畜牧业中抗生素的环境归趋·危害与防治

畜牧业大量使用抗生素造成了动物性食品中抗生素的残留,超量的抗生素残留会对人体、环境等造成危害。讨论了抗生素的来源、归趋和危害,提出了防治措施,即加强立法、完善检测方法、建立严格的管理体系、研制新的抗生素替代品。     

麦-稻轮作系统有机无机肥料配施协同氮素转化的机制研究Ⅰ.小麦季~(15)N去向分析

采用土培试验,以15氮(N)标记的硫酸铵和兔粪作为无机肥和有机肥氮源,进行交叉标记,研究了当季小麦种植下有机无机肥料配施处理协同氮素在土壤氮库和作物体内的去向。试验共设5个处理:对照无氮处理(CK),无机氮肥处理(IF),有机氮肥处理(OF),有机无机氮肥配施的两个处理,其中一个进行有机肥料的15N标记(IOF1),另一个进行无机肥料的15N标记(IOF2)。结果表明:1)无论黏壤土还是黏土,IF和IOF处理下小麦籽粒产量最高,且IF与IOF间没有显著差异;2)IOF处理无机肥料氮的存在显著提高了小麦籽粒和植株对有机肥料15N的吸收,黏壤土和黏土上籽粒增幅分别为57.1%和133.3%,植株增幅分别达220%和100%;3)与IF或OF处理相比较,黏壤土上IOF处理增加了无机肥料15N和有机肥料15N在小麦营养器官的积累,而在黏土上增加了无机肥料15N在营养器官、有机肥料15N在生殖器官籽粒的积累;4)与IF或OF相比较,小麦成熟期IOF处理有机肥料氮和无机肥料氮相互协同促进了对方在土壤微生物氮(MBN)库的固持,土壤—作物系统肥料15N回收率显著增加,相应地,有机肥料15N和无机肥料15N损失率显著降低。可见,与传统IF处理相比较,IOF处理取得与之相当的小麦籽粒产量。IOF处理无机肥料氮和有机肥料氮协同促进了肥料氮在土壤—作物系统的回收。     

应用~(15)N示踪研究设施蔬菜对氮肥的当季利用

在设施栽培条件下,采用田间多点位微区试验,研究莴苣、芹菜和生菜3种蔬菜氮肥的当季利用与损失。结果表明:3种蔬菜氮肥施用量在习惯施氮量的基础上减少25%,氮肥当季利用率增加,植株总吸氮量中来自于氮肥的比例降低。经过莴苣、芹菜和生菜一季的吸收,0～20 cm土层氮肥残留显著高于20 cm以下各土层当季氮肥残留。在莴苣种植系统中氮肥有23.90%～31.15%损失,在芹菜种植系统中氮肥有18.69%～27.71%损失,生菜种植系统中氮肥损失低于15%。     

不同利用年限不同坡位的红壤水稻田化肥氮去向

采用15N微区示踪法研究了不同利用年限、不同坡位的红壤水稻田N素的运移特征与去向.试验结果表明:红壤地区新、老水稻田成熟期肥料利用率为18.71%～29.10%;残留率在5.97%～18.73%之间;老稻田耕层的土壤N素残留高于新稻田,但新稻田剖面中15～50 cm土层15N残留量占总残留量的比率明显要高于老稻田;红壤水稻田肥料损失率高达52.24%～68.91%.此外,供试田块各生育期渗漏水中NH4 -N、NO3--N浓度均为:耕层＞犁底层.     

滇真冈种子萌发的生态生物学研究

由于种皮的抑制作用，滇青冈种子有休眠现象，新鲜种子萌发率极低，变温有利于克服种皮障碍，提高萌发率。砂藏可解除休眠，不同种子解除休眠的时间长短不一，种子种群有较宽广的可萌发时限。滇青冈林地上种子在落到地面后的9个月内，由于虫害和鼠害全部损失萌发能力，没有种子萌发转化成幼苗。滇青冈种子直播造林，应在10月采种，杀虫处理砂藏至次年雨季前播种。     

病毒在不同环境介质中去向研究进展

来自污水污泥等源头的病毒进入土壤和水环境后对人畜健康构成威胁,因而阐明病毒在不同环境中的去向是建立安全、高效病毒防治技术的基础.本文在已有研究的基础上,综述了病毒在水体、土壤中的去向,及病毒去除材料的去除效率和机制;明确了气-水界面、本土微生物、有机质含量及其组成等因素对病毒去向有显著影响;比较分析了基于高吸附性和铁铝氧化物致死性的活性炭和富铁铝材料等的病毒去除效率.最后从研究介质选择、病毒去除材料的潜在应用前景、及本土微生物组成对病毒去向影响角度提出了需进一步研究的一些建议.     

