Characteristics of heavy metal concentrations and risk assessment for giant pandas and their habitat in the Qinling Mountains, China

Heavy metal exposure risk to black-winged stilt (Himantopus himantopus) in a typical industrial city in northwest of China

Heavy metal pollution poses a critical threat to waterfowl, and a quantitative risk assessment model is significant for accurately evaluating the threat level and providing early warning of the potential harm before the situation becomes nonreversible. In this study, the exposure risk of heavy metals to black-winged stilt (Himantopus himantopus) was assessed in three districts (Dawukou District, Huinong District and Pingluo County) of Shizuishan, an important industrial city in northwestern China. The results showed that Cr, Cd, Pb and Zn concentrations in habitat soil or water exceeded the local background levels or the permissible safe limits, which were the main heavy metal pollutants in the habitats. Cd and Cr were the most major heavy metals causing potential ecological hazards in the habitat. The food pathway and soil pathway were the main routes of exposure to heavy metals in waterfowl, and Cr was the priority pollutant in waterfowl conservation in Shizuishan due to the high health risk grade. The combined risks of heavy metals were high in all three districts; however, the potential health hazards to waterfowl in Dawukou District, a region historically associated with coal mining activities that has undergone years of ecological remediation, especially need to focus attention. Our findings provide a scientific basis for waterfowl conservation and their habitat improvement management in industrial cities.

Pollution characteristics of heavy metals, antibiotic and antibiotic resistance genes in the crested ibis and their habitat across different lifestyle and geography

Antibacterial resistance in wild animals has been increasingly reported worldwide, even though they are usually not directly exposed to clinically relevant antibiotics. Crested ibis, one of the rarest birds in the world, usually forages in paddy fields and prefer to nest and breed near villages that is greatly influenced by anthropogenic activities. We sampled the feces of crested ibises, as well as their habitat environment samples, to explore the pollution characteristics of heavy metals, antibiotics and antibiotic resistance genes (ARGs). Results showed that the pollution characteristics of heavy metals, antibiotic, ARGs and gut microbiota of crested ibis were more related by host lifestyle and habitats. Captive ibises had higher relative abundances of the total ARGs and tetracycline concentrations compared with feralization and wild ibises, while the heavy metal contents had shown the opposite result. The Characteristics of pollutants in the corresponding environmental samples also exhibited high similarity with the results of fecal samples. The relative abundances of Proteobacteria and Actinobacteria were significantly different between captive and wild individuals, while the abundance of majority bacterial genera was generally higher in wild populations. The concentrations of heavy metals in soil (Cd, Cu and Zn) and water (Cd, Cu, Zn and Cr) were both exceeded the background soil levels or surface water quality standards, suggesting multi-element contamination in the habitat. Ecological risk assessments of soils by Igeo and Er showed that the habitats of wild ibises were heavily and moderately contaminated by Cd, which would possibly pose a threat to the health of ibises. PLS-PM analysis indicated that microbial compositions and residual antibiotics had the most substantial impact on the dynamic changes in ARGs of ibis. Overall, this work provides a comprehensive understanding of the characteristics, risks of those contaminations, and their effects on the ARGs in the habitat of crested ibis.

Factors influencing the distribution, risk, and transport of microplastics and heavy metals for wildlife and habitats in "island" landscapes: From source to sink

Microplastics (MPs) and heavy metals (HMs) are important pollutants in terrestrial ecosystems. In particular, the "island" landscape's weak resistance makes it vulnerable to pollution. However, there is a lack of research on MPs and HMs in island landscapes. Therefore, we used Helan Mountain as the research area. Assess the concentrations, spatial distribution, ecological risks, sources, and transport of MPs and HMs in the soil and blue sheep (Pseudois nayaur) feces. Variations in geographical distribution showed a connection between human activity and pollutants. Risk assessment indicated soil and wildlife were influenced by long-term pollutant polarization and multi-element inclusion (Igeo, Class I; PHI, Class V; RI (MPs), 33 % Class II, and 17 % Class IV; HI = 452.08). Source apportionment showed that tourism and coal combustion were the primary sources of pollutants. Meanwhile, a new coupling model of PMF/Risk was applied to quantify the source contribution of various risk types indicated transportation roads and tourism sources were the main sources of ecological and health risks, respectively. Improve the traceability of pollution source risks. Furthermore, also developed a novel tracing model for pollutant transportation, revealing a unique "source-sink-source" cycle in pollutant transportation, which provides a new methodological framework for the division of pollution risk areas in nature reserves and the evaluation of spatial transport between sources and sinks. Overall, this study establishes a foundational framework for conducting comprehensive risk assessments and formulating strategies for pollution control and management.

