Fungal inoculum properties: extracellular enzyme expression and pentachlorophenol removal in highly contaminated field soils

This study was conducted to improve the pentachlorophenol (PCP) bioremediation ability of white-rot fungi in highly contaminated field soils by manipulating bioaugmentation variables. These were the dry weight percentage of fungal inoculum addition (31-175 g kg(-1)), PCP concentration (100-2137 mg kg(-1) PCP), fungal inoculum formulation, and time (1-7 wk). Five fungal isolates were used: the New Zealand isolates Trametes versicolor (L.: Fr.) HR131 and Trametes sp. HR577; the North American isolates Phanerochaete chrysosporium Burds. (two isolates) and Phanerochaete sordida (Karst.) Erikss. & Ryv. Pentachlorophenol removal, manganese peroxidase, and laccase activity, and the formation of chloroanisoles in the contaminated field soils were measured. The majority of PCP removed by the Trametes isolates was in the first week after bioaugmentation. The maximum PCP removal by the fungi varied from 50 to 65% from a 1065 mg kg(-1) PCP contaminated field soil. Pentachlorophenol was preferentially converted to pentachloroanisole (PCA) by the Phanerochaete isolates (>60%), while 2 to 9% of the PCP removed by two Trametes isolates was converted to PCA. A pH increase was measured following bioaugmentation that was dependent on PCP concentration, fungal inoculum addition, and formulation. This, together with rapid initial PCP removal, possibly changed the bioavailability of the remaining PCP to the fungi and significantly decreased the sequestering of PCP in the contaminated field soils. The research supports the conclusion that New Zealand Trametes spp. can rapidly remove PCP in contaminated field soils. Bioavailability and extractability of PCP in the contaminated field soil may significantly increase after bioaugmentation.     

Statistical inference using the g or K point pattern spatial statistics

Spatial point pattern analysis provides a statistical method to compare an observed spatial pattern against a hypothesized spatial process model. The G statistic, which considers the distribution of nearest neighbor distances, and the K statistic, which evaluates the distribution of all neighbor distances, are commonly used in such analyses. One method of employing these statistics involves building a simulation envelope from the result of many simulated patterns of the hypothesized model. Specifically, a simulation envelope is created by calculating, at every distance, the minimum and maximum results computed across the simulated patterns. A statistical test is performed by evaluating where the results from an observed pattern fall with respect to the simulation envelope. However, this method, which differs from P. Diggle's suggested approach, is invalid for inference because it violates the assumptions of Monte Carlo methods and results in incorrect type I error rate performance. Similarly, using the simulation envelope to estimate the range of distances over which an observed pattern deviates from the hypothesized model is also suspect. The technical details of why the simulation envelope provides incorrect type I error rate performance are described. A valid test is then proposed, and details about how the number of simulated patterns impacts the statistical significance are explained. Finally, an example of using the proposed test within an exploratory data analysis framework is provided.     

Climate change adaptation planning for Global South megacities: the case of Dhaka

Megacities in low- and middle-income countries face unique threats from climate change as vulnerable populations and infrastructure are concentrated in high-risk areas. This paper develops a theoretical framework to characterize adaptation readiness in Global South cities and applies the framework to Dhaka, Bangladesh, a city with acute exposure and projected impacts from flooding and extreme heat. To gather case evidence from Dhaka we draw upon interviews with national and municipal government officials and a review of planning documents and peer-reviewed literature. We find: (1) national-level plans propose a number of adaptation strategies, but urban concerns compete with priorities such as protection of coastal assets and agricultural production; (2) municipal plans focus on identifying vulnerability and impacts rather than adaptation strategies; (3) interviewees suggest that lack of coordination among local government (LG) organizations and lack of transparency act as barriers for municipal adaptation planning, with national plans driving policy where LGs have limited human and financial resources; and (4) we found limited evidence that national urban adaptation directives trickle down to municipal government. The framework developed offers a systematic and standardized means to assess and monitor the status of adaptation planning in Global South cities, and identify adaptation constraints and opportunities.     

氮肥:迎接当代挑战

商业氮肥以8170万t之巨,约占现今所有抵达地球耕地氮肥的50%,至少给40%的人口提供了基本的食物需求.摆在我们面前的挑战是,继续帮助满足那种需求,而又要通过改善氮肥利用效率把对环境的负面影响减到最小.在美国,玉米上的氮肥效率在近20年里提高了30%以上,但在玉米和其它作物上尚有潜力可挖.在大多数亚洲国家目前的氮肥效率和生产率比北美一般要低,但他们正在做出努力加以改进.化肥工业认识到在满足人类现今和将来的基本需求方面它所担负的关键角色.它已准备好迎接新的挑战,采用新的实践和技术来提高效率,并以此不仅支持人类生命而且改善人们生活的质量.     

