植物化感物质壬酸和焦酚对大型溞生长繁殖的毒性效应

为评估植物化感抑藻物质的生态安全性,通过48 h急性毒性实验和21 d慢性毒性实验,研究了穗花狐尾藻（Myriophyllum spicatum）典型化感物质壬酸和焦酚对大型溞（Daphnia magna）生长和繁殖的毒性效应.结果显示,壬酸对大型溞24 h和48 h的LC₅₀分别为75.08 mg·L^-1和38.55 mg·L^-1,焦酚对大型溞24 h和48 h的LC₅₀分别为18.89 mg·L^-1和13.71 mg·L^-1.21 d慢性毒性实验中,2.0 mg·L^-1的壬酸和焦酚对大型溞生长仍没有显著影响（p>0.05）,但在高于0.5 mg·L^-1浓度水平即显著延长大型溞首次产溞时间,降低其产溞个数（p<0.05）.大型溞净增殖率和内禀增长率随壬酸和焦酚浓度增加而减小,2.0 mg·L^-1壬酸和焦酚对大型溞净增殖率的抑制率分别为42.40%和38.86%,对大型溞内禀增长率的抑制率分别为25.00%和20.83%.研究表明,壬酸和焦酚对大型溞的繁殖过程产生一定程度的影响,但仍需结合原位试验在更大尺度上评估植物化感抑藻物质的生态安全性.     

PVC微塑料对大型溞繁殖及应激与能量相关基因表达的影响

近年来,微塑料污染已成为海洋和淡水生态环境关注的热点问题.然而,目前有关微塑料对淡水生物影响的报道仍然较少.试验选择淡水模式动物大型溞作为受试生物,以2 μm聚氯乙烯微粒（PVC）作为研究对象,探讨了PVC微塑料对大型溞繁殖和基因表达的影响.急性毒性试验表明,PVC对大型溞的48 h LC₅₀为20.5 mg·L^-1.21 d慢性毒性试验发现,随着PVC浓度的增加,产第一胎时间显著延迟,第一胎产幼溞数明显下降;总胎数在2.56 mg·L^-1和5.125 mg·L^-1 PVC处理组无明显差异,而10.25 mg·L^-1处理组显著增加,但所有处理组产幼溞总数与对照组相比均显著下降.同时,PVC暴露大型溞48 h后显著上调超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、α-酯酶（EST）、热休克蛋白70（HSP70）、精氨酸激酶（AK）和血红蛋白（DHB）基因表达.试验结果表明,PVC微塑料能干扰大型溞体内基因表达,长期暴露可显著降低大型溞繁殖量,水体中PVC微塑料的长期存在将对水生态系统产生危害.     

我国硒淡水水生生物水质基准值推导

水体中硒含量过高会导致水生生态系统退化,而中国现有的地表水环境质量标准对硒的标准值设定并不是基于我国水生生物相关毒理学研究得出的,难以因地制宜地保护我国水生生物.为保护我国水生生物,本研究利用物种敏感度分布法,推导出基于最大无效应浓度（NOEC）、最低有效应浓度（LOEC）的慢性硒（无机）淡水水质一级基准值和基于半数致死效应浓度（LC₅₀）、半数最大效应浓度（EC₅₀）、半数抑制浓度（IC₅₀）的急性硒（无机）淡水水质二级基准值分别为0.58 μg·L^-1、0.52 mg·L^-1,发现我国现有的水质标准可能会对我国水生生物造成欠保护.进一步推导出为保护我国鱼类的硒（无机）淡水水质一级、二级基准值分别为0.21 μg·L^-1、1.60 mg·L^-1,以及硒淡水鱼类饲料有机硒和无机硒含量一级基准值分别为97 μg·kg^-1和98 μg·kg^-1.本研究基于硒对水生生物的急性和慢性毒性效应,推导出硒的系列基准值,为保护我国淡水水生生物安全的标准制定提供数据支撑和科学依据.     

