异噻唑啉酮类杀菌剂对黑斑蛙胚胎和蝌蚪的急性毒性

异噻唑啉酮类杀菌剂1,2-苯并异噻唑-3-酮(BIT)和甲基异噻唑啉酮(MIT)虽已在多种行业中广泛使用,但目前有关其毒性尤其对水体中生物毒性的数据还较少。鉴于BIT和MIT在水体中普遍存在,本文研究了这两种污染物对两栖动物黑斑蛙胚胎和蝌蚪的急性毒性。黑斑蛙胚胎和蝌蚪分别暴露系列浓度的BIT和MIT,观察化学品对其生长、发育和运动的影响,计算96小时半数致死浓度(96 h-LC50)和96小时半数致畸浓度(96 h-TC50),确定最小生长抑制浓度(MCIG)。结果发现,BIT对黑斑蛙胚胎的96 h-LC50和96 h-TC50分别为2.99 mg·L-1和0.60 mg·L-1,MCIG小于0.40 mg·L-1,对蝌蚪的96 h-LC50为6.44 mg·L-1。MIT对黑斑蛙胚胎的96 h-LC50和96 h-TC50分别为5.30 mg·L-1和2.36 mg·L-1,MCIG为2.59 mg·L-1,对蝌蚪的96 h-LC50为7.58 mg·L-1。根据《化学农药环境安全评价准则报批稿》中两栖动物蝌蚪急性毒性的分级标准,判定BIT和MIT的毒性等级为中等。该毒性数据可为异噻唑啉酮类杀菌剂的环境管理提供参考。     

应用黑斑蛙胚胎测试化学品发育毒性的方法

选择合适的尤其是本土生物种进行化学品生态毒性评估,对于各国化学品的环境管理十分重要.本文选择我国本土两栖种黑斑蛙的胚胎为试验生物,以半数致死浓度LC50、半数致畸浓度TC50、致畸指数TI及最小抑制生长浓度MCIG为终点指标,建立了黑斑蛙胚胎发育毒性试验方法.以五氯酚、视磺酸、氯化镉、重铬酸钾为测试物研究了方法的敏感性,并以五氯酚为测试物研究了方法的可重复性.结果显示:五氯酚、视磺酸、氯化镉和重铬酸钾对黑斑蛙胚胎的LC50分别为572.3 μg·L-1、54.8 μg·L-1、6.8 mg·L-1和97.5 mg· L-1.五氯酚、视磺酸和氯化镉对黑斑蛙胚胎的TC50分别为246.5 μg·L-1、18.7 μg· L-1和3.4 mg·L-1,TI分别为2.3、2.9和2.0,MCIG分别为160.0 μg· L-1、10.1 μg·L-1和2.4 mg·L-1.重复性试验发现,五氯酚的LC50、TC50、TI及MCIG的变异系数分别为12.6％、18.0％、23.0％和18.6％.与文献中非洲爪蟾胚胎试验的数据比较,这些数据显示黑斑蛙胚胎与非洲爪蟾胚胎对测试物的敏感性存在一定的差异,各个终点指标的变异系数相当.因此,本文建立的黑斑蛙胚胎发育毒性试验可以用于化学品的发育毒性评价,为我国化学品环境管理提供技术支持.     

低浓度废水厌氧处理中不同动力学模型对比研究

采用厌氧颗粒污泥处理低浓度废水来启动实验规模的沼气提升厌氧反应器,以啤酒废水为例,厌氧反应器在温度(35±1)℃和进水COD浓度在2100~2400mg/L条件下,通过提高进水量方式,来缩短水力停留时间HRT和提高有机负荷OLR.用First-order、Monod and Contois、Grau second-order和Modified Stover–Kincannon动力学模型,考察在不同的HRT和进水浓度Si条件下,出水浓度Se与前两者的关系,确定动力学参数.实验结果表明:First-order和Monod and Contois模型不适用本实验,Grau second-order和Modified Stover–Kincannon模型适用,通过后两个模型公式分别比较实验值Se与计算值Se的差别,Grau second-order模型比Modified Stover–Kincannon模型更接近实验值.     

