农业面源污染负荷空间分布及风险评价研究进展

为了研究农业面源污染负荷空间分布及风险评估,综述了国内外近10年的最新研究进展,发现在农业面源污染空间分布及风险评估上的研究较多,其中污染的源因子及迁移因子空间分布研究进展颇多,而在综合风险评价上的研究还比较缺乏,对污染负荷的分布特征及其相关性的研究还存在不足,今后还需研究污染负荷分级区划与管理控制措施研究。     

Efficient reduction of biomass,seed and season long pollen production of common ragweed (Ambrosia artemisiifolia L.)

Ragweed (Ambrosia artemisiifolia L.) is a noxious plant that not only is a troublesome agronomic weed that causes economic damage to agricultural crops but also − and even more importantly − causes severe health problems due to its severe allergenicity. The pollen of invasive ragweed has become a major allergenic risk factor in urban areas in newly occupied regions. Many urban areas prohibit herbicide application; thus, mowing is the most widely used control measure. Counting pollen is labour intensive; therefore, pollen production data are mainly based on estimations. Field experiments were conducted to determine the effects of different mowing scenarios, plant density and cutting height on the biomass, pollen production and seed production of common ragweed plants. Ragweed plants were mown twice: just before the flowering of terminal racemes (BBCH 59) and when the flowers of the re-sprouting lateral shoots reached BBCH 59. A 1- to 3-cm cutting height produced the greatest pollen reduction compared to that of intact control plants (94%) based on a season-long pollen collection. The number of female flowers also significantly decreased (97%). Compared to the control, the onset of pollen discharge was delayed by 5 weeks and the length of the pollen discharge period decreased from 9 to 4 weeks. The season-long unique and reproducible pollen production data can be integrated with airborne pollen modelling and population management strategies.     

国内湿地重金属污染评价的研究进展

湿地作为地球上重要的生态系统之一,具有稳定环境、物种基因保护及资源利用功能,被誉为自然之肾、生物基因库和人类摇篮。随着近年来湿地面临着面积萎缩、功能下降、污染日趋严重等危机,国内外学者对湿地保持着持续关注与研究,其中对湿地重金属的污染评价就是湿地科学研究领域的重要内容之一。笔者通过对国内十多年来有关重金属污染方面的报道进行整理分析,回顾总结了湖泊、河流、三角洲以及滨海等类型湿地的底泥、水体及土壤中重金属的污染现状与迁移特征,重点对重金属的种类、空间分布以及分析方法等进行总结归纳。在众多研究成果中,对污染物评价的方法以地累积指数法和潜在生态风险指数法使用最多。     

Community structure of arbuscular mycorrhizal fungi associated with Robinia pseudoacacia in uncontaminated and heavy metal contaminated soils

The significance of arbuscular mycorrhizal fungi (AMF) in soil remediation has been widely recognized because of their ability to promote plant growth and increase phytoremediation efficiency in heavy metal (HM) polluted soils by improving plant nutrient absorption and by influencing the fate of the metals in the plant and soil. However, the symbiotic functions of AMF in remediation of polluted soils depend on plant–fungus–soil combinations and are greatly influenced by environmental conditions. To better understand the adaptation of plants and the related mycorrhizae to extreme environmental conditions, AMF colonization, spore density and community structure were analyzed in roots or rhizosphere soils of Robinia pseudoacacia. Mycorrhization was compared between uncontaminated soil and heavy metal contaminated soil from a lead–zinc mining region of northwest China. Samples were analyzed by restriction fragment length polymorphism (RFLP) screening with AMF-specific primers (NS31 and AM1), and sequencing of rRNA small subunit (SSU). The phylogenetic analysis revealed 28 AMF group types, including six AMF families: Glomeraceae, Claroideoglomeraceae, Diversisporaceae, Acaulosporaceae, Pacisporaceae, and Gigasporaceae. Of all AMF group types, six (21%) were detected based on spore samples alone, four (14%) based on root samples alone, and five (18%) based on samples from root, soil and spore. Glo9 (Rhizophagus intraradices), Glo17 (Funneliformis mosseae) and Acau3 (Acaulospora sp.) were the three most abundant AMF group types in the current study. Soil Pb and Zn concentrations, pH, organic matter content, and phosphorus levels all showed significant correlations with the AMF species compositions in root and soil samples. Overall, the uncontaminated sites had higher species diversity than sites with heavy metal contamination. The study highlights the effects of different soil chemical parameters on AMF colonization, spore density and community structure in contaminated and uncontaminated sites. The tolerant AMF species isolated and identified from this study have potential for application in phytoremediation of heavy metal contaminated areas.     

