东莞市蔬菜基地蔬菜中喹诺酮类抗生素污染特征及健康风险

利用超高效液相色谱-串联质谱(UPLC-MS/MS)技术分析了东莞市蔬菜基地蔬菜中4种喹诺酮类抗生素的污染特征,并对其健康风险进行评价.结果表明,东莞市蔬菜中普遍检出喹诺酮类抗生素,以诺氟沙星和环丙沙星为主,其次是恩诺沙星,检出率均在80%以上,最高含量均大于100μg/kg(干重),平均含量近20μg/kg;不同基地和不同类型的蔬菜中喹诺酮类抗生素的含量与组成特征差异较大,总含量为叶菜类(49.87μg/kg)>根茎类(44.81μg/kg)>瓜果类(11.21μg/kg);通过食用东莞市蔬菜摄入喹诺酮类抗生素的量低于日允许摄入量,健康风险较小.     

Radioactive Isotopes of Strontium,Caesium and Plutonium in Sediments of the Northern Adriatic Sea

Changes in nitrification rates of an acid grassland soil with and without air drying have been monitored over 9 days, after first flushing native nitrate from the soils with deionised water. The results confirmed that full re-establishment of nitrification after air drying takes several days, supporting the hypothesis that any immediate first flush of nitrate from air-dried soils originates from cell lysis or flushing of ‘stored’ nitrate. Ammonium spiking confirmed that nitrification was not ammonium substrate limited. It was also found that ammonium accumulates in the soil during the drying process, providing a substrate pool once the population of nitrifiers has re-established. Over the first week of incubation, nitrate immobilisation was less conspicuous in the soil that had been rewetted after air drying compared with the incubated field moist soil.     

Metal accumulation risks in regularly flooded and non-flooded parts of floodplains of the River Rhine: Extractability and exposure through the food chain

Ecotoxicological risks of sediment contamination in floodplains are supposed to be highest in the regularly flooded parts. Therefore, in risk assessments, the non-flooded parts are neglected or considered to be reference areas. We investigated the metal extractability and levels in important food sources for vertebrates, viz. grass shoots and earthworms, in flooded as well as non-flooded parts and compared these with total metal concentrations. A comparison of these areas in the moderately polluted ‘Afferdensche en Deestsche Waarden’ floodplains along the River Rhine showed that total Zn, Pb, and Cd concentrations were highest in the regularly flooded parts. However, CaCl₂-extractable Zn concentrations were highest in non-flooded areas, and those of Pb and Cd were equal in both areas. Total Cu concentrations were not significantly different between the two areas, but CaCl₂-extractable Cu concentrations were highest in the regularly flooded areas. The metal concentrations in grass shoots of non-flooded areas were equal to (Zn, Cu, Cd) or higher than (Pb) those in regularly flooded areas. Zn concentrations in earthworms in regularly flooded areas were higher, but concentrations of Cu, Pb, and Cd were not. Ecotoxicological risk assessments require analysis of the total and potentially bioavailable metal concentrations in soils as well as concentrations in biota. This study shows that the less contaminated non-flooded areas in moderately polluted floodplains cannot be neglected in metal accumulation studies and cannot be used as pristine reference areas.     

Polybrominated diphenyl ether (PBDE) levels in the blood of pure vegetarians (vegans)

Intake of many persistent organic pollutants (POPs) including dioxins, dibenzofurans and PCBs is almost exclusively from gastrointestinal ingestion of animal fats in the diet. With polybrominated diphenyl ether (PBDE) brominated flame retardants (BFRs), no consensus exists at present as to the extent of intake from food, from indoor dust or other routes of intake. Vegans, or pure vegetarians, were previously found to have low body burden of dioxins and dibenzofurans in blood. Data reported here for the first time show a trend towards lower PBDE levels with longer time periods without ingestion of food of animal origin in 8 adult residents of the United States. A stronger relationship between lower PBDE levels and time without meat, specifically, is consistent with substantial PBDE intake from meat relative to fish or dairy products in Americans. These vegans had somewhat lower PBDE levels with a range 12.4–127 and a median 23.9?ppb than published reports of US general population samples which had a range of 4–366 and median of 26?ppb. Our findings suggest that food of animal origin may be a major but not the sole contributor to human body burden of PBDEs.     