Infection dynamics of an oyster parasite in its newly expanded range

Over a 2-year period in 1990 and 1991, coincident with a pronounced warming episode, Dermo disease outbreaks in the oyster, Crassostrea virginica, caused by the parasite Perkinsus marinus, occurred over a 500-km range from Delaware Bay to Cape Cod, in the northeastern United States. The parasite had not previously been recorded or known to cause mortalities in this region. To document infection patterns and levels in this region several years after the initial outbreaks, and to compare them with those in the parasite’s historic southern range, we deployed and sampled oysters from 1996 to 1998 at multiple sites spanning the expanded range. During this 2-year period, the parasite was documented to occur in oysters at high prevalences throughout the new range, in sites varying from small, enclosed embayments to large estuaries, and in both cultured and wild-set oysters. Infection and mortality patterns, and levels were similar to those in southern locations where the parasite has been enzootic for at least decades. The persistence of high P. marinus infection levels in the new range after the initial expansion is probably due to several factors: (1) winter temperatures continued to increase during the 1990s and early 2000s, albeit at a slower rate than in 1990–1991, facilitating overwinter survival of the parasite; (2) many oyster-growing sites in the northeast are in relatively shallow water in which summer temperatures offer ample time for the parasite to proliferate and spread; and (3) the combination of high parasite burdens and high host densities in oyster farms results in an abundance of parasites and high transmission rates. Colder winters and high rainfall after 2002 reduced prevalences in some regions, but P. marinus can survive low temperatures and low salinities, and epizootic conditions are likely to return if temperatures rise again, as predicted by climate-change models.     

Organochlorine contaminants in narwhal (Monodon monoceros) from the Canadian Arctic

Organochlorine pesticides (DDT, chlordane, polychlorinated camphenes (PCCs), dieldrin, hexachloroheclohexanes (SigmaHCH), mirex), polychlorinated biphenyl congeners (PCBs) and chlorobenzenes (SigmaCBz) were determined in blubber and liver of narwhal (Monodon monoceros) collected during 1982-1983 from Pond Inlet on northern Baffin Island in the Canadian Arctic. PCCs were the predominate organochlorines in narwhal blubber, ranging in concentration from 2990 to 13 200 ng g(-1) (wet wt) in males and from 1910 to 8390 ng g(-1) in females. PCCs consisted of two major components, an octachlorobornane and a nonachlorobornane with gas chromatographic retention times of 1.05 and 1.22, relative to 4,4'-DDE. SigmaPCB concentrations in blubber ranged from 2250 to 7290 ng g(-1) in males and from 894 to 5710 ng g(-1) in females. Seven PCB congeners (tetra-, penta- and hexachlorobiphenyls) accounted for 45% of total PCB (SigmaPCB) in narwhal blubber. Narwhal had 1.4- to 8.6-fold higher ratios of tetra- and pentachlorobiphenyls to PCB-153 (2,2',4,4',5,5'-hexachlorobiphenyl), lower 4,4'-DDE/SigmaDDT ratios and lower proportions of trans-nonachlor to total chlordane components than reported for odontocetes living in more contaminated environments. Mean SigmaPCB concentrations in narwhal were 6- to 15-fold lower than in dolphins from the Canadian east coast and belugas from the St Lawrence River estuary, respectively, while PCC levels were from 4- to about 2-fold lower, and SigmaHCH, dieldrin and SigmaCBz differed by <2-fold. The pattern of organochlorines in narwhal tissues suggests they are exposed to proportionally more volatile compounds, and may have less capacity to metabolize some of these compounds, relative to odontocetes living nearer sources of these contaminants.     

STRATIFICATION VARIABILITY IN THREE MORPHOMETRICALLY DIFFERENT LAKES UNDER IDENTICAL METEOROLOGICAL FORCING1

ABSTRACT: Synoptic water temperature measurements were taken in three temperate lakes located within 25 km of one another to study the effects of morphometry (and changes in weather) on seasonal and short-term thermal stratification characteristics. Two of the lakes had nearly the same surface areas and two had nearly identical mean depths; all were exposed to identical weather conditions. The dominance of weather over morphometry on the water surface temperature response was illustrated by the synoptic measurements in two different years. Stratification structure was also found to be dominated by weather for sufficiently deep lakes. Surface area effects were most subtle but explainable as sheltering effects. The onset of stratification was not, as traditionally described, a simple, gradual response of a lake to the annual solar radiation cycle. Rather it depends on a series of alternating heating, cooling, and mixing cycles similar to annual and diel cycles but with a period of approximately five days. These were in direct response to the passage of major weather systems and displayed no apparent time lag. No comparable synoptic water temperature data set could be found in the literature.