Speciation of methylmercury in rice grown from a mercury mining area

Monomethylmercury (CH₃Hg⁺ and its complexes; MeHg hereafter) is a known developmental neurotoxin. Recent studies have shown that rice (Oryza sativa L.) grain grown from mercury (Hg) mining areas may contain elevated MeHg concentrations, raising concerns over the health of local residents who consume rice on a daily basis. An analytical method employing high performance liquid chromatography (HPLC) - inductively coupled plasma mass spectrometry (ICP-MS) following enzymatic hydrolysis was developed to analyze the speciation of MeHg in uncooked and cooked white rice grain grown from the vicinity of a Hg mine in China. The results revealed that the MeHg in the uncooked rice is present almost exclusively as CH₃Hg-l-cysteinate (CH₃HgCys), a complex that is thought to be responsible for the transfer of MeHg across the blood-brain and placental barriers. Although cooking does not change the total Hg or total MeHg concentration in rice, no CH₃HgCys is measurable after cooking, suggesting that most, if not all, of the CH₃HgCys is converted to other forms of MeHg, the identity and toxicity of which remain elusive.     

Organohalogen exposure in a Eurasian Eagle owl (Bubo bubo) population from Southeastern Spain: temporal-spatial trends and risk assessment

Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organochlorine insecticides (OCs) were analysed in 58 Eurasian Eagle owl (Bubo bubo) unhatched eggs collected between 2004 and 2009 in Southeastern Spain. Levels of p,p′-DDE were found to be higher than in eggs laid by other European owls in the same decade, probably due to the greater agricultural activity in our study area. Compared to other European raptors, exposure to PCBs can be considered intermediate, but low to PBDEs. Land use differences and prey availability were the rationale to divide the study area in two subareas in further assessments. Temporal trends of HCB, p,p′-DDE, β-HCH, PCBs and PBDEs were significantly different in each subarea, generally increasing over time in the Southern but decreasing or remaining stable in the Northern. On the contrary, levels of cyclodienes tended to decrease in both subareas. Dietary shifts with a greater amount of birds are suggested as a cause for increasing organochlorine loads in raptors. This may explain the increasing trend in the Southern territories. However, due to the proximity of most of these nests to Cartagena, an important industrial city, increasing environmental pollution cannot be ruled out. Although average levels of the compounds analysed are below threshold levels, 17% of the samples exceeded 400 pg g⁻¹ ww (wet weight), the LOAEC for Total TEQs. Moreover, a negative correlation between TEQ concentrations and the metabolizable fraction of PCBs (F_prob = 0.0018) was found when TEQs values were above 10 pg g⁻¹ ww. This could be indicative of hepatic enzymes induction in the birds exposed at higher concentrations, which are mainly breeding in the Southern subarea. These females could be suffering from Ah-receptor-related toxic effects, some of which have been related to altered bird reproduction. Finally, a significant negative correlation between p,p′-DDE levels and eggshell thickness (r = −0.469, p < 0.001) was observed, with about 17% of eggshell thinning for eggs with p,p′-DDE levels above 100 μg g ⁻¹ lw. The persistence of this degree of thinning over a period of time has been related to population declines in other raptor species.     

Hexabromocyclododecanes (HBCDs) in marine fishes along the Chinese coastline

This study reports concentrations of hexabromocyclododecanes (HBCDs) in two species of marine fish, large yellow croaker (Pseudosciaenacrocea) and silver pomfret (Pampusargenteus) (n = 46), from nine Chinese coastal cities (Dalian, Tianjin, Qingdao, Shanghai, Zhoushan, Wenzhou, Fuzhou, Quanzhou and Xiamen). HBCDs were detectable in all samples analyzed, indicating ubiquitous contamination of these compounds in the Chinese coastal environment. The average total HBCD concentration was 3.7 ng g⁻¹ lipid weight (range: 0.57-10.1 ng g⁻¹ lipid weight), which is relatively lower than other regions of the world, especially Europe, where HBCDs are intensively used. Among the three individual HBCD isomers (α-, β- and γ-HBCD) in all fish samples, the α-isomer showed a remarkable predominance (from 87.5% to 100% of total contribution), indicating its higher bioaccumulative potential. Geographically, the highest HBCD level present in fish was found in Dalian in northern China, and the lowest occurred in Wenzhou. Estimated daily intakes of HBCDs via fish consumption for the Chinese population were 0.004-1.00 ng kg body weight⁻¹ d⁻¹. These exposure levels were much lower than the effect levels.     

Assessment of persistent organic pollutants in sediments from Lower Mekong River Basin

Organochlorine compounds (OCs) in sediments collected from various locations in Lower Mekong River Basin (MRB) in Laos and Thailand were examined to elucidate their occurrence, distribution and potential ecological risk. Concentration of PCBs and DDTs were higher than other OCs, ranging from 0.18 to 310 μg kg⁻¹ dry wt. and from 0.027 to 52 μg kg⁻¹ dry wt., respectively, whereas CHLs, HCHs and HCB were 1-3 orders of magnitude lower. Geographical distribution indicates that levels of PCBs, DDTs and CHLs in the Vientiane canal were significantly higher than those in mainstream of Mekong River, Phong River and its surrounding areas, indicating significant sources of these compounds in urbanized areas. Comparison with other parts of MRB indicates that PCBs were higher in Laos, whereas DDTs were more prevalent in Mekong Delta, indicating location specific contaminations of these compounds in MRB. The ratios of DDTs composition indicate possible difference in the historical input of DDT among locations in and around Mekong River. Hazard assessment of PCBs and DDTs indicate possible toxic potential particularly in areas close to point sources such as intensive human activities and agricultural areas which highlight the need for further study.     

