几种母质土壤及糙米中重金属含量差异性初探

砂页岩、河流冲积物、洪积物、第四纪红土和花岗岩是桂东北地区农业土壤的主要成土母质.本文对这5种成土母质的稻田土壤及糙米中的 Cu、Zn、Pb、Cd、Ni、As、Cr、Hg 8种重金属元素含量的差异性进行了检验,对这5种母质的土壤糙米重金属元素含量相关性进行了分析.结果表明,多数元素在多数母质及糙米中的含量差异不显著;除 Cu在第四纪红土—糙米、Pb 在砂页岩—糙米中的含量相关性达显著水平外,其它的母质—糙米中重金属含量相关不显著.     

小龙潭电厂脱硫工艺的探讨

介绍了国外几种成熟的脱硫工艺，通过分析与比较并结合小龙潭电厂的实际情况，最终选择烟气循环流化床半干法作为该电厂褐煤锅炉的脱硫工艺。     

还原棕BR染料废水预处理工艺的研究

利用“中和絮凝－电化学还原－混凝－空气吹脱”法对还原棕BR清洁工艺生产废水进行预处理，废水中的重金属污染物得到有效去除，其COD、NH4^ -N、氟化物以度的去除率可分别达到94％、93％、99％及95％，同时提高了废水的可生化性，减轻了后续生化系统的有机负荷和对生物的毒性。重点论述了工艺的作用机理以及最佳操作参数的确定。     

不同水稻品种对重金属的积累特性

采用田间试验法,以南方主要种植的129个水稻品种为研究对象,通过对稻米样品中镉(Cd)、铅(Pb)、铬(Cr)、无机砷(As)和总汞(Hg)重金属含量的测定,分析不同品种和类型的水稻对重金属吸收能力的差异.结果表明,35个早稻糙米Cd含量在0. 35～0. 60 mg·kg~(-1)之间,超标率100%,糙米Pb含量在0. 08～0. 30 mg·kg~(-1)之间,超标率14. 29%; 54个中稻糙米Cd含量在0. 03～0. 45 mg·kg~(-1)之间,超标率33. 33%; 40个晚稻糙米Cd含量在0. 08～0. 20 mg·kg~(-1)之间,均未超过国家标准.早、中、晚稻都表现出三系杂交稻糙米Cd含量高于两系杂交稻,但是差异不明显;早稻三系杂交稻糙米Cr和总Hg含量显著高于两系杂交稻.中稻糙米Cd含量与Pb和总Hg含量间呈显著正相关;与糙米中无机As含量间存在极显著负相关;而与糙米中Cr含量间相关性不明显.总之,水稻对重金属的吸收积累,受遗传背景、品种类型和重金属互作的影响较大.     

覆草旱作稻田CH4和N2O的排放

通过田间试验比较水稻覆草旱作常规施氮肥、覆草旱作推荐施氮肥和常规水作水稻全生育期内稻田土壤微量气体的排放.结果表明,旱作稻田N2O排放总量比水作稻田高1.5~3.7倍,在旱作覆草处理中常规施肥N2O排放较推荐施肥高2.4倍.水作稻田CH4排放总量比旱作稻田多5~6倍,而两旱作处理间差异不显著.水作稻田CH4的排放与水稻生育期关系密切,以分蘖盛期的2.2mg/(m2h)为最大;旱作稻田CH4的排放与施氮关系不明显.施氮是影响旱作稻田N2O排放的关键因素,每次施氮后,旱作稻田均会出现剧烈的排放高峰.水稻不同栽培方式的增温潜势的高低顺序为:覆草旱作常规施氮肥>常规水作>覆草旱作推荐施氮肥.     

