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Application of Ecosystem Service Bundles and Tour Experience in Land Use Management: A Case Study of Xiaohuangshan Mountain (China)
No full textWith the deterioration of human-terrestrial relations and the intensification of global warming, development in all countries is facing difficulties. Whether in highly urbanized countries or in rapidly urbanizing developing countries such as China, the research on ecosystem services (ES) and land use management has attracted increasing attention. The general management of land use unilaterally pursues economic benefits and neglects ecological benefits, which aggravates the disparity between ecological development and the economic benefits of land resources. How to strike up a balance between ecologic protection and economic development remains a difficult problem during urbanization. It may be a better choice to formulate regional development strategies by combining natural conditions with humanistic and social tendencies. Identifying regional cultural ecosystem services (CES) and other important ES while performing zoning planning for regional land use can be a viable approach in land use management. Here, our study quantitatively evaluates the tourism experience of Xiaohuangshan Mountain (XHSM) and various ES, including recreation, biodiversity, history, aesthetics, soil conservation, surface water regulation, and soil nutrition. All ES were classified into four bundles for XHSM. Different ES bundles generated are suitable for different land use management methods and development forms according to their outstanding ES. The results show that quantifying and mapping regional ES bundles can provide the necessary information to support a win-win solution and provide decision support for land and spatial planning in areas with different social and ecological characteristics
Response of summer extreme precipitation over East Asia during the mid-Holocene versus future global warming
No full textChanges in extreme precipitation have significant impacts on society and the environment. In recent years, the response of extreme precipitation over East Asia to global warming has received considerable attention; however, few studies have focused on the extreme precipitation in geological warm periods, especially the mid-Holocene-the most recent warm period on the orbital timescale. In this study, the outputs of mid-Holocene, preindustrial and CO2-induced warming experiments using a coupled climate model (MPI-ESM-P) were employed to examine the changes in extreme precipitation over East Asia in the mid-Holocene and under future warming scenario, respectively. The results show that, during the mid-Holocene, summer extreme precipitation increases over the east of China but decreases over Japan and the surrounding oceans. However, under CO2-induced warming, summer extreme precipitation increases over the southeast of China, Japan, and the surrounding oceans, but decreases over the north of East Asia. Moisture budget analysis shows that these distinct responses come from different changes in moisture and circulation during the two periods. During the mid-Holocene, higher insolation over the Northern Hemisphere leads to a larger ocean-land thermal contrast and a stronger East Asian summer monsoon (EASM). The strengthened EASM brings more moisture to continental East Asia, resulting in an increase in both mean and extreme precipitation. In contrast, the CO2-induced warming facilitates an anomalous heating center in the upper troposphere over the tropical part of Northwestern Pacific ocean, which weakens the EASM. However, enhanced atmospheric moisture counterbalances the effect of the weakened EASM, resulting in more extreme precipitation over the south of East Asia
Correlation and anti-correlation of the Asian summer monsoon and westerlies during the Holocene
No full textThe relationship between the Asian summer monsoon (ASM) and westerlies at different timescales is still under discussion. In this paper, we present Holocene precipitation records derived from loess and lake sediment in the northeastern Tibetan Plateau and reconstruct changes in the strength of the ASM during the Holocene. Compared with other Eurasian paleohydroclimatic records, we find that precipitation variations between ASM- and westerlies-dominant regions are positively correlated (anti-correlated) at millennial (sub-orbital) timescales. Based on the analysis of the TraCE-21 results, we suggest that Atlantic meridional overturning circulation may be the primary reason for this in-phase pattern at millennial timescales whereas this anti-phased pattern at sub-orbital timescales is attributed to precessional changes. Due to different response mechanisms, the relationship between the ASM and westerlies may differ significantly at different timescales, which highlights the complex dynamic characteristics of atmospheric systems in the Northern Hemisphere and the challenges for future predictions. (C) 2020 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved
Estimating Absorption Angstrom Exponent of Black Carbon Aerosol by Coupling Multiwavelength Absorption with Chemical Composition
No full textLight absorption by black carbon (BC) and brown carbon (BrC) aerosols determines their impacts on climate warming, and the absorption Angstrom exponent (AAE ) attribution method often is used to distinguish the contributions of the two species to light absorption, but obtaining an accurate value for BC AAE (AAE(BC)) has proven challenging. In this study, a receptor model was coupled with multiwavelength absorption information for light-absorbing aerosols used to retrieve a site-dependent AAE(BC) that reflected the optical properties of the bulk BC aerosol. The results of a positive matrix factorization model showed that AAE(BC )could be separated in contributions from two BC-related factors (pure-BC and BC-rich) during the campaign, and the retrieved average AAE(BC) was 1.19, which is within the range of values obtained through source-related experiments and numerical calculations. The BrC light absorption estimated from AAE(BC) = 1.19 was significantly different from the value (i-e.,AAE(BC) = 1.0) usually assumed in the literature. Our study provides insights that can improve the accuracy in quantifying the light absorption caused by carbonaceous aerosols, especially BrC
