NEVPT2/6-311++G**-level single-point energy calculations based on the CASSCF results is also performed to obtain accurate energy values. The formation reaction is analyzed from two processes: glyoxime nitration and 3,4-dinitroglyoxime (nitration product) oxidative cyclization. Calculation results indicate that the electrophilic substitution of nitronium ions from the protonated HNO3 and the abstraction of hydrogen ions by HNO3 molecules are requisites of glyoxime nitration. The formation of a furoxan ring from 3,4-dinitroglyoxime involves two possible mechanisms: 1) oxydehydrogenation by NO2 molecules and the subsequent torsion of NO radical groups to form a ring and 2) the alternation of dehydrogenation and cyclization. The intermediates and transition states in both routes exhibit monoradical and diradical characteristics. Singlet and triplet reactions are considered for the diradical species. Results show that the singlet reaction mechanism is more favorable for cyclization than the triplet reaction. The formation of a furoxan ring from oxime is in accordance with the stepwise intermolecular dehydrogenation and intramolecular torsion to the ring.

High Prevalence and Widespread Distribution of Zoonotic Enterocytozoon bieneusi Genotypes in Swine in Northeast China: Implications for Public Health.

This study analyzed 563 fecal specimens of asymptomatic pigs from five cities of northeast China for the prevalence and genetic characteristics of Enterocytozoon bieneusi. The parasite was detected in 267 of 563 (47.4%) pigs by nested PCR of the ribosomal internal transcribed spacer (ITS). The differences in prevalence between preweaned (58.0%, 94/162) and growing pigs (39.6%, 114/288) and between weaned (52.2%, 59/113) and growing pigs are significant (p < 0.05). Genotypic typing and phylogenetic analysis facilitated identification of six human-pathogenic genotypes EbpC, O, CS-4, EbpA, Henan-IV, and PigEBITS5 and six potentially zoonotic genotypes EbpB, CC-1, CS-1, CS-3, CHN7, and CS-10. Genotypes CS-4 (32/35) and EbpC (3/35) from Harbin and Henan-IV (5/64) from Qiqihar determined in pigs herein represented the main causative agents of human microsporidiosis in Harbin. The most dominant genotype EbpC found in pigs from Daqing (35/65) and Qiqihar (a close neighbor to Daqing) (47/64) contributed significantly to human infections in Daqing. Genotype EbpC was also a leading E. bieneusi pathogen in humans, drinking water, and wastewater in central China. This study provided robust evidence that pigs could be an outstanding source of human microsporidiosis and water contamination in China.

Molecular investigation of Cryptosporidium in small caged pets in northeast China: host specificity and zoonotic implications.

This study screened 151 pet-derived fecal specimens randomly collected from four commercial markets in northeast China for the presence of Cryptosporidium by genus-specific nested PCRs of the small subunit rRNA gene. Of these, 14 specimens (9.3 %) from nine species of birds, two types of rodents, and a hedgehog were positive for Cryptosporidium. Sequence analysis on the PCR-positive isolates facilitated identification of three Cryptosporidium species (C. baileyi, C. galli, and C. ubiquitum) and two Cryptosporidium genotypes (ferret genotype and avian genotype V). The study birds were affected predominantly with bird-specific C. baileyi (Atlantic canary, budgerigar, crested myna, rock dove, and silky fowl), C. galli (Chinese hwamei), and Cryptosporidium avian genotype V (Fischer's lovebird and rosy-faced lovebird). Cryptosporidium ferret genotype previously considered rodent-adapted was identified in three specimens from budgerigar, chipmunk, and red squirrel. Two specimens collected from common hill myna and hedgehog were positive for C. ubiquitum. The species of birds that can be colonized by Cryptosporidium were extended. Moreover, the data expanded the host range of Cryptosporidium ferret genotype and C. ubiquitum, especially the birds. The carriage of zoonotic C. ubiquitum in small caged pets is of public health importance.