Differential fate of metabolism of a disperse dye by microorganisms Galactomyces geotrichum and Brevibacillus laterosporus and their consortium GG-BL

The present work aims to evaluate Brown 3 REL degrading potential of developed microbial consortium GG-BL using two microbial cultures, Galactomyces geotrichum MTCC 1360 (GG) and Brevibacillus laterosporus MTCC 2298 (BL). Microbial consortium GG-BL showed 100% decolorization of a dye Brown 3 REL, while individually G. geotrichum MTCC 1360 and B. laterosporus MTCC 2298 showed 26% and 86% decolorization under aerobic condition (shaking) respectively. Measurements of biochemical oxygen demand (BOD) (76%) and chemical oxygen demand (COD) (68%) were done after decolorization by consortium GG-BL. No induction in activities of oxidoreductive enzymes found in G. geotrichum while B. laterosporus showed induction of veratryl alcohol oxidase, Nicotineamide adenine dinucleotide-dichlorophenol indophenol (NADH-DCIP) reductase and riboflavin reductase indicating their role in dye metabolism. Consortium GG-BL showed induction in the activities of laccase, veratryl alcohol oxidase, tyrosinase, NADH-DCIP reductase and riboflavin reductase. Two different sets of induced enzymes from G. geotrichum and B. laterosporus work together in consortium GG-BL resulting in faster degradation of dye. The degradation of Brown 3 REL was analyzed using high performance thin layer chromatography (HPTLC), high performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FT-IR) and gas chromatography mass spectroscopy (GC-MS). Phytotoxicity study revealed that metabolites formed after degradation was significantly less toxic in nature.     

Variation of grain Cd and Zn concentrations of 110 hybrid rice cultivars grown in a low-Cd paddy soil

Enhanced Cd uptake and Zn depletion in rice grains and high potential for food Cd exposure by the high-yielding hybrid cultivars of China had been addressed. A field experiment was conducted in 2006 to determine the di erence in grain Cd and Zn between cultivars. Total 110 cultivars including super rice and common hybrid rice cultivars were grown on a single paddy soil (Entic Haplaquept) with a neutral reaction and low total Cd content. Grain Cd and Zn concentrations were determined with graphite atomic adsorption spectrophotometer (GFAAS) and flame atomic adsorption spectrophotometer (AAS) respectively.Wide variation of Cd content in grain was found in a range of 0.004–0.057 mg/kg, while the Zn content in a range of 10.25–30.06 mg/kg among the cultivars. Higher Cd but lower Zn concentration in grains of super rice cultivars was observed compared to the common hybrid ones. A highly significant positive linear correlation of grain Cd/Zn with grain Cd was found for super rice and common hybrid cultivars, meanwhile much higher slope for these hybrid cultivars than the reported non-hybrid cultivars was also observed. Using the limit value of the Chinese chemical guidelines for foods (MOHC and SSC, 2005), calculated potential risk of food Cd exposure with “Zn hungry” through diet intake was prominent with all the studied 110 hybrid rice cultivars, possessing high potential health problems for rice production in South China using the super rice cultivars. Breeding of genotypes of rice cultivars with low grain Cd and low Cd/Zn ratio is needed for rice production in acidic red soils where Cd bioavailability is prevalently high.     

Significant coal combustion contribution to water-soluble brown carbon during winter in Xingtai, China: Optical properties and sources

To understand the characteristics of atmospheric brown carbon (BrC), daily PM_2.5 samples in Xingtai, a small city in North China Plain (NCP), during the four seasons of 2018-2019, were collected and analyzed for optical properties and chemical compositions. The light absorption at 365 nm (abs_{λ=365 nm}) displayed a strong seasonal variation with the highest value in winter (29.0±14.3 M/m), which was 3.2∼5.4-fold of that in other seasons. A strong correlation of abs_{λ=365 nm} with benzo(b)fluoranthene (BbF) was only observed in winter, indicating that coal combustion was the major source for BrC in the season due to the enhanced domestic heating. The mass absorbing efficiency of BrC also exhibited a similar seasonal pattern, and was found to correlate linearly with the aerosol pH, suggesting a positive effect of aerosol acidity on the optical properties and formation of BrC in the city. Positive matrix factorization (PMF) analysis further showed that on a yearly basis the major source for BrC was biomass burning, which accounted for 34% of the total BrC, followed by secondary formation (26.7%), coal combustion (21.3%) and fugitive dust (18%). However, the contribution from coal combustion was remarkably enhanced in winter, accounting for ∼40% of the total. Our work revealed that more efforts of “shifting coal to clean energy” are necessary in rural areas and small cities in NCP in order to further mitigate PM_2.5 pollution in China.     

