Ya Tang

Marginal Land‐based Biomass Energy Production in China

Fast economic development in China has resulted in a significant increase in energy demand. Coal accounts for 70% of Chinas primary energy consumption and its combustion has caused many environmental and health problems. Energy security and environmental protection requirements are the main drivers for renewable energy development in China. Small farmland and food security make bioenergy derived from corn or sugarcane unacceptable to China: the focus should be on generating bioenergy from ligno-cellulosic feedstock sources. As China cannot afford biomass energy production from its croplands, marginal lands may play an important role in biomass energy production. Although on a small scale, marginal land has already been used for various purposes. It is estimated that some 45 million hm(2) of marginal land could be brought into high potential biomass energy production. For the success of such an initiative, it will likely be necessary to develop multipurpose plants. A case study, carried out on marginal land in Ningnan County, Sichuan Province with per capita cropland of 0.07 ha, indicated that some 380,000 tons of dry biomass could be produced each year from annual pruning of mulberry trees. This study supports the feasibility of producing large quantities of biomass from marginal land sources.

The effect of grazing on bumblebees in the high rangelands of the eastern Tibetan Plateau of Sichuan

Many Tibetans who were formerly nomadic yak herders are settling near towns. However, yak remain a traditional symbol of wealth, which can lead to increased local stocking densities and severe over-grazing. We used belt-transect counts to study the area around Hongyuan in Sichuan. We find that intensive summer grazing significantly reduces the vegetation height and is associated with significant reductions in bumblebee-food-plant abundance and bumblebee diversity. For the significantly reduced bumblebee species, we identify the most frequently used and preferred bumblebee-food plants. For the food plants, we identify changes in absolute flower availability and changes in bumblebee visits. In particular, reductions in the bumblebees Bombus supremus, B. filchnerae, B. humilis and B. impetuosus are associated with reductions in flowers of the food plants Hedysarum and Saussurea.

Bioavailability assessment of phosphorus and metals in soils and sediments: a review of diffusive gradients in thin films (DGT)

This paper provides an overview of the principle and latest development of the diffusive gradients in thin films (DGT) technology and its applications in environmental studies with a focus on bioavailability assessment of phosphorus and metals in sediments and soils. Compared with conventional methods, DGT, as a passive sampling method, has significant advantages: in situ measurement, time averaged concentrations and high spatial resolution. The in situ measurement avoids artificial influences including contamination of samples and sample treatment which may change the forms of chemicals. The time averaged concentration reflects representative measurement over a period of time. The high-resolution information captures the biogeochemical heterogeneity of elements of interest distributed in microenvironments, such as in the rhizosphere and the vicinity of the sediment-water interface. Moreover, DGT is a dynamic technique which simultaneously considers the diffusion of solutes and their kinetic resupply from the solid phases. All the advantages of DGT significantly promote the collection of “true” information of the bioavailable or labile forms of chemicals in the environment. DGT provides potential for applications in agriculture, environmental monitoring and the mining industry. However, the applications are still at the early testing stage. Further studies are needed to properly interpret the DGT-measured results under complex environmental conditions, and standard procedures and guideline values based on DGT are required to pave the way for its routine applications in environmental monitoring.

The bumblebees of Sichuan (Hymenoptera: Apidae, Bombini)

Abstract Bumblebees are important pollinators in mountainous regions. The highland region of Sichuan and Chongqing (together, Sichuan in the former broad sense) includes part of the greatest hotspot of bumblebee diversity worldwide, with half of the species of China and more than a fifth of the worlds species. In this paper we present the first review of this diverse but particularly poorly known fauna, drawing on 6705 bees from selective samples made by the authors during field work and from museum collections, together with 1123 literature records (an overlapping set). Among this material we recognise 56 species that have 847 names (including infrasubspecific names). One new species, Bombus (Pyrobombus) wangae, is described from Sichuan and Gansu. B. laesus is found to have a colour pattern in this part of its range that was previously undescribed. Six species are recorded from the Sichuan‐Chongqing region for the first time (B. avanus, B. branickii, B. difficillimus B. humilis, B. norvegicus, B. tibetanus), of which B. avanus is only the second published record worldwide. One species, B. braccatus, is endemic to Sichuan and is confirmed as extant in 2005. We provide diagnoses and keys to species for both sexes. Colour variation is described, distributions within the Sichuan‐Chongqing region are mapped, altitudinal and seasonal activity are plotted, and the authors’ records of food plants are listed.

Outlier identification and visualization for Pb concentrations in urban soils and its implications for identification of potential contaminated land.

