Loading...
43 results
Search Results
Now showing 1 - 10 of 43
- Relative contribution of rice and fish consumption to bioaccessibility-corrected health risks for urban residents in eastern ChinaPublication . Wang, Wenqin; Gong, Yu; Greenfield, Ben K.; Nunes, Luís; Yang, Qianqi; Lei, Pei; Bu, Wenbo; Wang, Bin; Zhao, Xiaomiao; Huang, Lei; Zhong, HuanThere are global concerns about dietary exposure to metal(loid)s in foods. However, little is known about the relative contribution of rice versus fish to multiple metal(loid) exposure for the general population, especially in Asia where rice and fish are major food sources. We compared relative contributions of rice and fish consumption to multi-metal(loid) exposure on the city-scale (Nanjing) and province-scale in China. The effects of ingestion rate, metal(loid) level, and bioaccessibility were examined to calculate modeled risk from Cu, Zn, total As (TAs), inorganic As (iAs), Se, Cd, Pb, and methylmercury (MeHg). Metal(loid) levels in rice and fish samples collected from Nanjing City were generally low, except iAs. Metal(loid) bioaccessibilities in fish were higher than those in rice, except Se. Calculated carcinogenic risks induced by iAs intake (indicated by increased lifetime cancer risk, ILCR) were above the acceptable level (1 0 − 4) in Nanjing City (median: 3 × 10− 4 for female and 4 × 10− 4 for male) and nine provinces (1.4 × 10− 4 to 5.9 × 10− 4) in China. Rice consumption accounted for 85.0% to 99.8% of carcinogenic risk. The non-carcinogenic hazard quotients (HQ) for single metals and hazard index (HI) for multi-metal exposure were < 1 in all cases, indicating of their slight non-carcinogen health effects associated. In Guangdong and Jiangsu provinces, results showed that rice and fish intake contributed similarly to the HI (i.e., 42.6% vs 57.4% in Guangdong and 54.6% vs 45.4% in Jiangsu). Sensitivity analysis indicated that carcinogenic risk was most sensitive to rice ingestion rate and rice iAs levels, while non-carcinogenic hazard (i.e., HQ and HI) was most sensitive to ingestion rate of fish and rice, and Cu concentration in rice. Our results suggest that rice is more important than fish for human dietary metal(loid) exposure risk in China, and carcinogenic risk from iAs exposure in rice requires particular attention.
- Optimizing the location of weather monitoring stations using estimation uncertaintyPublication . Amorim, Ana M. T.; Gonçalves, Alexandre B.; Nunes, Luis Miguel; Sousa, António JorgeIn this article, we address the problem of planning a network of weather monitoring stations observing average air temperature (AAT). Assuming the network planning scenario as a location problem, an optimization model and an operative methodology are proposed. The model uses the geostatistical uncertainty of estimation and the indicator formalism to consider in the location process a variable demand surface, depending on the spatial arrangement of the stations. This surface is also used to express a spatial representativeness value for each element in the network. It is then possible to locate such a network using optimization techniques, such as the used methods of simulated annealing (SA) and construction heuristics. This new approach was applied in the optimization of the Portuguese network of weather stations monitoring the AAT variable. In this case study, scenarios of reduction in the number of stations were generated and analysed: the uncertainty of estimation was computed, interpreted and applied to model the varying demand surface that is used in the optimization process. Along with the determination of spatial representativeness value of individual stations, SA was used to detect redundancies on the existing network and establish the base for its expansion. Using a greedy algorithm, a new network for monitoring average temperature in the selected study area is proposed and its effectiveness is compared with the current distribution of stations. For this proposed network distribution maps of the uncertainty of estimation and the temperature distribution were created. Copyright (c) 2011 Royal Meteorological Society
- Monitoring networks optimization with simulated annealingPublication . Nunes, LuísIn this work some methods to optimize environmental monitoring networks are proposed. These methods share simulated annealing as the approximation algorithm. Only monitoring networks reduction is treated here. Monitoring network optimization is a very actual problem given the large number of existing networks in many countries operating large numbers of stations, some of which may be redundant, with very high exploitation costs. Difficulties appear when exploitation costs pushes the dimension of a network towards a minimum, and the statistical reliability pushes in the opposite direction. Finding the optimal dimension may be a very difficult optimization problem due to the large number of combinations, even for small network dimensions. Further complications appear when the available data is too incomplete or come from different homogeneous areas. Some practical answers to these problems were sought in this work. Results showed that optimizing a monitoring network dimension and location of stations, without compromising the quality of the collected data, could attain large reductions in exploitation costs. Simulated annealing showed to be a very flexible and efficient algorithm.
