Investigation on the influence of methanol on adsorption and leaching of pesticides with soil column liquid chromatography

The effect of methanol of low concentration on adsorption and leaching of atrazine and tebuconazole was studied in this paper. The adsorption coefficients and the retardation factors (R^m) of pesticides on EUROSOIL 3# log-linearly decreased as volumetric fraction of methanol (f^c) was increased in the binary solvent mixtures of methanol and water. These data are consistent with solvophobic theory formerly outlined for describing the adsorption and transport of hydrophobic organic chemicals from mixed solvents. Nevertheless, the adsorption of these pesticides in soil–water system slightly increased when the soil was pre-washed with methanol in comparison with that pre-washed with water (pure water system). Furthermore, their adsorption coefficients were still higher in binary solvent systems with methanol of very low concentrations, i.e. f^c<0.03 for atrazine and f^c<0.01 for tebuconazole, than those in pure water system. The adsorption coefficients (logK^w) of atrazine and tebuconazole predicted by solvophobic theory were 0.5792 and 1.6525, respectively, and their experimental logK^w were 0.3701 and 1.6275 in pure water system. Obviously, the predicted logK^w of the two pesticides was higher than the experimental log K^w in pure water system. The predicted K^w and the retardation factor (R^w) in pure water system by solvophobic theory are thus possibly inaccurate.     

铁路取弃土场生态恢复调查分析

选择我国不同地域6条铁路,现场调查铁路取土、弃土(渣)场的使用及恢复情况,从取弃土场的占地面积及类型、取土量、弃土量等方面分析了其利用现状,并对植被恢复效果和难易程度进行了讨论。调查表明:北方平原区、荒漠区铁路的取土量较多,南部丘陵区的弃土(渣)场及弃渣量较多。从恢复效率和程度看,南部地区植被恢复相对容易且在1年内可以恢复到较好程度,但植被恢复不到位,较易发生水土流失等次生灾害;东北、华北地区植被恢复2年左右可以恢复至良好程度;西北地区植被恢复需求较小;对于部分高原地区,海拔越低、降雨越多,恢复越好,但部分地区降雨量是生态恢复的首要制约因子,保水措施是这类地区生态恢复的重点。     

鼎湖山针阔叶混交林土壤COS和CO_2通量研究

运用静态箱-预浓缩-气相色谱-质谱法和静态箱-色谱法分别测量了南亚热带鼎湖山针阔叶混交林土壤-大气COS和CO2通量。结果表明,土壤吸收COS,凋落物保留样地COS吸收速率显著高于凋落物去除样地,3月土壤COS吸收速率最高。土壤COS吸收速率与大气COS浓度正相关。土壤COS吸收速率与土壤温度、土壤含水量单独未表现出显著相关性,但凋落物保留样地COS吸收速率与土壤温度和含水量两者共同呈二次多项式相关。凋落物保留样地CO2释放速率高于凋落物去除样地。与土壤COS吸收速率相反,土壤CO2释放速率3月最低,7月最高,主要受温度和土壤含水量的影响。土壤CO2释放速率与土壤温度呈指数相关,与土壤含水量直线相关,多元回归分析表明,土壤CO2释放受温度和含水量的共同影响。土壤COS吸收速率随土壤CO2释放速率的增加而增加,表明两者可能受某些共同因素的影响。     

GC/MS测定土壤中的酞酸酯

本文针对土壤中酞酸酯类化合物,采用快速压力溶剂萃取仪(ASE)提取,弗罗里柱净化,气相色谱-质谱联用仪(GC/MS)对酞酸酯类有机物进行定性、定量分析。实验过程中采用浓硫酸对实验器皿进行清洗,有效地防止环境中酞酸酯类有机物对样品的污染。结果表明:平均加标回收率在87%～106%之间,相对标准偏差在2.5%～6.5%之间,检出限在0.51μg/kg～1.6μg/kg之间。     

菌株BL—21解磷能力的研究

本实验以自行分离得到的具有解磷能力的菌株BL-21为研究对象,经鉴定为侧孢芽孢杆菌(Bacilluslaterosporus),以蜡状芽孢杆菌BC-01为对照菌株,对菌株BL-21的解磷能力进行研究。分别以4种不同土壤(大豆土、小麦土、玉米土、水稻土)为唯一磷源进行测定。结果表明,在以小麦土为唯一磷源的培养液体中菌株BL-21的解磷能力要大于菌株BC-01.在以玉米土,大豆,水稻土唯一磷源的无机磷液体培养基中BL-21的解磷能力于BC-01的解磷能力基本相同。     

Wheat volatile emissions modified by top-soil chemical characteristics and herbivory alter the performance of neighbouring wheat plants

Plant emission of volatile organic compounds (VOCs) has a significant impact on arthropods and plants and alters important functions in the agroecosystems. Three field source–sink microcosm experiments evaluated variation in wheat plants volatile emissions and its impact on neighbouring wheat plants’ performance caused by genotype, aphid herbivory and soil nutrient availability due to different cropping histories. An electronic nose detected qualitative differences in volatile emissions. Two of the experiments established the source–sink relationships forcing the volatiles through pipes. In these experiments wheat genotype was introduced as a variable of the source plants. In the third experiment, the emissions of volatiles dispersed naturally affecting the neighbourhood only by proximity and wheat genotype was a controlled factor. Plant genotype, aphid attack and soil chemical changes caused by different cropping histories affected wheat volatile emissions despite independent variations in plant biomass or resource allocation. This is the first report of changes in distant plant biomass according to neighbouring plant genotype and agricultural history. Wheat VOCs emissions were associated with changes in soil organic C, Ca, Mg, total nitrogen and cation exchange capacity caused by the different cropping histories of the soils tested. Variability in total biomass and resource allocation increased due to changes in VOCs emissions promoted by longer cropping history or aphid feeding in two genotypes. When volatiles were naturally dispersed into the neighbourhood, tiller weight in the sink individuals depended on plant genotype and cropping history of its neighbours (i.e. VOCs source). These findings highlight that ecological and environmental consequences of agricultural practices are more complex than normally thought.     