Outliers in urban soil geochemical databases may imply potential contaminated land. Different methodologies which can be easily implemented for the identification of global and spatial outliers were applied for Pb concentrations in urban soils of Galway City in Ireland. Due to its strongly skewed probability feature, a Box-Cox transformation was performed prior to further analyses. The graphic methods of histogram and box-and-whisker plot were effective in identification of global outliers at the original scale of the dataset. Spatial outliers could be identified by a local indicator of spatial association of local Morans I, cross-validation of kriging, and a geographically weighted regression. The spatial locations of outliers were visualised using a geographical information system. Different methods showed generally consistent results, but differences existed. It is suggested that outliers identified by statistical methods should be confirmed and justified using scientific knowledge before they are properly dealt with.

Challenges for sustainable tourism at the Jiuzhaigou World Natural Heritage site in western China

Although modern mass tourism in China has a history of only about 30 years, the market has expanded quickly. Endowed with the spectacular scenery of turquoise water lakes and marvelous waterfalls, Jiuzhaigou is one of the most visited tourist destinations in China. Between 1984 and 2012, the region witnessed a tourism growth of 130 times, resulting in extreme economic and environmental impacts. The fast increasing and large tourist population in the limited area has caused many changes in the local environment, including: increasing algae in water, increasing nutrients in water, increasing sediment in lakes, degrading travertine, and increasing threat on biodiversity. These changes will threaten the sustainability of tourism in Jiuzhaigou. Carrying capacity represented by daily visitor numbers theoretically has been used to control the number of tourists but has proved not useful in practical management. Efforts have been made to reduce the environmental impacts of the increasing number of tourists, but environmental degradation continues to develop as the number of tourists is not controlled. The sustainability issue in Jiuzhaigou is mired in the conflict between the conservation of the natural beauty and local economic development. To promote sustainable tourism, the number of tourists must be controlled. A daily numeric limit, based on adequate environmental monitoring and well‐designed scientific research, will help determine the daily number of visitors in Jiuzhaigou.

Demonstrating urban pollution using toxic metals of road dust and roadside soil in Chengdu, southwestern China

As one of the largest economical hubs in southwestern China, Chengdu is witnessing fast urbanization characterized by rapid urban sprawl, population growth, infrastructural construction, and motorization. However, this rapid urbanization may lead to environmental degradation, placing human health at risk. In this study, toxic metals in road dust and roadside soil are used as proxies to illustrate environmental changes of Chengdu. In August 2009, 133 dust and 132 soil samples were collected from the first, second and third ring roads, along which areas have urbanized for different times. By means of a portable X-ray fluorescence analyzer, concentrations of Pb, Zn and Cu in the samples were determined. The results indicate that the concentrations and contamination levels of Pb, Zn and Cu in dust declined significantly from the first to the third ring roads, paralleling the decreasing trends in traffic and building densities from the first to the third ring roads. However, concentrations of the three elements in roadside soil were relatively stable among the roads. These data may suggest that the metals in road dust can be used as proxies to demonstrate environmental degradation during the urbanization of Chengdu, while concentrations of the metals in roadside soil are affected more by natural factors (e.g., background concentrations, precipitation, and distance to road) than by anthropogenic factors (e.g., traffic and building densities). Furthermore, compared to Pb concentrations measured in the 1990s, Pb concentrations in road dust have been reduced most likely owing to the exclusion of leaded petrol since 2000. Similar situations may be found in many other cities that are experiencing fast urbanization.

Atmospheric wet deposition of sulfur and nitrogen in Jiuzhaigou National Nature Reserve, Sichuan Province, China

In the last two decades, remarkable ecological changes have been observed in Jiuzhaigou National Nature Reserve (JNNR). Some of these changes might be related to excessive deposition of sulfur (S) and nitrogen (N), but the relationship has not been quantified due to lack of monitoring data, particularly S and N deposition data. In this study, we investigated the concentrations, fluxes, and sources of S and N wet deposition in JNNR from April 2010 to May 2011. The results show that SO4(2-), NO3-, and NH4+ concentrations in the wet deposition were 39.4-170.5, 6.2-34.8, and 0.2-61.2 μeq L(-1), with annual Volume-Weighted Mean (VWM) concentrations of 70.5, 12.7, and 13.4 μeq L(-1), respectively. Annual wet deposition fluxes of SO4(2-), NO3-, and NH4+ were 8.06, 1.29, and 1.39 kg S(N)ha(-1), respectively, accounting for about 90% of annual atmospheric inputs of these species at the monitoring site. The results of Positive Matrix Factorization (PMF) analysis show that fossil fuel combustion, agriculture, and aged sea salt contributed to 99% and 83% of annual wet deposition fluxes of SO4(2-) and NO3-, respectively. Agriculture alone contributed to 89% of annual wet deposition flux of NH4+. Although wet deposition in JNNR was polluted by anthropogenic acids, the acidity was largely neutralized by the Ca2+ from crust and 81% of wet deposition samples had a pH higher than 6.00. However, acid rain mainly caused by SO4(2-) continued to occur in the wet season, when ambient alkaline dust concentration was lower. Since anthropogenic emissions have elevated S and N deposition and caused acid rain in JNNR, further studies are needed to better quantify the regional sources and ecological effects of S and N deposition for JNNR.