Residual behaviour and risk assessment of flubendiamide on chickpea (Cicer arietinum L.)

The study was undertaken to determine the disappearance trends of flubendiamide residues on chickpea under field conditions and thereby, ensure consumer safety. Average initial deposits of flubendiamide on chickpea pods were found to be 0.68 and 1.17 mg kg⁻¹, respectively, following three applications of flubendiamide 480SC @ 48 and 96 g a.i. ha⁻¹ at 7 d intervals. Half-life of flubendiamide on chickpea pods was observed to be 1.39 and 1.44 d, respectively, at single and double dosages whereas with respect to chickpea leaves, these values were found to be 0.77 and 0.86 d. Desiodo flubendiamide was not detected at 0.05 mg kg⁻¹ level on chickpea samples collected at different intervals. Theoretical maximum residue contribution (TMRC) for flubendiamide was calculated and found to be well below the maximum permissible intake (MPI) on chickpea pods and leaves at 0-day (1 h after spraying) for the both dosages. Thus, the application of flubendiamide at the recommended dose on chickpea presents no human health risks and is safe to the consumers.     

Phytotoxicity of silver nanoparticles to Lemna minor L

The use of silver nanoparticles (AgNPs) in commercial products has increased significantly in recent years. Although there has been some attempt to determine the toxic effects of AgNPs, there is little information on aquatic plants which have a vital role in ecosystems. This study reports the use of Lemna minor L. clone St to investigate the phytotoxicity of AgNPs under modified OECD test conditions. AgNPs were synthesised, characterised and subsequently presented to the L. minor. Results showed that inhibition of plant growth was evident after exposure to small (∼20 nm) and larger (∼100 nm) AgNPs at low concentrations (5 μg L⁻¹) and this effect became more acute with a longer exposure time. There was a linear dose-response relationship after 14 d exposure. Using predicted environmental concentrations for wastewaters it was found that AgNPs may pose a significant potential risk to the environment.     

Natural disasters and older US adults with disabilities: implications for evacuation

We analysed 2003 and 2004 Behavioral Risk Factor Surveillance System (BRFSS) data from New Orleans-Metairie-Kenner, LA to produce estimates of the number of community dwelling people aged 65 years or older with a disability and requiring special equipment.(4) Approximately, 47,840 (31.6 per cent) older adults with a disability and 24,938 (16.6 per cent) older adults requiring the use of special equipment were community dwelling and might require assistance to evacuate or a shelter that could accommodate special equipment. Older adults who need special equipment were likely to be female, unmarried and white, and to rate their health as fair or poor. Personnel who plan and prepare for evacuations and temporary shelter during disasters need baseline information on the number of older adults with a disability or who require special equipment. A surveillance system, such as the BRFSS, gathers information that planners can use to prepare for and to deliver services.     

Towards a spatial information infrastructure for flood management in The Netherlands

The immense value of a geographic information system for flood control has been experienced by the decision-markers of the Dutch province of Gelderland during the flood of the Rivers Meuse (Maas) and Waal in January 1995. Super-imposing different ‘data layers’, GIS-experts could detect the weak parts in the dikes and generate and evacuation plan. Shortcomings within the organization were experienced as well: important data could not be retrieved, and the coordination of efforts by the different governmental departments and institutions was not optimal. To overcome these shortcomings and to optimize the modelling process, a spatial decision support system (SDSS) is being proposed, aggregating several models, heuristic and procedural, into integrated software tools. As becomes clear from two cases of flood control described, ‘emergency managers’ should be able to communicate about spatial data available and have access to selected spatial data. In order to improve communication between data sources, data processing and the use of relevant spatial data in GISs, a new ‘Spatial Information Infrastructure’ (SII) needs to be developed. This requires both technical and organizational solutions and standards. Proper documentation of the data will allow the GIS-experts to more quickly find, store, update and reuse the data. A range of ‘metadata’ services exist documenting data sets, typically limited by thematic or national boundaries. There are no standards in common practice for structuring and classifying spatial information. The user of spatial information cannot easily browse across Web-sites and compare products from different suppliers. Even, if the search has been successful, the user all too often has to face a complex process of negotiation, and highly technical data integration issues. A consortium of European GIS-experts has addressed these problems and launched the ‘European Spatial Metadata Infrastructure’ (ESMI) project with the objective to link existing and future metadata systems using Internet.     

对不完备样本下风险分析方法的改进及应用——以湖南省农村种植业水灾为例

对自然灾害的风险分析,核心是对某一指标进行概率密度估计。本文首先对不完备样本的密度估计方法——信息扩散方法进行了修正,通过计算机仿真证实了修正后的模型提高了估计精度。在此基础上,应用修正后的模型对湖南省农村种植业水灾进行了风险分析,建立了自然灾害风险评估模型,并通过绘制风险等值线图,直观地展示了全省农村种植业的水灾风险分布,以及随着灾害程度增大的风险的空间变化趋势。     

有关化工石化建设项目环境风险评价技术评估的探讨

根据国家化工石化行业建设项目加强环境风险评价的主要规定,结合化工石化行业建设项目特点及环境影响技术评估,反思化工石化项目评价及评估工作,重点从环境风险评价方面,对进一步完善环境风险评价与防范的后评估,从严建设项目技术评估与环境管理等进行了初步探讨,目的是为建设项目环境影响技术评估和环境管理提供参考。