Effects of the interaction among climate, terrain and human activities on biodiversity on the Qinghai-Tibet Plateau.

Disentangling the driving factors of biodiversity is critical for understanding biogeographical patterns of vegetation and ecosystem function. However, the biotic and abiotic attributes that shape biodiversity on the Qinghai-Tibet Plateau (QTP) are still not been quantified. Previous studies have not distinguished the direct and indirect effects of climate, terrain, and human disturbance on biodiversity. In this study, we applied a structural equation model (SEM) to assess the interactions among 4 attributes and biodiversity. A conceptual framework with 8 explanatory variables was built to identify the driving forces of biodiversity. A geographically weighted regression (GWR) model was applied to explore the response sensitivity of biodiversity to climate, terrain, and human attributes. We found that the SEM passed the tests of validity, reliability and fit, indicating that the hypothetical model was reasonable and credible. Among terrain conditions, elevation had the greatest, most-negative effect on biodiversity. Among the human factors, distance to town showed the strongest and most negative influence on biodiversity. Among the climate factors, precipitation had the greatest influence on biodiversity. Moreover, the direct effects of terrain and human activity were 0.348 and 0.135, respectively, and their indirect effects were 0.769 and 0.213, respectively, revealing that they had stronger indirect effects on biodiversity than direct effects. Climate exhibited only direct effects on biodiversity and had no indirect effects. The total effects of climate, terrain and human activity on biodiversity were 1.39, 0.35 and 0.13, respectively, indicating that climate was the main driving force of biodiversity on the QTP. The response sensitivity of biodiversity to climate, terrain and human factors showed obvious spatial variations. This study contributes to exploring the interactive effects and driving mechanisms of human-natural attributes on biodiversity and provides further effective guidance and support for biodiversity conservation and restoration.

Long-term dynamics of nitrogen flow in a typical agricultural and pastoral region on the Qinghai-Tibet Plateau and its optimization strategy.

Nitrogen (N) plays a central role in livestock development and food production in agricultural and pastoral regions, while its flow and loss can affect environmental quality, biodiversity and human health. A comprehensive understanding of the sources, patterns and drivers of N flow helps to alleviate its negative effects and promote sustainable management. We developed a county-scale N flow model to quantitatively analyze the N use efficiency (NUE), N losses and their driving forces in the food production and consumption system (FCPS) on the Qinghai-Tibet Plateau (QTP). More sustainable N utilization was further investigated through scenario analyses. Our results revealed that N fluxes doubled from 1998 to 2018 to maintain the growing demands for human food production and consumption in Ledu County, which was related to the increasing N losses to the atmosphere and water environment. The surging N fluxes greatly changed the N distribution pattern, resulting in a relatively low NUE (mean value: 29.41%) in the crop-production subsystem (CPS) and a relatively high NUE (mean value: 23.50%) in the livestock-breeding subsystem (LBS). The CPS contributed the most to the N losses. The urban population, animal-derived consumption, crop planting structure, imported fodder and N fertilizer application level were closely associated with N losses. The scenario analysis indicated that combined reasonable changes in planting structure, precision animal feeding, fertilizer management, diets and conversion of cropland into pasture could reduce N losses in 2030 to 5%-61% of Business as usual level. Our results highlighted the strong anthropogenic impact on the N flow of food production and consumption and suggested a sustainable N flow management strategy to harmonize the relationship between N flow and anthropogenically driven factors on the QTP.

Air pollution and cause-specific mortality: A comparative study of urban and rural areas in China.

Air pollution increases the risks of all-cause mortality, cardiovascular mortality and respiratory mortality across China. However, the urban-rural differences in the associations between air pollution and mortality have not been clearly identified. In this study, a distributed lag nonlinear model was used to examine whether the air pollutants-mortality associations vary between urban and rural areas. Then, we used logistic regression analyses to evaluate the air pollutants-mortality relations. Also, generalized additive models were simulated to evaluate the nonlinear curves. Our results showed that the relative risks of air pollution-related mortality were generally higher in rural areas, where PM2.5 pollution was the dominant factor (p-value < 0.05). Mortality risks for all-cause, cardiovascular and respiratory will increase when average annual PM2.5 concentrations exceed approximately 38 µg/m3, 41 µg/m3 and 41 µg/m3, respectively, all of which exceed the annual Grade II standards. In urban areas, PM10-2.5 and NO2 were associated with mortality (p-value < 0.05). We proposed some area-specific strategies for controlling the NO2 pollution and PM10-2.5 pollution in urban areas and the PM2.5 pollution in rural areas to eliminate the gaps. Our findings identify that rural residents are more sensitive to air pollution than urban residents in China, and this result challenges previous assumptions about the more adverse effects of urbanization on residents' health in developing countries.

