Assessing the health risk of heavy metals in vegetables to the general population in Beijing,China

A systematic survey of As, Cd, Cr, Cu, Ni, Pb and Zn concentrations in vegetables from 416 samples （involving 100 varieties） in Beijing was carried out for assessing the potential health risk to local inhabitants. The results indicated that the metal concentrations in vegetables ranged from 〈 0.001 to 0.479 μg/g fresh weight （fw） （As）, 〈 0.001 to 0.101 μg/g fw （Cd）, 〈 0.001 to 1.04 μg/g fw （Cr）, 0.024 to 8.25μg/g fw （Cu）, 0.001 to 1.689 μg/g fw （Ni）, 〈 0.001 to 0.655 μg/g fw （Pb） and 0.01 to 25.6 μg/g fw （Zn）, with average concentrations of 0.013, 0.010, 0.023, 0.51, 0.053, 0.046 and 2.55 μg/g fw, respectively. The results showed that the concentrations of As, Cr, Cu, Cd, Pb and Ni in vegetables from open-fields were all significantly higher than those grown in greenhouses. In addition, in local-produced vegetables, all HMs except Zn were significantly higher than those in provincial vegetables. The estimated daily intake （EDI） of As, Cd, Cr, Cu, Ni, Pb and Zn from vegetables was 0.080, 0.062, 0.142, 3.14, 0.327, 0.283 and 15.7 μg/（kg body weight （bw）.d） for adults, respectively. Arsenic was the major risk contributor for inhabitants since the target hazard quotient based on the weighted average concentration （THQw） of arsenic amounted to 44.3% of the total THQ （TTHQ） value according to average vegetable consumption. The TTHQ was lower than 1 for all age groups, indicating that it was still safe for the general population of Beijing to consume vegetables.

Analysis of Factors Influencing Second-hand Housing Prices in Beijing based on Hierarchical Linear Model

In recent years,housing prices have attracted widespread attention,and the fluctuation of housing prices is due to a combination of many factors.In addition to the characteristics of the house itself,the price of a house is also affected by other factors,such as the community in which the house is located.This article used Beijing’s 2017 second-hand housing transaction data (based on second-hand housing transaction records on Lianjia.com),introduced a hierarchical linear model,and employed Stata software to analyze from different levels.It is intended to find the correlation between housing prices and different levels of characteristics,so to pin down the factors that affect prices of the second-hand housing.

Characteristics of soil seed bank in plantation forest in the rocky mountain region of Beijing, China

We investigated characteristics （scales and composition） of soil seed banks at eight study sites in the rocky mountain region of Beijing by seed identification and germination monitoring. We also surveyed the vegetation communities at the eight study sites to explore the role of soil seed banks in vegetation restoration. The storage capacity of soil seed banks at the eight sites ranked from 766.26 to 2461.92 seeds·m？2. A total of 23 plant species were found in soil seed banks, of which 63–80% of seeds were herbs in various soil layers and 60% of seeds were located in the soil layer at 0–5 cm depth. Biodiversity indices indicated clear differences in species diversity of soil seed banks among different plant communities. The species composition of aboveground vegetation showed low similarity with that based on soil seed banks. In the aboveground plant community, the afforestation tree species showed high importance values. The plant species originating from soil seed banks represented natural regeneration, which also showed relatively high importance values. This study suggests that in the rocky mountain region of Beijing the soil seed banks played a key role in the transformation from pure plantation forest to near-natural forest, promoting natural ecological processes, and the role of the seed banks in vegetation restoration was important to the improvement of ecological restoration methods.

Water pricing towards sustainability of water resources: a case study in Beijing

The role of water pricing for managing water resources is widely recognized in many areas of the world because of the increasing scarcity of water resources, a high competition between water uses and environmental degradation. Based on the analysis of cost of water, this paper explores which types of cost should be reflected in the water pricing enhancing the sustainability of water resources. The principle of full cost pricing in which the cost should include supply cost, opportunity cost and externalities is proposed as a means to achieve the sustainability of water resources. In a case study of Beijing, low water price is analyzed as one reason for unsustainable water consumption. Thus water pricing justified is necessary and pressing. It is proposed to justify water price in phased manner and eventually towards full cost pricing. The assessment of impacts on water resources by raising water price shows water pricing could alleviate the conflict between water supply and demand. This paper concludes that water pricing can play an effective role in enhancing the sustainability of water resources in Beijing.