- Environmental impacts on soil and groundwater at airports: origin, contaminants of concern and environmental risksPublication . Nunes, L.; Zhu, Y.-G.; Stigter, T. Y.; Monteiro, José Paulo; Ribau Teixeira, MargaridaEnvironmental impacts of airports are similar to those of many industries, though their operations expand over a very large area. Most international impact assessment studies and environmental management programmes have been giving less focus on the impacts to soil and groundwater than desirable. This may be the result of the large attention given to air and noise pollution, relegating other environmental descriptors to a second role, even when the first are comparatively less relevant. One reason that contributes to such ‘‘biased’’ evaluation is the lack of systematic information about impacts to soil and groundwater from airport activities, something the present study intends to help correct. Results presented here include the review of over seven hundred documents and online databases, with the objective of obtaining the following information to support environmental studies: (i) which operations are responsible for chemical releases?; (ii) where are these releases located?; (iii) which contaminants of concern are released?; (iv) what are the associated environmental risks? Results showed that the main impacts occur as a result of fuel storage, stormwater runoff and drainage systems, fuel hydrant systems, fuel transport and refuelling, atmospheric deposition, rescue and fire fighting training areas, winter operations, electrical substations, storage of chemical products by airport owners or tenants, and maintenance of green areas. A new method for ranking environmental risks of organic substances, based on chemical properties, is proposed and applied. Results show that the contaminants with the highest risks are the perfluorochemicals, benzene, trichloroethylene and CCl4.
- Contamination and carcinogenic risks of lead in lip cosmetics in ChinaPublication . Gong, Yu; Chu, Junru; Kwong, Raymond; Nunes, Luís; Zhao, Di; Tang, Wenli; Li, Chengjiu; Wei, Zhongbo; Ju, Yongming; Li, Hongbo; Ma, Lena Q.; Yu, Xiezhi; Zhong, HuanThere are growing concerns about elevated lead (Pb) levels in lip cosmetics, yet in China, the largest lip cosmetic market, recent Pb contamination in lip cosmetics and associated Pb exposure remain unclear. Here, we measured Pb levels of 29 popular lip cosmetics in China and conducted the bioaccessibility-corrected carcinogenic risk assessments and sensitivity analysis regarding Pb exposure for consumers using Monte Carlo simulation. The Pb concentrations of collected samples ranged from undetectable (< 0.05 mu g/kg) to 0.21 mg/kg, all of which were well below the Pb concentration limit set for cosmetics in China (10 mg/kg). The 50th percentile incremental lifetime cancer risk (ILCR) of Pb in Chinese cosmetics (1.20E-07) was below the acceptable level (1E-06), indicating that the application of lip cosmetics and subsequent Pb exposure does not pose carcinogenic risks to consumers in most cases. The results of this study provide new insights into understanding the Pb risk in lip cosmetics.
- Normas para elaboração de relatórios técnicos e científicosPublication . Nunes, LuísEste trabalho pretende fornecer algumas regras orientadoras para a elaboração de trabalhos científicos e técnicos não periódicos sem pretender ser exaustivo, sendo antes um guia de consulta rápida. Este documento segue o estabelecido pelas Normas Portuguesas que se aplicam à formatação de documentos técnicos (IPQ 1968a; IPQ 1968b; IPQ 1969; IPQ 1986a; IPQ 1986b; IPQ 1989a; IPQ 1989b; IPQ 1993a; IPQ 1993b; IPQ 1994; IPQ 1995; IPQ 1998).