多菌灵在稻田水、土壤及稻米中的残留研究

采用田间试验方法,研究了多菌灵在水稻上的消解动态及最终残留。结果表明:多菌灵在田水和土壤中的消解动态均符合一级动力学方程,原始沉积量与施药剂量、施药次数密切相关,其半衰期分别为3.07~3.25d和6.12~6.25d。按推荐剂量231g/hm2最多施药3次,在收获的稻米中多菌灵的残留量低于中国、食品法规委员会(CAC)及日本的MRL标准。     

粉煤灰净化低浓度SO2烟气试验研究

中国是一个以煤为主要燃料的国家,粉煤灰的综合利用问题早已受到人们的关注。褐煤粉煤灰中含有较多的碱性物质,它是一种优良且价廉的低浓度二氧化硫烟气脱硫吸收剂。试验研究结果表明,采用粉煤炭吸收液碱法脱硫在技术上是可行的,控制吸收液pH值大于6即可获得良好的脱硫效果。试验中考察了固液比、pH、温度、SO₂浓度和气体流墓等因素对粉煤灰吸收液净化效率的影响情况。粉煤灰碱法脱硫在经济性方面优于石灰/石灰石法。      

某电子废弃物拆卸区土壤、水和农作物中砷含量状况研究

为研究电子废弃物拆卸、废旧金属冶炼等是否对周围环境造成砷积累和污染,选取浙江省台州路桥区为调查对象,通过测定在该区采集的水、沉积物、土壤以及稻米和蔬菜中的砷,以了解该地区环境中砷的含量特征和潜在风险,并对土壤-水稻系统砷的分布和吸收转运规律进行了初步分析.结果表明,地表水和地下水砷含量平均值分别为 8.26μg/L和18.52μg/L,部分地下水超过WHO推荐的饮用水标准(10μg/L),但没有超过我国相关环境标准Ⅲ级限值(50μg/L).沉积物砷含量平均值为9.62mg/kg.水田土壤和菜地砷含量平均值分别为7.11mg/kg和6.17mg/kg,均在一级标准范围内,该区农田土壤总体上未受砷的污染.糙米和蔬菜中的砷平均值分别为165.1μg/kg和144.2μg/kg,均未超过我国规定的食品卫生标准.土壤-米糠-糙米中砷含量之间相关性显著.冶炼源周围的土壤和米糠中砷含量较其他源高,可能已经对周围土壤-水稻砷积累产生影响.     

桂林毛村岩溶区三种亚类石灰土有机碳矿化研究

应用土壤培养法,比较分析了桂林毛村典型岩溶区黑色石灰土、棕色石灰土、红色石灰土三种亚类石灰土在25℃和70%田间饱和含水量条件下培养90d有机碳矿化速率的差异。结果显示:各亚类土壤有机碳矿化速率和累积释放CO2-C量总体上都随土层加深而递减。0～20cm至20～40cm层递减幅度最大。各亚类石灰土有机碳矿化速率和累计释放量的大小顺序为:黑色石灰土>棕色石灰土>红色石灰土,黑色石灰土的矿化速率远远大于棕色石灰土和红色石灰土,其中0～20cm土层差异最大。土壤有机碳矿化速率和有机碳含量呈正相关。黑色石灰土土壤有机碳矿化释放的CO2-C分配比例最高,达到3.33%,其次是红色石灰土,比例为2.92%,旱地棕色石灰土矿化比例最低,为1.90%,说明桂林毛村典型岩溶区黑色石灰土和红色石灰土有机碳稳定性较弱,旱地棕色石灰土具有较强的固定有机碳能力。     

水稻秸秆阴离子吸附剂的制备及其性能的研究

为了合理利用我国过剩的水稻秸秆,同时解决水体富营养化问题,将水稻秸秆通过化学修饰合成得到阴离子吸附剂,探究其对磷的去除效果.通过测定带电情况、比表面积、扫描电镜、红外光谱,分析该阴离子吸附剂的性能;同时考察了吸附剂投加量、磷酸根溶液初始pH值、温度等因素对吸附效果的影响,并分析了修饰后的水稻秸秆对磷酸根的吸附机理.结果表明:吸附剂投加量为5g/L,pH值为4~10时,对磷酸根的吸附效果最好,去除率达90%以上,而温度对吸附效果影响不大;Langmuir模型适用于修饰后的水稻秸秆对磷酸根的吸附,最大的吸附量达1.96mmol/g.     

