The study of threshold levels of heavy metals in soil is essential for the assessment and management of soil environmental quality. This study reviewed the influencing factors, the derivation, and application aspects of heavy metals’ threshold values comprehensively by a combination of bibliometric analysis and scientific knowledge mapping. A total of 1106 related studies were comprehensively extracted from the Web of Science database during the period from 2001 to 2020. The results showed that the publication output has been growing strongly. An analysis on the subject, journal, country, and institution was carried out to demonstrate the development and evolution of this research branch during the two decades. According to high-frequency keywords analysis, external factors (e.g., soil physicochemical properties) and internal factors (e.g., crop genotype) can affect heavy metal threshold values in the soil–crop system. The current methods mainly include the Point model (e.g., evaluation factor method), the Probability model (e.g., species sensitivity distribution method), and the Empirical model (e.g., ecological environment effect method). A threshold study can be applicable to the risk assessment for soil heavy metal contamination in order to determinate the soil pollution degree and its spatial and temporal distribution characteristics. Moreover, challenges and prospects of the study of heavy metal threshold values are proposed, indicating that research should focus on the relationships between human health risks and the established threshold values of heavy metals in the soil, long-term field trials and bioavailability of heavy metals for the derivation of the thresholds, and the establishment of more scientific and rational soil environmental benchmarks.
Based on the achievements of the reform of China's power production system, the paper proposes a new market operation model that the power production organizations of Gansu Province may follow. As required by the new market system, the power production system is subjected to changes of the production mechanism, the internal operation mechanism and the internet bidding measures, so as to adapt the business to the new market environment.
Edible oil is an important part of the human daily diet, which is popular in the food industry. People are paying increasing attention to the safety of edible oil as flawed oils have caused enormous international losses and posed a huge threat to consumer health issues. Therefore, it is necessary and important to analyze the quality and safety of oil product. In the present study, we particularly reviewed recent literature on analysis of emerging pollutants in edible oil including mycotoxins, pesticide residues and heavy metals. In addition, a series of emerging analytical technologies (HPLC, LC-MS/MS and GC-MS) for these contaminants were also summarized in this paper.
The urban and rural integration in China is an inevitable trend to promote the building of new countryside.It brought along China' s rural economic development, meanwhile it has also brought new challenges to China' s rural environmental pollution prevention and control.Taking Liaoning province for example, pollution in rural areas caused by household garbage, dirty water,agricultural planting,livestock and poultry breeding is becoming so serious that it should be solved immediately and effectively.Among so many factors that influence the rural environmental pollution prevention and control, the most profound reason is the dually-structured form of city-country environment, and the legal reason is the lack of legal system and supervision system in the area of rural environmental pollution prevention and control.Therefore, rural environmental pollution prevention and control should be based on the trend of urban and rural integration, the legislation in the area of rural environmental prevention should be improved, and the supervision on the rural pollution should be intensified.Meanwhile,we can also try to introduce such measures as subsidies in order to ease and curb the rural environmental pollution.
On the discussion of food safety, the majority of Chinas scholars believe that the food manufacturer should responsible for its inferior productis, The food manufacturer should be punished by government more than that of wholesaler retailer. But the punishment produces less effect on the food manufacturers adverse selection. This paper establishes a three-sector model, and analyzes empirically the distribution of benefits among food manufacturer, wholesaler and retailer. The research result shows that the unreasonable distribution of benefits resulting in manufacturers adverse selection on food safety in supply chain. Therefore, in order to improve the governance of food quality and safety, government should concern about the distribution of benefits among food manufacturer, wholesaler and retailer in supply chain. Based on the above analysis, this paper puts forward some corresponding recommendations.
Taking Haimen agricultural information network as platform,this system combines the vegetable variety to the agricultural investment in accordance with several representational harmful agricultural product bases.When clicking on the map and choosing the button of farmer production query,the user will see the agricultural investment in one year.It provides safe fruit and vegetable information for consumer,and lay foundation for the traceability of agricultural product safety.
We introduce trademarks as a new measure of innovation output, and examine the relation between CEO incentives and trademarks in a broad set of industries. Our new dataset contains over 123,545 USPTO trademark registrations by S&P 1500 firms from 1993 to 2011. As compared with patents, trademarks measure innovation over a wider range of industries and focus on the development portion of innovation that culminates more immediately as new products and services. We find that, on average, firms with more new product trademarks have more volatile stock returns, sales, and earnings after relevant controls, consistent with new trademarks being an indicator of risky product development innovation. We find that the fraction of CEO pay in the form of stock options, the convexity of CEO incentives, and the amount of unvested stock options held by the CEO are strongly positively associated with future trademarks. We also examine subsets of industries based on their patent production, and find generally similar results for all levels of patent-intensive industries. Finally, we document a positive relation between changes in stock option compensation around the implementation of SFAS 123(R) and subsequent changes in trademark creation, suggesting that stock option compensation is an important driver of product development innovation.
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