固相萃取-高效液相色谱法测定水中微囊藻毒素质量控制指标研究

采用固相萃取－液相色谱法,通过统计全国多家实验室的测定数据,对水中微囊藻毒素测试的平行样测定相对偏差、空白加标回收率、实际样品加标回收率、空白加标回收率平行样相对偏差以及样品加标回收率平行样相对偏差5个质控指标进行了研究,并给出了质控指标评价标准,提出在概率P和γ均为0.90时,其平行样测定允许最大相对偏差应控制在7.3%;空白加标质量浓度为0.005~20 μg/L时,回收率的控制范围为61%~125%;样品测定浓度为未检出、加标质量浓度在0.2~3.6 μg/L时,实际样品加标回收率控制范围为66%~108%;空白加标、样品加标回收率平行样最大相对偏差应分别控制在3.9%和8.9%。在概率P和γ均为0.95时,其平行样测定允许最大相对偏差应控制在8.3%;空白加标质量浓度为0.005~20 μg/L时,回收率的控制范围为49%~137%;样品测定浓度为未检出、加标质量浓度在0.2~3.6 μg/L时,实际样品加标回收率控制范围为60%~114%;空白加标、样品加标回收率平行样最大相对偏差应分别控制在5.2% 和14.8%。     

Classification and mapping forest sites using geographic information system (GIS): a case study in Artvin Province

The productivity of forest sites has been indirectly determined with solo wood production objective in forest management. Forest site productivity should, however, be determined directly in order to implement ecosystem based multipurpose forest management philosophy. This article tackles the problem in distinguishing and mapping forest sites using both direct method and indirect method in Genya Mountain located in central of Artvin State Forest Enterprise. About 112 sample plots were designed and distributed over the area. In each sample plot, soil samples were collected and the classical timber inventory measurements were taken. According to direct method, Soil Moisture Regime (SMR) method is preferred due to a water deficiency in the study area. Water holding capacity was used as an essential criterion for the classification of the forest site. Forest site classifications were assigned regarding the physiographic factors such as landform, aspect, and slope. Five different forest sites classes; dry, moderate fresh, fresh, humid and hygric were determined. According to direct method, the guiding curve was used to generate anamorphic site index (SI) equations and three site index classes; good (SI=I–II), medium (SI=III) and low (SI=IV–V) were determined. Some important differences between the methods were realized. The forest sites determined with site index estimation method indicate that site index I and II is 505.99 ha, III 1095.79 ha and IV and V 992.95 ha, whereas forest sites determined with direct method related to dry site of 937.58 ha, moderate fresh site of 931.90 ha, fresh site of 1,797.71 ha, humid site of 80.48 ha and hygric site of 356.55 ha. The forest site maps of both methods were created using GIS functions. The forest sites of open and degraded areas should be determined according to direct method.     

广州地区大气能见度与颗粒物关系的初探

采用番禺大气成分站2007—2013年的能见度、颗粒物(PM1、PM2.5、PM10)及番禺气象局站的相对湿度(RH)资料,对颗粒物7年来的变化状况进行了分析。以RH为标准,将能见度和颗粒物数据分为RH≥90%、80%RH90%和RH≤80%3个部分,并以相关系数(R2)为判断标准,分别对其之间的相关性进行了分析。结果表明,PM10、PM2.5、PM1多年日平均值分别为56.6、43.0、38.5μg/m3,颗粒物值旱季高于雨季。当RH≤80%时,颗粒物与能见度的相关性最好,R2大小顺序为:PM10(0.47)PM2.5(0.57)PM1(0.58);当80%RH90%时,颗粒物与能见度的相关性次之,分别为PM10(0.4)PM2.5(0.46)PM1(0.49);当RH≥90%时,颗粒物与能见度的相关性较差。     

Ecological Risk Assessment of Neem-Based Pesticides

Abstract

A tiered process was used to evaluate the risks of pure azadirachtin (AZA) and two neem-based insecticides (Neemix? and Bioneem?) on six aquatic animals [crayfish (Procambarus clarkii), white shrimp (Penaeus setiferus), grass shrimp (Palaemonetes pugio), blue crabs (Callinectes sapidus), water fleas (Daphnia pulex), and mosquito larvae (Culex quinquefasciatus)] through short term acute toxicity tests. The risk was calculated using the level of concern endpoints (Q values) and relative hazard index (RHI) for acute and chronic exposure scenarios. The Q values of Neemix?, Bioneem?, and pure AZA derived from acute exposure tests indicated that D. pulex is the only sensitive species to the test pesticides. Furthermore, the RHI values of Neemix? and Bioneem? for D. pulex were above the critical limit of 10 indicating that these pesticides may pose a moderate hazard to this species and related crustaceans in acute exposure scenarios. The RHI values of the two pesticides and pure AZA were all below the critical limit of 10 for P. clarkii, P. setiferus, P. pugio, C. sapidus, and C. quinquefasciatus. The aquatic risk assessment process showed that the risk values of tested pesticides did not exceed the criteria, and therefore, no ecological hazard is likely to result from their use.     

Relevant parameters for assessing the environmental impact of some pyridinium, ammonium and pyrrolidinium based ionic liquids

Several physico-chemical properties relevant to determine the environmental impact of ionic liquids - aqueous solubility, octanol/water partition coefficient, chromatographically derived lipophilicity and infinite dilution diffusion coefficients in water - were measured in ionic liquids based on pyridinium, ammonium and pyrrolidinium cations with bis(trifluoromethylsulfonyl)imide anions. The influence of the presence of hydroxyl or ester groups in the physico-chemical properties of these liquids was checked. It appeared that the presence of functional oxygenated moieties reduces the lipophilicity of ionic liquids and so decreases the risk of bioaccumulation in environment.     

