Impact of variable nitrogen fertilisation on arthropods in cotton in Georgia, USA

Reducing fertiliser applications can reduce production costs for cotton (Gossypium hirsutum L.) growers, as well as nitrogen (N) leaching into the soil and contamination of surface and ground water. But altered N fertilisation may also affect pests and their natural enemies. In this study, plots with four different levels of fertiliser input (0, 45, 90 and 135 kg ha⁻¹ N) were used to investigate the influence of N on cotton pest and beneficial arthropod populations, and on cotton yield in Tifton, GA, USA. We predicted that (1) N fertilisation will correlate positively with cotton plant growth; (2) increased N fertilisation will increase pest populations because plants with more N will be more nutritious for and attractive to herbivores; (3) populations of beneficial arthropods and predation of pests will decline with increased N fertilisation because of reduced plant signaling; (4) increased N fertilisation will increase pest mortality due to parasitoids because of increased host quality. Cotton plant growth was enhanced by N fertilisation but yield was unaffected. N fertilisation significantly affected some pest arthropods but inconsistently. Mirids were most abundant in the high N treatment in 1 year of the study and cotton aphids were most abundant in the highest N treatment in the other year of the study. Arthropod predators were generally more abundant in the high N treatment but only spiders and Geocoris spp. were significantly affected by N treatment, with highest numbers present in the highest N treatment but the significant differences were each only in a single year. The greatest mortality of sentinel pest eggs (Spodoptera exigua) due to predation occurred under low N conditions. N fertilisation had no significant effects on parasitism of feral or sentinel caterpillars.     

改性活性炭净化PH3实验研究

通过钢瓶配气模拟和气相色谱GC-14C测定的方法,研究了改性活性炭吸附净化黄磷尾气中PH3的相关问题。结果表明:改性液浓度0.05mol/L、干燥温度120℃、焙烧温度250℃为改性炭制备的最佳条件;吸附反应阶段较适宜的温度为95℃,氧含量为1%。再生方法可行,可通过再生液回收磷酸。     

贫瘠营养条件下转cry1Ab/c基因水稻的生态适合度

以抗虫转cry1 Ab/c基因水稻华恢1号(Bt水稻)及其非转基因亲本明恢63(CK水稻)为研究材料,在模拟贫瘠营养条件下(不施肥、无靶标虫压)初步评估了转cry1Ab/c抗虫基因水稻的生态适合度效应.结果表明:贫瘠条件下Bt水稻cry1 Ab/c基因的基本表达规律与大田条件下相似,但是Bt蛋白表达量更低.与亲本明恢63相比,Bt水稻在主要生长发育期的株高、叶绿素含量、叶形和根系等指标方面呈现出显著的生态适合度利益,Bt水稻实粒数、谷粒数、实粒重和千粒重这些重要繁殖指标也较亲本水稻显示出明显的生态适合度正效应,表明其种群在自然界中的生存能力和延续能力可能超越CK水稻,从而产生环境风险.     

SO_2和BaP复合暴露诱导小鼠心脏线粒体损伤的分子机制初探

采用C57BL6小鼠作为模型,SO2(7 mg·m-3)动式吸入染毒28 d,每天染毒6 h;SO2吸入染毒开始后的第1~5 d,每天在SO2吸入染毒结束后对小鼠进行腹腔注射Ba P(40 mg·kg-1(b.w.)),1 d注射1次.吸入染毒结束后,采用荧光定量PCR技术检测小鼠心肌细胞中由核DNA(n DNA)编码的细胞色素C氧化酶亚基CO4和由线粒体DNA(mt DNA)编码的ATP合酶亚基ATP6,以及调控线粒体呼吸链组分的核转录因子PGC1-α、NRF1和mt TFA的mRNA水平;并采用Western blot技术检测上述3种线粒体调控基因的蛋白表达.结果发现,SO2和Ba P复合暴露后,小鼠心肌线粒体氧化磷酸化复合体亚基CO4和ATP6的mRNA表达水平均显著降低,调控基因PGC1-α、NRF1和mt TFA的mRNA和蛋白水平也显著降低.提示小鼠在SO2和Ba P复合暴露后,可能通过降低心肌中NRF1表达,影响其对mt TFA的调控,进一步抑制相关基因组的转录和翻译,最终可能导致小鼠心肌线粒体的氧化磷酸化功能受损,进而引发心血管疾病.     