Genetic variation of mini- and microsatellites and a clonal structure in Enterocytozoon bieneusi population in foxes and raccoon dogs and population differentiation of the parasite between fur animals and humans.

Enterocytozoon bieneusi is an obligate intracellular protozoan parasite that infects a wide range of mammal hosts and birds. Previous genotypic surveys were limited to measure the polymorphisms at the ribosomal internal transcribed spacer (ITS) that evolved slowly. Data on population structure are available only on E. bieneusi isolates from primates. This study explored the genotypic and phylogenetic characteristics of four mini- and microsatellites and performed a population genetic analysis in 39 E. bieneusi isolates of potentially zoonotic ITS genotype D from farmed foxes and raccoon dogs in China. Sequence polymorphisms facilitated determination of six, two, four, and five genotypes at markers MS1, MS3, MS4, and MS7, respectively. Patterns of phylogeny revealed different levels of diversity within and among the genetic markers. Clear genotypic and phylogenetic divergences between E. bieneusi isolates of ITS genotype D from fur animals and humans were observed at individual markers. Complete linkage disequilibrium and very limited recombination in subsequent population genetic analysis supported a clonal structure for E. bieneusi population from fur animals (FID). Phylogenetic analysis, genetic network, and measures of F ST and gene flow demonstrated population differentiation of FID from two known human E. bieneusi populations HID (with a clonal structure) and HIA (with an epidemic structure). The data indicated an ideal resolving power of MLST compared to the previously widely used ITS genotyping and confirmed the clonal nature and population differentiation of E. bieneusi in various hosts.

Cadmium accumulation in Panax notoginseng: levels, affecting factors and the non-carcinogenic health risk.

Cadmium (Cd) contamination has been reported to be a problem for the safe usage of Panax notoginseng (Sanchi); thus, it is necessary to elucidate the Cd accumulation in Sanchi and to assess its associated health risk. Samples were collected from major producing areas in Yunnan, China. The average concentration of Cd in Sanchi was 0.43 mg/kg, which exceeds the standard level for herbal medicine in China (0.3 mg/kg). A stepwise regression analysis showed that zinc and the pH were the related factors that most significantly impacted Cd in Sanchi roots. The hazard quotient values were estimated as 0.0010 (men) and 0.0012 (women) for consumers taking preparations and were 0.011 (men) and 0.013 (women) for consumers taking health products, implying that there is no non-carcinogenic hazard associated with Sanchi consumption. However, a Monte Carlo simulation showed that approximately 0.80 % of male and 1.02 % of female consumers via drug consumption and 36.28 % of male and 41.87 % of female consumers via health product consumption had an exposure exceeding the acceptable daily intake (ADI) of Cd from drugs (1 % of the total oral ADI as suggested by the World Health Organization). These people should control their oral Cd intake from both Sanchi consumption and diet as a whole.

Zoonotic and Potentially Host-Adapted Enterocytozoon bieneusi Genotypes in Sheep and Cattle in Northeast China and an Increasing Concern about the Zoonotic Importance of Previously Considered Ruminant-Adapted Genotypes.

This study investigated fecal specimens from 489 sheep and 537 cattle in multiple cities in northeast China for the prevalence and genetic characteristics of Enterocytozoon bieneusi by PCR and sequencing of the ribosomal internal transcribed spacer. Sixty-eight sheep specimens (13.9%) and 32 cattle specimens (6.0%) were positive for E. bieneusi. Sequence polymorphisms enabled the identification of 9 known genotypes (BEB4, BEB6, CM7, CS-4, EbpC, G, I, J, and OEB1) and 11 new genotypes (NESH1 to NESH6 and NECA1 to NECA5). The genotypes formed two genetic clusters in a phylogenetic analysis, with CS-4, EbpC, G, NESH1 to NESH3, and NECA1 to NECA5 distributed in zoonotic group 1 and BEB4, BEB6, CM7, EbpI, J, OEB1, and NESH4 to NESH6 distributed in potentially host-adapted group 2. Nearly 70% of cases of E. bieneusi infections in sheep were contributed by human-pathogenic genotypes BEB6, CS-4, and EbpC, and over 80% of those in cattle were by genotypes BEB4, CS-4, EbpC, I, and J. The cooccurrence of genotypes BEB4, CS-4, EbpC, I, and J in domestic ruminants and children in northeast China and the identification of BEB6 and EbpC in humans and water in central China imply the possibility of zoonotic transmission. This study also summarizes E. bieneusi genotypes obtained from ruminants worldwide and displays their host ranges, geographical distributions, and phylogenetic relationships. The data suggest a host range expansion in some group 2 genotypes (notably BEB4, BEB6, I, and J) that were previously considered to be adapted to ruminants. We should be concerned about the increasing zoonotic importance of group 2 genotypes with low host specificity.

