典型地区农用地污染调查及风险管控标准探讨

针对《土壤污染风险管控标准——农用地土壤污染风险管控标准》(GB 15618—2018),提出以土壤中全量浓度筛选值和管控值作为衡量农用地土壤污染风险管控的标准,对湖南省部分稻田农用地土壤及点对点稻米样品中镉、铅、砷、汞的总量和有效态浓度及稻米中含量进行监测,根据重金属总量浓度分为低风险、中风险、高风险3组。结果显示:(1)土壤及稻米中镉含量基本为随着风险级别的升高而增加,铅、砷在土壤和稻米中含量无规律性结果,汞监测结果均为未检出。(2)低风险组稻米镉超标率为12. 0%,高风险组稻米镉达标率为33. 3%,表明利用总量浓度对农用地土壤潜在风险进行分组存在一定的局限性。(3)依据4种重金属在土壤中总量及稻米(早稻)中含量情况,对风险级别进行调整并综合判断:有58个样品为低风险组,占样品总数的68. 2%,超标率为零;有15个样品为中风险组,占样品总数的17. 7%,超标率为80. 0%;有12个样品为高风险组,占样品总数的14. 1%,超标率为100. 0%。调整后评价结果与上述标准的划分目标更接近,能够提高上述标准的准确性和实用性。     

Impact of posture and upper-limb muscle activity on grip strength

Purpose. The current research was carried out to determine grip strength (GS) with change in posture and upper-limb muscle activity of manual workers and investigate the impacts of these changes. Methods. For the current research, 120 male and 80 female participants were selected and GS was assessed using a digital hand grip dynamometer in various conditions. Results. The outcomes showed that male participants had higher GS as compared to female participants. Maximum GS was found in a standing posture with the fixed forward shoulder at 45°, elbow at 90° and a neutral position of the wrist and forearm for all participants. Conclusions. Higher values of GS were attained in standing postures which may result in attainment of higher performance levels by the workers. The outcomes justify the importance of correct postures during manual work in industries employing traditional methods.     

Traditional agriculture in transition: examining the impacts of agricultural modernization on smallholder farming in Ghana under the new Green Revolution

Following the renewed effort at achieving a new green revolution for Africa, emphasis has been placed on modernizing smallholder agriculture through the deployment of improved inputs especially mechanized technologies. In Ghana, the government has in the last decade emphasized the provision of subsidized mechanized ploughing services to farmers alongside a rapidly growing private sector tractor service market. While mechanized technology adoption rates have increased rapidly, the deployment of these technologies has been without critical analysis of the impacts on production patterns and local agrarian systems. This paper examines the distributional impacts of agriculture mechanization on cropping patterns and farm sizes of smallholder farmers in northern Ghana using Geographic Information Systems (GIS) techniques, and semi-structured interviews with smallholder farmers (n=60). Specifically, comparative analysis of the field sizes and cropping patterns of participant farmers prior to and after the adoption of mechanized technologies was conducted. In-depth interviews were used to contextualize the experiences of smallholder farmers toward understanding how mechanization may be impacting traditional agriculture. Our findings reveal a mechanization paradox in which farm sizes are expanding, while cropping patterns are shifting away from traditional staple crops (pearl millet and sorghum bicolor) to market-oriented crops (maize, rice and groundnuts). This transition we argue, has adverse implications on the cultural dimension of food security, the organization of social life, and climate change adaptation. We recommend a retooling of the current agricultural policy focus to ensure context sensitivity for a more robust battle against food insecurity.     

Potential of microalgae as biopesticides to contribute to sustainable agriculture and environmental development

The loss of yields from agricultural production due to the presence of pests has been treated over the years with synthetic pesticides, but the use of these substances negatively affects the environment and presents health risks for consumers and animals. The development of agroecological systems using biopesticides represents a safe alternative that contributes to the reduction of agrochemical use and sustainable agriculture. Microalgae are able to biosynthesize a number of metabolites with potential biopesticidal action and can be considered potential biological agents for the control of harmful organisms to soils and plants. The present work aims to provide a critical perspective on the consequences of using synthetic pesticides, offering as an alternative the biopesticides obtained from microalgal biomass, which can be used together with the implementation of environmentally friendly agricultural systems.     

Mapping shifts in spatial synchrony in grassland birds to inform conservation planning

Spatial synchrony, defined as the correlated fluctuations in abundance of spatially separated populations, can be caused by regional fluctuations in natural and anthropogenic environmental population drivers. Investigations into the geography of synchrony can provide useful insight to inform conservation planning efforts by revealing regions of common population drivers and metapopulation extinction vulnerability. We examined the geography of spatial synchrony and decadal changes in these patterns for grassland birds in the United States and Canada, which are experiencing widespread and persistent population declines. We used Bayesian hierarchical models and over 50 years of abundance data from the North American Breeding Bird Survey to generate population indices within a 2° latitude by 2° longitude grid. We computed and mapped mean local spatial synchrony for each cell (mean detrended correlation of the index among neighboring cells), along with associated uncertainty, for 19 species in 2, 26-year periods, 1968–1993 and 1994–2019. Grassland birds were predicted to increase in spatial synchrony where agricultural intensification, climate change, or interactions between the 2 increased. We found no evidence of an overall increase in synchrony among grassland bird species. However, based on the geography of these changes, there was considerable spatial heterogeneity within species. Averaging across species, we identified clusters of increasing spatial synchrony in the Prairie Pothole and Shortgrass Prairie regions and a region of decreasing spatial synchrony in the eastern United States. Our approach has the potential to inform continental-scale conservation planning by adding an additional layer of relevant information to species status assessments and spatial prioritization of policy and management actions. Our work adds to a growing literature suggesting that global change may result in shifting patterns of spatial synchrony in population dynamics across taxa with broad implications for biodiversity conservation.     