左右岸省界缓冲区水质达标评价方法研究

左右岸省界缓冲区作为协调省际间用水关系的重要水域,其水质达标评价及污染责任划分是流域限制纳污红线制度实施的重要内容。从左右岸省界缓冲区的相关概念出发,根据省份的位置关系将其分为缓冲区完全在两省省界上、缓冲区部分在两省省界上以及缓冲区在多省交界上三种情形,并结合左右岸省界缓冲区特点确定调整浓度核算法、代表断面判断法、限制排污总量-污染物入河量评估法等水质达标评价方法,以判断左右岸省份缓冲区的水质达标情况,从而划分缓冲区左右岸省份的污染责任。实例验证模拟显示,确定的方法切实可行,研究方法可为流域污染责任划分提供技术支撑,从而促进限制纳污制度的顺利实施。     

离子交换纤维对麦田土壤铅污染的修复效果

为探讨土壤Pb污染的治理方法,通过盆栽试验,比较了离子交换纤维的两种不同放置方式(分层放置与混匀放置)对麦田土壤Pb污染的修复效果。结果表明,在土壤1 000 mg·kg~(-1) Pb污染水平下,Pb污染处理(T1:Pb胁迫;T2:Pb+在土壤中分三层放置纤维;T3:Pb+在土壤中混匀剪碎的纤维)的土壤pH值、总有机碳含量较对照(CK:未添加Pb和离子交换纤维)有所降低。在小麦成熟期,T2、T3处理下土壤和植株各部位的Pb含量均低于T1处理,其中T3处理变化显著;T2、T3处理中纤维吸附的Pb含量则分别达到115.01和128.26 mg·kg~(-1)。T2、T3处理的Pb富集系数低于T1处理及CK。由此说明,离子交换纤维能够有效吸附土壤中的Pb,降低Pb从土壤向植株的转运能力,且离子交换纤维混匀放置方式的修复效果较好。     

中国农业面源污染排放的空间差异及其动态演变

以2003—2014年为研究时段,在测算农业面源污染排放强度的基础上,综合运用基尼系数和非参数估计方法,研究我国农业面源污染的空间差异及其动态演变,结果表明:1)我国农业面源污染排放总体下降,且表现出明显的空间差异,东部和中部地区的排放强度较高,西部和东北地区则相对较低。2)2003—2014年,中国农业面源污染排放强度的区域差异略微扩大,地区间差异是其总体差异的主要来源。3)核密度估计结果表明,中国农业面源污染排放总体差异表现为"下降-上升-下降"的波动变化趋势。4)马尔科夫链分析表明,中国农业面源污染在不同类型间的相互流动较为微弱,但从长期来看,存在向两极分化发展的趋势特征。     

土壤重金属污染及对生物体影响的研究进展

重金属污染是当今社会世界性的环境生态问题。由于人类社会城市化进程加剧、工业生产中"三废"的不合理排放以及现代农业中各种农药化肥的大量使用,导致土壤中重金属的含量剧增,污染问题严重,其中尤以重金属镉、汞、铅等在生物体内的富集与抗生性的研究日益受到关注。笔者综述了土壤重金属污染及对生物体影响的研究进展,以期为土壤重金属综合治理与污染修复提供科学依据。     

Comparison of the effects of seed coating with tungsten and molybdenum compounds on seedling establishment rates of rice,wheat, barley,and soybean under flooded conditions

Seed coating with molybdenum compounds improves seedling establishment for rice, wheat, barley, and soybean when such seeds were sown under flooded conditions. Tungsten belongs to the same chemical group as molybdenum in the periodic table, and similar to molybdenum, inhibits the generation of sulfide ions. Here, the effects of tungsten and molybdenum containing seed coatings on seedling establishment under flooded conditions were compared using rice, wheat, barley, and soybean. In rice, the effects of tungsten compounds on seedling establishment varied. Tungsten trioxide had little effect but tungstic acid and ammonium phosphotungstate significantly improved seedling establishment when the amounts were at least .1–.2 mol W kg^?1. Although the effect of tungsten coating varied depending on the compound used, ammonium phosphotungstate, along with other tungsten compounds, improved seedling establishment in a manner comparable with that of molybdenum compounds. For wheat and barley, ammonium phosphotungstate treatment resulted in a significant increase in establishment that was only slightly less than the results observed using molybdenum compounds. Tungstic acid and ammonium phosphotungstate treatments improved soybean establishment in a significant manner that was comparable with those of molybdenum compounds. Collectively, these results suggest that tungsten compounds, as well as molybdenum compounds, improve seedling establishment under flooded conditions.     

Analysis and Assessment on Heavy Metal Contamination in Cotton Seeds of Hunan Province

[Objective] In order to guarantee the quality and safety of cotton products and to explore the feasibility of alternative planting, the contamination condition of the heavy metals in cotton seeds in Hunan province was investigated and evaluated. [Method] Fifty-six cotton seed samples, collected in 6 counties of Hunan province, were collected to determine 6 indicators including cadmium, lead, copper, chromium, mercury and inorganic arsenic contents. This was followed by pollution index calculation, correlation analysis, and cluster analysis. [Results] The range of comprehensive pollution indexes of Junshan district, Anxiang county, Nanxian county, Wangcheng and Dingcheng districts varied between 0.366 5–0.577 0, which belonged to a secure level. However, the single pollution indexes of Hengyang county are relatively high. The comprehensive pollution index of Hengyang county was 0.801 6, meaning a mild pollution level. [Conclusion] The pollution status of cadmium, lead, copper, chromium, mercury and arsenic in Hunan cottonseed samples are generally acceptable. Cotton could be a substitute for rice on contaminated soil.