Studies of a Naturally Occurring Selenium-Induced Microcytic Anemia in the Przewalski's Gazelle

Due to the fencing of the Przewalski's gazelle (Procapra przewalskii), the microcytic anemia incidence rate continues to increase. The primary pathological symptoms include emaciation, anemia, pica, inappetence, and dyskinesia. To investigate the cause of microcytic anemia ailment in the Przewalski's gazelle, the Upper Buha River Area with an excessive incidence was chosen as the experimental pasture, and the Bird Island Area without microcytic anemia disease was chosen as the control field. Then, the mineral contents in the soil, forage, blood, and liver, as well as the blood routine parameters and biochemical indexes were measured. The findings showed that the experimental pasture had much lower Se content in the soil and forage than the control field (p < 0.01), while the impacted pasture had significantly higher S content in the forage. The damaged gazelles had considerably lower Se and Cu contents and higher S content in the blood and liver than the healthy gazelles (p < 0.01). The presences of Hb, HCT, MCV, and MCH were significantly decreased compared to those in healthy gazelles (p < 0.01). The experimental group had a significantly lower level of GSH-Px activity in their serums compared to the control group (p < 0.01). In the treatment experiment, ten gazelles from the affected pasture were orally administered CuSO4, 6 g/animal once every 10 days for two consecutive times, and all gazelles were successfully cured. Therefore, it is possible that low Se content in the soil induced an increase in the absorption of S content by forage, leading to the deficiency of secondary Cu in the Przewalski's gazelles, resulting in microcytic anemia.

The potential risks and exposure of Qinling giant pandas to polycyclic aromatic hydrocarbon (PAH) pollution

Rapid industrialization and urbanization have created a substantial urban-rural gradient for various pollutants. The Qinling Mountains are highly important in terms of biodiversity, providing habitat for giant pandas, which are endemic to China and are a widely recognized symbol for conservation. Whether polycyclic aromatic hydrocarbon (PAH) exposure risks regarding in situ animal conservation zones are affected by environmental pollution or even enhanced by the mountain-trapping effect requires further research. Our group carried out a large-scale investigation on the area ranging from Xi'an to Hanzhong across the giant panda habitat in the Qinling Mountains by collecting atmosphere, soil, bamboo, and fecal samples from different sites over a two-year period. The total toxicity of atmospheric PAHs and the frequencies of soil PAHs above effect range low (ERL) values showed a decreasing trend from urban areas to the central mountains, suggesting a distance effect from the city. The proportions of total 5- and 6-ring PAHs in the atmosphere were higher in the central mountainous areas than in the urban areas, while this difference was reversed in the soil. Health risk assessments showed that the incremental lifetime carcinogenic risks (ILCR) of PAH exposure by bamboo ingestion ranged from 2.16 × 10^-4 to 3.11 × 10^-4, above the critical level of 10^-4. Bamboo ingestion was the main driver of the PAH exposure risks. The concentration difference between bamboo and fecal samples provided a reference for the level of PAHs absorbed by the panda digestive system. Since the Qinling Mountains possess the highest density of giant pandas and provide habitats to many other endangered animal and plant species, we should not ignore the probability of health risks posed by PAHs. Monitoring the pollution level and reducing the atmospheric emissions of toxic pollutants are recommended actions. Further detailed research should also be implemented on pandas' health effects of contaminant exposure.