Widespread presence of human-pathogenic Enterocytozoon bieneusi genotype D in farmed foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) in China: first identification and zoonotic concern.

Enterocytozoon bieneusi is a well-known causative agent of microsporidial infections in a variety of mammal hosts including humans in China, whereas there were no epidemiological data on wild animals bred in captivity, and the role of the neglected hosts in transmission of zoonotic microsporidiasis remains unknown. Herein, we investigated feces from 191 farmed foxes (Vulpes vulpes) and 162 farmed raccoon dogs (Nyctereutes procyonoides) for the prevalence and genotypic characteristics of E. bieneusi in Harbin City, northeast China. Polymerase chain reaction (PCR) targeting the internal transcribed spacer (ITS) of the rRNA gene enabled the identification of 53 (27.7%) and 17 (10.5%) positives from fox and raccoon dog specimens, respectively. There was only minor difference in prevalence between juvenile and adult foxes. Adult raccoon dogs have an infection rate significantly higher than juveniles. The most common human-pathogenic E. bieneusi, genotype D, is widespread among foxes and raccoon dogs of various ages by sequence analysis of the ITS locus. Genotypes CHN-DC1 and mixed CHN-DC1/WildBoar3 were detected in one adult raccoon dog each. Here is the first report describing the presence of zoonotic E. bieneusi genotypes in farmed foxes and raccoon dogs. The widespread existence of genotype D in surveyed animals is of great concern for public health.

Levels of arsenic pollution in daily foodstuffs and soils and its associated human health risk in a town in Jiangsu Province, China.

The development of industries in rural areas can aggravate the arsenic (As) contamination of the local environment, which may pose unacceptable health risks to the local residents. This paper estimated the health risk posed by inorganic As (iAs) to residents via ingestion of soil, skin contact with soil and consumption of foodstuffs in a typical rural- industrial developed town in southern Jiangsu, China. The average concentrations of total As in soil, rice, fish, shrimp and crab, pork and eggs, vegetables and fruits were detected to be 10.367, 0.104 mg/kg dw (dry weight), 0.050, 0.415, 0.011, 0.013 and 0.017 mg/kg fw (fresh weight), respectively. All of these values are below the maximum allowable concentration in food and soil in China. The deterministic estimation results showed that the hazard quotient (HQ) and excess lifetime cancer risk (R) were 1.28 (0.78-2.31) and 2.38 × 10(-4) (2.71 × 10(-5)-5.09 × 10(-4)) for all age groups, respectively. Males in the age range of 2-29 years and females in the age range of 2-13 years and 18-29 years exhibited non-carcinogenic risk (HQ>1). Carcinogenic risk exceeded the acceptable level of 1 × 10(-)(5) for both genders at all ages. Furthermore, this risk rose with age. The probabilistic estimation results showed that about 28% of residents had non-carcinogenic risk due to over ingestion of iAs. The R value of 90% of residents was greater than 10(-)(5). The sensitivity analysis indicated that the cancer slope factor (SF), the ingestion rates of rice and the iAs concentration in rice were the most relevant variables affecting the assessment outcome. Based on these results, it is recommended that residents reduce their consumption of rice, though it should be noted that the assessment outcome has uncertainty due to estimating iAs from foodstuffs and not considering the bioaccessibility of iAs in foodstuffs. Nevertheless, measures like reducing industrial As emissions, forbidding the use of pesticides, fertilizers and sludge which contain As and optimizing water management in rice paddy fields should be taken to mitigate the risks.