Exponential Collapse of Benthic Depurative Capacity in A Eutrophic Tropical Marine Ecosystem: A Threshold Response to Organic Nitrogen Loading

Microbial decomposition of particulate organic matter in sediments can substantially modulate eutrophication of nearshore marine environments. Flux budgets for nitrogen compounds and quantification of rates of microbial transformation can provide important information on the process of eutrophication. This survey documents sediment nitrogen budgets for a eutrophic nearshore marine environment at La Parguera on southwest coast of Puerto Rico, including consideration of the organic fraction in addition to microbial transformations.

Sediments of the inshore channel at La Parguera denote the input of heavy organic loads with low redox potentials and high ammonium contents. Benthic fluxes of dissolved organic nitrogen are below those recorded for ammonium. These observations suggest that nearshore tropical sediments subject to heavy nitrogen loads act as a sink for organic nitrogen and that ammonification is a key process in the release of nitrogen from sediments to the water column. Nitrification and denitrification rates are low overall and inversely related to the redox potential. Depuration of excess nitrogen through denitrification is ineffective in these sediments. in contrast to more robust temperate environments, our work demonstrates that tropical marine systems are particularly susceptible to eutrophication given their limited capacity for depuration of excess nitrogen.     

Distribution,removal and chemical forms of heavy metals in polluted rice seed

In this paper, the distribution, removal and binding forms of heavy metals in polluted seeds of rice were studied using the methods of histochemistry and biochemistry. The results indicate that the distribution of heavy metals in rice grains was very uneven. The heavy metals in rice grains chiefly exist in association with the parts of high protein. Separation of proteins by Sephadex chromatography and subsequent analysis by atomic absorption spectroscopy revealed that Cd, Pb and As were mainly bound to protein of 54.5 and 5.50 kD molecular weights. During the rice processing, the concentrations of heavy metals in the edible rice decrease greatly, for some heavy metals in these parts of chaff, coarse rice bran and fine rice bran were removed.     

China's dairy crisis: impacts,causes and policy implications for a sustainable dairy industry

The dairy industry is an important part of the global economy, and the rapidly developing dairy enterprises in China have become increasingly important to the rest of the world. Due to increasing demand for dairy products and support from the government, China's dairy industry has thrived in recent decades. But rapid growth has been accompanied by a suite of industry/structural problems associated with raw milk supply, processing enterprises, product retailing and profit allocation. Thus, a major dairy crisis took place in 2008, triggered by a notorious melamine-contaminated milk event. The dairy crisis has had devastating impacts on China's dairy industry, negatively affecting farmers, consumers, processing enterprises and even government agencies. The Chinese government has developed rigorous measures to prevent future incidents of this sort, including the enactment of the Food Safety Law and reinstatement of the no-exemption quality inspection of food products. In this paper, we analyse the wide-ranging impacts and root causes of the recent dairy crisis in China. We also examine how the crisis has been handled and what measures have been put in place in its aftermath. Then we discuss policy implications for promoting the sustainability of China's dairy industry. Lessons learned from this crisis, as well as implications for policy improvements, should be valuable for the development of a sustainable dairy industry in other regions of the world.     

Fostering food and energy security through by-product valorization within agricultural and agro-industrial networks: study of the province of Santiago de Cuba

ABSTRACT

The aim of this study is to investigate of how the concept of ‘integrated food and energy systems’ or IFES production networks could be applied – within the specific context of Eastern Cuba’s agricultural and agro-industrial sectors – as an innovative approach to improve food and energy security. The Province of Santiago de Cuba in southeast Cuba was the focus of this study; its existing operations, infrastructure, resource flows and scarcities, and actor relationships provide the basis of the data used for the evaluation.

