Spatial distribution and human health risk assessment of mercury in street dust resulting from various land-use in Ahvaz,Iran

Mercury as a toxic element and its associated health hazard has been an important topic of research for urban pollution for many years. In this paper, the spatial distribution, pollution assessment, and health risk associated with Hg in roadside dust 96 street dust samples, representing differing land-uses, have been investigated. Land-uses included residential areas (RA), industrial areas (IA), public gardens (PG), roadside areas (RS), and suburban areas (SA) in the city of Ahvaz, Iran were investigated. Compared with other cities, the concentration of Hg in Ahvaz was considerably higher with a mean value of 2.53 mg kg^?1, ranging from 0.02 to 8.75 mg kg^?1. Residential areas exhibited higher Hg in street dust than other areas, as demonstrated by spatial mapping illustrating hot spots associated with old urban areas with high residential density, high volume traffic of roadside areas, and industrial districts: including oil-drilling activities, steel smelting-related industries, and small industrial towns around Ahvaz. However, Hg concentrations in street dust near to the public gardens (PG) and suburban areas (SA) were not at elevated levels compared other land-uses investigated in this study. A health risk assessment model of non-carcinogenic effects was evaluated for both children and adults. The HQ values also revealed that the main exposures route for children and adults decreased as follows: vapour > ingestion > dermal contact > inhalation. The hazard index (HI) in each area is less than the safe level (HI ≤ 1) for children and adults, but higher for children. The HI value decreases as the following order: RS > IA > RA > SA > PG, which indicates potentially serious health hazards for children in the study areas.     

False elevation of amniotic fluid enzymes of relevance for prenatal diagnosis: Creatine kinase measurement in relation to duchenne muscular dystrophy

The creatine kinase activity of amniotic fluid was measured in samples collected at fetoscopy. In our first study, the control sample range was 0-25 IU/1, although four samples had activities of 35–85 IU/1. Elevated values did not correlate with the activities in the fetal or maternal circulations. Electrophoresis revealed the presence of the BB isozyme of creatine kinase rather than just the MM form as expected. This suggested that the source of the elevated enzyme activity was from the myometrium, damaged by insertion of the trocar and cannula. In a further series the first 2 ml of amniotic fluid withdrawn yielded a much higher creatine kinase activity than a second aliquot. A control series of such second samples (first 2 ml discarded) gave an activity range of 0–7 IU/1 with no spuriously high values. This compares favourably with a series from single samplings taken by amniocentesis. Normal creatine kinase activities were found in the amniotic fluids from 20 pregnancies at risk for Duchenne muscular dystrophy. We conclude that for accurate measurement of amniotic fluid enzyme activity the first portion withdrawn should be discarded. Amniotic fluid creatine kinase activity is of no value for the prenatal diagnosis of Duchenne muscular dystrophy.     

Creatine kinase estimation in pure fetal blood samples for the prenatal diagnosis of duchenne muscular dystrophy

This paper compares the results of a survey of plasma creatine kinase (CK) activity measured in fetuses at-risk for Duchenne muscular dystrophy (DMD) with a reliable control series. Only pure fetal blood samples obtained by fetoscopy at between 17–24 weeks gestational age were used. Of the at-risk group 19 male pregnancies, mostly at low risk for DMD, proceeded to term with a normal outcome; there was no significant difference between their fetal plasma CK activities and the control group. Another 21 male pregnancies were terminated. This group included the highest risk mothers and hence was expected to contain a significant proportion of affected fetuses. The fetal plasma CK activity range was overlapping but significantly higher than the control group. No grossly elevated CK value was obtained. We conclude that, on average, DMD fetuses at this gestational age have higher plasma CK activity than controls. The problems of applying this finding to the prenatal diagnosis of DMD are discussed.     

Reactive oxygen species responsible for the enhanced desorption of dodecane in modified Fenton's systems.

The enhanced treatment of sorbed contaminants has been documented in modified Fenton's reactions; contaminants are desorbed and degraded more rapidly than they desorb by fill-and-draw or gas-purge desorption. The reactive species responsible for this process was investigated using dodecane as a model sorbent. Hydroxyl radical, hydroperoxide anion, and superoxide radical anion were generated separately to evaluate their roles in enhanced dodecane desorption. Dodecane desorption from silica sand over 180 minutes was negligible in gas-purge systems and in the hydroxyl radical and hydroperoxide anion systems. In contrast, enhanced desorption of dodecane occurred in superoxide systems, with >80% desorption over 180 minutes. Scavenging of superoxide eliminated the enhanced desorption of dodecane in both superoxide and modified Fenton's systems, confirming that superoxide is the desorbing agent in modified Fenton's reactions. Conditions that promote superoxide generation in Fenton's reactions may enhance their effectiveness for in situ subsurface remediation of sorbed hydrophobic contaminants.     