细菌生长过程中的病毒消失行为研究

环境中土著微生物存在及微生物的不同生长阶段可能影响病毒去向.本研究选择自然界广泛存在的3株细菌:恶臭假单胞菌(PP)、铜绿假单胞菌(PA)、枯草芽孢杆菌(BS)为微生物代表,以噬菌体φX174为指示病毒,通过30℃ (PP)和35℃(PA和BS)条件下病毒与细菌同步生长的培养实验和4℃条件下病毒与不同生长时段的菌株培养物的静态吸附实验,比较分析了细菌生长发育阶段对病毒消失(包括可逆/不可逆吸附和消亡)的影响.培育实验结果表明,病毒在30℃和35℃培养基中的浓度随着培育时间持续降低;但当培养基中接菌时,病毒浓度从接种至对数期6h间急剧降低,降低幅度超过对照处理,其中在BS处理中降幅最大,其次为PA和PP处理;随着细菌由对数期进入稳定期和衰亡期,病毒浓度先反弹升高,然后后持续降低,反弹最高点病毒浓度在3株菌处理中均高于各自对照处理,反弹持续时间和病毒浓度的反弹提升程度依不同菌株而异.静态实验结果表明,菌株培养物的培育时间从6h延长至18h时,病毒的消失比例逐渐降低,继续延长至24 h时又迅速升高,然后随着培育时间的进一步延长而持续降低.以上结果表明细菌对病毒消失的影响随细菌生长发育阶段和菌种而异,暗示在研究病毒在环境中去向时,必须考虑环境中本土微生物的存在及其组成.     

Impacts of particulate organic carbon and dissolved organic carbon on removal of polycyclic aromatic hydrocarbons, organochlorine pesticides, and nonylphenols in a wetland

Background, aim, and scope  The potential of wetlands for controlling point- and nonpoint-source pollution in surface water has attracted increasing interest. The partitioning process of organic contaminants between water, particulate organic carbon (POC) and dissolved organic carbon (DOC), impacts their behaviors in the aquatic environments. Meantime, the partitioning process of organic contaminants is closely related to their physicochemical properties, such as hydrophobicity (or K _ow), and their fates in wetlands may vary greatly depending on physicochemical properties. The aim of this study was to examine fates and removals of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and nonylphenols (NPs) in a wetland in Beijing, China, and provide useful information for ecological remediation. Materials and methods  Water samples, collected at five sites from inlet to outlet of the wetland once a month in summer 2006, were immediately filtered within 2 days through 0.45-μm glass fiber prefilters and enriched by solid-phase extraction. The filtered particulates were collected as the total suspended particulates (TSPs), freeze-dried, and Soxhlet-extracted. After extraction, samples were purified following a clean-up procedure and analyzed by GC-MS. Results  TSPs could be removed efficiently with a removal rate of 97.4%, and DOC could be moderately removed with a removal rate of 44.7% from inlet to outlet. The total removals of target contaminants varied widely from null to 82.0%. A good correlation between logK _ow and logK _oc (organic-carbon-normalized suspended-particulate partition coefficient) was observed (r ² = 0.84 for PAHs and r ² = 0.86 for OCPs, p < 0.01). Ratios of the POC-bound fraction of target contaminants (or DOC-bound fraction) to the freely dissolved fraction increased with their K _ow values. The removal of the POC fraction contributed more than 50% to the total removal for the contaminants with logK _ow > 5.0. Only a small portion of the removal was attributed to the removal of the freely dissolved fraction. Discussion  Hydrophobic compounds such as PAHs and OCPs with higher K _ow values would show stronger POC or DOC preference. Their removal depended greatly on their K _ow values and the removal of total suspended particulates. On the other hand, concentrations of NPs decreased little in the wetland, probably due to their production through degradation of their precursors and relatively low hydrophobicity. Conclusions  POC and DOC play essential roles on the fates and removals of hydrophobic organic contaminants in the wetland. The removal of target contaminants with a high K _ow should be mainly through association with the suspended particulates which were precipitated and retained in the wetland. The fates of the organic contaminants in the wetland greatly depended on their hydrophobicities. Recommendations and perspectives  Further work should be done to study the influence of hydraulic retention time and some other environmental factors, e.g., temperature, on removals and fates of organic contaminants. Behavior of NPs and their precursors in the wetland should also be investigated more thoroughly.     

权近(1352-1409)的人性与天命观:理学在韩国发展的几个特征

权近从心性的角度处理天人关系,认为其非常现实且与生命息息相关.在对心的阐释上与朱子不同,认为心虽由气构成,但更主要的是由来自天的理构成,并且把恶与心分割开来.其天人关系的意义及其重要性主要体现在政治实践当中,提出了体用、圣学等重要思想.他用图解的形式来处理天人关系的方法得到了广泛的使用和继承.     

黑土-春小麦中三种化学氮肥的去向

用＾１５Ｎ田间微区试验研究了黑土－春小麦中作基肥施用的尿素、碳 和硝酸钾三种氮肥的氮素去向。试验设在黑龙江省海伦市郊区,氮肥用量为纯Ｎ７５ｋｇ／ｈｍ＾２,施肥深度为１０ｃｍ。结果表明,硝酸钾和尿素的氮素利用率相当,分别为５８．４％和５５．９％,显著高于碳铵（４２．６％）。硝酸钾的土壤中的残留率（２８．７％）显著低于碳铵（３８．８％）和尿素（３８．２％）,氮素总损失在５．８％￣１８．６％之间,碳铵的