高效降解1,4-二烷的固态菌剂制备及其性能研究

1,4-二烷污染的生物修复效果很大程度上取决于其降解菌的活性和数量.本研究在前期获得1,4-二烷高效降解菌Xanthobacter flavus DT8的基础上,研究了该菌的扩大培养方法,并制备了易于贮藏和运输的固态菌剂,考察了菌剂的性能.实验结果表明,菌株X. flavus DT8可在富营养培养基中培养,较优的培养基配方为：Na₂HPO₄·12H₂O 1.0 g·L^-1,NH₄Cl 1.0 g·L^-1,MgSO₄·7H₂O 0.2 g·L^-1,酵母粉5.0 g·L^-1,蛋白胨1.0 g·L^-1,丙酮酸钠1.0 g·L^-1,pH 7.0~7.2.X. flavus DT8经发酵罐中扩大培养后,以草炭、硅藻土为载体,经进一步固态发酵制备了固态菌剂,微生物含量为2.17×10¹¹ CFU·g^-1,对1,4-二烷的降解效果明显优于活菌液.该菌剂具有良好的贮藏稳定性,4℃保藏90 d后对100 mg·L^-1的1,4-二烷48 h内去除率为63%;同时具有良好的底物广谱性,对醇类、苯系物和醚类物质也有很好的降解能力.     

ZnMnxCo2-xO4活化过一硫酸盐降解有机污染物

分别以Zn（CH₃COO）₂·2H₂O、Mn（CH₃COO）₃·2H₂O和Co（CH₃COO）₂·4H₂O为锌源、锰源和钴源,采用溶胶-凝胶自燃烧法成功制备了ZnMn_xCo_2-xO₄（x=0~2）复合物,并用X射线衍射和X射线光电子能谱对其进行表征.同时,还研究了Mn/Co物质的量比、催化剂用量及PMS用量对目标污染物降解的影响.结果表明,该复合物可催化活化过一硫酸钾（PMS）降解有机污染物,当催化剂中x=0.8,催化剂投加量为0.2 g·L^-1,PMS用量为0.4 mmol·L^-1（0.25 g·L^-1）时,20 μmol·L^-1（10 mg·L^-1）罗丹明B（RhB）可在15 min内完全降解.ZnMn_0.8Co_1.2O₄的高催化活性主要归功于Mn³⁺和Co²⁺的协同效应.将ZnMn_xCo_2-xO₄-PMS体系用于亚甲基蓝、结晶紫、金橙、双酚A、4-氯酚等其他污染物的降解,也取得了较好的效果.基于电子自旋共振ESR和自由基猝灭实验的结果,可以推测该反应体系中活性物种为硫酸根自由基和羟基自由基.     

地膜覆盖对菜地垄沟CH4和N2O排放的影响

为了探讨地膜覆盖对菜地垄沟温室气体CH₄和N₂O排放的影响,以位于西南大学农业部重庆紫色土生态环境重点野外科学观测试验站内辣椒-萝卜轮作菜地为研究对象,采用静态暗箱/气相色谱法,进行为期1 a的田间原位观测.本试验设置常规和覆膜两种处理方式,研究地膜覆盖对菜地垄沟中CH₄和N₂O排放的影响.结果表明,地膜覆盖能极显著提高土壤全年pH（P<0.01）,显著提高全年的地表温度和地下5 cm温度（P<0.05）,显著提高萝卜季土壤含水率（P<0.05）.不论是辣椒季还是萝卜季,覆膜显著降低了垄的CH₄排放（P<0.05）,辣椒季垄的CH₄平均排放通量常规和覆膜处理分别为0.110 mg·（m²·h）^-1和0.028 mg·（m²·h）^-1,萝卜季分别为0.011 mg·（m²·h）^-1和-0.019 mg·（m²·h）^-1,但覆膜对沟的CH₄排放没有显著影响（P>0.05）,辣椒季常规和覆膜处理分别为0.058 mg·（m²·h）^-1和0.057 mg·（m²·h）^-1,萝卜季分别为0.083 mg·（m²·h）^-1和0.092 mg·（m²·h）^-1,对比垄和沟,除了辣椒季常规处理下垄CH₄排放量显著高于沟,其它均为沟显著高于垄,这与西南地区较高的降雨量下沟内较稳定的缺氧环境有关.覆膜处理对N₂O没有显著影响,辣椒季垄N₂O的平均排放通量常规和覆膜处理下分别为65.41 μg·（m²·h）^-1和68.39 μg·（m²·h）^-1,萝卜季分别为78.43 μg·（m²·h）^-1和66.19 μg·（m²·h）^-1,辣椒季沟N₂O的平均排放通量分别为19.82 μg·（m²·h）^-1和22.85 μg·（m²·h）^-1,萝卜季分别为35.80 μg·（m²·h）^-1和40.00 μg·（m²·h）^-1,均无显著差异（P>0.05）,对比垄和沟,垄N₂O的排放量显著高于沟,N₂O主要由垄向大气排放.CH₄排放通量与地表及地下5 cm温度呈显著正相关,N₂O的排放通量仅与碱解氮和铵态氮含量呈显著正相关.     