盐渍化环境下秸秆还田对稻米汞及甲基汞累积的影响

通过盆栽试验探讨了盐渍化环境下秸秆还田对土壤中总汞（THg）、甲基汞（MeHg）含量和转化以及对水稻吸收汞的影响.试验用土采集自天津典型污灌地区,人为添加不同梯度的盐分（0、0.2%、0.5% NaCl）及外源汞（0、5mg/kg~Hg（NO₃）₂）,秸秆还田按照0.1%进行处理.结果显示：1.秸秆还田促进稻田系统中无机汞的甲基化.与未添加秸秆的处理相比,秸秆还田后土壤MeHg含量提高了56.8%~76.8%,水稻MeHg含量增加了127%~171.6%.2.在轻度盐渍化稻田开展秸秆还田,会进一步提高稻田土壤中汞的甲基化水平,进而增加水稻籽粒中甲基汞含量.与不添加盐分处理相比,轻度盐渍化环境中（0.2% NaCl）,秸秆还田处理导致土壤MeHg含量提高了92.2%~101.2%,水稻籽粒MeHg含量增长了52.8%~132.1%.更高的盐渍化水平会抑制土壤汞甲基化趋势,水稻籽粒中甲基汞含量降低.在中度盐渍化环境中（0.5% NaCl）,秸秆还田导致土壤MeHg含量降低了57.9%~88.6%,水稻籽粒MeHg含量降低了72.9%~86.8%.以上研究结果表明,在盐渍化且汞污染稻田开展秸秆还田可能大幅度增加该地区汞食物链暴露风险,因此在中轻度盐渍化的污灌区,对秸秆还田等农艺措施需要格外慎重.     

水稻根系中多环芳烃的动态变化

水稻根系的多环芳烃浓度随着水稻的生长不断变化,呈现出初期逐渐升高,到成熟期趋于稳定的一般趋势.幼穗期、乳熟期、蜡熟期、完熟期和枯熟期水稻根系的多环芳烃总含量(PAH15)平均分别为464、969、592、1075 ng·g-1和1059ng·g-1,并主要由3环化合物组成.根系的脂含量、比表面和生物量等指标对根系多环芳烃的变化起到了一定影响.其中,脂含量和比表面的影响比生物量的影响更为显著.随着水稻的成熟,水稻土多环芳烃含量逐渐降低,而5、6环化合物的比例逐渐增加.水稻根系和水稻土中的多环芳烃含量之间存在明显的负相关关系.     

Light absorption properties and potential sources of brown carbon in Fenwei Plain during winter 2018–2019

A distinctive kind of organic carbon aerosol that could absorb ultraviolet-visible radiation is called brown carbon (BrC), which has an important positive influence on radiative budget and climate change. In this work, we reported the absorption properties and potential source of BrC based on a seven-wavelength aethalometer in the winter of 2018–2019 at an urban site of Sanmenxia in Fenwei Plain in central China. Specifically, the mean value of BrC absorption coefficient was 59.6 ± 36.0 Mm^?1 at 370 nm and contributed 37.7% to total absorption, which made a significant impact on visibility and regional environment. Absorption coefficients of BrC showed double-peak pattern, and BrC had shown small fluctuations under haze days compared with clean days. As for the sources of BrC, BrC absorption coefficients expressed strong correlations with element carbon aerosols and primary organic carbon aerosols, indicating that most of BrC originated from primary emissions. The linear correlations between trace metal elements (K, As, Fe, Mn, Zn, and Pb) and BrC absorption coefficients further referred that the major sources of BrC were primary emissions, like coal burning, biomass burning, and vehicle emissions. The moderate relationship between BrC absorption coefficients and secondary organic aerosols suggested that secondary production of BrC also played an important role. The 120 hr backward air mass trajectories analysis and concentration-weighted trajectories analysis were also used to investigate potential sources of BrC in and around this area, which inferred most parts of BrC were derived from local emissions.     