Mobility in pastoral systems: Dynamic flux or downward trend?

Several interdependent strategies have allowed pastoralists to survive for centuries in patchy and unpredictable low-productivity environments while sustaining their resource base: mobility, diversity, flexibility, reciprocity and reserves. Recent decades have witnessed curtailed mobility due to agricultural expansion into rangelands, the establishment and enforcement of political and administrative boundaries, the usurpation of local institutional control and disruption of local practices, increased labour costs, and the development of stationary goods and services. Pastoralists have responded by becoming sedentary, diversifying or intensifying their production strategies, leaving the herding sector, or adapting and transforming their practices and institutions. While these trends may be significant, an historical precedence of ebbs and surges in mobility indicates they may not be new or unidirectional. Emerging political trends and technologies may provide an opportunity for pastoral populations to maintain or increase their mobility in the future, but will the customary pastoral institutions that support sustainable practices still be viable, or will new, viable institutions emerge? These institutions are often subtle, contextual, and norm-based; 'invisible' and easily dismantled or replaced by more authoritarian regimes. There is relatively little understanding of how they work or how to support them. Without them, the trend may be towards open access or privatization.     

The effectiveness of incentives in protected area management: An empirical analysis

Incentive approaches are believed to be indispensable for effective conservation and successful management in protected areas. However, the actual effectiveness of these approaches is still debatable. We carried out a case study in Wolong Biosphere Reserve (WBR), the largest reserve for the giant panda (Ailuropoda melanoleuca), to evaluate the effectiveness of incentives. We obtained data from government documents and statistics, interviews and surveys on the employment status of public sector and industries. Results indicated that government-paid community-based conservation projects provided the most widespread and direct economic incentives. The conservation sector and several industries including hotels, hydropower and tourism have directly raised the employment level of local communities. The hotel industry, driven by the development of tourism, has been the most effective means of increasing local employment. However, the problem of immigrants attracted by the improved economic situation in WBR should be considered in the management plans. Suggestions for WBR management include development of quality ecotourism, vocational education for local young adults and new policies encouraging employment of local labour, both in the reserve and outside. Lessons learned from this research are constructive for the management of other protected areas.     

Rain forest dwellers' livelihoods: income generation,household wealth and NTFP sales,a case study from Xishuangbanna,SW China

Through annual in-depth household questionnaire interviews of 60% of households in Daka and Baka villages from 1998 to 2004, we explored wealth-related differences and similarities in the sale of NTFPs of tropical rain forest fringe dwellers in Xishuangbanna, SW China. Contribution of different NTFPs to cash income and different seasonal access to NTFPs between Baka and Daka were analysed. There were significant differences in income and role of NTFPs per household between Baka and Daka related to different access to: NTFPs in forests, labour and market sales in different seasons. In Baka, the ranking of NTFP income was: fungi, wild vegetables, bamboo shoot in 2000 and 2001. Differences in gender and generational involvement in NTFP sales was also examined. For example, households without a son, as well as those with a female householder depended more on income from NTFPs and less on income from rubber than other households. Resource use patterns between relatively wealthy and poor households were also analysed. Wealthy households sold 2.50 ± 0.50 types while poor households sold 2.08 ± 0.26 NTFPs. The Gini coefficient of gross income per household for Baka in recent years was 0.393, increasing to 0.414 without NTFPs. The Gini coefficient of gross income for Daka in recent years was 0.291, increasing to 0.292 without NTFPs, showing the different role of NTFPs in mitigating wealth inequality in the two villages.     

