The effects of burial by sand on survival and growth of Pitcher’s thistle (Cirsium pitcheri) along lake huron

Greenhouse experiments were conducted to determine the effects of sand burial on survival and growth of seedlings ofCirsium pitcheri. In 1992–1993, seedlings were buried to depths of 0, 25, 50, 75, and 100% of their height while in 1993–1994, the seedlings were buried to depths of 0, 4 cm (single burial), 4 cm (repeated burial of 1 cm every 8 days), 8 cm (single burial) and 8 cm (repeated burial of 2 cm every 8 days). Several physiological traits, net photosynthetic rate, chlorophyll a∶b ratio, leaf area, number and length of leaves, number of internodes, amount of tillering, and biomass, were measured. The results showed that all seedlings died in the complete (100%) burial, 20% died in the 75% burial and none died in the 0, 25 and 50% burial treatments. Burial of seedlings to a depth of 25% stimulated their growth but 75% burial significantly decreased the total dry weight. Repeated burial treatments exhibited significantly greater stimulation of growth than single burial. Surviving seedlings grew through the sand deposit by elongating the stem and leaf petioles, increasing the number of nodes and the length of internodes. This elongation occurred at the expense of development of the root system indicating that available energy was re-allocated to above-ground parts.     

园林植物除菌能力的研究

为挑选出除菌能力较强的园林植物,应用撞击平皿法进行样品采集与培养,通过多元素方差分析法对23种园林植物除菌的能力进行比较研究.结果表明,火炬树、树锦鸡儿、杜松和红皮云杉等的除菌率小于40%;新疆圆柏和榆叶梅等的除菌率大于40%.     

Review on industrial wastewater energy sources and carbon emission reduction: towards a clean production

This review provides an innovative approach of treating palm oil mill effluent (POME) from open pond and closed anaerobic sludge reactor for generation of green energy in the form of biogas containing methane. Improper techniques for the treatment and management of POME produce hazards to people and contribute to global warming. In all over the world, the total crude oil palm production in the countries like Malaysia, Indonesia, Africa, Latin America, Asian countries, Solomons and other were around 51, 31, 7, 6, 3, 2 and 1% compared with soya 41.8% and coconut 3.48%, respectively. In the year 2014–15, Malaysia generated at least 87.8 million tonnes of palm effluent per year. Various studies reveal that about 80% of palm effluent is disposed off partially treated in open dumps. The generated certified emission reductions (CERs) estimated and favoured the treatment of POME in anaerobic reactor by replacing open lagoon of aerobic system for cleaner production. The clean development mechanism (CDM) encourages the utilisation of upflow anaerobic sludge blanket reactors for POME treatment and methane capture to earn CER credits as a source of revenue.     

Polycentric agglomeration and haze pollution: evidence from China

Polycentric agglomeration has gradually become a salient feature of rapid growth in urbanization in China. Using province-level balanced panel data over the period 2000–18, we examine the impact of polycentric agglomeration on haze pollution and its mechanism of action. The results show that the impact of polycentric agglomeration on haze pollution exhibits a significant inverted U-shaped feature. Nevertheless, except for a few provinces where polycentric agglomeration exceeds the turning point, the degree of polycentric concentration in most provinces lies to the left of the turning point. Further, a mediating effect model illustrates that industrial structure rationalization and technological progress are effective paths through which polycentric agglomeration affects haze pollution. Finally, we demonstrate that the effect of polycentric agglomeration on haze pollution is influenced by transportation and communication infrastructure; improved transportation and communication infrastructure contributes to the haze control effect of polycentric agglomeration.

     

Risk posed by chlorinated organic compounds in Abu Qir Bay,East Alexandria,Egypt

Introduction  

In Egypt, the picture of threats to humans and the environment from the exposure to organic pollutants is still incomplete. Thus the objectives of this study were to assess the occurrence and distribution of polychlorinated biphenyls (PCBs), organochlorine pesticides, and chlorpyrifos in sediments and mussels of Abu Qir Bay and their risks for environment and human health.     