Assessing NO2-related health effects by non-linear and linear methods on a national level.

Exposure to NO2 pollution has a significant adverse effect on residents' health. However, few studies have assessed the health effects associated with NO2 pollution. Compared with PM2.5 pollution, the harmfulness of NO2 pollution has not been quantitatively studied or clearly identified. In this study, we assessed the NO2 exposure-related health effects by non-linear and linear methods, taking advantage of online monitoring and survey data. We also assessed the economic cost of NO2 pollution in 338 cities in China. Our results showed that the average annual concentration of NO2 in the top fifteen cities with more than ten million permanent residents (except for Shenzhen, in the Guangdong province) exceeded the annual Grade II standards (40 µg/m3). The estimated national NO2-related all-cause mortality for non-linear and linear methods were 388.5 × 103 (95% CI: 198.1 × 103-748.2 × 103) and 374.1 × 103 (95% CI: 194.3 × 103-695.9 × 103), respectively. The total calculated national economic cost was about 28.8 billion US$ (95% CI: 14.7-55.4) in 2016. In addition, the comparison results showed that the harm caused by PM2.5 pollution was about four times that of NO2 pollution. Our statistics contribute to the limited research on NO2 pollution's effects on health and the economy in China.

The spatio-temporal patterns of the topsoil organic carbon density and its influencing factors based on different estimation models in the grassland of Qinghai-Tibet Plateau.

The grassland soils of the Qinghai-Tibet Plateau (QTP) store a large amount of organic carbon because of the cold, humid climate, and topsoil organic carbon is quite sensitive to global climate changes. However, the spatio-temporal dynamics and factors that influence the soil organic carbon (SOC) on the QTP's grassland are not understood well. Moreover, there are few comparative analyses of different approaches to estimate the QTP' SOC. In this study, we estimated the storage and patterns of SOC density (SOCD) using several methods, including MODIS (moderate-resolution imaging spectroradiometer) retrieval, field data and previous empirical models (Models1-4, and soil organic matter (SOM)). And their relations with aboveground biomass, soil moisture, temperature, elevation, and soil conductivity were further explored. The results showed that SOC showed a similar variation trend in the different models, in which it decreased with increasing bulk density (BD) in the topsoil at 30 cm. For meadow and steppe grasslands, Models 1, 2, and 4 showed similar estimated values of SOCD, while Model3 had a lower value than them. SOC storage in the BD 3 and SOM methods had abnormal values, while the MODIS-NDVI, BD 1, 2, and 4 methods had similar SOC stock values for meadow and steppe grassland. Moreover, meadow grassland had a higher SOC storage than did steppe grassland, with means values of 397.9×1010 kg and 242.2×1010 kg, respectively. SOCD's spatial distribution using MODIS-NDVI method differed clearly from the empirical models, with a significant tendency for spatial variation that increased from the northwestern to southeastern regions on the QTP. Therefore, based on the values estimated and spatial variation features, the MODIS-NDVI method may be a more feasible and valid model to estimate SOC. Moreover, the mean annual SOCD values during 2000-2015 showed an increasing trend, with a higher mean value in meadow and a lower mean value in steppe. Further, SOCD was correlated significantly and positively with aboveground biomass and soil moisture, and negatively correlated with elevation and soil conductivity. Increasing temperature had negative effects on SOCD, which was consistent with the global trend. These results indicated that topsoil moisture plays a key role in SOCD spatial patterns. Our results provide valuable support for the long-term estimation of SOCD in future research on the QTP.

The alpine meadow around the mining areas on the Qinghai-Tibetan Plateau will degenerate as a result of the change of dominant species under the disturbance of open-pit mining.

Mining is well-known as one of the most aggressive human disturbances leading to massive and irreversible damages to natural ecosystems. However, the influence mechanisms of open-pit mining on plant communities and soil properties of alpine meadow on the Qinghai-Tibetan plateau are not well understood. In this study, we used structural equation modeling (SEM) to study the influence mechanisms in the disturbed areas of the Qulong copper mine. Our results revealed that the soil parameters of alpine meadow have been significantly changed by mining activities. SEM results showed that Plantago depressa Willd. was more suitable for growing in current soil conditions due to its tolerance to heavy metals than other dominant species, which meant that it would substitute the current two dominant species (Kobresia myosuroides (Villars) Fiori and Blysmus sinocompressus Tang et Wang) in the future and become the most important dominant species in the study area. Unfortunately, the Shannon-Wiener index, Alatalo evenness index and M-Gordon stability index are relatively low in the plot with Plantago depressa Willd. as the dominant species. In a word, the fragile alpine meadow ecosystem may degenerate in the future due to plants and soil disturbed by mining activities. Further, eight targeted recommendations were proposed to protect alpine meadow on the Qinghai-Tibetan plateau.