Integrated effects of slope aspect and land use on soil nutrients in a small catchment in a hilly loess area,China

This study addressed the integrated effect of slope aspect and land use on soil nutrients in a loess hilly catchment in the western Loess Plateau of China. Soil samples were collected from five land-use types: wasteland, cropland, woodland, shrubland and abandoned cropland, at two depths (0–20 and 20–40 cm) in the middle slope position of both north-facing and south-facing slopes. Soil nutrient changes and the relationships between soil nutrients and slope aspect were investigated, based on statistical analysis and expert knowledge. Soil organic matter, total N, total P, nitrate nitrogen and available K of the 0–20 cm soil layer differed significantly between land uses and slope aspects. Soil nutrients in the north-facing slope were better than in the south-facing slope. Revegetation has an enrichment effect, especially on soil organic matter, total N, total P, nitrate nitrogen and available K. Planting of trees, shrubs and grasses could improve soil fertility and favours a policy of revegetation and sustainable land use in the hilly loess area of China. Conversion of slope farmlands into more sustainable land uses, such as shrubland or grassland is a cost-efficient way to achieve soil conservation and ecological restoration. Terracing and the use of agro-techniques for soil conservation, such as furrow-ridging tillage and leaving crop residues on fields, can increase the input of C to soils. Growing crops in rotation with alfalfa and beans could be a promising choice for the sustainability of agriculture and the environment.     

低温弱光条件下毒死蜱对黄瓜的毒性效应及油菜素内酯的调控作用

农药在使用中可能对农作物产生药害作用,而在低温弱光的亚适宜条件下,设施作物对农药暴露的应激响应可能具有特殊性。同时,作为一种新型植物激素,油菜素内酯在亚适宜条件下是否能够缓解农药的药害作用的研究有限。以典型的设施作物黄瓜为受试生物,通过人工气候箱模拟低温弱光的亚适宜条件,在毒死蜱(浓度分别为0.3和1mmol·L-1)暴露1、3和7d后,以实时荧光定量PCR对黄瓜叶片中光合作用基因(psaB、psbA和rbcL)、抗氧化系统相关基因(cAPX、DHAR、GR、CAT和GPX)、防御和应激相关基因(PAL、HPL、ADC和HSP70)的转录水平进行检测,阐明其毒性效应。并对比24-表油菜素内酯的预处理组,探讨油菜素内酯如何调控作物对农药胁迫的响应。结果表明,在低温弱光条件下,毒死蜱暴露抑制了黄瓜叶片中上述大部分基因的转录,而24-表油菜素内酯预处理后其转录水平显著上升,表明24-表油菜素内酯可有效且持续地缓解毒死蜱的药害效应。     

Dechlorination of 2,2＇,4,4＇,5,5＇-hexachlorobiphenyl by thermal reaction with activated carbon-supported copper or zinc

Activated carbon （AC）-supported copper or zinc made from ion exchange resin （IRCu-C and IRZn-C） have an increased metal load of 557.3 mg·g^-1 and 502.8 mg·g^-1 compared to those prepared by the traditional method involving impregnation with AC and copper （II） citrate or zinc citrate solution （LaCu-C and LaZn-C） of 12.9 mg·g^-1 and 46.0 mg·g^-1 respectively. When applied to decompose 2,2＇,4,4＇,5,5＇-hexachlorobiphenyl at 250 ℃, IRCu-C achieved higher activity of 99.0% decomposition efficiency than LaCu-C of 84.7%, IRZn-C of 90.5% and LaZn-C of 62.7%. When the reaction temperature rose to 350 ℃, all the four kinds of reactants can decompose PCB- 153 with efficiency above 90%. Further, X-ray photoelec- tron spectroscopy characterization of IRCu-C before and after the reaction indicated transformation of 19.1% of Cu atoms into Cu^2＋, illustrating that Cu is the active ingredient or electron donor promoting the decomposition of PCB- 153. The mechanism underlying this process differs from a traditional H donor. However, there is no significant change on the surface of IRZn-C before and after the reaction, suggesting that Zn acts as catalyst during the process of PCB-153 decomposition.