小型养殖塘水体中CH4、CO2和N2O浓度的时空变化特征及影响因素

养殖塘作为重要的温室气体排放源,水体中温室气体浓度的变化不仅是准确量化温室气体排放量的基础,还是明确其影响因素的重要依据.基于顶空平衡-气相色谱仪法对长三角一处典型的小型养殖塘水体中CH₄、CO₂和N₂ O浓度的时空变化特征以及影响因素进行了分析.结果表明,除春季外,在水温影响下,CH₄和N₂ O浓度在午间或午后出现高值;受水温和水生植物光合作用影响,CO₂浓度的高值出现在晨间光合作用较弱的时候.养殖塘水体中CH₄和CO₂浓度呈现秋季最高、冬季最低的季节变化特征,c（CH₄）在秋季和冬季的均值分别为176.34 nmol·L^-1和32.75 nmol·L^-1,主要受气温、水温和溶解氧（DO）影响;c（CO₂）秋季和冬季的均值分别为134.37 μmol·L^-1和23.10 μmol·L^-1,主要受水生植物光合作用和pH影响;c（N₂ O）在夏季最高,冬季最低,均值分别为97.05 nmol·L^-1和19.41 nmol·L^-1,主要受气温和水温影响.在空间上,垂直方向上,夏季养殖塘c（CH₄）随水深的加深而降低,表层与底层、中间层的浓度差值为71.28 nmol·L^-1和42.80 nmol·L^-1,秋季随水深的加深而升高,底层与表层的浓度差值为163.94 nmol·L^-1.c（CO₂）在夏季和秋季都表现为随着水深的加深而升高,其底层与表层的浓度差值分别为18.69 μmol·L^-1和29.90 μmol·L^-1.N₂ O浓度在垂直方向上无明显变化规律.水平方向上,夏季饲料及春季鸡粪投放的区域会出现CH₄、CO₂和N₂ O浓度的高值,春季和夏季CH₄浓度约为其他区域的1.34~1.98倍和1.95~2.42倍,春季N₂ O浓度和夏季CO₂浓度约为其他区域的1.13~1.26倍和1.39~1.74倍.     

诺氟沙星对地下水中反硝化过程的影响:反硝化酶活性的证据

为探究不同初始浓度诺氟沙星对地下水反硝化过程中NO₃^--N和NO₂^--N降解的影响,选取以乙酸钠为电子供体,硝酸盐为电子受体驯化的反硝化细菌进行厌氧反硝化批实验研究,从反硝化细菌生长特性和反硝化酶活性等方面揭示诺氟沙星对反硝化过程的影响机制.结果表明,浓度为10 μg·L^-1和100 μg·L^-1的诺氟沙星对反硝化细菌的生长及NO₃^--N降解均有抑制作用,100 μg·L^-1诺氟沙星对NO₃^--N降解的抑制程度更大,抑制率为77.3%;且100 μg·L^-1诺氟沙星减少了NO₂^--N积累,最大积累量降低了67.9%.诺氟沙星初始浓度大于10 μg·L^-1时抑制了硝酸盐还原酶活性,在此过程中,亚硝酸盐还原酶活性在一定程度上有所增强.反硝化酶活性与NO₃^--N及NO₂^--N降解规律相符.因此,诺氟沙星对反硝化酶活性的控制作用是其影响反硝化过程的主要原因.     