Carbon Sequestration in Forest Vegetation of Beijing at Sublot Level

Based on forest inventory data (FID) at sublot level,we estimated the carbon sequestration in forest vegetation of Beijing,China in 2009.In this study,the carbon sequestration in forest vegetation at sublot level was calculated based on net biomass production (ΔB) which was estimated with biomass of each sublot and function relationships between ΔB and biomass.The biomass of forested land was calculated with biomass expansion factors (BEFs) method,while those of shrub land and other forest land types were estimated with biomass,coverage and height of referred shrubs and shrub coverage and height of each sublot.As one of special forested land types,the biomass of economic tree land was calculated with biomass per tree and tree number.The variation of carbon sequestration in forest vegetation with altitude,species and stand age was also investigated in this study.The results indicate that the carbon sequestration in forest vegetation in Beijing is 4.12 × 106 tC/yr,with the average rate of 3.94 tC/(ha·yr).About 56.91% of the total carbon sequestration in forest vegetation is supported by the forest in the plain with an altitude of < 60 m and the low mountainous areas with an altitude from 400 m to 800 m.The carbon sequestration rate in forest vegetation is the highest in the plain area with an altitude of < 60 m and decreased significantly in the transitional area from the low plain to the low mountainous area with an altitude ranging from 200 m to 400 m due to intensive human disturbance.The carbon sequestration of Populus spp.forest and Quercus spp.forest are relatively higher than those of other plant species,accounting for 25.33% of the total.The carbon sequestration in vegetation by the forest of < 40 years amounts to 45.38% of the total.The carbon sequestration rate in forest vegetation peaks at the stand age of 30–40 years.Therefore,it would be crucial for enhancing the capability of carbon sequestration in forest vegetation to protect the forest in Beijing,to limit human disturbance in the transitional area from the plain to the low mountain area,and to foster the newly established open forest.

STUDY ON VEGETATION AND CLIMATE CHANGES IN BEIJING REGION SINCE LATE PLEISTOCENE

A complex history of the Late Pleistocene vegetation and environmental changes for the northern part of the deciduous forest is revealed in an exceptionally well dated pollen diagram from Dongganchi in Beijing area. In 15?800- 14?700 a B.P., the arbors and aquatic plants were sparse, and the climate was cold and dry. In 14 700-13?400 a B.P., forest growth was limited, it was dominated by conifers, presumably in responded to a cooling climate. Aquatic plants became abundant. During 13?400 to 12?600 a B.P., there was a widespread development of coniferous and broad leaved mixed forest, aquatic plants decreased which corresponded to climate gradually becoming warming and dry. In 12?600-11?400 a B.P., there was alternation of coniferous and broad leaved mixed forest, so were aquatic plants. From 11?400 to 9?600 a B.P., the decreasing of trees and increasing of herbs and shrubs suggested an opening up of the vegetation in responded to cooling, probably corresponded to Younger Dryas from 10?600 to 10?300 a B.P. About 9600-7270 a B.P., the climate changed from cooler and dry to warmer and humid. About 7270-3390 a B.P., the coniferous and the broad leaved mixed forest increased, it was in responding to the “climatic optimum". About 3390-1000 a B.P., climate became cooler and dry. After 1000 a B.P., there was a severe fluctuation, indicating the temperature drop and the environmental deterioration.