Megadrought and cultural exchange along the proto-silk road, in the context of debate over human-environment interactions
No full textDistinct effects of winter monsoon and westerly circulation on dust aerosol transport over East Asia
No full textThe transport of dust aerosol in East Asia is affected by the East Asian winter monsoon (EAWM) and westerly circulation both for modern and geological periods. There are obvious seasonal changes in the intensity and range of EAWM and westerly jet; however, their impacts and relative contributions to East Asian dust transmission are still unclear. In this study, we use Regional Climate Model 4 (RegCM4) to simulate the changes in the East Asian dust cycle under present conditions, assessing the effects of EAWM and westerly jet on dust transport. The results show that the dust at the upper level is mainly transported by the westerly circulation, while that of the lower layer is mainly transported by the EAWM. In March, the westerly jet is located on the south side of the Tibet Plateau, and the high-level dust aerosol is transmitted eastward to the northern Pacific. Low-level dust is transmitted to the southeastern China with the influence of EAWM. With the northward shift of the westerly jet, the control range of the westerly winds increases in May and their correlations are weakened. In contrary, the impact of EAWM on the lower layer dust is enhanced. Due to the strengthened interaction between the westerly winds and the EAWM, they can both affect the middle-level dust transmission. The effect of EAWM is sensitive to the dust particle sizes. Under the action of EAWM, fine-grained dust is transmitted far away, while coarse-grained dust is limited to the vicinity of the source area. Once the dust is carried to the westerly layer, the influence of westerly winds on the transmission of different particle sizes dust is similar
Asymmetric Effect of El Nino-Southern Oscillation on the Spring Precipitation over South China
No full textSouth China is one of the most densely populated and agriculture-based regions in China. Local spring precipitation is crucial to the people's livelihood and social economic development. Using the observed and reanalysis datasets for the period 1958-2019, this study revealed an asymmetric effect of El Nino-Southern Oscillation (ENSO) on the following spring precipitation over South China. During the years with positive ENSO phases, a strong positive correlation between spring precipitation and the preceding winter ENSO sea surface temperature (SST) anomalies existed over Guangdong province. For the years with negative ENSO phases, such a strong positive correlation shifts westwards to Guangxi province. To be specific, the El Nino events usually result in a precipitation surplus in the decaying spring over Guangdong province, while the La Nina events usually lead to a precipitation deficit in the decaying spring over Guangxi province. This is attributed to the nonlinear effects of ENSO on the atmospheric circulation. Compared with El Nino, the abnormal center of La Nina evidently extends westwards, inducing a westward movement of the anomalous low-level atmospheric circulation, which eventually results in a westward-shifted effect on the following spring precipitation over South China. Our findings emphasize the nonlinear responses of spring precipitation over South China to ENSO. This has important implications for the seasonal climate predictions over South China
Characteristics of indoor dust in an industrial city: Comparison with outdoor dust and atmospheric particulates
No full textThere is a considerable connection between indoor and outdoor environments. However, few studies have explored their intrinsic relationship until now. This study conducted morphologic observation, heavy metal monitoring and isotopes analysis in indoor and outdoor dust, as well as the atmospheric particulates in Hefei. Morphologic analysis demonstrated atmospheric particulates were affected by fly ash and construction, road dust mainly came from automobile exhaust and indoor dust particles were interfered by multiple sources, including the secondary reaction of fly ash. Chemical speciation analysis of heavy metals showed the exchange of heavy metals between atmospheric particulates and indoor dust was dominated by non-residual metals, while the exchange between road dust and indoor dust tended to rely on residual metals. The assessment results of heavy metals in particulates showed that indoor carcinogenic risks were greater than outdoor for children, however, for adults, outdoor carcinogenic risks were greater than indoor. Stable isotopes analysis indicated carbon in the dust outside buildings was derived from flying dust, and atmospheric particulates might derive from vehicle exhaust, or partly from natural gas. While sulfur in atmospheric particulates was derived mainly from coal combustion. The release from indoor activities, especially natural gas exhaust emitted from cooking had a certain impact on atmospheric particulates. (C) 2021 Elsevier Ltd. All rights reserved
A new method for long-term source apportionment with time-dependent factor profiles and uncertainty assessment using SoFi Pro: application to 1 year of organic aerosol data
No full textA new methodology for performing long-term source apportionment (SA) using positive matrix factorization (PMF) is presented. The method is implemented within the SoFi Pro software package and uses the multilinear engine (ME-2) as a PMF solver. The technique is applied to a 1-year aerosol chemical speciation monitor (ACSM) dataset from downtown Zurich, Switzerland.
