Variation of dust layer height in the northern Taklimakan Desert in April 2002

LIDAR observations were conducted in the northern Taklimakan Desert to investigate the vertical distribution of dust in April 2002. During the observation period, a dust outbreak occurred on 13 April, remaining over the desert for several days. Despite only slight variations being observed in dust layer height before the dust event, marked diurnal variation in dust layer height was observed after the dust event. In this study, we conducted two numerical simulations to investigate differences in the variation exhibited by the dust layer heights before and after the dust event, and assessed the influence of meteorological conditions on this variation. The simulated results show that the clearly diurnal variation in dust layer height is strongly influenced by local circulation which is affected by the characteristic topography and synoptic conditions of the Tarim Basin.     

Decolorization of azo dye reactive black B by Bacillus cereus strain HJ-1

Reactive black B (RBB) is a group of azo dyes that are widely used in the textile industry. In this study, a new microbial strain was isolated from azo dye contaminated river sediment which is capable of degrading RBB. The strain was identified as Bacillus cereus strain HJ-1 by 16S rRNA gene sequences analysis. The optimal conditions for RBB decolorization by B. cereus strain HJ-1 are: 25 °C, pH 8, 1 CMC of triton X-100, 0.15 g L^?1 of added yeast extract, 0.125 g L^?1 of added glucose and static culture. Then the toxicity of RBB on the green algae Chlorella vulgaris was determined. The results showed that the median effective concentration (EC₅₀) of RBB for C. vulgaris is 48 mg L^?1 and toxicity will really decrease after decolorization. In the end, B. cereus strain HJ-1 was amended into the origin river sediment and analyzed the whole microbial community structure of river sediment samples by PCR-DGGE technique. The result showed that B. cereus strain HJ-1 could survive in the river sediment after 12 d of incubation. Based on this work, we hope that these findings could provide some useful information for applying the decolorization of RBB in our environment.     

Incorporating differences between genetic diversity of trees and herbaceous plants in conservation strategies

Reviews that summarize the genetic diversity of plant species in relation to their life history and ecological traits show that forest trees have more genetic diversity at population and species levels than annuals or herbaceous perennials. In addition, among-population genetic differentiation is significantly lower in trees than in most herbaceous perennials and annuals. Possible reasons for these differences between trees and herbaceous perennials and annuals have not been discussed critically. Several traits, such as high rates of outcrossing, long-distance pollen and seed dispersal, large effective population sizes (N_e), arborescent stature, low population density, longevity, overlapping generations, and occurrence in late successional communities, may make trees less sensitive to genetic bottlenecks and more resistant to habitat fragmentation or climate change. We recommend that guidelines for genetic conservation strategies be designed differently for tree species versus other types of plant species. Because most tree species fit an LH scenario (low [L] genetic differentiation and high [H] genetic diversity), tree seeds could be sourced from a few populations distributed across the species’ range. For the in situ conservation of trees, translocation is a viable option to increase N_e. In contrast, rare herbaceous understory species are frequently HL (high differentiation and low diversity) species. Under the HL scenario, seeds should be taken from many populations with high genetic diversity. In situ conservation efforts for herbaceous plants should focus on protecting habitats because the typically small populations of these species are vulnerable to the loss of genetic diversity. The robust allozyme genetic diversity databases could be used to develop conservation strategies for species lacking genetic information. As a case study of reforestation with several tree species in denuded areas on the Korean Peninsula, we recommend the selection of local genotypes as suitable sources to prevent adverse effects and to insure the successful restoration in the long term.     

Air Pollution from Secondary Aluminum Production: Determining the Applicability of MACT Requirements

EPA's Maximum Achievable Control Technology rule for secondary aluminum production is intended to substantially reduce emissions of hazardous air pollutants. It may also impose significant costs on affected facilities. © 2001 John Wiley & Sons, Inc.     

Terrigenous Inputs and Accumulation of Trace Metals in the Southeastern Taiwan Strait

Abstract

Terrigenous inputs and sedimentary fluxes of trace metals were studied to understand the metal sources, transport and sinks in the southeastern Taiwan Strait. the major terrigenous metals come from seven major rivers in the southwestern Taiwan, even though significant fractions of most metals were retained in estuaries. the net fluxes of river borne metals contributed from 65% (Pb) to 92% (Fe, Zn) of total inputs. the remainder was attributed to marine sewage discharges (0.6–6.9%) and atmospheric inputs (5.3–31.5%). Sedimentary fluxes of trace metals were spatially variable as a result of derivation from site-specific sedimentation rates and metal distributions in sediments. in spite of imbalance between sources and sinks of trace metals, an accumulation of metals in the sediment of southeastern Taiwan Strait was found for sites close to Taiwan Island. Surface enrichment of metals in near-shore sediments beginning around 1976 was coincident with a time of industrial boom in Taiwan. the metal enrichment hierarchy was found as (Cd, Pb < Cu < Zn < Mn, Fe).     

