Mapping Invasive Aquatic Vegetation in the Sacramento-San Joaquin Delta using Hyperspectral Imagery

The ecological and economic impacts associated with invasive species are of critical concern to land managers. The ability to map the extent and severity of invasions would be a valuable contribution to management decisions relating to control and monitoring efforts. We investigated the use of hyperspectral imagery for mapping invasive aquatic plant species in the Sacramento-San Joaquin Delta in the Central Valley of California, at two spatial scales. Sixty-four flightlines of HyMap hyperspectral imagery were acquired over the study region covering an area of 2,139 km² and field work was conducted to acquire GPS locations of target invasive species. We used spectral mixture analysis to classify two target invasive species; Brazilian waterweed (Egeria densa), a submerged invasive, and water hyacinth (Eichhornia crassipes), a floating emergent invasive. At the relatively fine spatial scale for five sites within the Delta (average size 51 ha) average classification accuracies were 93% for Brazilian waterweed and 73% for water hyacinth. However, at the coarser, Delta-wide scale (177,000 ha) these accuracy results were 29% for Brazilian waterweed and 65% for water hyacinth. The difference in accuracy is likely accounted for by the broad range in water turbidity and tide heights encountered across the Delta. These findings illustrate that hyperspectral imagery is a promising tool for discriminating target invasive species within the Sacramento-San Joaquin Delta waterways although more work is needed to develop classification tools that function under changing environmental conditions.     

洱海沉水植物空间分布及生物量估算

为研究洱海沉水植物空间分布特征并估算全湖沉水植物的生物量,于2009年8—9月采用回声测深仪和RTK-GPS定位仪测定了洱海沉水植物分布区面积,通过样方调查研究了不同基底高程下沉水植物的平均生物量. 结果表明,洱海沉水植物分布区的面积为19.40km2,占整个湖泊面积的7.7%;其中东区、南区、西区和北区水生植物分布面积分别占25.1%、7.4%、41.0%和26.5%. 沉水植物分布的基底高程范围为1959.0~1965.0m,最深分布线水深的平均值为4.9m,最大值为6.2m. 其中水深2.0~3.0m处平均生物量最大. 从各区域看,北区沉水植物最深分布线水深平均值(5.2m)最大,西区(5.0m)和南区(4.8m)其次,东部(4.6m)最小;沉水植物平均分布宽度表现为北区(399.2m)>南区(213.6m)>西区(175.0m)>东区(86.4m). 沉水植物生物量在8—9月达到最大值,为1.60×105t.      

洱海沉水植物残体风浪输移量及其时空分布

为研究洱海沉水植物残体风浪输移特征,掌握由此而引起的N、P变动情况,通过为期1a的野外定点调查,研究了风浪对洱海湖滨带沉水植物作用引起的植物残体向滨岸的输移特征,估算了沉水植物残体带出的N、P质量. 结果表明:①洱海湖滨带有残体输出的沉水植物总计10种,分别为菹草(Potamogeton crispus)、黑藻(Hydrilla verticillata)、轮藻(Eichhornia crassipes)、穿叶眼子菜(P. perfoliatus)、扭叶眼子菜(P. intortifolius)、穗花狐尾藻(Myriophyllum spicatum)、金鱼藻(Ceratophyllum demersum)、马来眼子菜(P. malaianus)、苦草(Vallisneria natans)及微齿眼子菜(P. maackianus);②沉水植物残体风浪输移量存在明显的时序变化,在4次采样中,2009年12月(冬季)风浪输移量最高;③微齿眼子菜和苦草的风浪输移量最大,植物残体风浪输移量主要受沉水植物的分布和生物量的影响;④单位岸线沉水植物残体风浪输移总量在空间上表现为西部(1.91t/km)>北部(1.73t/km)>南部(1.61t/km)>东部(0.86t/km);⑤洱海湖滨带沉水植物残体风浪输移总量约为2.27×103t/a(以鲜质量计),由此可输出的TN为5.64t,TP为0.85t.      

Production of an antimicrobial cytochalasan by an endophytic Chaetomium globosum HYML55 from Hypericum mysorense and its RNA secondary structure analysis

The mutualistic benefits and disadvantages of non-clavicipitaceous endophytes for their hosts are not well studied and are postulated as being distinct from free-living or pathogenic counterparts. The defensive metabolites and antioxidants produced by endophytes are postulated to be the benefits offered for the hosts. Therefore, the antimicrobial and free-radical-scavenging activities of a foliar endophyte Chaetomium globosum HYML55 isolated from Hypericum mysorense of Western Ghats, India were studied. RNA secondary structure analysis refuted the unique biotope postulation because strain HYML55 was more similar to a coprophilous strain than to endophytic strains. Ethyl acetate extract of the fungus inhibited bacteria and fungi. The extract also quenched 98.65% 1,1-diphenyl- 2-picrylhydrazyl radicals with total antioxidant capacity of 13.62 mg ascorbic acid equivalent/g. A yellow amorphous antimicrobial compound purified from the extract was identified as chaetoglobosin F, which had a minimum inhibitory concentration of 7.8–15.6 μg/mL, except against Pseudomonas aeruginosa. This is the first report on the antimicrobial activity of chaetoglobosin F and other bioactivities of any endophytes from H. mysorense. The study emphasises the inter-habitat cycling of endophytes and possible benefits of C. globosum for the host. Chaetoglobosin F is an anti-inflammatory and anti-neoplastic compound, and C. globosum HYML55 could be exploited for the industrial production of this compound.     

