盐城市生猪屠宰废水污染现状及防治对策研究

根据生猪屠宰场污染现状,提出了防治对策与建议。严把准入关、集中建设、优胜劣汰、强化监管是减少污染的必要措施。     

农地整理对农户农地固定资本投入的影响研究

农地整理是政府农村公共投入的一种,农户的农地固定资本投入是农户的私人投资,研究农地整理对农户农地固定资本投入的投入效应将为农地整理的有效实施和促进农业机械化提供理论依据。在理论分析的基础上,基于农户调查数据,分别运用Tobit和Logit模型,分析了农地整理变量对农户农地固定资本投入的现状和意愿的影响。研究结果表明:农户对农地整理的满意程度对农户农地固定资本投入有正向影响;农户参与农地整理的意愿对农户农地固定资本投入意愿有正向作用;农地整理对农户农地固定资本投入的意愿比农户农地固定资本投入现状影响更为明显。因此,需要提高农地整理的质量,确保农地整理的实施;应该完善农户参与农地整理的机制,提高农户参与农地整理项目的意识和程度,充分保障农民权益;在农地整理项目实施的基础上,应该进一步克服农业机械化的障碍,从而推动农户发展农业机械化。     

排污补贴视角下的养殖户环保投资影响因素研究——基于沪、苏、浙生猪养殖户的调查分析

随着畜牧业的发展,畜牧业污染问题日益突出。解决污染问题的关键是增强养殖户参与,鼓励他们自发进行环保投资,而政府补贴对于具有外部性的生产投资活动均具有刺激作用。为了量化分析影响农户环保投资行为的各因素的作用程度,特别是政府补贴的激烈效果,本文运用调查结合实证的研究方法,在农户模型的分析框架上,以沪、苏、浙地区394户生猪养殖户的调查数据为基础,应用有序logit模型验证排污补贴、养殖户生产经营特征、环保需求特征对养殖户环保投资的作用。研究表明除了政府补贴会刺激养殖户的环保投资外,养殖规模对环保投资有激励作用,而养殖年限却会抑制环保投资。养殖户的个人特征,对污染的认知及参与污染治理的意愿也对环保投资水平有正的影响,但作用效果不明显。在此基础上,本文提出了合理制定和推进排污补贴政策,以"离牧补助"等形式促使养殖规模和环保要求不符的养殖户退出养殖业,加大畜牧业污染危害的宣传力度以及政府加强对污染处理技术的研发投资,从而降低处理成本等政策建议。     

Assays of PCB congeners and organochlorine insecticides with the transgenic Arabidopsis and tobacco plants carrying recombinant guinea pig AhR and GUS reporter genes

Certain congeners of polychlorinated biphenyls (PCBs) and organochlorine insecticides are ligands of aryl hydrocarbon receptors (AhRs) in animals. A recombinant guinea pig (g) AhR, XgDV, was constructed by fusing the ligand-binding domain of gAhR, the DNA-binding domain of LexA, and the transactivating domain of VP16. Then, the expression unit of β-glucuronidase (GUS) reporter gene regulated by XgDV was introduced into Arabidopsis and tobacco plants. When the transgenic Arabidopsis XgDV plants were cultured on Murashige–Skoog (MS) medium containing PCB congeners, the GUS activity in the plants increased toxic equivalent (TEQ)-dependently. The GUS activity in the transgenic Arabidopsis XgDV plants cultured on MS medium containing the organochlorine insecticide dieldrin was also induced. On the other hand, in the case of DDT, the GUS activity induced by 3-methylcholanthere in the plants decreased. The transgenic Arabidopsis XgDV plants detected 1000 ng g^?1 PCB126 in 1 g of soils. Thus the XgDV plants seemed to be useful for convenient assays of PCB congeners and organochlorine insecticides, without any extraction and purification steps.     