The authors investigated the regional context, identify potential members of an agricultural and agro-industrial network in three municipalities of the province, and identify the main residuals and by-products of key facilities. Potential avenues for by-product valorization are investigated along with the possible influence/impacts on the sustainability of the surrounding systems and actors. A conceptual model for a regional network for integrated food and energy production is then provided based upon the development of three agricultural/agro-industrial scenarios: influence at the farm level, regional agro-industrial networks, and ‘anchor tenant’ eco-industrial systems. The main challenges and opportunities for the development of the networks are described with recommendations for addressing such where possible.     

Sharing and preparing: cross-institutional,food security-based knowledge in Canada

This study proposes a framework for the collection and management of knowledge related to food security in Canada. This paper has several goals. First, the paper summarizes the current state of food security knowledge in Canada. Second, the paper presents data from an experiment where food security issues were discussed by stakeholders at two fora, the first of which was held in western Canada and the second held in eastern Canada. Finally, based on the notes taken during and feedback received after the fora, this paper suggests a framework for organizing and managing the multiple perspectives and complex types of knowledge about food security and sustainable development from a Canadian context. Two fora were held in Canada where food security issues were presented and discussed by multiple stakeholders. Most provinces in Canada were represented in at least one of the two sessions. Sessions were designed to be informative and interactive; agenda were designed to take advantage of the needs and experiences of multiple stakeholders in both western and eastern regions of Canada. To develop the framework, the sessions were also designed to assess the types of issues and knowledge about food security in Canada. Evidence presented from this experiment supports arguments that food security work must be approached in a collaborative manner, no matter the approach or discipline. Data from fora held in western and eastern regions of Canada indicate a number of specific ways in which those along the food continuum have the desire to share knowledge and enter into partnerships to work toward secure and sustainable food systems. Data also indicate how academia and institutions of higher learning might play a key role in sharing food security-based knowledge. The data from this study suggest that academia could play a leadership role in collecting and sharing information about food security-based knowledge from all disciplinary approaches that could help collaborative in addressing the complexity of food security challenges. The framework developed in this paper could provide the guide for organizing knowledge about food security and sustainable development. The framework could be used as a map to guide understanding about the different ways in which food security can be approached and understood; this could help reduce tensions among partners in projects where a wide variety of experiences are attempting to work collaboratively. The two food security fora brought together stakeholders with specialized knowledge about food security in a Canadian context. The analysis of data arising from the fora permitted unique insights to arise about the nature of knowledge by region. The data in this study also allowed us to build a framework for food security knowledge from these regional knowledge bases. This paper suggests that academia actively take a leadership role and openly share knowledge about food security. Open sharing of knowledge will help collaborates in dealing with complex food security issues understand in-depth other approaches; this sharing may help to make explicit the tensions that arise during collaborative work.     

Effects of cotton straw amendment on soil fertility and microbial communities

Maintaining soil fertility, while controlling pollution from excessive chemical fertilizer application is important for keeping soil productivity of sustainable agriculture. Variety of straws have been used and proven to be good soil amendments for increasing soil organic matter (OM) and a range of additional soil nutrients. However, little is known about the utilization of cotton straw for soil amendment. To better understand the mechanism behind cotton straw soil amendments, investigations were performed upon cucumber seedlings, where changes to soil nutrients and microbial communities were investigated. The results revealed that the cotton straw application promoted the cucumber seedling growth by significantly increasing the soil OM, available nitrogen, available phosphorus, and available potassium. The concentration of cotton straw was positively correlated to both the number of the culturable microorganisms and also the total microbial biomass within soil. Furthermore, assessment of cotton straw application using Biolog metabolic profiling and phospholipid fatty acid analysis revealed that such application increased the microbial community metabolic activity, and markedly changed the structure of microbial community. 16S rRNA gene clone library construction and phylogenetic analysis of soil bacteria revealed γ- Proteobacteria sequences dominated the cotton straw amendment soil, comprising 27.8% of the total number of analyzed sequences, while they were less represented in control soil (13.4%). On the contrary, the Sphingobacteria (7.8%) and Verrucomicrobia (2.4%) in the cotton straw amendment soil decreased after application when compared to the control soil 15.2% and 15.2%.