澜沧江流域梯级水库建设下水体营养盐和叶绿素a的空间分布特征

澜沧江梯级水库群建设对流域水生态环境产生了一定的影响,将流域水体划分为自然河道段和水库段.为了探究梯级水库建设后澜沧江流域不同类型水体氮、磷营养盐和叶绿素a浓度的空间变化规律以及叶绿素a浓度与环境因子之间的关系,于2017年6月对澜沧江流域生态环境进行了调查分析.结果表明,澜沧江水体总氮质量浓度变化范围为0.37~1.22 mg·L^-1,均值为0.70 mg·L^-1;总磷质量浓度变化范围0.01~0.19 mg·L^-1,均值为0.04 mg·L^-1.单因素ANOVA分析表明,总氮空间差异显著,表现为支流段 > 水库段 > 自然河道段;但总磷没有明显的空间差异.澜沧江水库段水体叶绿素a浓度变化范围为2.6~10.2μg·L^-1,均值为5.8μg·L^-1.Pearson相关性分析结果显示,水体叶绿素a浓度与总磷浓度、水温和真光层与混合层之比（Z_eu/Z_mix）等具有显著相关性,其中与Z_eu/Z_mix的相关性最高（R²=0.689,P=0.001）,表明水温分层驱动下的Z_eu/Z_mix是影响澜沧江水库水体中浮游植物生长的关键性指标.     

干湿交替对自然沟渠沉积物反硝化速率的影响

以川中丘陵区自然沟渠沉积物为研究对象,设置低强度、中强度、高强度的干湿交替频率和长期淹水对照处理,运用室内原状土柱-乙炔抑制培养法和实时荧光定量PCR技术,研究了干湿交替对自然沟渠沉积物反硝化速率及相关功能基因的影响.结果表明：在试验模拟过程中,干湿交替显著降低了沉积物中NH₄⁺-N和DOC含量,沉积物中NO₃^--N含量则表现为先增加后减少的趋势.沉积物反硝化速率均值表现为中强度（266.42 μg·m^-2·h^-1） > 高强度（199.10 μg·m^-2·h^-1） > 低强度（152.93 μg·m^-2·h^-1） > 长期淹水（9.57 μg·m^-2·h^-1）.干湿交替增加了反硝化功能基因的拷贝数（p<0.05）,nosZ基因拷贝数在实验前后无显著差异;低强度和中强度处理的nirK基因拷贝数在实验前后差异显著,中强度处理的nirS基因拷贝数在实验前后差异显著.Pearson相关分析结果表明,沉积物的反硝化速率与NO₃^--N含量、ORP和nirK基因拷贝数呈显著正相关（p<0.05）.干湿交替可能主要通过改变沉积物的NO₃^--N含量、ORP和nirK基因拷贝数影响沉积物反硝化速率.     

黄土高原两种针叶树种不同器官水碳氮磷分配格局及其生态化学计量特征

植物不同器官水、碳、氮、磷等元素含量及其生态化学计量特征能够反映植物的生态策略及其环境适应性。本研究以黄土高原两种乡土树种油松(Pinus tabulaeformis)和柴松(Pinus tabulaefirmis f.shekanensis)为研究对象,分析了研究区两种树种水、碳、氮和磷在不同器官的含量及其生态化学计量特征,探讨了两种树种基于水、碳、氮和磷分配格局的生态适应策略。结果表明:(1)油松和柴松对水分和碳素的分配格局总体表现为根和叶最大,其次为枝和干,树皮最小;对氮、磷的分配格局则表现为叶片显著高于其他器官。(2)油松将更多的水和氮分配给叶、根等生产性器官,而柴松将更多的水和碳分配给枝、干等防御性器官,反映了柴松较油松具有更加保守的生长策略,能够更好适应逆境条件。(3)植物器官不同元素间通过相互耦合后可以表现出较好的相关性,反映了植物元素之间具有高度复杂的协同关系,这种协同关系的体现形式可能与植物类型及其对外界环境变化的生长适应策略密切相关。     