- Is filter packing important in a small-scale vermifiltration process of urban wastewater?Publication . Lourenco, N.; Nunes, L.Nowadays, natural resources are under increasing stress which fosters wastewater reuse planning and emphasizes on the decentralized wastewater treatment. Vermifiltration has been described as a viable alternative to treat domestic and urban wastewater, but few studies have focused on the impact of different filter packings on vermifiltration performance. This study evaluates the effect of vermicompost and sawdust in a single-stage vermifilter (VF) for urban wastewater treatment. After an acclimation period of 45 days, urban wastewater from a combined sewage collection system was applied continuously for 24 h. Earthworm stock density was of 20 g L-1, HRT of 6 h, HLR of 0.89 m(3) m(-2) day(-1) and OLR of 7.38 g BOD5 day(-1). System performance was assessed by the removal efficiencies of BOD5, COD, TSS, NH4 (+), TN and TP, and fecal coliforms and helminth eggs elimination. Vermicompost (VE) and sawdust (SE) were tested, using an earthworm abundance of 20 g L-1. Treatment efficiencies were 91.3% for BOD5, 87.6% for COD, 98.4% for TSS and 76.5% for NH4 (+) in VE, and 90.5% for BOD5, 79.7% for COD, 98.4% for TSS and 63.4% for NH4 (+) in SE. Earthworms contributed to reduce NH4 (+) and TN removal and to increase NO3 (-) concentration. No treatment was able to eliminate fecal coliforms down to guidelines values for wastewater irrigation as helminth eggs were completely eliminated. Single-stage vermifiltration system using both filter packings is inconsistent and cannot meet EU guideline values for discharge in sensitive water bodies and WHO guidelines for irrigation with treated wastewater.
- The water crisis in southern Portugal: how did we get there and how should we solve itPublication . Nunes, Luís; Monteiro, José Paulo; Cunha, M. C.; Vieira, J.; Lucas, H.; Ribeiro, L.; Brebbia, C. A.; Conti, M. E.; Tiezzi, E.Until very recently, the public water supply in the Algarve region was almost entirely supported by groundwater wells. However, in the last years of the 20th Century, the Portuguese government defined a scheme for the public water supply sector entirely based on surface water from large dams, in order to guarantee the public water supply. The efforts to abandon groundwater as a source for public supply started in 1998, after a large investment in new infrastructures and rehabilitation of some existing ones. However, the practical implementation of this water supply scheme showed that an integrated resource management is needed in order to implement a more economical and reliable solution. The present paper describes the historical background and the evolution of water use in recent decades until the present time in the Algarve, and a proposal for restructuring the management of the water supplies based on the development of a decision support system within an integrated water resources management scheme.
- A new method for groundwater plume detection under uncertaintyPublication . Nunes, Luís; Cunha, Maria da Conceição; Ribeiro, Luís; Azevedo, JoãoGroundwater contamination plumes characterization is a very hard task to perform, requiring usually a large number of sampling sites. In this article a method to optimize a monitoring network for plume detection and delimitation is proposed. It is assumed that a prior extensive sampling campaign was made, and only a few sampling sites must be included in the optimal monitoring network. The objective function incorporates the prior knowledge about concentration variability, in the form of its density function, and also a measure of spatial coverage (space-filling method), in order to best distribute the stations over the field. The method was applied to a synthetic case-study with 160 sampling locations, and a final optimal monitoring network with 40 stations was obtained. Simulated annealing optimization algorithm was used to solve this very difficult combinatorial problem, which has more than 8,6x1037 possible solutions).
- Review of dry and wet decentralized sanitation technologies for rural areas: applicability, challenges and opportunitiesPublication . Lourenço, Nelson; Nunes, L.This paper reviews decentralized sanitation technologies comparing dry and wet solutions currently available, discussing their operational requirements, applicability, effluent output quality, efficiencies, environmental impacts, costs, challenges, as well as their advantages and implementation difficulties. Sanitation technologies vary from conventional centralized systems, typically used on urban areas, to decentralized systems, more common in sparse dwellings and small communities of rural areas. Compared with centralized sanitation, decentralized sanitation is being progressively considered as more sustainable solution. Most do not require energy or expensive or sophisticated operation, being easy to adapt to different geographic contexts. A general lack of consistent regulatory control over most dry rudimentary systems and primary treatment systems may compromise water quality and human health. In the future, a mix of new policies and accurate accounting of the location, performance, and degree of failure of such systems should be performed. However, forcing users and communities to face the capital, operational, or repairing costs may be challenging. Since many of the discussed technologies may be important sources of contamination with nutrients, pathogens and toxic chemicals, new opportunities are still open, which include the conversion of dry rudimentary systems into dry controlled systems.