Use of Bioassay Methods to Evaluate Mutagenicity of Ambient Air Collected Near a Municipal Waste Combustor

An ambient air sampling study was conducted around a municipal waste combustor; a primary goal was to develop procedures and methods to evaluate the emissions of organic mutagens resulting from incomplete combustion of municipal waste. The products of Incomplete combustion from incineration include complex mixtures of organics, particularly polycycllc aromatic compounds, which are present after atmospheric dilution and cooling In emissions as semi-volatile or particle bound organic compounds. Combustion emissions are generally recognized as a potential cancer risk since they contain many carcinogenic and mutagenlc polycyclic aromatic hydrocarbons. Analyzing such a complex mixture for the presence of even a few selected chemicals is difficult and provides risk information on only a fraction of the chemicals present. Bioassay methods, however, may be directly applied to evaluate the mutagenic and potential carcinogenic activity of the complex organics from combustion emissions. The Salmonella (Ames) assay was used to determine the mutagenicity associated with particles from ambient air collected near a municipal waste combustor. Dose-response data was generated, and mutagenicity concentrations were calculated to demonstrate the utility of bioassay In assessing the potential Impact of emissions from municipal waste combustion. This phase of study quantified mutagenicity concentrations In ambient air but did not detect organic mutagens that could be attributed to Incinerator emissions.     

Water quality parameters controlling the photodegradation of two herbicides in surface waters of the Columbia Basin,Washington

The water quality parameters nitrate-nitrogen, dissolved organic carbon, and suspended solids were correlated with photodegradation rates of the herbicides atrazine and 2,4-D in samples collected from four sites in the Columbia River Basin, Washington, USA. Surface water samples were collected in May, July, and October 2010 and analyzed for the water quality parameters. Photolysis rates for the two herbicides in the surface water samples were then evaluated under a xenon arc lamp. Photolysis rates of atrazine and 2,4-D were similar with rate constants averaging 0.025 h⁻¹ for atrazine and 0.039 h⁻¹ for 2,4-D. Based on multiple regression analysis, nitrate-nitrogen was the primary predictor of photolysis for both atrazine and 2,4-D, with dissolved organic carbon also a predictor for some sites. However, at sites where suspended solids concentrations were elevated, photolysis rates of the two herbicides were controlled by the suspended solids concentration. The results of this research provide a basis for evaluating and predicting herbicide photolysis rates in shallow surface waters.     

A Yin‐Yang approach to education policy regarding health and the environment: early‐careerists' image of the future and priority programmes

Since the inception of sustainable development (SD), there has been a somewhat ignored contradiction between paradigms that are ecosystem‐based and paradigms that are human‐based or purely economic. We suggest that this contradiction can be unified through a balance of the two. The Chinese Yin‐Yang philosophy is applied as a tool or approach to seeking balance between these ecocentric and anthropocentric paradigms. Priority education policy design for the merging of ecology and health are projected through an Ecohealth lens in response to increasing SD challenges and the intention of the international Ecohealth organization to contribute to SD goals. Meeting SD goals along the nexus of health and environment is further considered through early‐careerist cultural assessments and projections. The groups considered for their professional image of the future are: members of the Ecohealth Association Student Section and Chinese early‐careerists participating in a related conference. In response to SD goals, a problem‐based learning design is suggested as an education policy priority. Rather than approaching SD as a boolean concept, for example, by either focusing on ecosystem sustainability or economic development, we suggest education policy for programmes and curriculums that will help emerging professionals balance these paradigms, so as to best address national and global challenges.     

Long-term tillage effects on atrazine and fluometuron sorption in Coastal Plain soils

Conservation tillage (CnT) management practices are known to increase levels of soil organic matter (SOM) in southeastern Coastal Plain soils. Plant residues in CnT systems accumulate at the surface and, with time, will form a layer enriched in SOM. The authors hypothesize that herbicide sorption will be highest in this SOM-enriched zone of CnT systems when compared to sorption at a similar depth in conventional tillage (CT) systems. The objective was to characterize the impact of two different tillage systems, CnT and CT, on sorption of atrazine [6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine] and fluometuron [N,N-dimethyl-N′-3-(trifluoromethyl)phenyl urea] in plots of Norfolk loamy sand (fine-loamy, siliceous thermic Typic Kandiudult). The plots have been under CnT and CT management for 18 yrs. Bulk (0–15 cm) and five equal incremental soil samples to a 15 cm depth were collected from 10 CnT and 10 CT plots, and the atrazine (ATR) and fluometuron (FLMT) sorption coefficients (K_d) were measured using batch equilibration. Significantly higher herbicide K_d values occurred in the CnT 0–3 cm samples, indicating that the highest amount of herbicide sorption occurred in the top few cm of soil. This corresponded to the stratified soil organic carbon (SOC) contents in topsoil of the CnT plots. In addition, analyses of covariance using SOC as the covariant to test for tillage effects indicated complex interactions among SOC, tillage, and depth. Those results confirm that tillage and soil depth will affect SOC contents of a Norfolk loamy sand, which correspondly will influence the magnitude of ATR and FLMT sorption.