短链氯化石蜡研究现状

作为一种潜在的持久性有机污染物,短链氯化石蜡(Short chain chlorinated paraffins,SCCPs)近年来正在接受斯德哥尔摩公约的审查。它具有持久性、生物富集性,长距离迁移、高毒性等特点,可能会对生态环境和人体健康造成威胁,目前许多国家已经对SCCPs推出了禁令。中国生产的氯化石蜡(CPs)由于没有相关产品标准的限制,其成份多少都会含有一定SCCPs,中国每年都会消费大量的CPs,在消耗的同时会产生较大的排放量,这些排放所造成的潜在环境污染风险是不可估量的。本文通过查阅相关文献,对短链氯化石蜡研究现状进行了整理。     

Factors affecting the quantitative uncertainty of the estimated short-term intake. Part II—Practical examples

ABSTRACT

The effects of the spread of residue concentrations in the samples derived from the selected supervised trials and the number of trials were studied on the magnitude and uncertainty of the short-term dietary intakes calculated with the proposed new procedure (IESTI_p) and that one used currently by the FAO (Food and Agriculture Organization) and WHO (World Health Organization) Joint meeting on Pesticide Residues (JMPR) (IESTI_c). The residue data of 10 pesticides were obtained from supervised trials conducted on apples and pears. The methods described in Part I were used for the calculations of the uncertainty. The results indicate that the ratio of IESTI_P to IESTI_c (φ_IESTI) is directly proportional to the ratio of the estimated maximum residue level (MRL), recommended by the JMPR; to the highest residue (HR) observed in supervised trials, and it may have a wide range depending on the particular conditions. The φ_IESTI becomes greater with the increase of the difference between the mrl or maximum residue limit (MRL, established by the Codex Alimentarius Commission, CAC) and HR, and becomes smaller if the difference between the large portion (LP) and unit mass (U) decreases. The φ_IESTI ranged between 2 and 5.1 in the 16 cases examined indicating that the IESTI_p calculation method leads to higher intake estimates. The ratio of CV_IESTIp and CV_IESTIc ranged typically between 0.62 and 1.71. It rapidly increased up to 12 trials. For a larger number of trials, the ratio remained practically constant (1.69–1.71). The processing factor (PF) equally affects the MRL and HR values, therefore, it will not practically influence the φ_IESTI. The uncertainty of the estimated median residues depends on the spread and number of values in the residue datasets, which affects the uncertainty of the conversion factor (CF) and subsequently the uncertainty of the estimated IESTI_p. Residue values obtained from minimum nine independent trials are required for the correct calculation of the 95% confidence intervals of the calculated median residues. The uncertainty of the analytical results directly affects the median, HR values and indirectly the calculated mrl and the MRL derived from it. Therefore, it should also be considered for the calculation of the combined uncertainty of the conversion factors. For the correct interpretation of the results of dietary exposure calculations, the upper 95% confidence limit of the short-term intake should also be considered. However, it is not the current practice of regulatory agencies or JMPR.     

Determination and health risk assessment of enrofloxacin,flumequine and sulfamethoxazole in imported Pangasius catfish products in Thailand

The goals of this study were to determine the levels of three antibiotics – enrofloxacin, flumequine and sulfamethoxazole – in Pangasius catfish products imported into Thailand and to assess the health risks from consumption. To extract these antibiotic residues, acetonitrile, methanol and a small amount of formic acid were used as solvents. Determination of the antibiotics after extraction steps was carried out by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) technique. The results showed that 14 and 3 samples of Pangasius catfish products were contaminated with enrofloxacin and sulfamethoxazole, respectively. No flumequine residue was found. While the concentration levels of these antibiotics in most contaminated samples were lower than the European Union (EU) standard, one sample was found to contain sulfamethoxazole at 245.91 µg kg^?1, which was higher than the EU standard (100 µg kg^?1), indicating the likelihood that some contaminated freshwater fish products are widely distributed in Thai markets. Notably, the concentration levels of enrofloxacin in samples of Pangasius catfish with skin were higher than in non-skin products, suggesting that products with skin might retain more antibiotic residues than non-skin products. Although the hazard quotient showed that consuming imported Pangasius catfish products, based on the current consumption rate, will not adversely affect consumer health, antibiotic residues in Pangasius catfish products imported into Thailand should be continually monitored.     