Parasitoid-induced mortality of Araneus omnicolor (Araneae, Araneidae) by Hymenoepimecis sp. (Hymenoptera, Ichneumonidae) in southeastern Brazil

All species included in the Polysphincta genus-group develop as ectophagous parasitoids of active spiders, killing their hosts prior to pupation. However, little information regarding natural history and ovipositing behavior of most species are available. In this study we inspected 85 webs of Araneus omnicolor to evaluate the frequency of parasitism and host size preferences of the wasp Hymenoepimecis sp. We also described the web characteristics of normal and parasitized spiders and the wasp ovipositing behavior. About 41% of the adult females of A. omnicolor inspected were parasitized. The highest incidence of parasitism was observed among relatively small females while no egg or larva was found in large individuals. Araneus omnicolor builds a strong web composed of an orb and barrier threads, where the spider rests within a curled leaf. The parasitoid larva builds its cocoon within this refuge, and modified cocoon webs were not observed. The ovipositing behavior of Hymenoepimecis sp. was very similar to that of Hymenoepimecis argyraphaga parasitizing Leucauge argyra, including the position of the sting, the killing of a previously attached larva, and the expelling of the egg from the base of the ovipositor.     

Spatial heterogeneity of cyanobacterial communities and genetic variation of Microcystis populations within large, shallow eutrophic lakes (Lake Taihu and Lake Chaohu, China)

Cyanobacteria, specifically Microcystis, usually form massive blooms in eutrophic freshwater lakes. Cyanobacterial samples were collected from eight sites of both Lake Taihu and Lake Chaohu in late summer to determine the diversity and distribution pattern of cyanobacteria and Microcystis in large, shallow, entropic lakes with significant spatial heterogeneity and long-term Microcystis bloom. Molecular methods based on denaturing gradient gel electrophoresis and clone library analysis were used. A similar heterogeneous distribution pattern of cyanobacteria in both lakes was observed. Most parts of these two lakes with high trophic level were dominated by Microcystis. However, in the regions with low trophic levels as well as low concentrations of chlorophyll a, Synechococcus occupied a considerable percentage. Different morphospecies and genotypes dominated the bloom-forming Microcystis populations in these two lakes. Microcystis viridis and Microcystis novacekii were dominant in Lake Chaohu, whereas Microcystis flos-aquae was dominant in Lake Taihu. Only 2 of the13 Microcystis operational taxonomic units were shared between these two lakes. Analysis of molecular variance based on 16S to 23S internal transcribed spacer sequences indicated the significant genetic differentiation of Microcystis between these two lakes (F_st = 0.19, p < 0.001). However, only 19.46% of the genetic variability was explained by the population variation between lakes, whereas most (80.54%) of the genetic variability occurred within the lakes. Phylogenetic analysis revealed no phylogeographic structure of Microcystis population in these two lakes, as illustrated by their cosmopolitan nature. Our results revealed that spatial heterogeneity within lakes has more impact on the cyanobacterial diversity than geographical isolation in a local scale.     

一株降解微囊藻毒素的缺陷短波单胞菌的分离鉴定及降解特性研究

从太湖水华腐烂蓝藻中筛选出一株能够降解MC-LR的细菌,将其编号为Q3.经形态、生理生化及16S rRNA基因序列分析鉴定为缺陷短波单胞菌(Brevundimonas diminuta).研究发现,在实验条件下该菌能以MC-LR为唯一碳源和氮源生长;7 d内可将初始浓度为0.96 mg·L-1的MC-LR降解为0.37 mg·L-1,降解效率达到61.5%.同时,本研究首次发现缺陷短波单胞菌能够降解藻毒素,并且在此菌种中扩增出了降解过程的关键基因mlr A,推测该菌可能与已报道的Sphingomonas sp.ACM-3962等菌具有相同的降解机制.     