Enterocytozoon bieneusi genotypes in children in Northeast China and assessment of risk of zoonotic transmission.

The prevalence (7.5%, 19/255) and genotypes of Enterocytozoon bieneusi in children of various age categories and clinical presentations were determined herein. The co-occurrence of the known genotypes (CS-4, EbpC, and Henan-IV) in children and pigs in the same study area, the phylogenetic characterization of novel genotypes (NEC1 to NEC5), and the assessment of potential risk factors associated with zoonotic transmission robustly suggested that pigs could be a significant source of human E. bieneusi infections in northeast China.

Penile skin lesions and urinary tract obstruction: A rare presentation of Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) can manifest in any organ or system, but the occurrence of cutaneous lesions on the penis, causing urethral stenosis, is particularly uncommon. The diagnosis primarily relies on typical clinical manifestations and pathological examination. Treatment involves the excision of local lesions combined with chemotherapy, with a generally favorable prognosis. A 3-year-old male patient experienced voiding difficulties after circumcision, revealing penile skin lesions upon examination. Postoperative pathological analysis and immunohistochemistry confirmed the diagnosis of LCH. Langerhans cell histiocytosis can present as cutaneous lesions on the penis, leading to symptoms of urinary tract obstruction.

Estimating the geographical patterns and health risks associated with PM2.5-bound heavy metals to guide PM2.5 control targets in China based on machine-learning algorithms.

PM2.5 is the main component of haze, and PM2.5-bound heavy metals (PBHMs) can induce various toxic effects via inhalation. However, comprehensive macroanalyses on large scales are still lacking. In this study, we compiled a substantial dataset consisting of the concentrations of eight PBHMs, including As, Cd, Cr, Cu, Mn, Ni, Pb and Zn, across different cities in China. To improve prediction accuracy, we enhanced the traditional land-use regression (LUR) model by incorporating emission source-related variables and employing the best-fitted machine-learning algorithm, which was applied to predict PBHM concentrations, analyze geographical patterns and assess the health risks associated with metals under different PM2.5 control targets. Our model exhibited excellent performance in predicting the concentrations of PBHMs, with predicted values closely matching measured values. Noncarcinogenic risks exist in 99.4% of the estimated regions, and the carcinogenic risks in all studied regions of the country are within an acceptable range (1 × 10-5-1 × 10-6). In densely populated areas such as Henan, Shandong, and Sichuan, it is imperative to control the concentration of PBHMs to reduce the number of patients with cancer. Controlling PM2.5 effectively decreases both carcinogenic and noncarcinogenic health risks associated with PBHMs, but still exceed acceptable risk level, suggesting that other important emission sources should be given attention.

Potential Risk, Spatial Distribution, and Soil Identification of Potentially Toxic Elements in Lycium barbarum L. (Wolfberry) Fruits and Soil System in Ningxia, China.

Eight potentially toxic elements (PTEs, including nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), lead (Pb), chromium (Cr), and mercury (Hg)) in Lycium barbarum L. (wolfberries) and the associated root soil from a genuine producing area were analyzed. The potential ecological risk of PTEs in the soil and the health risk of PTEs through wolfberry consumption were determined. Geostatistical methods were used to predict the PTE concentrations in the wolfberries and soil. Positive matrix factorization (PMF) was applied to identify the source of PTEs in the soil. The PTE concentrations in the soils were within the standard limits, and Cd in the wolfberries exceeded the standard limit at only one site. The bioconcentration factors (BCF) order for the different PTEs was Cd > Cu > 1 > Zn > Cr > As > Ni > Pb, indicating that Cd and Cu were highly accumulated in wolfberries. The multiple regression models for Ni, Cu, Zn, As, Pb, and Cr concentrations in the wolfberries exhibited good correlations (p < 0.1). The ecological risk for Hg in the soil was high, whereas the risks for the remaining PTEs were mostly medium or low. Health risks for inhabitants through wolfberry consumption were not obvious. The spatial distributions of the PTEs in the soil differed from the PTE concentrations in the wolfberries. Source identification results were in the order of natural source (48.2%) > industrial activity source (27.8%) > agricultural activity source (14.5%) > transportation source (9.5%). The present study can guide the site selection of wolfberry cultivation and ensure the safety of wolfberry products when considering PTE contamination.