Occurrence of aflatoxin M1 in human milk samples in Vojvodina,Serbia: Estimation of average daily intake by babies

The objectives of the study were to determine the aflatoxin M1 content in human milk samples in Vojvodina, Serbia, and to assess the risk of infants' exposure to aflatoxins food contamination. The growth of Aspergillus flavus and production of aflatoxin B1 in corn samples resulted in higher concentrations of AFM1 in milk and dairy products in 2013, indicating higher concentrations of AFM1 in human milk samples in 2013 and 2014 in Serbia. A total number of 60 samples of human milk (colostrum and breast milk collected 4–8 months after delivery) were analyzed for the presence of AFM1 using the Enzyme Linked Immunosorbent Assay method. The estimated daily intake of AFM1 through breastfeeding was calculated for the colostrum samples using an average intake of 60 mL/kg body weight (b.w.)/day on the third day of lactation. All breast milk collected 4–8 months after delivery and 36.4% of colostrum samples were contaminated with AFM1. The greatest percentage of contaminated colostrum (85%) and all samples of breast milk collected 4–8 months after delivery had AFM1 concentration above maximum allowable concentration according to the Regulation on health safety of dietetic products. The mean daily intake of AFM1 in colostrum was 2.65 ng/kg bw/day. Results of our study indicate the high risk of infants' exposure, who are at the early stage of development and vulnerable to toxic contaminants.     

Co-creating an alternative: the moral economy of participating in farmers’ markets

Growing dissatisfaction with the globalised food system, articulated on the behalf of both producers and consumers, has caused a variety of public debates surrounding the ethics of food production and consumption to become increasingly visible in society over the last two decades. Simultaneously, farmers’ markets (FMs) and other forms of direct marketing have experienced a noteworthy increase in participants, indicating an emerging demand for an alternative to conventional food networks, alternatives that are often perceived as providing a more just and moral relationship to food production and consumption. This study examines consumer and producer motivations for participation in FMs and opinions towards conventional and alternative agriculture in order to elucidate what (if any) values and morals are shared among producers and consumers. This study draws upon the theoretical framework of moral economy to understand whether these shared values suggest FM participants are working to co-create an alternative economy based on “moral” principles such as fairness, justice, and reciprocity. This mixed-methods study consists of consumer surveys (N?=?377) and semi-structured interviews with producers (N?=?17) from five FMs in the state of Delaware. The results suggest that producer and consumer motivations to participate in FMs, particularly a shared emphasis on social value, are indicative of a sense of moral economy. However, this moral economy is complicated by tension towards consumers and the alternative food movement more generally expressed on behalf of producers.     

Influence of Bioenergy Crop Production and Climate Change on Ecosystem Services

Land use change can significantly affect the provision of ecosystem services and the effects could be exacerbated by projected climate change. We quantify ecosystem services of bioenergy‐based land use change and estimate the potential changes of ecosystem services due to climate change projections. We considered 17 bioenergy‐based scenarios with Miscanthus, switchgrass, and corn stover as candidate bioenergy feedstock. Soil and Water Assessment Tool simulations of biomass/grain yield, hydrology, and water quality were used to quantify ecosystem services freshwater provision (FWPI), food (FPI) and fuel provision, erosion regulation (ERI), and flood regulation (FRI). Nine climate projections from Coupled Model Intercomparison Project phase‐3 were used to quantify the potential climate change variability. Overall, ecosystem services of heavily row cropped Wildcat Creek watershed were lower than St. Joseph River watershed which had more forested and perennial pasture lands. The provision of ecosystem services for both study watersheds were improved with bioenergy production scenarios. Miscanthus in marginal lands of Wildcat Creek (9% of total area) increased FWPI by 27% and ERI by 14% and decreased FPI by 12% from the baseline. For St. Joseph watershed, Miscanthus in marginal lands (18% of total area) improved FWPI by 87% and ERI by 23% while decreasing FPI by 46%. The relative impacts of land use change were considerably larger than climate change impacts in this paper. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