The importance of tangible and intangible factors in human–carnivore coexistence

Conflict with humans is one of the major threats facing the world's remaining large carnivore populations, and understanding human attitudes is key to improving coexistence. We surveyed people living near Hwange National Park about their attitudes toward coexisting with lions. We used ordinal regression models with the results of the survey to investigate the importance of a range of tangible and intangible factors on attitudes. The variables investigated included the costs and benefits of wildlife presence, emotion, culture, religion, vulnerability, risk perception, notions of responsibility, and personal value orientations. This was for the purpose of effectively tailoring conservation efforts but also for ethical policy making. Intangible factors (e.g., fear and ecocentric values) were as important as, if not more important than, tangible factors (such as livestock losses) for understanding attitudes, based on the effect sizes of these variables. The degree to which participants’ fear of lions interfered with their daily activities was the most influential variable. The degree to which benefits accrue to households from the nearby protected area was also highly influential, as was number of livestock lost, number of dependents, ecocentric value orientation, and participation in conflict mitigation programs. Contrary to what is often assumed, metrics of livestock loss did not dominate attitudes to coexistence with lions. Furthermore, we found that socioeconomic variables may appear important when studied in isolation, but their effect may disappear when controlling for variables related to beliefs, perceptions, and past experiences. This raises questions about the widespread reliance on socioeconomic variables in the field of human–wildlife conflict and coexistence. To facilitate coexistence with large carnivores, we recommend measures that reduce fear (through education and through protective measures that reduce the need to be fearful), reduction of livestock losses, and ensuring local communities benefit from conservation. Ecocentric values also emerged as influential, highlighting the need to develop conservation initiatives tailored to local values.     

Estimation of Organic Carbon Blank Values and Error Structures of the Speciation Trends Network Data for Source Apportionment

Abstract

Because the particulate organic carbon (OC) concentrations reported in U.S. Environment Protection Agency Speciation Trends Network (STN) data were not blank corrected, the OC blank concentrations were estimated using the intercept in particulate matter ≤2.5 µm in aerodynamic diameter (PM_2.5) regression against OC concentrations. The estimated OC blank concentrations ranged from 1 to 2.4 μg/m³ showing higher values in urban areas for the 13 monitoring sites in the northeastern United States. In the STN data, several different samplers and analyzers are used, and various instruments show different method detection limit (MDL) values, as well as errors. A comprehensive set of error structures that would be used for numerous source apportionment studies of STN data was estimated by comparing a limited set of measured concentrations and their associated uncertainties. To examine the estimated error structures and investigate the appropriate MDL values, PM_2.5 samples collected at a STN site in Burlington, VT, were analyzed through the application of the positive matrix factorization. A total of 323 samples that were collected between December 2000 and December 2003 and 49 species based on several variable selection criteria were used, and eight sources were successfully identi?ed in this study with the estimated error structures and min values among different MDL values from the ?ve instruments: secondary sulfate aerosol (41%), secondary nitrate aerosol (20%), airborne soil (15%), gasoline vehicle emissions (7%), diesel emissions (7%), aged sea salt (4%), copper smelting (3%), and ferrous smelting (2%). Time series plots of contributions from airborne soil indicate that the highly elevated impacts from this source were likely caused primarily by dust storms.     

Mercury contamination in agricultural soils from abandoned metal mines classified by geology and mineralization

The concentrations and loadings of major and trace elements in coal mine drainage (CMD) from 49 abandoned mines located in the coal fields of the Brazilian state of Santa Catarina were determined. The CMD sites typically displayed a wide spatial and temporal variability in physical and geochemical conditions. The results of our CMD analyses in Santa Catarina State were used to illustrate that the geochemical processes in the rock piles can be deduced from multiple data sets. The observed relationship between the pH and constituent concentrations were attributed to (1) dilution of acidic water by near-neutral or alkaline groundwater and (2) solubility control of Al, Fe, Mn, Ba and Sr by hydroxide, sulfate, and/or carbonate minerals. The preliminary results of the CMD analyses and environmental health in the Santa Catarina region, Brazil, are discussed.     

A simultaneous optimization approach for the design of wastewater and heat exchange networks based on cost estimation

A new systematic methodology for designing wastewater and heat exchange networks for process industries involving effluent streams containing multiple contaminants is proposed. A simultaneous optimization approach mathematically combines the problems of wastewater and heat exchanger network optimization into a single step. This process includes two global iterations of a similar two-stage approach and optimizes networks for water and heat exchange simultaneously based on cost estimation. The objective function is to minimize the total annual cost of the wastewater and heat exchange network design which is subject to the mass and energy balance constraints on all the pertinent flows and to constraints related to the concentrations of contaminants. The proposed method employs a strategy to address a mixed integer non-linear programming (MINLP) formulation. Cost estimates for optimized wastewater and heat exchange networks for an oil refinery process are generated, illustrating the effectiveness of the proposed methodology.