Evaluation of the antimutagenic and antiradical potentials of extracts from the tubers of (Tunisian) Cyperus rotundus

The mutagenic potential of aqueous, total oligomers flavonoids (TOF), ethyl acetate and methanol extracts from tubers of Cyperus rotundus L. was assessed using Ames Salmonella tester strains TA98 and TA100, and SOS chromotest strain Escherichia coli PQ37 with and without metabolic activation (S9). None of the different extracts produced a mutagenic effect. Likewise, the antimutagenicity of the same extracts was tested using the “Ames test” and the “SOS chromotest”. Our results showed that C. rotundus extracts possess antimutagenic effects against S. typhimurium TA98 and TA100 strains towards the mutagen aflatoxin B1 (AFB1), similar to E. coli PQ37 strain against AFB1 and Nifuroxazide mutagens using the SOS chromotest assay. A free radical scavenging test was used in order to explore the antioxidant capacity of the extracts obtained from the tubers of C. rotundus. TOF, ethyl acetate and methanol extracts showed an important free radical scavenging activity towards the 1,1-diphenyl-2-picrylhydrazine (DPPH) free radical. These extracts showed an IC50 value of respectively 5, 20 and 65?µg?mL^?1. The beneficial effects of TOF, ethyl acetate and methanol extracts of C. rotundus were assessed by antioxidant and antimutagenic activities.     

二价铁催化过碳酸钠处理水中乙苯

采用Fe(II)催化过碳酸钠(SPC)体系处理水溶液中的乙苯(EB),考察c(SPC)、c(Fe(II))、阴离子浓度、天然有机物(NOM)以及溶液初始pH值对EB降解效果的影响,并确定EB降解过程中起主导作用的自由基.结果表明,对于浓度为1mmol/L的EB溶液,c(SPC)、c(Fe(II))均为12mmol/L时,20min内EB可被完全去除; Cl^-、HCO₃^-、NOM的存在均会抑制EB降解,SO₄^2-和NO₃^-对EB降解无影响;溶液初始pH值(pH3.00~11.00) 越高,EB去除率越低,但当pH=9时,降解效果仍很显著,表明该体系能够在较宽pH值范围内高效降解水溶液中EB;自由基探针试验证实体系中存在^·OH和O₂^·-,自由基清扫试验表明^·OH对EB降解起主导作用.     

不同浓度藻类水华对两种沉水植物的影响

为了研究藻类水华对沉水植被恢复的影响,通过模拟不同浓度的藻类水华,开展了篦齿眼子菜（Potamogeton pectinatus）和伊乐藻（Elodea nuttallii）在不同浓度藻类水华下（0,6.25×10⁸,2.5×10⁹,10¹⁰cell/L）的生长和生理试验.结果表明,低浓度（6.25×10⁸cell/L）处理组中伊乐藻的干重显著低于对照组,而藻浓度达到10¹⁰cell/L时,篦齿眼子菜的干重才显著低于对照组.与其它处理组相比,在藻浓度为10¹⁰cell/L的情况下,篦齿眼子菜的株高最矮,而伊乐藻的株高最高.叶绿素荧光特性表明藻浓度为10¹⁰cell/L的情况下,篦齿眼子菜的光合活性从0.77降低至0.50,而伊乐藻的光合活性无显著性变化,在0.72～0.79之间波动.沉水植物的抗氧化酶活性在藻类水华胁迫环境下先增加后降低.这表明,藻类水华对水生植物的生长影响有差异性;水体中过高的藻浓度会影响植物的抗性生理.沉水植物能忍耐短期低浓度的藻类水华胁迫,但是长期高浓度的藻类水华会严重影响沉水植物的生长,进而影响水生植被的恢复.     

水生植物材料与传统植物材料吸油性能比较

将水生植物材料(凤眼莲叶和茎、大薸叶)作为新型吸油材料,与传统植物材料(水稻秸秆、夏威夷坚果壳、甘蔗渣)的吸油性能进行比较。通过研究各材料的表面结构特征、表面基团特征、吸油能力和表面疏水性,来对比各材料的吸油性能。结果表明:水生植物材料具有较大吸油容量,且其叶子部分疏水性很强,适合作为水上浮油原位处理的吸附剂;水稻秸秆疏水性稍弱,但也是一种良好的水上浮油吸附剂;凤眼莲茎吸水性较强,与夏威夷坚果壳、甘蔗渣一样具有浮力较小、疏水性较弱的特点,但对正己烷的吸附速率非常快,可考虑作为填充滤料处理含油废水。     

均相Co(Ⅱ)/PMS体系对二氯喹啉酸的降解特性研究

采用高级氧化技术,以Co2+为催化剂分解单过氧硫酸氢钾(PMS)所产生的强氧化性硫酸根自由基(SO4·-)降解水中的二氯喹啉酸(QC).考察了PMS用量、Co(Ⅱ)/PMS比值和Cl-浓度以及QC初始浓度对该均相Co(Ⅱ)/PMS体系降解QC的影响.结果表明,QC的降解遵循准一级动力学过程.当QC初始浓度在0.02~0.2mmol/L时,QC的降解速率随着QC/PMS比值的降低而增大,但当QC/PMS比值小于1/100时,则相反.QC的降解速率随着PMS浓度升高而线性增大,当PMS浓度为32mmol/L时,4h内QC的降解率可达94%.增大Co(Ⅱ)/PMS的摩尔比能够促进QC的降解,而Cl-对QC的降解有一定的抑制作用.LC/MS分析结果表明,3,7-二氯-8-羟基喹啉和7-氯-8-喹啉甲醛为QC降解过程中两种主要的中间产物.