[Distribution Characteristics of Soil Phosphorus Forms and Phosphatase Activity at Different Altitudes in the Soil of Water-Level-Fluctuation Zone in Pengxi River, Three Gorges Reservoir].

Phosphatases play important roles in converting organic phosphorus into inorganic phosphorus in soil. However, studies from this perspective on the water-level-fluctuation zone (WLFZ) of the Three Gorges Reservoir are limited. In this study, phosphatase activity and the forms of phosphorus were analyzed. Soil samples were collected in the river basin of the Penxi River in the WLFZ during a drying period. The correlation between phosphatase activity and phosphorus forms and the impacts of phosphatase activity on the phosphorus forms were analyzed. The results showed that the contents of H2O-Pi, NaHCO3-Pi, and NaOH-Pi in the soils of the WLFZ were higher than those in the soils by the river. In addition, a higher altitude resulted in higher contents of bio-enzymatically hydrolysable phosphorus and NaOH-Po. Furthermore, redundancy analysis (RDA) showed that the contents of organic matter and amorphous Fe and Mn were the main factors affecting soil organic phosphorus forms. The average activities of acid phosphomonoesterase (ACP), alkaline phosphomonoesterase (ALP), phosphodiesterase (PDE) (all in p-NP), and phytase (PAE) (in P) in the soils of the WLFZ were 1.40, 2.60, 0.44, and 11.43 µmol·(g·h)-1, respectively. Moreover, the activities of different phosphatases increased with altitude. Soil plant biomass and microbial biomass were important reasons for the difference in spatial distribution of phosphatase activity in the soil of the WLFZ. Phosphatase activities were significantly positively correlated with the contents of organic phosphorus forms but negatively correlated with the content of bioavailable phosphorus. A higher soil phosphatase activity and a lower content of bioavailable phosphorus were usually detected in soil samples taken at a higher altitude. In the early stage of flooding, phosphatase converted organic phosphorus into inorganic phosphorus at a relatively high rate, and the risk of phosphorus release to the overlying water body was also high. This study contributed to a comprehensive understanding of the geochemical cycle of soil phosphorus in the soil of the WLFZ.

High concentration and high dose of disinfectants and antibiotics used during the COVID-19 pandemic threaten human health.

The issue of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has created enormous threat to global health. In an effort to contain the spread of COVID-19, a huge amount of disinfectants and antibiotics have been utilized on public health. Accordingly, the concentration of disinfectants and antibiotics is increasing rapidly in various environments, including wastewater, surface waters, soils and sediments. The aims of this study were to analyze the potential ecological environment impacts of disinfectants and antibiotics by summarizing their utilization, environmental occurrence, distribution and toxicity. The paper highlights the promoting effects of disinfectants and antibiotics on antibiotic resistance genes (ARGs) and even antibiotic resistant bacteria (ARB). The scientific evidences indicate that the high concentration and high dose of disinfectants and antibiotics promote the evolution toward antimicrobial resistance through horizontal gene transformation and vertical gene transformation, which threaten human health. Further concerns should be focused more on the enrichment, bioaccumulation and biomagnification of disinfectants, antibiotics, antibiotic resistance genes (ARGs) and even antibiotic resistant bacteria (ARB) in human bodies.

The biotransformation of soil phosphorus in the water level fluctuation zone could increase eutrophication in reservoirs.