水稻秸秆生物炭对水体中DDE的吸附性能研究

通过模拟实验,初步考察了一款水稻秸秆生物炭对水中滴滴涕农药的吸附效应。吸附动力学与吸附等温线的结果表明,水稻秸秆生物炭对水中滴滴涕具有吸附速度快、吸附容量高的特点,在水体有机污染物防治中具有较好应用前景。     

生态经济学视角下的循环农业：理论、实践与发展方向

农业经历了生态农业、化学农业到生态农业的变迁,生态农业是起点也是终点。发达国家饱尝了发展化学农业的苦果,随后转轨到生态农业的道路上,最后认识到只有发展循环农业才能够做到农业可持续发展。发达国家的循环农业特别强调生态内涵和变废为宝理念,政府的财政投入和科研投入力度很大。相比之下,我国虽然已经开始发展循环农业,但目前还并不普遍,化学农业还占有很大比例。学习吸收发达国家的经验,会让我国尽早走上循环农业的发展道路。循环农业是我国农业的发展方向,为了做到这一点,需要强化农业产业化力度、加大财政补贴力度和科研投入力度。     

水稻种植对中亚热带红壤丘陵区小流域氮磷养分输出的影响

以湖南省长沙县的脱甲流域(高水稻种植面积比例)和涧山流域(低水稻种植面积比例)为研究对象,对比研究红壤丘陵地区典型农业流域水稻种植对河流水体氮磷浓度和输出强度的影响.连续16个月的监测结果表明,脱甲和涧山流域河流水体均存在比较严重的养分污染,尤其是氮污染;对比两个流域,脱甲流域河流水体的氮磷浓度水平和水质恶化程度均高于涧山流域.从养分组成来看,脱甲流域河流水体中氮以铵态氮为主(占总氮的58.5%),而涧山流域主要是硝态氮(占总氮的76.1%).脱甲流域中可溶性磷占总磷比例为47.1%,高于涧山流域的37.5%.从养分浓度变化的时间动态而言,两个流域河流中各形态氮素水平在1~2月和7月较高,而可溶性磷和总磷在5~6月和10~12月出现两个峰值.由于两个流域河道径流主要集中在水稻种植期间的4~10月,脱甲流域河流中较高的氮磷养分浓度意味着潜在的氮磷流失风险.脱甲流域月平均总氮输出通量为1.67 kg·(hm2·月)-1,总磷为0.06 kg·(hm2·月)-1,均高于涧山流域的0.44 kg·(hm2·月)-1和0.02kg·(hm2·月)-1.考虑到两个流域的气候、地形地貌、土壤类型、农田耕作方式相似而只是水稻种植面积比例不同,因此,在该地区传统的水稻栽培管理模式下,较高面积比例的水稻种植对流域河流水体环境存在潜在威胁.     

Expression of sulfur uptake assimilation-related genes in response to cadmium, bensulfuron-methyl and their co-contamination in rice roots

The responses of sulfur （S） uptake assimilation-related genes＇ expression in roots of two rice cultivars to cadmium （Cd）, bensulfuron-methyl （BSM） and their co-contamination （Cd＋BSM） were investigated by gene-chip microarray analysis and quantitative real-time PCR （QRT-PCR） technology. Treatments of Cd and Cd＋BSM induced expression of sulfate transporter and permease genes, and promoted sulfate uptake in rice roots. Cd＋BSM could alleviate Cd toxicity to cv. Fengmeizhan seedlings, probably due to Cd＋BSM promoting greater S absorption by seedlings. Cd and Cd＋BSM induced expression of sulfate assimilation-related genes, and thus activated the sulfur assimilation pathway. Cd and Cd＋BSM induced expression of phytochelatin synthase and metallothionein genes, and induced expression of glutathione S-transferases （GSTs）, glutathione synthase （GS） and S- containing antioxidation enzyme genes, which detoxified Cd2＋. It is suggested that （to cope with the toxicity of Cd, BSM and their co-contamination） the S uptake and assimilation pathway was activated in rice roots by increased expression of related genes, thus enhancing the supply of organic S for synthesis of Cd or BSM resistance-related substances.     

不同含磷物质对重金属污染土壤-水稻系统中重金属迁移的影响

通过水稻盆栽试验研究磷酸氢二钠(DSP)和羟基磷灰石(HAP)对污染土壤中重金属(Pb、Cd、Zn)向水稻迁移的影响.结果表明,①DSP和HAP都显著提高了土壤pH值和有效磷含量(p0.05),降低了土壤中Pb、Cd、Zn交换态含量,且HAP降低重金属交换态的效果较DSP好.水稻地上部分重金属含量与土壤中重金属交换态含量呈明显正相关关系,说明DSP和HAP通过降低土壤中重金属交换态含量从而达到减少重金属向水稻中迁移的目的.②DSP和HAP明显降低了水稻各器官Pb、Cd的含量,同时使水稻根、壳、糙米中Zn含量降低,但增加了茎叶中Zn的含量.与对照相比,DSP和HAP分别使糙米中Pb、Cd、Zn最大降低了48.72%、22.22%、25.35%和62.82%、66.67%、39.88%,但是糙米中Pb、Cd含量仍未达到食品卫生标准限值(GB2762—2012).③DSP和HAP处理都使水稻根干重逐渐减少,使茎叶、壳、糙米干重先增加后降低,在0.12 g·kg-1时使水稻糙米产量最大.综上,DSP和HAP都能有效控制土壤中Pb、Cd、Zn向水稻中迁移,且HAP效果比DSP好,但磷添加量不宜过高.