PM2.5对秦岭野生大熊猫健康的潜在风险评估

Health risk assessment of PM2.5 exposure for wild giant pandas in the Qinling Mountains

关键词:  大熊猫  PM_2.5  秦岭山脉  健康风险

Key words:  giant panda  PM_2.5  Qinling Mountains  health risk

摘要:

秦岭大熊猫栖息地人迹罕至且管理严格，栖息地内的环境污染物主要来自大气运动与颗粒物沉降过程，然而其对野生大熊猫产生的健康风险却知之甚少。基于对陕西佛坪国家级自然保护区大气PM_2.5的长期监测与分析，评价PM_2.5对秦岭野生大熊猫健康的潜在风险。结果表明：通过进食竹叶而摄入附着在叶面上的大气颗粒物是危害大熊猫健康的主要方式之一，该途径的大气PM_2.5年暴露剂量约为72787.12 mg，其中，As、Cr、Mn元素具有较高的非致癌风险，As、Co、Cr、Ni元素具有较高的致癌风险。通过呼吸途径的大气PM_2.5年暴露剂量仅为98.35 mg。大熊猫主食竹的调查结果表明：保护区内两种主食竹的分布区域、生存环境、外观形态以及对大熊猫产生的影响均具有明显差异，秦岭箭竹（Fargesia qinlingensis）竹叶的单位质量面积约为巴山木竹（Arundinaria fargesii）的1.89倍。野生大熊猫通过取食巴山木竹，日均大气PM_2.5的暴露剂量约为171.76 mg，通过取食秦岭箭竹日均暴露剂量约为325.15 mg。气候变暖会延长野生大熊猫在高海拔区域的栖息时间，增长其进食秦岭箭竹的周期，间接增加大气颗粒物的暴露剂量，增大环境污染物对野生大熊猫的威胁。

Abstract:

Background, aim, and scope In recent years, there have been increasing concerns about the impact of environmental pollutants on the health of giant pandas (Ailuropoda melanoleuca). Originating primarily from external sources, pollutants that enter panda habitats are transported and deposited through atmospheric processes and particulate matter (PM) deposition. Specifically, PM_2.5 can directly enter the bodies of giant pandas via inhalation and ingestion. These fine particles adhere to the surface of bamboo leaves, the primary food source for giant pandas, thereby posing a substantial threat to their health. Aiming to assess the potential health risks of PM_2.5 exposure for wild giant pandas in the Qinling Mountains, this study quantified intake doses through inhalation and dietary pathways. Associated carcinogenic and non-carcinogenic risks were systematically evaluated and combined with PM_2.5 source apportionment analysis to lay a scientifically robust foundation for future conservation strategies. Materials and methods The concentration of PM_2.5 and its elements, along with the distribution and morphology of bamboo, were analyzed in the Shaanxi Foping National Nature Reserve. Afterward, a health risk assessment model recommended by the United States Environmental Protection Agency was used to examine the potential impact of PM_2.5 on wild giant pandas in the Qinling Mountains. Results In wild giant pandas, dietary intake is the primary route of PM_2.5 ingestion, with an annual exposure dose of 72787.12 mg; in contrast, the inhalation route contributes only 98.35 mg. The results of carcinogenic and non-carcinogenic risk assessments similarly suggest that dietary intake is the dominant route through which PM_2.5 poses health risks to giant pandas. Among the elements analyzed, As, Cr, and Mn exhibited elevated non-carcinogenic risks, whereas As, Co, Cr, and Ni demonstrated elevated carcinogenic risks. A morphological analysis of bamboo leaves in the reserve revealed significant differences between Arundinaria fargesii and Fargesia qinlingensis in leaf area and mass: the specific area per unit mass of the latter is about 1.89 times greater than that of the former. Consequently, the average daily PM_2.5 exposure doses for wild pandas from the consumption of A. fargesii and F. qinlingensis amounted to 171.76 mg and 325.15 mg, respectively. Discussion Based on source apportionment of PM_2.5 in the reserve, the primary emission sources from the surrounding regions included coal and biomass combustion, as well as transportation. Therefore, to mitigate the threat of these pollutants, it is crucial to upgrade the local energy mix and promote the adoption of energy-efficient and low-emission vehicles. Global warming is extending the habitat duration of wild pandas in high-altitude regions, lengthening the period during which wild giant pandas feed on F. qinlingensis. This indirectly increases the exposure dose of PM_2.5 through dietary intake, elevating the risk of giant panda exposure to environmental pollution. Conclusions Dietary intake is the primary means by which wild giant pandas ingest PM_2.5, which is also the principal factor threatening the health of giant pandas in the wild. Global warming is likely to prolong the habitat duration of wild pandas in high-altitude regions, driving up F. qinlingensis consumption, and consequently intensifying the threat of environmental pollutants. Recommendations and perspectives This study has analyzed the primary pathways through which PM_2.5 poses potential health risks for wild giant pandas in the Qinling Mountains. Furthermore, global warming has been shown to potentially exacerbate the impact of atmospheric PM in combination with the distribution of bamboo forests in the reserve. However, to reduce the threat of environmental pollution to pandas, further research is still needed on pollutants and the toxicology of giant pandas.