Social capital and food security in post-conflict rural Lira District,northern Uganda

While a strong relationship has been established between social capital and food security in the research literature, it is uncertain whether this holds in post-conflict situations. This study examines associations between social capital and food security in post-conflict Lira District, northern Uganda. Since factors affecting food security are complex, we explored the roles of households' characteristics in food security outcomes. Data were collected from March to July 2011 through face-to-face interviews with 221 heads of household in rural Lira. Using multinomial logistic regression, a strong positive association was identified between social capital and household food security. The study also found significant associations of food security with sex, education of household head, amount of cultivated land, and farm and home possessions. The results of this analysis can aid the design of food security programmes that empower poor people while targeting the most vulnerable groups, thereby promoting sustainable development in post-conflict communities.     

"Novel" brominated flame retardants in Belgian and UK indoor dust: implications for human exposure

Concentrations of several “novel” brominated flame retardants (NBFRs) are reported in indoor dust samples from Belgian houses (n = 39) and offices (n = 6) and from day-care centers and schools in the West Midlands of the UK (n = 36). Using a GC-ECNI/MS method, the following NBFRs were quantified: decabromodiphenyl ethane (DBDPE) (range <20-2470 ng g⁻¹), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) (range <0.5-1740 ng g⁻¹), tetrabromobisphenol A-bis(2,3-dibromopropylether) (TBBPA-DBPE) (range <20-9960 ng g⁻¹), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB) (range <2-436 ng g⁻¹) and bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH) (range <2-6175 ng g⁻¹). Hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO), another NBFR, was below the detection limit of 2 ng g⁻¹ dust in all dust samples. No correlation was detected between concentrations of NBFRs and PBDEs. The ratio of TBB:TBPH in the dust samples ranged from 0.01 to 4.77 (average 0.42), compared to the ratio present in the commercial flame retardant product FM 550 (TBB:TBPH = 4:1). Furthermore, no correlation was detected between concentrations in dust of TBB and TBPH. This may suggest different sources of these NBFRs, or similar sources but compound-specific differences in their indoor fate and transport. Exposure via dust ingestion was estimated for both adults and toddlers under low-end (5th percentile), typical (median), and high-end (95th percentile concentrations) scenarios. These were calculated assuming 100% absorption of intake dust and using mean dust ingestion (adults = 20 mg d⁻¹; for toddlers = 50 mg d⁻¹) and high dust ingestion (adults = 50 mg d⁻¹; for toddlers = 200 mg d⁻¹). Typical exposure with high dust ingestion estimates for adults were 0.01, 0.2, 0.01, 0.02 and 0.08 ng kg⁻¹ bw d⁻¹ and for toddlers 0.05, 1.9, 0.08, 0.4 and 1.12 ng kg⁻¹ bw d⁻¹ for BTBPE, DBDPE, TBB, TBPH and TBBPA-DBPE, respectively. Our results showed that, similar to PBDEs, toddlers have higher exposure to NBFRs than adults. This study documents the presence of NBFRs in indoor environments, and emphasizes the need to evaluate the health implications of exposure to such chemicals.     

Impacts of charcoal characteristics on sorption of polycyclic aromatic hydrocarbons

Sorption of three polycyclic aromatic hydrocarbons (PAHs, phenanthrene, anthracene and pyrene) on three charcoals and their precursor substance (sawdust) was studied. The charcoals obtained by heating at 400 °C for different periods were different in chemical composition and structure. Sorption characteristics were described by a Polanyi–Dubinin–Manes model combined with poly-parameter linear free energy relationships. The results revealed that though partition could not be neglected for sawdust and charcoal containing large sawdust residue, adsorption controlled the sorption of PAHs on matured charcoals, where π–π electron donor–acceptor (EDA) exerted as the main molecular-scale interactions. Charring elevated partition coefficients (K_oc) of the three PAHs more than one order of magnitude, which ranged from 10^5.74 to 10^6.58 on charcoals (for PAHs at equilibrium concentration C_e = 0.005S_w). Adsorption increased with the aromaticity of the charcoals, however, polar aromatic structure may stimulate sorption of PAHs due to the presence of π–π EDA interactions.