Resource identity modifies the influence of predation risk on ecosystem function

It is well established that predators can scare as well as consume their prey. In many systems, the fear of being eaten causes trait-mediated cascades whose strength can rival or exceed that of more widely recognized density-mediated cascades transmitted by predators that consume their prey. Despite this progress it is only beginning to be understood how the influence of predation risk is shaped by environmental context and whether it can exert an important influence on ecosystem-level processes. This study used a factorial mesocosm experiment that manipulated basal-resource identity (either barnacles, Semibalanus balanoides, or mussels, Mytilus edulis) to determine how resources modify the influence of predation risk, cascade strength, and the efficiency of energy transfer in two, tritrophic, rocky-shore food chains containing the predatory green crab (Carcinus maenas) and an intermediate consumer (the snail, Nucella lapillus). The effect of predation risk and the strength of trait-mediated cascades (both in absolute and relative terms) were much stronger in the barnacle than in the mussel food chain. Moreover, predation risk strongly diminished the efficiency of energy transfer in the barnacle food chain but had no significant effect in the mussel food chain. The influence of resource identity on indirect-effect strength and energy transfer was likely caused by differences in how each resource shapes the degree of risk perceived by prey. We suggest that our understanding of the connection between trophic dynamics and ecosystem functioning will improve considerably once the effects of predation risk on individual behavior and physiology are considered.     

Temporal analysis of population genetic composition in the overexploited Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis>

The Japanese eel has dramatically declined in Asia since the 1970s. Over the past two decades, glass eel productivity in Taiwan has decreased, but is highly variable among each year catch, though the cause for this is unknown. The impact of both population decline and instability on genetic diversity, however, is unknown. In this study, we investigated changes in allele frequencies of Japanese eel recruitment events over the past 20 years using six polymorphic microsatellite DNA loci. Specimens of glass eels were collected yearly from a single location in northern Taiwan from 1986 to 2007. Overall genetic differentiation among all samples was very low but significant (F_ST = 0.002, P = 0.002), and only 2 out of 120 pairwise tests were significant. The relationship between genetic and temporal distance showed a slight but insignificant correlation (R² = 0.03, P = 0.0504). There were no overall significant differences in allelic richness (P = 0.35) or genetic heterozygosity (P = 0.73) among annual recruitment events. No apparent loss of genetic diversity and occurrence of a genetic bottleneck for eel populations were observed. Estimates of the effective population size (N_e) generally exceeded 500, although confidence intervals were very wide. While El Niño /Southern Oscillation (ENSO) events had little impact on genetic diversity, they may account for the annual fluctuation in glass eel catch. These results indicate long-term stability of genetic diversity in the Japanese eel with little evidence for sweepstakes recruitment.     

Effect of cadmium alone and in combination with butachlor on soil enzymes

The ecological toxicity of cadmium (Cd, 10 mg kg⁻¹ of dry weight soil) and butachlor (10, 50 and100 mg kg⁻¹ of dry weight soil) in both their single and combined effects on soil urease and phosphatase was studied after 1, 3, 7, 14, 21 and 28 days exposure under controlled conditions in paddy and phaeozem soils. The results showed that Cd reduced the activities of urease and phosphatase at early incubation time (1–7 days), while the reduction almost disappeared at the end of the incubation. The effect of Cd on phosphatase was more pronounced than that on urease. The activities of urease and phosphatase were reduced by butachlor, while urease activity was significantly (P < 0.05 or P < 0.01) improved when the concentrations of butachlor were 10 and 50 mg kg⁻¹ at the end of the incubation. When Cd (10 mg kg⁻¹) was combined with butachlor (50 and 100 mg kg⁻¹), the activities of urease and phosphatase became lower than without combination at early incubation time, which indicated that the toxicity of Cd significantly increased (P < 0.05 or P < 0.01). However, when Cd (10 mg kg⁻¹) was combined with butachlor (10 mg kg⁻¹), the activities of urease and phosphatase became higher than those without combination at the end of the incubation, which indicated that the toxicity of Cd decreased. It was indicated that the combined effects depended largely on the incubation time and the concentration ratio of Cd and butachlor. In addition, it was showed that the combined effects of butachlor and Cd appeared different in paddy from phaeozem, which may be related to the different properties of these soils.     

添加乙醇碳源对驯化菌种降解油制气废水的影响

进行了添加乙醇作为碳源强化油制气废水生物降解的研究,并利用GC／MS分析对油制气废水中芳烃类化合物的降解进行了初步研究。研究表明,共代谢基质乙醇的加入,可使菌种S-2、Y-3、XH-3、M-3对COD、氨氮、可萃取有机物等指标的去除率分别提高17．6％～25．6％、34．9％～42．8％、10．4％～14．2％;但在所采用的时间范围内,酚类化合物的去除率降低;芳烃类化合物的去除率提高15．4％～21．2％。除了维持无共代谢条件下对芳环数≤3的芳烃类化合物的良好降解能力外,对芳环数为4～6的化合物降解能力也有所提高。     

烟气脱硝技术研究新进展

简介了国内外已工业应用的主要烟气脱硝技术如选择性催化还原法（SCR）、选择性非催化还原法（SNCR）和电子柬脱硝技术（EBA）的应用现状及其发展,并对近年来国内外发展的烟气脱硝新工艺、新技术的原理及研究现状进行了评述,最终展望了中国烟气脱硝技术的未来的发展方向。     

乐果好氧降解菌的驯化和筛选

为了获得有效降解有机磷农药乐果的微生物,采用北京大兴黄村施用过乐果的土壤为菌源,以乐果作为唯一碳源和能源分离得到5株对乐果有一定降解能力的细菌。正交实验结果显示:降解菌在温度为40℃,pH值为9,NaCl浓度为0 .5g/L条件下生长良好。     

Land use change simulation and spatial analysis of ecosystem service value in Shijiazhuang under multi-scenarios

Environmental Science and Pollution Research - Simulating changes in the value of ecosystem services caused by land use changes in large cities under multiple scenarios is of great significance for...     

Anaerobic co-digestion of kitchen waste and fruit/vegetable waste: Lab-scale and pilot-scale studies

The anaerobic digestion performances of kitchen waste (KW) and fruit/vegetable waste (FVW) were investigated for establishing engineering digestion system. The study was conducted from lab-scale to pilot-scale, including batch, single-phase and two-phase experiments. The lab-scale experimental results showed that the ratio of FVW to KW at 5:8 presented higher methane productivity (0.725 L CH₄/g VS), and thereby was recommended. Two-phase digestion appeared to have higher treatment capacity and better buffer ability for high organic loading rate (OLR) (up to 5.0 g (VS) L^?1 d^?1), compared with the low OLR of 3.5 g (VS) L^?1 d^?1 for single-phase system. For two-phase digestion, the pilot-scale system showed similar performances to those of lab-scale one, except slightly lower maximum OLR of 4.5 g (VS) L^?1 d^?1 was allowed. The pilot-scale system proved to be profitable with a net profit of 10.173 $/ton as higher OLR (?3.0 g (VS) L^?1 d^?1) was used.