The measured organic aerosol mass spectra were analyzed by PMF using a small (14 d) and rolling PMF window to account for the temporal evolution of the sources. The rotational ambiguity is explored and the uncertainties of the PMF solutions were estimated. Factor-tracer correlations for averaged seasonal results from the rolling window analysis are higher than those retrieved from conventional PMF analyses of individual seasons, highlighting the improved performance of the rolling window algorithm for long-term data.
In this study four to five factors were tested for every PMF window. Factor profiles for primary organic aerosol from traffic (HOA), cooking (COA) and biomass burning (BBOA) were constrained. Secondary organic aerosol was represented by either the combination of semi-volatile and low-volatility organic aerosol (SV-OOA and LV-OOA, respectively) or by a single OOA when this separation was not robust. This scheme led to roughly 40 000 PMF runs. Full visual inspection of all these PMF runs is unrealistic and is replaced by predefined user-selected criteria, which allow factor sorting and PMF run acceptance/rejection. The selected criteria for traffic (HOA) and BBOA were the correlation with equivalent black carbon from traffic (eBC(tr)) and the explained variation of m/z 60, respectively. COA was assessed by the prominence of a lunchtime concentration peak within the diurnal cycle. SV-OOA and LV-OOA were evaluated based on the fractions of m/z 43 and 44 in their respective factor profiles. Seasonal pre-tests revealed a noncontinuous separation of OOA into SV-OOA and LV-OOA, in particular during the warm seasons. Therefore, a differentiation between four-factor solutions (HOA, COA, BBOA and OOA) and five-factor solutions (HOA, COA, BBOA, SVOOA and LV-OOA) was also conducted based on the criterion for SV-OOA.
HOA and COA contribute between 0.4-0.7 mu g m(-3) (7.8 %-9.0 %) and 0.7-1.2 mu g m(-3) (12.2 %-15.7 %) on average throughout the year, respectively. BBOA shows a strong yearly cycle with the lowest mean concentrations in summer (0.6 mu g m(-3), 12.0 %), slightly higher mean concentrations during spring and fall (1.0 and 1.5 mu g m(-3), or 15.6% and 18.6 %, respectively), and the highest mean concentrations during winter (1.9 mu g m(-3), 25.0 %). In summer, OOA is separated into SV-OOA and LV-OOA, with mean concentrations of 1.4 mu g m(-3) (26.5 %) and 2.2 mu g m(-3) (40.3 %), respectively. For the remaining seasons the seasonal concentrations of SV-OOA, LV-OOA and OOA range from 0.3 to 1.1 mu g m(-3) (3.4 %-15.9 %), from 0.6 to 2.2 mu g m(-3) (7.7 %33.7 %) and from 0.9 to 3.1 mu g m(-3) (13.7 %-39.9 %), respectively. The relative PMF errors modeled for this study for HOA, COA, BBOA, LV-OOA, SV-OOA and OOA are on average +/- 34 %, +/- 27 %, +/- 30 %, +/- 11 %, +/- 25 % and +/- 12 %, respectively
Orbital-scale Asian summer monsoon variations: Paradox and exploration
No full textThe Asian summer monsoon (ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in understanding variations on a wide range of timescales, yet several significant issues remain unresolved. Of note are two long-standing problems concerning orbital-scale variations of the ASM. (1) Chinese loess magnetic susceptibility records show a persistent glacial-interglacial dominated similar to 100 kyr (thousand years) periodicity, while the cave oxygen-isotope (delta O-18) records reveal periodicity in an almost pure precession band (similar to 20 kyr periodicity)-the "Chinese 100 kyr problem". (2) ASM records from the Arabian Sea and other oceans surrounding the Asian continent show a significant lag of 8-10 kyr to Northern Hemisphere summer insolation (NHSI), whereas the Asian cave delta O-18 records follow NHSI without a significant lag-a discrepancy termed the "sea-land precession-phase paradox". How can we reconcile these differences? Recent and more refined model simulations now provide spatial patterns of rainfall and wind across the precession cycle, revealing distinct regional divergences in the ASM domain, which can well explain a large portion of the disparities between the loess, marine, and cave proxy records. Overall, we also find that the loess, marine, and cave records are indeed complementary rather than incompatible, with each record preferentially describing a certain aspect of ASM dynamics. Our study provides new insight into the understanding of different hydroclimatic proxies and largely reconciles the "Chinese 100 kyr problem" and "sea-land precession-phase paradox"