Identifying the contributions of multiple driving forces to PM10-2.5 pollution in urban areas in China.

Economic development and urban expansion have accelerated particulate matter pollution in urban areas in China. Particulate matter-driven haze poses a serious threat to human beings from a public health point of view. Substantial evidences had linked adverse health effects with exposures to PM2.5, but recent research indicated that PM10-2.5 also had great risk. However, the relative contributions of driving forces to PM10-2.5 pollution are not well understood in the urban areas in China, and no targeted policies have been regulated to control the pollution. In this study, we quantified the contributions of potential driving factor across China with the structural equation model (SEM). Our results showed that in 2015 and 2016, the annual average concentrations of PM10-2.5 in the 290 prefecture-level cities with a mean value of 36 and 35 µg/m3, respectively. Industrial scale contributed more to PM10-2.5 pollution than city size and residents' activities in urban areas based on SEM results. Driving forces included in our model could explain 42% of variations in PM10-2.5 pollution, which indicated that there existed influences from other anthropogenic sources and natural sources. Eleven targeted recommendations were then proposed to control PM10-2.5 pollution based on our mechanism analysis. Findings from our study are beneficial to control PM10-2.5 pollution on a national scale, and also can provide a theoretical basis for the formulation of PM10-2.5 pollution control policy in China.

Temporal dynamics of SO2 and NOX pollution and contributions of driving forces in urban areas in China.

SO2 and NOX pollution have significantly reduced the air quality in China in past decades. Haze and acid rain have negatively affected the health of animals, plants, and human beings. Documented studies have shown that air pollution is influenced by multiple socioeconomic driving forces. However, the relative contributions of these driving forces are not well understood. In this study, using the structural equation model (SEM), we quantified the contributing effects of various forces driving air pollution in 2015 in prefecture-level cities of China. Our results showed that there has been significant control of SO2 pollution in the past 20 years. The annual average SO2 concentration has dropped from 83 µg/m3 in 1996 to 21 µg/m3 in 2015, while the annual average NOX concentration has increased from 47 µg/m3 in 1996 to 58 µg/m3 in 2015. We evaluated data on the annual average concentrations of SO2, which in some cities may mask the differences of SO2 concentrations between different months. Hence, SO2 pollution should continue to be controlled in accordance with existing policies and regulations. However, we suggest that NOX should become the new focus of air pollution prevention and treatment. The SEM results showed that industrial scale, city size, and residents' activities have a significant impact on NOX pollution. Among these, industrial scale had the highest contribution. The findings from our study can provide a theoretical basis for the formulation of NOX pollution control policy in China.

Excision of a mediastinal parathyroid adenoma after coronary artery bypass surgery.

In this report we describe the removal of a mediastinal parathyroid adenoma in a patient who had two previous coronary artery bypass graft procedures. The surgical approach and intraoperative localization of the adenoma under these unusual circumstances are reviewed.

Rapid preoperative preparation for severe hyperthyroid Graves' disease.

Thyroidectomy (TX) is no longer the preferred choice for the therapy of hyperthyroid Graves' disease but is an alternative in patients who are noncompliant with or have reactions to antithyroid drugs, have moderate to severe ophthalmopathy, have large goiters, or who refuse (131)I therapy and/or long-term antithyroid drug therapy. Seventeen clinically and biochemically severely thyrotoxic patients (16 female, mean age of 35 yr), all but one with large goiters, underwent TX after rapid preparation. The potent inhibitors of the deiodination of T(4) to T(3), iopanoic acid (IOP) (500 mg twice a day) and dexamethasone (DEX) (1 mg twice a day), were given with propylthiouracil or methimazole, when possible, and beta-blockers. Thyroid function tests were obtained before treatment and at TX. All patients were thyrotoxic (mean +/- SE: T(4), 21.6 +/- 1.2 micro g/dl; free T(4) index (FTI), 10.3 +/- 0.8; total T(3), 510 +/- 48 ng/dl). IOP and DEX rapidly lowered T(3) values (P < 0.0001; total T(3), 147 +/- 13 ng/dl) with a smaller but significant (P < 0.05) decrease in T(4)/FTI (T(4), 17.9 +/- 1.3 micro g/dl; FTI, 7.9 +/- 0.6). All patients were clinically euthyroid before surgery. None developed hypoparathyroidism, laryngeal nerve damage, or worsening of ophthalmopathy after surgery. The restoration of hyperthyroid Graves' disease to euthyroidism is rapidly accomplished with IOP and DEX, beta-blockers, and, when possible, antithyroid drugs. This is especially relevant in noncompliant patients with large goiters.