1株扑热息痛降解新菌株的选育及其代谢特性研究

通过选择性富集培养,从活性污泥样品中选育到1株能以扑热息痛为唯一碳源生长的好氧细菌F1.根据菌株F1的形态特征、生理生化特性、16S rRNA基因序列分析及和Biolog测试,初步鉴定为亲铜(Cupriavidus necator)菌属.菌株F1降解扑热息痛最适pH值和温度分别为7.0和30℃;菌株降解扑热息痛的过程遵...     

Intrageneric differences in the four stereoisomers of stenusine in the rove beetle genus, Stenus (Coleoptera, Staphylinidae)

Most species of the rove beetle genus Stenus employ the spreading alkaloid stenusine as an escape mechanism on water surfaces. In the case of danger, they emit stenusine from their pygidial glands, and it propels them over the water very quickly. Stenusine is a chiral molecule with four stereoisomers: (2′R,3R)-, (2′S,3R)-, (2′S,3S)-, and (2′R,3S)-stenusine. The percentile ratio of these four isomers is only known for the most common species of the genus: Stenus comma. With the intention of determining the stereoisomer ratios of five additional species from the two subgenera, Stenus and Hypostenus, we used GC/mass spectrometry measurements with a chiral phase. The results showed that the ratio differs among the genus. These findings can be a basis for chemotaxonomy. It is also possible that the biological function of stenusine, e.g., as antibiotic or fungicide, varies with changing stereoisomer composition.

鸡粪热裂解对重金属Mn、Cu、Zn和Cr生物有效性的影响

畜禽粪便直接农用引起的重金属污染是社会普遍关注的问题,探索如何有效降低畜禽粪便重金属生物有效性的技术是急需解决的难题.本文通过分析鸡粪(CM)裂解前后Mn、Cu、Zn和Cr等4种重金属形态分布变化,并采用林地大型盆栽试验研究添加CM和鸡粪炭(CMB)处理对湿地松地上部分重金属吸收状况的影响.结果表明,与CM直接还田相比,添加CMB(400℃)处理降低Mn、Cu和Zn在湿地松地上部分的吸收量和富集系数,而处理之间植株Cr元素的吸收量和富集系数差异不显著. Tessier连续提取结果表明, Mn、Cu和Zn的交换态含量分别由CM的94.8、10.0和34.9 mg·kg~(-1)显著降为CMB的16.6 mg·kg~(-1)、未检测出和1.8 mg·kg~(-1). CM裂解成CMB后, Cr元素残渣态含量显著提高.从元素质量守恒来看, CM制成CMB后Mn、Cu、Zn和Cr损失率分别为29.3%、35.6%、33.5%和3.3%.裂解油中Mn、Cu、Zn和Cr的金属总量分别占CM金属损失量的51.7%、53.0%、32.9%和13.1%. CM裂解成CMB后,91.7%的交换态Mn、几乎100%交换态Cu和97.5%的交换态Zn会随裂解转化为铁锰氧化态、有机结合态和残渣态形式或挥发而降低有效性. 1年盆栽试验结果表明,在CMB处理中,土壤Mn、Cu和Zn交换态含量显著低于CM处理.相关性分析发现,植物体内重金属吸收量与土壤金属有效态含量显著相关,而与总量相关性不明显.由此可见,将鸡粪制成鸡粪炭是一种有效降低Mn、Cu和Zn生物有效性的途径.     