The massive amounts of phosphorus (P) entering into rivers and reservoirs may induce eutrophication. However, the link between the transport and transformation of soil P and the dynamics of P availability in reservoir regions are not well demonstrated. The present study selected the Pengxi River suffering the anti-seasonal water level fluctuation of the Three Gorgers Reservoir as the study area. Soil nutrients along the longitudinal and lateral gradients of the Pengxi River were investigated to illustrate the spatial distribution patterns, analyzed by the Hedley extraction schemes. The effects of biotic and abiotic factors on soil P transformation and the dynamics of bioavailable P were evaluated via determinations of enzymatic hydrolysis phosphorus (EHP) with and without ultraviolet (UV) irradiation. The results indicated that soil nutrients varied significantly between the water level fluctuation zone (WLFZ) and upland along the river longitudinal gradients, where the trends of the extracted OP were the same in H2O, NaHCO3 and NaOH extractions. The EHP accounted for 33.67 ± 15.87% of the total extracted OP, of which Monoester P, Phytate-like P and NHOP were determined at all extracts but Diester P was mainly found at H2O and NaOH extracts. UV irradiation significantly increased P bioavailability up to 24.44%. These results could demonstrate the mechanism of soil P transformation via UV irradiation and enzymatic hydrolysis. Therefore, the bioavailable P enters the water body during the submergence period may lead to eutrophication in the Pengxi River, which could pose a risk to the reservoir ecosystem.

Urbanization-related changes in soil PAHs and potential health risks of emission sources in a township in Southern Jiangsu, China.

Urbanization, which is characterized by population aggregation, industrial development, and increased traffic load, may change local polycyclic aromatic hydrocarbons (PAH) emissions and their associated health risks. To investigate these changes, we collected soil samples in 2009 and 2014 in a rapidly developing small town in Southern Jiangsu (China) and measured the concentrations of 16 PAHs via gas chromatography-mass spectrometry. Although the total PAHs decreased from 4586.6 to 640.6ng/g, the concentrations of the high-molecular-weight PAHs benzo(b)fluoranthene and benzo(a)pyrene increased due to changes in the PAH sources. Source apportionment by positive matrix factorization indicated that the two sources responsible for the highest soil PAH contributions changed from biomass combustion (42%) and coal combustion (32%) in 2009 to coal, biomass and natural gas combustion (35%) and diesel combustion (33%) in 2014. However, the two sources with the highest associated health risks were diesel and gasoline combustion in both years. The incremental lifetime cancer risk for residents exposed to PAHs in the soil via incidental ingestion and dermal contact decreased from 1.75×10-6 to 1.60×10-6. The ban on open burning of straw and the substitution of coal with natural gas offset the PAH health risks due to increased urbanization.

Determination of arsenic speciation and the possible source of methylated arsenic in Panax Notoginseng.

Arsenic species and a possible source of methylated arsenic in a Panax Notoginseng (PN) medicinal plant were explored to further understand the change of inorganic arsenic to the less toxic methylated form to minimize the health risks associated with its medicinal use. Arsenic speciation in PN from major planting areas was determined using high-performance liquid chromatography coupled with hydride generator-atomic fluorescence (HPLC-HG-AFS). Pot experiments were performed to explore the source of methylated arsenic in PN, and the arsenite methyltransferase (arsM) gene abundance was determined using quantitative reverse transcription PCR (q-RTPCR). Methylated arsenic (monomethylarsonic acid (MMA) + dimethylarsinic acid (DMA)) accounted for 43% ± 30% of the total arsenic in PN from planting areas, while the primary species in soil was As(V) (94% ± 0.12%). In the pot experiments, methylated arsenic accounted for 37%-49% of the total arsenic in PN, and As (V) was the primary species in soil (>98%). The four detected arsenic species in PN increased as the amount of As added to soil increased. The methylated arsenic contents in the PN root were significantly positively correlated with the ArsM gene abundance in soil, suggesting that methylated arsenic in PN is likely from the planting soil.