The productivity assessment tool: computer-based cost benefit analysis model for the economic assessment of occupational health and safety interventions in the workplace

INTRODUCTION AND MEthod: This paper describes the concepts behind cost benefit analysis in occupational health and safety and introduces the Productivity Assessment Tool, a method by which an analysis may be performed relatively easily in a service or manufacturing workplace. The advantage of using such analyses is to show the important financial role that safe and efficient workplaces play in the workplace. RESULTS: By using analytical tools, the effectiveness of an intervention (workplace change) may be estimated prior to its introduction. IMPACT ON INDUSTRY: This places occupational health and safety on the same financial footing as other proposed workplace changes and thus places occupational health and safety in a strong position to attract scarce resources.     

Plant Community Composition and Biomass in Gulf Coast Chenier Plain Marshes: Responses to Winter Burning and Structural Marsh Management

Many marshes in the Gulf Coast Chenier Plain, USA, are managed through a combination of fall or winter burning and structural marsh management (i.e., levees and water control structures; hereafter SMM). The goals of winter burning and SMM include improvement of waterfowl and furbearer habitat, maintenance of historic isohaline lines, and creation and maintenance of emergent wetlands. Although management practices are intended to influence the plant community, effects of these practices on primary productivity have not been investigated. Marsh processes, such as vertical accretion and nutrient cycles, which depend on primary productivity may be affected directly or indirectly by winter burning or SMM. We compared Chenier Plain plant community characteristics (species composition and above- and belowground biomass) in experimentally burned and unburned control plots within impounded and unimpounded marshes at 7 months (1996), 19 months (1997), and 31 months (1998) after burning. Burning and SMM did not affect number of plant species or species composition in our experiment. For all three years combined, burned plots had higher live above-ground biomass than did unburned plots. Total above-ground and dead above-ground biomasses were reduced in burned plots for two and three years, respectively, compared to those in unburned control plots. During all three years, belowground biomass was lower in impounded than in unimpounded marshes but did not differ between burn treatments. Our results clearly indicate that current marsh management practices influence marsh primary productivity and may impact other marsh processes, such as vertical accretion, that are dependent on organic matter accumulation and decay.     

Effect of NOx and RH on the secondary organic aerosol formation from toluene photooxidation

The secondary organic aerosol (SOA) formation mechanism and physicochemical properties can highly be influenced by relative humidity (RH) and NOx concentration. In this study, we performed a laboratory investigation of the SOA formation from toluene/OH photooxidation system in the presence or absence of NOx in dry and wet conditions. The chemical composition of toluene-derived SOA was measured using Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). It was found that the mass concentration of toluene decreased with increasing RH and NOx concentration. However, the change of SOA chemistry composition (f₄₄, O/C) with increased RH was not consistent in the condition with or without NOx. The light absorption and mass absorption coefficient (MAC) of the toluene-derived SOA only increased with RH in the presence of NOx. In contrast, MAC is invariant with RH in the absence of NOx. HR-ToF-AMS results showed that, in the presence of NOx, the increased nitro-aromatic compounds and N/C ratio concurrently caused the increase of SOA light absorption and O/C in wet conditions, respectively. The relative intensity of CHON and CHO_xN family to the total nitrogen-containing organic compounds (NOCs) increased with the increasing RH, and be the major components of NOCs in wet condition. This work revealed a synergy effect of NOx and RH on SOA formation from toluene photooxidation.     

Changes in wet meadow vegetation after 20 years of different management in a field experiment (North-West Germany)

Conservation and restoration of semi-natural wet grasslands often suffer from poor knowledge on successional pathways of respective habitats under different mowing treatments to derive profound management concepts. In this study, we present the results of a 20-year experiment in six semi-natural wet grassland sites in NW Germany including mowing with and without fertilizer addition and fallow. Succession was recorded by permanent plots. The studied wet grassland communities responded quite similar under equal management. Fallow resulted in the most significant changes in floristic and functional composition facilitating highly competitive rushes and tall forbs. The changes were more pronounced the more the experimental management treatment differed from the former use. For all mowing treatments without fertilizer application, we still observed directed changes in the floristic composition even after 20 years. In particular mowing twice led to a shift in floristic composition towards stress-tolerant plants with low nutrient demands, which was paralleled by decreasing productivity and strongly diminishing Ellenberg nutrient values. Our results documented that restoration of low-yielding target communities by regular mowing is possible – even in an area with high atmospheric nitrogen inputs. However, our results also show that succession did not come to an end even after 20 years, most obviously due to the continuous but very slow immigration and spread of new species.     

Variation in levels of reactive oxygen species is explained by maternal identity, sex and body-size-corrected clutch size in a lizard

Many organisms show differences between males and females in growth rate and crucial life history parameters, such as longevity. Considering this, we may expect levels of toxic metabolic by-products of the respiratory chain, such as reactive oxygen species (ROS), to vary with age and sex. Here, we analyse ROS levels in female Australian painted dragon lizards (Ctenophorus pictus) and their offspring using fluorescent probes and flow cytometry. Basal level of four ROS species (singlet oxygen, peroxynitrite, superoxide and H₂O₂) measured with a combined marker, and superoxide measured specifically, varied significantly among families but not between the sexes. When blood cells from offspring were chemically encouraged to accelerate the electron transport chain by mitochondrial uncoupling, net superoxide levels were three times higher in daughters than sons (resulting in levels outside of the normal ROS range) and varied among mothers depending on offspring sex (significant interaction between maternal identity and offspring sex). In offspring, there were depressive effects on ROS of size-controlled relative clutch size, which relies directly on circulating levels of vitellogenin, a confirmed antioxidant in some species. Thus, levels of reactive oxygen species varies among females, offspring and in relation to reproductive investment in a manner that makes its regulatory processes likely targets of selection.