Deciphering the impact of novel coronavirus pandemic on agricultural sustainability,food security,and socio-economic sectors—a review

Environmental Science and Pollution Research - The Spanish flu, Asian flu, Hong Kong flu, HIV/AIDS, SARS, Ebola, and Swine flu, among others, have had a significant impact on agriculture,...     

开都河下游绿洲耕地土壤重金属污染及潜在生态风险

开都河下游绿洲采集98个耕地土壤样品,测定其中As、Cd、Cr、Cu、Mn、Ni、Pb和Zn等8种重金属元素的含量.基于地统计法,污染负荷指数法和潜在生态风险指数法研究耕地土壤重金属污染和潜在生态风险,并对重金属的来源进行讨论.结果表明:(1)研究区Cd含量平均值超出《国家土壤环境质量标准》中Ⅱ级标准的11.08倍.Cd、Cr、Ni、Pb和Zn含量的平均值分别超出新疆灌耕土背景值的55.42、1.32、1.36、3.40和5.14倍.重金属元素空间分布各不相同,部分区域出现高值区,表明人类活动对耕地土壤环境具有负面效应.(2)研究区耕地土壤Cd呈现重度污染,Pb呈现中度污染,Cr、Cu、Ni和Zn呈现轻度污染,As和Mn呈现无污染态势.Cd是污染面积最大,污染程度最高的元素.研究区污染负荷指数PLI的平均值为1.68,呈现轻度污染.(3)各重金属元素单项生态风险指数(E)的平均值从大到小依次为:Cd、Ni、As、Cu、Pb、Cr与Zn.研究区综合生态风险指数(RI)的平均值为355.31,属于较强生态风险.(4)研究区耕地土壤As、Cd、Pb和Zn主要受到人类活动的影响,Cr、Cu、Mn和Ni主要受到土壤地球化学特征的控制.Cd是研究区耕地土壤主要的污染因子,对PLI和RI的贡献很大,耕地土壤中Cd污染必须关注.     

乌鲁木齐市安宁渠蔬菜基地土壤重金属污染现状及潜在生态风险评价

为了认识蔬菜产地土壤重金属富集现状，探索其解决途径，为污染防治措施提供科学依据，促进无公害蔬菜生产，确保蔬菜质量安全。在乌鲁木齐北郊蔬菜地采集26个土壤样品和7个水体样品，分别测定样品中Hg、As、Cr、Cd、Pb和Zn 6种重金属的含量。采用地积累指数（I_geo）、污染负荷指数（PLI）、潜在生态风险评价（RI）对蔬菜地土壤重金属污染及潜在生态风险进行分析。通过土壤与水样的结合，采用主成分分析法进行污染来源分析，结果表明：（1）乌鲁木齐安宁渠蔬菜基地土壤中Hg、Cr和Zn重金属含量的均值分别为新疆土壤背景值的5.74、1.74、1.52倍，其中Cd含量的均值是国家二级标准的2.69倍。地下水中Cr含量均值超过国家灌溉水限制标准，是其8.89倍。（2）6种重金属I_geo的平均值依次为Cd > Hg > Cr > Zn > As > Pb，其中Cd属于中-强度污染，Hg为中度污染，Cr为轻度污染，Zn、As和Pb均为清洁水平。研究区土壤区域污染负荷指数PLI_zone为1.91，属于中度污染，其中Cd的贡献率最大，为56%，其次是Hg，贡献率为22%。土壤RI均值为673.1，属于严重潜在生态风险态势。（3）研究区土壤Pb、Cr和Zn，主要来自交通和农业活动等人为污染，As、Cd主要受自然母质和大气沉降的影响。该蔬菜基地潜在生态风险主要来自Cd和Hg，建议在农业生产中防范Cd、Hg的污染。