Assessment of oxidative stress due to exposure to pesticides in plasma and urine of traditional limited-resource farm workers: Formation of the DNA-adduct 8-hydroxy-2-deoxy-guanosine (8-OHdG)

The objective of this study was to assess the risk of genotoxicity caused due to oxidative stress using plasma and urinary levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) in farm workers for six months during a growing season. Blood and urine samples were collected once a month for six months (June to November 2003) from farm workers (n = 15) and urban unexposed controls (n = 10). Plasma and urinary levels of 8-OHdG were evaluated by Enzyme Linked Immunosorbent Assay (ELISA) technique. There was no significant difference in the urinary levels of 8-OHdG between the farm workers and the control group, but there was an approximately four-fold increase in mean values of plasma 8-OHdG levels in the farm worker group (P ≤ 0.05).     

Median lethal concentration of formaldehyde and its genotoxic potential in bullfrog tadpoles (Lithobates catesbeianus)

In order to avoid that contaminated frog farms animals escaping in the environment and become potential vector of emergent diseases, studies with disinfection protocol are strictly necessary. The formaldehyde is one of the compounds tested in fungal disinfection protocols and also used in aquaculture. This study aimed to determine the median lethal concentration (LC_50–96h) of formaldehyde in bullfrog tadpoles and to evaluate the possible genotoxic effects in acute exposition. Accordingly, the animals were exposed to formaldehyde in the concentrations of 6, 9, 12, 15, and 18 mg L^?1, and after 96 h blood samples were drawn for the micronucleus (MN) test. The LC_50–96h was 10.53 mg L^?1, and the MN frequency increased in proportion to the formaldehyde concentrations, with an estimated frequency in the negative control being 1.35 MN/individual. We concluded that formaldehyde is genotoxic to tadpoles of bullfrogs in the tested concentrations, and the choice of this chemical should be contemplated before its use in animals in captivity.     

混合水解对打捆麦秸水解产酸的影响

为研究混合水解对麦秸水解产酸的影响,以猪粪、厨余和蔬菜废物为原料,研究其分别与麦秸混合水解产酸的特性,分析了水解过程中pH值、COD、SCOD和VFAs的变化。结果表明,除麦秸＋蔬菜废物最佳出料时间为3～9d外,麦秸、麦秸＋厨余垃圾、麦秸＋猪粪水解液最佳出料时间均为3～7d,7d后水解液COD浓度下降;将蔬菜废物与麦秸混合水解,水解液pH值降低幅度最大,水解液中总有机酸浓度最高,pH值最低为5．31,有机酸浓度最高达6．46g／L,且水解液中SCOD浓度、SCOD／COD比值最大;添加猪粪明显促进了麦秸有机物的水解溶出,麦秸单位干物质水解率和产酸率较对照分别提高了43％～134％和50．53％,但对提高水解液SCOD浓度、SCOD／COD比、TVFA浓度、降低水解液pH值的效果不如蔬菜废物;添加厨余垃圾的效果介于猪粪和蔬菜废物之间。从促进麦秸水解产酸的角度,以添加猪粪的效果最好。     

猪粪堆肥中铜锌与腐殖质组分的结合竞争

为研究猪粪堆肥中铜锌与腐殖质组分的结合竞争,以猪粪和秸秆为堆腐原料,进行了为期36 d的好氧堆肥实验,研究猪粪堆肥过程中腐殖质组分(胡敏酸和富里酸)、胡敏酸结合态铜锌、富里酸结合态铜锌含量的变化。结果表明,堆肥结束后,腐殖化程度提高,胡敏酸碳含量增加394.4%,富里酸碳含量降低64.9%,腐殖化指数从0.24增加到3.33;随着堆肥的进行,胡敏酸结合态铜锌含量分别增加394.3%和56%,而富里酸结合态铜锌含量分别下降17.5%和28.4%;相关分析表明,胡敏酸结合态铜、富里酸结合态锌与胡敏酸、富里酸碳含量及腐殖化指数均成显著相关(P<0.01);堆肥过程中,胡敏酸结合态铜与富里酸结合态铜之比大于1,而胡敏酸结合态锌与富里酸结合态锌小于1,另外,胡敏酸中的Cu/Zn大于1,而富里酸中的Cu/Zn小于1,表明在腐殖质中铜主要与胡敏酸结合,而锌主要与富里酸结合。研究揭示了猪粪堆肥中重金属铜锌与不同腐殖质组分的结合竞争关系,为畜禽粪便堆肥土地利用的风险评估和风险控制提供科学依据。     