渤海龙口湾沉积物中烃类物质的分布特征、来源解析及风险评价

随着《山东半岛蓝色经济区发展规划》（国函[2011]）的实施,龙口湾的海洋开发活动得到空前发展,人类活动不仅影响了其潮汐和沉积环境,也使石油类成为该海域主要污染物之一.采用网格布点法采集了龙口湾表层（0~5 cm）沉积物样品,使用GC-MS对烃类物质（正构烷烃和多环芳烃）进行研究,通过其特征参数和比值丰度识别沉积物中有机物来源及污染排放源,并对沉积物进行生态风险评价.结果表明:正构烷烃参数碳优势指数（CPI_25-35）最大值为1.5（< 4）,陆海比（TAR）和海洋与水生输入比（P_mar-aq）的范围分别为0.15~1.08和0.28~0.74,指示沉积物中有机物的海源性浮游动植物贡献较大;nC₁₆指数〔w（∑C_11-36）/w（nC₁₆）〕最大值为20.76（< 30）,且71%站位的天然正构烷烃比率（NAR）值小于0,说明海洋开发活动造成了石油类污染物注入.沉积物中2环、3环PAHs（多环芳烃）的占比均超过50%,16种PAHs的总浓度范围为460.03~2 448.29 ng/g,平均值为1 328.60 ng/g,且86%的站位达到PAHs的中度、重度污染;PAHs的特征比值分析指示,龙口湾沉积物中PAHs属于石油和燃烧源的混合来源.以沉积物中PAHs含量为基础,与加拿大土壤质量指南比较,结果显示低分子量PAHs（Acy、Ace、Flu、Phe和Ant）偶尔会产生生态危害;致癌性PAHs比重（∑Car-PAHs）和BaP毒性当量（TEQ_BaP）综合评价表明,在当前的经济开发活动下龙口湾沉积物中PAHs具有一定的潜在毒性,但处于安全水平内.研究显示,龙口湾沉积物中正构烷烃属于陆源、海源和石油烃混合来源;PAHs主要属于石油和燃烧源的混合来源,其生态风险处于安全水平.      

Community fire use,resource change,and livelihood impacts: The downward spiral in the wetlands of southern Sumatra

Fire is an important community wetland management tool in Indonesia, but its increasing use in the wetlands of southern Sumatra is degrading the landscape and diminishing household incomes and livelihood options. We studied evolving community land and fire use, resource and livelihood impacts on two sites of roughly 250 km² each using satellite image analysis and biological and socio-economic surveys. Uncontrolled fire use expanded over time in relation to sonor or swamp rice cultivation, logging, fishing, grazing, and annual cropping on drained wetlands. As a result, most of the landscape has been subject to repeated fires of varying intensities, more extensive in El Niño years. Direct burning by companies played a smaller transitory role in fire ignition over the two decades. But company activities and other large-scale developments contributed to expanding community fire-based land use by bringing in more people, improving access to remote wetlands or making them more flammable. Widespread, repeated fires have transformed the landscape from mature high swamp forests to uniform stands of fire-resistant Gelam (Melaleuca cajuputi) forests and thickets, open savannas and grasslands. These new types of land cover are also degrading. Local communities have rapidly adapted to the changing resources and new opportunities. Logging and fishing declined in importance, and sonor and harvesting of Gelam expanded. But resource depletion has led to falling incomes and fewer livelihood options. The impacts extend beyond local areas as workers migrate into neighbouring forests to extract resources. Large-scale developments, community fire-based management practices and landscape transformation are spreading from accessible to formerly more remote wetlands.     

Effects of nature organic matters and hydrated metal oxides on the anaerobic degradation of lindane, p, p '-DDT and HCB in sediments

Effects of natural organic matters(NOM) and hydrated metal oxides(HMO) in sediments on the anaerobic degradation of γ-666,p, p‘-DDT and HCB were investigated by means of removing NOM and HMO in Liaohe River sediments sequentially. The results showed that the anaerobic degradation of γ-666, p, p‘ -DDT and HCB followed pseudo-first-order kinetics in different sediments. But, the extents and rates of degradation were different, even the other conditions remained the same. Anaerobic degradation rates of γ-666, p, p ‘-DDT and HCB were 0.020 d^-1, 0.009 d^-1 and 0.035 month^-1 respectively for the sediments without additional carbon resources. However, with addition ofcarbon resources, the anaerobic degradation rates of γ-666, p, p‘-DDT and HCB were 0.071 d^1, 0.054 d^-1 and 0.088 month^-1 in the original sediments respectively. After removing NOM, the rates were decreased to 0.047 d^-, 0.037 d^-1 and 0.066 month^-1 ; in thesediments removed NOM and HMO, the rates were increased to 0.067 d^-1 , 0.059 d^-1 and 0.086 month^-1 . These results indicated that NOMin the sediments accelerated the anaerobic degradation of γ-666, p, p‘-DDT and HCB ; the HMO inhibited the anaerobic degradation of γ-666,p, p ‘-DDT and HCB.