Seasonal variation and positive matrix factorization result reveal the sources of giant pandas' exposure to POPs

Persistent organic pollutant (POPs) contamination was analyzed in samples collected from wild and captive giant pandas to characterize seasonal variation in concentrations of POPs and possible sources. POP concentrations in bamboo and fecal samples collected from captive pandas showed significant fluctuations compared with those collected from wild pandas in each season. The highest polychlorinated biphenyl (PCB) and organochlorine pesticide (OCP) concentrations were 1380 pg g^-1 dw and 3140 pg g^-1 dw, respectively, which were observed in captive bamboo samples in the summer. PCBs varied seasonally, whereas OCPs did not show apparent seasonal variation. Based on the seasonal variability, component analysis, and the positive matrix factorization results, we determined that the secondary volatilization of POPs during periods of high temperatures was the leading cause of the exposure of pandas to pollutants (45%), and atmospheric transport played a crucial role in the secondary distribution of pollutants in panda food. The other two sources of pollution were historical residues transmitted over long distances to protected areas (28%), as well as UP-POPs and new inputs from agricultural activities (27%). The concentrations of pollutants in bamboo shoots were significantly lower than those in bamboo. Therefore, bamboo shoots should be incorporated into the diet of captive pandas in the spring to reduce their exposure to pollutants. The absorption capacity of pollutants associated with the consumption of bamboo shoots was significantly lower than that associated with the consumption of bamboo. The diet of young captive pandas in the summer should also be managed with caution given their slightly stronger ability to absorb pollutants.

Quantifying the heavy metal risks from anthropogenic contributions in Sichuan panda (Ailuropoda melanoleuca melanoleuca) habitat

Heavy metals (HM) are ubiquitous in environments, and HM pollution has become a severe global crisis. Previous studies have identified HM levels in Qinling panda habitats but their levels and the associated risks in Sichuan panda habitats are still unknown. Risk-based conservation management is in urgent need and should rely upon identifying risk distributions, quantified risk-source apportionment and collaborative governance. We carried out research in Sichuan panda (Ailuropoda melanoleuca melanoleuca) habitats taking soil, bamboo, and water samples from three different areas (nature reserves, potential habitats, and surrounding regions) of five mountains. The concentrations of HM in the soil were higher than those in bamboo, but both exceeded the background or national standards to varying degrees, suggesting long-term pollution and multi-element contamination. Regional and geographical distribution differences revealed a positive correlation between intensity of human activities and HM pollution. HM contaminants observed in the Sichuan panda habitats, based on their sources, were categorized into coal combustion (34%), industry (44%), and traffic (22%). In particular, our results showed the northern and southern parts of habitat were of highest concern, as they had environmental conditions that could be harmful to the health of giant pandas. Coupling models applying positive matrix factorization model/risk were used to quantify source contributions to various risk types, which was based on real-time monitoring and served as a positive role in multi-step process for developing countermeasures, with the goal of collaboratively reframing the vision and governance of panda conservation in order to incorporate regional disparities.

Characteristics and impacts of solid waste on giant panda habitat in Wanglang Nature Reserve

Systematic research on solid waste pollution in giant panda habitat is lacking. To fill in this gap in the literature, a survey for solid waste was conducted in Wanglang Nature Reserve in July and August of 2018 and 2019. A total of 16 transects, 16 giant panda habitat plots, 16 livestock habitat plots, and 16 common habitat plots were surveyed. We analyzed the type and distribution of solid waste and the possible impacts of typical solid waste. Results showed that 133 solid waste samples from the five categories (livestock feces, plastic waste, metal waste, construction waste, and paper waste) were detected. Livestock feces accounted for the highest proportion of solid waste at 82.7%, while the remaining types of waste accounted for only 17.3% of the solid waste observed. Livestock feces were distributed relatively evenly within 400 m from roads, while 69.6% of non-livestock fecal waste were distributed 0-100 m away from roads. Giant panda habitat and common habitat (shared by giant pandas and livestock) did not significantly differ in habitat characteristics, but livestock habitat was significantly different from them in the number of trees and the height of bamboo. Specifically, livestock habitat had more trees and shorter bamboo. Based on the short bamboo located in livestock habitat, we predicted that bamboo in the common habitat has a high probability of being damaged by livestock. To limit solid waste pollution, livestock should be forbidden from entering giant panda habitat. In addition, tourism and infrastructure construction activities should be strictly controlled. To ensure the effectiveness of conservation, the needs and possible contributions of residents in surrounding communities should be taken into account in the giant panda conservation plan, and routine monitoring of solid waste should be performed.