生态景观质量的游客感知及支付意愿评价——以福友休闲农场为例

在近年来国内休闲农业快速发展的背景下,由于缺乏对其非使用价值的正确认识和判断,出现了高速增长与效果欠佳的矛盾,如何科学评价休闲农场开发的非使用价值,对于该产业发展具有重要意义。条件价值评估方法(CVM)是国内外评估非使用价值和支付意愿较为成熟的方法,但尚未用于对具有"三产融合"和"三生一体"特性的休闲农场的评估,本研究以福建开发较为成熟的长泰福友休闲农场为研究取样点,采用该方法探究游客对休闲农场生态景观质量的感知水平及支付意愿。结果表明:游客对福友休闲农场生态保护价值支付意愿的下限为18.26元,支付上限为23.10元,游客对福友休闲农场生态景观保护的支付意愿为96.45万元/年;提供便捷的支付渠道和公开资金的使用途径能有效提升游客购买生态景观保护价值的支付意愿;农场空气的好坏、农场的生态体验设计、农场的田园功能分区在主题设计、耕作体验形式、内容等方面的创新程度对游客生态保护的支付意愿影响较大;对于大部分拥有一定农场阅历但对农业多功能性认识不足的游客,在便捷的支付手段和珍稀植物品种的吸引下,更倾向于形成较低水平的生态保护价值支付意愿,而那些文化素质较高,特别是拥有农场、生态相关领域研究背景,对于农场生态功能性、体验养生内容拥有一定认知的游客,则愿意在更高的价格水平支付农场的生态保护价值。     

外加纤维素酶和α-淀粉酶对猪粪厌氧发酵的促进机制

为有效缩短有机物厌氧发酵限制阶段的反应时间,提高发酵底物的生物产甲烷效率,以猪粪为发酵底物,添加外源纤维素酶和α-淀粉酶,应用一级动力学模型和Gompertz模型拟合厌氧发酵过程.结果表明:适量添加纤维素酶和α-淀粉酶对厌氧发酵系统的水解反应具有积极的促进作用,当两种酶的总添加量为40 mg/g、纤维素酶和α-淀粉酶配比为1:3时促进作用最为显著,其多糖浓度、TVFAs（乙酸、丙酸、丁酸和戊酸的统称）浓度峰值、累积沼气产气量、甲烷产率（基于猪粪中挥发性固体含量计算）分别为4 494 mg/L、8 666 mg/L、187 688 mL、392.1 mL/g,与CK（对照）组比分别提高了171.0%、23.3%、23.5%、24.3%.相关性分析表明,外源酶的添加对厌氧发酵系统中微生物可利用的C/N具有显著影响,可有效促进TVFAs转化产甲烷,当纤维素酶和α-淀粉酶配比为1:3时,厌氧发酵过程具有最大反应速率〔32.95 mL/（g·d）〕,与CK组相比水力停留时间（HRT）缩短了2.5 d,生物产甲烷效率提高了24.3%,厌氧发酵过程符合Gompertz模型（R2=0.999 2）.研究显示,纤维素酶和α-淀粉酶对促进猪粪厌氧发酵有协同作用,当α-淀粉酶添加量不超过30 mg/g时,α-淀粉酶添加量与甲烷产率呈正相关;当纤维素酶添加量超过10 mg/g时,纤维系酶添加量与甲烷产率呈负相关.