Carbon price impacts on sector cost:based on an input-output model of Beijing

Under the pressure of sustained growth in energy consumption in China,the implementation of a carbon pricing mechanism is an effective economic policy measure for promoting emission reduction,as well as a hotspot of research among scholars and policy makers.In this paper,the effects of carbon prices on Beijing's economy are analyzed using input-output tables.The carbon price costs are levied in accordance with the products'embodied carbon emission.By calculation,given the carbon price rate of 10 RMB/t-CO_2,the total carbon costs of Beijing account for approximately 0.22-0.40%of its gross revenue the same year.Among all industries,construction bears the largest carbon cost Among export sectors,the coal mining and washing industry has much higher export carbon price intensity than other industries.Apart from traditional energy-intensive industries,tertiary industry,which accounts for more than 70%of Beijing's economy,also bears a major carbon cost because of its large economic size.However,from 2007 to 2010,adjustment of the investment structure has reduced the emission intensity in investment sectors,contributing to the reduction of overall emissions and carbon price intensity.

The Variation Law of the Market Price of Pork in Beijing City

In order to research the fluctuation law of price of pork in Beijing City and determine its fluctuation cycle,we use level indicator analysis,speed indicator analysis,the coefficient of variation,the seasonal adjustment model and the HP filter method,to analyze the data on the market price of pork in 8 wholesale markets in Beijing City during the period 2002-2011.The results show that the annual price of pork in wholesale markets in Beijing City shows a gradual upward trend;during the period 2002-2011,the price of pork in Beijing City experienced three full fluctuation cycle,and each fluctuation cycle was roughly 38 months;the price of pork within the year shows a trend of " one trough,one crest",and the interval of high prices is mainly concentrated in June-december;the amount of pork for sale within the year is basically inversely correlated with the price.Therefore,we should strengthen the monitoring of pig production information and market information,to ensure the sufficient supply of pork,and stabilize the market price of pork.In addition,according to the variation law of the market price of pork,improving the purchasing,storage and allocation work mechanism of the reserve meat is also necessary to stabilizing the market price of pork.

Low Carbon Beijing:Research on the Influencing Factors of Carbon Emission Trading Price

The international community has taken extensive actions to achieve carbon neutrality and sustainable development with the intensification of global warming and climate change.China has also carried out a long-term layout,setting the goal of achieving a carbon peak by 2030 and carbon neutrality by 2060.In 2021,with the official launch of a unified national carbon emissions trading market,China’s nationwide carbon emissions trading kicked off.Carbon emission trading is an important policy tool for China’s carbon peak and carbon-neutral action and an essential part of the country’s promotion of a comprehensive green transformation of the economy and society.This study uses a VAR(Vector Autoregressive)model to analyze the influencing factors of the Beijing carbon emissions trading price from January 2014 to December 2019.The study found that coal prices have the most significant impact on Beijing’s carbon emissions trading prices.Oil prices,industrial development indexes,and AQI(Air Quality Index)impacted Beijing’s carbon emissions trading prices.In contrast,natural gas prices and economic indexes have the most negligible impact.These findings will help decision-makers determine a reasonable price for carbon emissions trading and contribute to the market’s healthy development.

Distribution Pattern of Urban Housing Price Based on Multiple Big Data:A Case Study of Beijing,Shanghai,Guangzhou,and Wuhan

The housing price has been paid close attention by people in all walks of life,and the development of big data provides a new data environment for the study of urban housing price.Housing price data of four national central cities (Beijing,Shanghai,Guangzhou and Wuhan) are taken as research samples.With the help of software GIS,exploratory spatial data analysis method is used to depict the spatial distribution pattern of urban housing price,and commonness and difference of spatial distribution of housing price are explored.The conclusions are as below:①regional imbalance of housing price in national central cities is significant.②Spatial distribution of urban housing price in Beijing,Shanghai,Guangzhou and Wuhan presents a polycentric pattern,and there is obvious spatial agglomeration.③The internal change of housing price in different cities has significant spatial difference.Beijing,Shanghai,Guangzhou and Wuhan are taken as typical city samples for research,with reference and practical significance,which could help to effectively predict spatial development trend of housing prices in other first and second tier cities.The research aims to provide certain reference for the government implementing real estate control policies according to local conditions,project location and reasonable pricing of real estate developers.