不同基因型水稻吸镉差异及其与根表铁氧化物胶膜的关系

采用琼脂培养方法，模拟铁在不同基因型水稻根表的氧化与淀积，研究了不央水稻吸镉的差异及其有表铁氧化物胶膜的关系，结果表明不同水稻基因型其根表淀积换的氧化物数量存在显著性差异，根表富集的镉量及根部，地上部合镉量均存在显著性差差，且镉在不同水稻植株体内转移运输能力不同；不同水稻基因型根膜中的含铁量与根表铁氧化物富集的镉量、根部的含镉量、地上部的含量存在显著性年线相关。     

稻草及其燃烧烟尘中正构烷烃的研究

利用气质联用仪测定了中国6种稻草及其明火和闷火燃烧烟尘中正构烷烃的含量.结果表明,稻草中正构烷烃的平均含量为73.0μg/g.碳数分布范围为C12~C37,呈以C29为主峰的单峰型分布.高碳数正构烷烃(>C23)具有明显的奇碳数优势,其平均碳优势指数是2.9.在明火焚烧和闷烧烟尘中正构烷烃的含量均值分别是 1633.1,5458.5μg/g.碳数分布范围为C14~C35,呈以C29或C31为主峰的单峰型分布.碳数在C27以上的正构烷烃具有明显的奇碳数优势,其平均碳优势指数分别是1.5和1.9.稻草烟尘中正构烷烃的组成与原秸秆存在显著的差别.     

水稻品种及典型土壤改良措施对稻米吸收镉的影响

水稻镉污染是我国当前重要的农产品安全问题,湖南攸县"镉大米"事件造成了严重的社会影响.针对南方酸性土壤镉污染特征,进行了"镉大米"治理技术研究.结果表明,当地主栽水稻品种株两优06的稻米Cd含量在大同桥和网岭镇的平均值分别为0.167 mg·kg-1和0.127 mg·kg-1,为其它品种的20%左右;石灰和矿物肥处理能够使稻米Cd含量降低到对照的20%~30%,覆膜处理使稻米Cd含量与对照相比降低约50%,而覆膜+生物炭+硅肥叶面肥处理能够降低80%左右,硅肥叶面肥单独施用及叶面肥和追肥配合施用能够显著降低稻米中的Cd含量90%以上;BCR法分析土壤Cd形态结果发现,供试大田土壤中Cd的弱酸可提取态比例较高,绝大多数样品达到55%以上,而施用石灰能够显著降低土壤中的弱酸可提取态和可还原态比例,增加残渣态比例,变化幅度达到20%左右;土壤Cd含量与p H值是影响稻米对Cd吸收的重要因素.     

水稻对不同土壤中硒酸盐/亚硒酸盐的吸收和富集

通过土培试验研究了在3种类型土壤(红壤、黑土和灰钙土)上施用不同价态硒肥(Na2 SeO3或Na2 SeO4)条件下,水稻地上部硒含量的变化.结果表明,在水稻幼苗期,3种土壤上Se4+硒肥处理的水稻幼苗地上部硒含量高于Se6+硒肥处理.施用Se4+硒肥,红壤、黑土及灰钙土中水稻幼苗的硒含量分别为5.76、1.18和1.11 mg· kg-1,分别为对照的2.5、4.7和6.9倍;施用Se6+硒肥,红壤、黑土及灰钙土中水稻幼苗的硒含量分别为4.70、0.66和0.73 mg·kg-1.在水稻成熟期,施用Se4+硒肥后,红壤、黑土及灰钙土中水稻籽粒中硒含量分别由对照中的0.34、0.05和0.05 mg·kg-1增加到0.94、0.14和0.20 mg·kg-1;施用Se6+硒肥后,红壤、黑土及灰钙土中水稻籽粒中硒含量分别为1.13、0.12、0.16mg·kg-1.不同价态硒肥处理和土壤类型对水稻幼苗和成熟地上部硒含量都有显著影响.在pH值低的红壤上施用Se6+硒肥效果更好,而在pH值高的黑土和灰钙土上施用Se4+硒肥效果更好;从环境风险和硒对植物毒性的角度考虑,硒肥以亚硒酸盐的形式施用比较好.