Changes in functional structure of soil bacterial communities due to fungicide and insecticide applications in canola

The fungicide vinclozolin and insecticide λ-cyhalothrin are widely used to control canola (Brassica spp.) diseases and insect pests, respectively, in Canada. We investigated non-target effects of these pesticides, applied at recommended rates, on soil microbial biomass, functional bacterial diversity and functional community structure of soil bacteria (by evaluating patterns of C substrate utilization) in canola rhizosphere and bulk soil at three locations in Alberta from 2002 to 2004. Experimental treatments were (a) untreated control, (b) vinclozolin fungicide foliar application, (c) λ-cyhalothrin insecticide foliar application, and (d) vinclozolin and λ-cyhalothrin applications. No significant pesticide effects on soil microbial biomass or functional bacterial diversity were observed, but the functional structures of soil bacteria were altered. In 1 of 12 cases, the control treatment had a different soil bacterial community structure from the 3 pesticide treatments. The fungicide treatment had different bacterial community structures from the control or insecticide treatments in 3 of 12 cases, the insecticide treatment had different community structures from the control or fungicide treatments in 4 of 12 cases, and the combined fungicide and insecticide treatment had different community structures from the other treatments in 3 of 12 cases. Therefore, evaluating soil bacterial functional structures revealed pesticide effects that were not detected when bacterial diversity or microbial biomass were measured in canola rhizosphere or bulk soil.     

Simulated dynamics of carbon stocks driven by changes in land use, management and climate in a tropical moist ecosystem of Ghana

Sub-Saharan Africa is large and diverse with regions of food insecurity and high vulnerability to climate change. This project quantifies carbon stocks and fluxes in the humid forest zone of Ghana, as a part of an assessment in West Africa. The General Ensemble biogeochemical Modeling System (GEMS) was used to simulate the responses of natural and managed systems to projected scenarios of changes in climate, land use and cover, and nitrogen fertilization in the Assin district of Ghana. Model inputs included historical land use and cover data, historical climate records and projected climate changes, and national management inventories. Our results show that deforestation for crop production led to a loss of soil organic carbon (SOC) by 33% from 1900 to 2000. The results also show that the trend of carbon emissions from cropland in the 20th century will continue through the 21st century and will be increased under the projected warming and drying scenarios. Nitrogen (N) fertilization in agricultural systems could offset SOC loss by 6% with 30 kg N ha⁻¹ year⁻¹ and by 11% with 60 kg N ha⁻¹ year⁻¹. To increase N fertilizer input would be one of the vital adaptive measures to ensure food security and maintain agricultural sustainability through the 21st century.     

Removal of 2-ClBP from soil–water system using activated carbon supported nanoscale zerovalent iron

We explored the feasibility and removal mechanism of removing 2-chlorobiphenyl(2-Cl BP)from soil–water system using granular activated carbon(GAC) impregnated with nanoscale zerovalent iron(reactive activated carbon or RAC).The RAC samples were successfully synthesized by the liquid precipitation method.The mesoporous GAC based RAC with low iron content(1.32%) exhibited higher 2-Cl BP removal efficiency(54.6%) in the water phase.The result of Langmuir–Hinshelwood kinetic model implied that the different molecular structures between 2-Cl BP and trichloroethylene(TCE) resulted in more difference in dechlorination reaction rates on RAC than adsorption capacities.Compared to removing2-Cl BP in the water phase,RAC removed the 2-Cl BP more slowly in the soil phase due to the significant external mass transfer resistance.However,in the soil phase,a better removal capacity of RAC was observed than its base GAC because the chemical dechlorination played a more important role in total removal process for 2-Cl BP.This important result verified the effectiveness of RAC for removing 2-Cl BP in the soil phase.Although reducing the total RAC removal rate of 2-Cl BP,soil organic matter(SOM),especially the soft carbon,also served as an electron transfer medium to promote the dechlorination of 2-Cl BP in the long term.     

土壤污染防治投融资体系改革与基金设立研究

分析了开展土壤污染防治投融资体系改革的必要性,并借鉴国外开展土壤修复的经验,提出通过设立基金推进我国土壤污染防治投融资体系改革,旨在破解当前土壤污染防治工作面临的困局。文中介绍了基金的设立思路、主要任务、规模及融资渠道以及管理措施,并从法律、管理和技术角度提出基金设立和运行的保障措施。土壤污染防治基金的建立,将从融资角度对即将出台的《土壤污染防治法》产生强力支撑,同时促使我国土壤污染防治工作向专业化、市场化和资本化发展。