Analysis and Countermeasures Research of Beijing Country Fair

Organic vegetables, does not use pesticides, synthetic fertilizers, herbicides, growth regulators in production process and refers to organisms and products got from genetic engineering. It follows the laws of nature and ecological principles, adopts a series of sustainable development of agricultural technology, to coordinate planting balanced, and stable agricultural ecosystems, and through the identification of organic certification, it will be recognized and awarded organic certification. Beijing Country Fair launched by a group of consumer volunteers concerned about ecological agriculture and rural issues, aiming to build a platform for farmers engaged in organic agriculture and consumers can communicate directly, exchange. It can help consumers find safe, assured products, but also help farmers to broaden market channels and encourage more farmers to engage in organic farming, thereby reducing environmental pollution produced by fertilizer and pesticide, safeguarding food security, and practicing fair trade.

H&M “Finally” Lands in Beijing Fashion and quality at the best price

Yes,the trend boys and girls can buy the latest collection of H&M in Beijing directly,finally.On April 23rd,H&M,Hennes&Mauritz AB,opened its

Research on the Longitudinal Transmission Mechanism of Prices for Urban Vegetable Supply Chain-Based on the Empirical Research in Chongqing

This paper mainly introduces the longitudinal transmission mechanism of urban vegetable prices in Chongqing area. On the basis of the supply chain theory,the " farm price- wholesale price- retail price" of vegetables in Chongqing has been identified as the research object. Through statistical analysis,it is found that the above three types of price show a modest annual fluctuation of 7- 12% from 2008 to2013. Later,the paper focuses on the empirical research on the weekly price data in 2013 applying the co-integration theory,which reveals that the farm price of vegetables is largely influenced by themselves; the wholesale price of vegetables is mainly affected by their own price,the production price and the retail price of the earlier stage without the current influence of the production price; and the retail price of vegetables is also affected by their own price,but is not affected by the their current local price and the wholesale price. Vegetable prices have shown an obvious positive transmission mechanism in the links from production to retail,but the feedback effect of retail on production is not brought into play.

Why Are There Great Fluctuations in the Prices of Vegetables?

The normal supply of vegetables is related to the people's livelihood and social stability,and smooth prices of vegetables are vital to social development. Based on the phenomenon of great fluctuations in the prices of vegetables in recent years,we use living example to analyze the real reasons for great fluctuations in the prices of vegetables from the perspective of supply chain node of vegetables and macroeconomic policies. Finally,from the balance of supply and demand,industry standardization,circulation,market order and the government mechanism,we put forth the following management strategies for controlling great fluctuations in the prices of vegetables: establishing and improving the channels of information transmission,making the production and marketing information symmetrical,and balancing supply and demand; actively promoting the industry standardization of vegetables; reducing the intermediate links,and curtailing the circulation cost of vegetables; regulating the " green channel" of vegetables,and preventing uptick in the prices of vegetables in the " last mile" ; cracking down on the vegetable speculation behavior to ensure the healthy development of the vegetable market; actively giving play to the role of government,and building the vegetable protection system.