Modeling dry and wet deposition of sulfate, nitrate, and ammonium ions in Jiuzhaigou National Nature Reserve, China using a source-oriented CMAQ model: Part I. Base case model results.

A source-oriented Community Multiscale Air Quality (CMAQ) model driven by the meteorological fields generated by the Weather Research and Forecasting (WRF) model was used to study the dry and wet deposition of nitrate (NO3(-)), sulfate (SO4(2-)), and ammonium (NH4(+)) ions in the Jiuzhaigou National Nature Reserve (JNNR), China from June to August 2010 and to identify the contributions of different emission sectors and source regions that were responsible for the deposition fluxes. The model performance is evaluated in this paper and the source contribution analyses are presented in a companion paper. The results show that WRF is capable of reproducing the observed precipitation rates with a Mean Normalized Gross Error (MNGE) of 8.1%. Predicted wet deposition fluxes of SO4(2-) and NO3(-) at the Long Lake (LL) site (3100 m a.s.l.) during the three-month episode are 2.75 and 0.34 kg S(N) ha(-1), which agree well with the observed wet deposition fluxes of 2.42 and 0.39 kg S(N) ha(-1), respectively. Temporal variations in the weekly deposition fluxes at LL are also well predicted. Wet deposition flux of NH4(+) at LL is over-predicted by approximately a factor of 3 (1.60 kg N ha(-1)vs. 0.56 kg N ha(-1)), likely due to missing alkaline earth cations such as Ca(2+) in the current CMAQ simulations. Predicted wet deposition fluxes are also in general agreement with observations at four Acid Deposition Monitoring Network in East Asia (EANET) sites in western China. Predicted dry deposition fluxes of SO4(2-) (including gas deposition of SO2) and NO3(-) (including gas deposition of HNO3) are 0.12 and 0.12 kg S(N) h a(-1) at LL and 0.07 and 0.08 kg S(N) ha(-1) at Jiuzhaigou Bureau (JB) in JNNR, respectively, which are much lower than the corresponding wet deposition fluxes. Dry deposition flux of NH4(+) (including gas deposition of NH3) is 0.21 kg N ha(-1) at LL, and is also much lower than the predicted wet deposition flux. For both dry and wet deposition fluxes, predictions from the 12-km resolution nested domain are similar to those from the 36-km resolution parent domain.

Source apportionment of PM2.5 for 25 Chinese provincial capitals and municipalities using a source-oriented Community Multiscale Air Quality model

Source contributions to fine airborne particulate matter with aerodynamic diameters <2.5μm (PM2.5) during 2013 were determined for 25 Chinese provincial capitals and municipalities using a source-oriented version of the Community Multiscale Air Quality (CMAQ) model. Based on the hierarchical clustering analysis of the observed PM2.5 concentrations, the 25 cities were categorized into nine groups. Generally, annual PM2.5 concentrations were highest in the cities in the north (81-154μgm-3) and lowest in the cities close to seas in the south and east (27-57μgm-3). Seasonal PM2.5 observations in the cities were generally higher in winter than in the other seasons. Industrial or residential sources were predicted to be the largest contributor to PM2.5 for all the city groups, with annually fractional contributions of 25.0%-38.6% and 9.6%-27%, respectively. The annual contributions from power plants, agriculture NH3, windblown dust, and secondary organic aerosol (SOA) for the city groups were 8.7%-12.7%, 9.5%-12%, 6.1%-12.5%, and 5.4%-15.5%, respectively. Meanwhile, the annual contributions from transportation, sea salt, and open burning were relatively low (<8%, <2%, and <6%, respectively). Secondary PM2.5 accounted for 47%-63% of total annual PM2.5 concentrations in the cities and contributed to as much as 70% of daily PM2.5 concentrations on PM2.5 pollution days (daily concentrations>75μgm-3). Industrial or residential sources were generally the largest contributor on PM2.5 pollution days for all the city groups in each season, except that open burning, SOA, and windblown dust could be more important on some days, particularly in spring. The results of this study would be helpful to develop measures to reduce annual PM2.5 concentrations and the number of PM2.5 pollution days for different regions of China.