Reluctant pioneers in the European periphery? Environmental activism,food consumption and “growing your own”

East European food self-provisioning (FSP) has fascinated scholars of post-socialism ever since the early 1990s. In keeping with its predominantly economic and cultural conceptualisations, much of this research has been concerned with FSP’s role in household economy and with the social profile of its practitioners. In contrast to western conceptualisations of FSP as an opportunity to expand food activism and foster social justice and environmental sustainability, post-socialist FSP has rarely been considered as such. In Czechia, FSP is practised by 43% of citizens and many of them do so in a relatively environmentally friendly way. Yet, most food-related campaigns run by environmental NGOs (ENGOs) pay little attention to FSP and focus on market-based ethical consumerism and alternative food networks instead. Using insights from actor-network theory, this paper discusses how Czech ENGO activists engage with FSP through discourse and in practice. Based on ethnographic fieldwork and interviews with leading activists, we show that FSP does figure in non-food-related campaigns and that the FSP practised by activists themselves or the FSP carried out by relatives and relatives’ friends are not the same as the FSP on which they are reluctant to campaign. These differences, which include controllability and the time-consuming nature of practising FSP according to some of the activists’ ideals, help this paper to come to an initial understanding of why Czech ENGOs do not run campaigns explicitly focused on FSP at the moment and shed some light on how this could change in the future.     

Relating to nature,food and community in community gardens

This paper sheds critical light on the motivations and practices of community gardeners in relatively affluent neighbourhoods. The paper engages with community garden, alternative food and domestic garden literatures, to understand how people fit food production into their everyday lives, how they develop relationships to plants and how these in turn shape relations between people in a community group. The paper draws on participant observation and semi-structured walking interviews conducted at three community gardens in Sydney, Australia. The paper concludes that to fit community gardening into busy lives, people strategically choose plants with biophysical qualities that suit personal as well as communal circumstances and objectives. The paper shows how community is relationally constituted through the practices of growing and sharing food. Tensions might arise through the practices of growing food on communal and private plots and the taking and giving of food, but it can also encourage people to reflect on community food production and on their roles as individuals in a community group.     

环境治理对红枫湖水生食物链中汞积累的影响

于2015年以贵州省贵阳市饮用水源地红枫湖的水生食物链作为研究对象,通过测定不同营养级生物的汞含量及稳定碳氮同位素,并结合2007年红枫湖的数据,对比红枫湖水体的汞含量及水生食物链中的汞含量、食物链长度及生物放大率的变化。结果发现:相比于2007年,湖水中的总汞浓度降低了40%,但鱼体总汞和甲基汞含量分别增加了140%与210%,甲基汞在总汞中占的比例平均增加了18%。食物链长度增加一级,汞的生物放大率降低。可能的原因是:2008年政府对红枫湖进行综合治理后,水体富营养化程度降低,湖中食物链结构发生改变,鱼类生长速度减慢,使得鱼体内汞的生物稀释作用减弱,鱼体的汞含量相对升高。同时,高强度捕捞,使得鱼样个体普遍偏小,导致生物放大率较低。     

近45 a来我国农业气象灾害变化特征及其对粮食产量的影响

利用农业部种植业管理司发布的数据,针对近45 a(1970~2014年)来我国农业气象灾害变化特征及其对粮食产量影响的问题,采用数理统计和偏相关分析方法进行了研究。结果表明:黑龙江、山东和河南是受灾和成灾面积最大的省份;山西和内蒙古是受灾率和成灾率最高的两个省份;旱灾是我国主要的气象灾害,洪涝灾害波动明显,沿海地区台风灾害持续上升;东北地区旱灾比重增加,低温灾害有所减轻;华东地区洪涝、低温和台风灾害比重增加;华北地区低温和风雹呈现上升趋势;华南地区台风灾害增长显著;西北地区风雹和低温增加;西南地区旱灾和洪涝走势相反;中南地区旱灾减轻,洪涝加重;气象灾害直接影响到粮食总产量,干旱和洪涝灾害影响尤为明显;气象灾害与粮食产量的关系呈现出先上升后下降趋势。