北京山区不同植被恢复类型土壤质量综合评价

[目的]综合评价北京山区不同植被恢复类型土壤质量,并进一步确定影响土壤质量的关键因素,为该地区植被恢复与重建提供数据支撑。[方法]以立地条件相近的侧柏纯林、油松纯林、侧柏油松混交林、侧柏针阔混交林、油松针阔混交林、落叶阔叶混交林和无林地(对照)为研究对象,测定14个土壤理化指标作为土壤质量评价的总数据集(TDS),采用主成分分析法(PCA)和Pearson相关性分析建立土壤质量最小数据集(MDS),利用线性(L)和非线性(NL)2种评分方法计算土壤质量指数(SQI)和一般线性模型(GLM)确定影响土壤质量的关键因素。[结果]植被恢复后相较于无林地,土壤容重、砂粒含量下降,而有机质、全氮、全钾、速效氮、速效钾等土壤养分含量增加。筛选出的研究区土壤质量评价MDS指标为全氮、砂粒、全钾、pH、有效含水量。4种方法(SQI-LT、SQI-NLT、SQI-LM、SQI-NLM)下,不同植被恢复类型的SQI值排序均为落叶阔叶混交林>侧柏针阔混交林>油松纯林>油松针阔混交林>侧柏油松混交林>侧柏纯林>无林地,植被恢复后土壤质量显著提升。SQI-NLM的土壤质量评价方法在北京山区具有更好的适用性。相较于无林地,其他植被恢复类型的SQI-NLM分别提高64%,48%,45%,36%,33%,27%。GLM模型解释了土壤质量指数总变异的85.24%,植被类型对土壤质量指数的解释比例最大(45.09%)。[结论]选择适宜的植被恢复类型是改善区域土壤质量的关键。未来实施植被恢复时,树种选择上优先考虑阔叶树种。造林配置方式的选择应取决于树种而定,如侧柏纯林中引入本土阔叶树种形成侧柏针阔混交林或选择油松纯林是最佳造林模式。

京津冀地区蔬菜废弃物污染风险及资源化利用潜力分析

以京津冀地区13个地级市为研究对象,通过文献整理和数据分析,估算出各地级市蔬菜废弃物的污染负荷、污染强度和污染风险,并结合各地化肥施用量,探究蔬菜废弃物的资源化利用潜力。结果表明,2020年京津冀地区的蔬菜废弃物、TN、TP和TK污染负荷分别为2 199 836、46 627、28 509和49 674 t。各地级市中,唐山市、张家口市、石家庄市和邯郸市的污染负荷较高;廊坊市、唐山市、秦皇岛市和石家庄市的污染风险较高。若将京津冀地区蔬菜废弃物资源化利用,所利用带来的肥料化效益达到124 802 t,相当于区域内4.06%的化肥施用折纯量,资源化效益显著。因此,推动京津冀地区蔬菜废弃物的资源化利用对于缓解资源紧缺和环境污染具有重要意义。

2023年天津市蔬菜田头市场价格分析与未来展望

蔬菜是人们生活中必不可少的重要食品,市场供应水平关系到菜农和消费者利益以及社会的稳定。本研究选取天津市25种蔬菜田头价格开展分析与研究,结果表明,2023年天津市蔬菜田头价格走势相对平稳,与历年的走势大致相当,呈现“W”型特征,即3个高位期、两个低位期。从价格波动特点看,蔬菜田头价格波动受气象条件影响明显,蔬菜上市期气象条件好,价格通常走低;如遇到极端天气,价格短期内迅速上涨。天津作为超大城市,建议完善蔬菜市场信息监测预警机制,健全部门信息共享机制,提升地产蔬菜稳产保供能力。

基于环京周边蔬菜生产基地建设的京津冀协同发展机制研究

环京合作圈是北京蔬菜生产供应体系建设的重要内容之一。环京周边蔬菜生产基地建设成为京津冀协同发展的重要载体,是农业领域践行京津冀协同发展战略的重要体现。基于调研,梳理了三地协同推进环京周边蔬菜生产基地建设的相关机制,并以基地建设为基础分析了三地协同发展面临的问题,最后提出对策建议,旨在推进环京基地建设、健全京津冀三地农业协同发展政策机制提供借鉴与参考。

多用途条件下水经济价值的最小用水效益决定论

基于劳动价值论以及边际效用价值论,提出了价值的边际劳动价值决定论以及多用途条件下水经济价值的评估理论和方法,认为水经济价值取决于供需平衡时各种用途用水效益的最小值或供水成本的最大值。基于该理论和方法,对北京市原水经济价值进行了评估,结果表明,北京市的水经济价值是由效益低的农业用水界定,北京市农业用水效益的估计值更接近水的价值。结合可视为北京市边际供水成本的南水北调水价,2020年北京市原水经济价值应在2.33~4.82元/m^(3)之间。