Sorption of naphthoic acids and quinoline compounds to estuarine sediment

The sorption of 16 ionizable organic compounds (IOCs) to an estuarine sediment was measured in synthetic estuarine water as a function of IOC concentration (1-100 microM) at fixed ionic strength (0.4 M), pH (7.6), and sediment concentration (0.018 g sediment kg(-1) suspension). Of the 16 IOCs, 11 were naphthoic acids and five were quinoline compounds. The linear sorption distribution coefficient (Kd) was used to correlate sorption to IOC physicochemical and molecular characteristics. With respect to naphthoic acid, sorption increased with the addition of ortho-substituent groups and with increasing chain length of the 1-acid group, and the greatest increase occurred with ortho-hydroxyl, carbonyl, and carboxyl groups. With respect to quinoline, sorption decreased with substituent group addition (except for nitro group) and with additional heterocyclic N atoms. For the naphthoic acids, log Kd exhibited a positive correlation with water solubility (log Sw) indicative of sorption primarily to mineral surfaces under the solution chemistry. For the quinoline compounds, log Kd exhibited a negative correlation with log Sw and a positive correlation with n-octanol/water partition coefficient (log K(OW)) indicative of sorption primarily to organic matter. For both compounds, poor or no correlations were established between log Kd and acid dissociation constant (pKa1), and between log Kd and a variety of molecular connectivity indexes. The results from this study demonstrate that the sorption of IOCs differ depending on their backbone structure and may differ between parent compound and ionizable degradation product.     

Non-homogeneous Poisson models with a change-point: an application to ozone peaks in Mexico city

In this paper, we use some non-homogeneous Poisson models in order to study the behavior of ozone measurements in Mexico City. We assume that the number of ozone peaks follows a non-homogeneous Poisson process. We consider four types of rate function for the Poisson process: power law, Musa–Okumoto, Goel–Okumoto, and a generalized Goel–Okumoto rate function. We also assume that a change-point may or may not be present. The analysis of the problem is performed by using a Bayesian approach via Markov chain Monte Carlo methods. The best model is chosen using the DIC criterion as well as graphical approach.     

Prenatal foetal diagnosis of partial trisomy 3q and monosomy 13p due to a maternal balanced rearrangement

The authors describe a case of a male foetus whose ultrasound at 20 weeks' gestation revealed cystic hygroma, cleft lip and ventricular septal defect. Amniotic fluid cytogenetics using GTG banding showed a 46,XY,der(13)t(3;13)(q12;p11.1) rearrangement, and fluorescence in situ hybridization (FISH) delineated the relevant breakpoints. Familial studies identified a maternal balanced translocation involving chromosomes 3 and 13. The post-mortem examination confirmed the prenatal ultrasound findings. Copyright © 2005 John Wiley & Sons, Ltd.     

Tropical montane cloud forests: current threats and opportunities for their conservation and sustainable management in Mexico

Tropical montane cloud forests (TMCF) are among the most threatened ecosystems globally in spite of their high strategic value for sustainable development due to the key role played by these forests in hydrological cycle maintenance and as reservoirs of endemic biodiversity. Resources for effective conservation and management programs are rarely sufficient, and criteria must be applied to prioritize TMCF for conservation action. This paper reports a priority analysis of the 13 main regions of TMCF distribution in Mexico, based on four criteria: (1) forest quality, (2) threats to forest permanence, (3) threats to forest integrity, and (4) opportunities for conservation. Due to the diverse socio-environmental conditions of the local communities living in Mexican TMCF regions, their associated social characteristics were also evaluated to provide a background for the planning of conservation actions. A set of indicators was defined for the measurement of each criterion. To assign priority values for subregions within each main region, an international team of 40 participants evaluated all the indicators using multicriteria decision-making analysis. This procedure enabled the identification of 15 subregions of critical priority, 17 of high priority, and 10 of medium priority; three more were not analysed due to lack of information. The evaluation revealed a number of subjects that had hitherto been undetected and that may prove useful for prioritization efforts in other regions where TMCF is similarly documented and faces equally severe threats. Based on this analysis, key recommendations are outlined to advance conservation objectives in those TMCF areas that are subjected to high pressure on forest resources.     

Natural factors and mining activity bearings on the water quality of the Choapa basin, North Central Chile: insights on the role of mafic volcanic rocks in the buffering of the acid drainage process

This contribution analyzes water chemical data for the Choapa basin, North Central Chile, for the period 1980-2004. The parameters considered are As, Cu Fe, pH, EC, SO??2, Cl?1, and HCO[Formula: see text], from samples taken in nine monitoring stations throughout the basin. Results show rather moderate contents of As, Cu, and Fe, with the exception of the Cuncumén River and the Aucó creek, explained by the influence of the huge porphyry copper deposit of Los Pelambres and by the presence of mining operations, respectively. When compared against results obtained in previous researches at the neighboring Elqui river basin, which host the El Indio Au-Cu-As district, a much reduced grade of pollution is recognized for the Choapa basin. Considering the effect of acid rock drainage (ARD)-related Cu contents on the fine fraction of the sediments of both river basins, the differences recorded are even more striking. Although the Los Pelambres porphyry copper deposit, on the headwaters of the Choapa river basin, is between one and two orders of magnitude bigger than El Indio, stream water and sediments of the former exhibit significantly lower copper contents than those of the latter. A main factor which may explain these results is the smaller degree of H(?+?)-metasomatism on the host rocks of the Los Pelambres deposit, where mafic andesitic volcanic rocks presenting propylitic hydrothermal alteration are dominant. This fact contrast with the highly altered host rocks of El Indio district, where most of them have lost their potential to neutralize ARD.     

Multi-year monitoring of estuarine sediments as ultimate sink for DDT, HCH, and other organochlorinated pesticides in Argentina

Forty-nine superficial sediment samples used in this study were collected from eight sites in the Bahia Blanca Estuary, located in the Buenos Aires Province southwest, Argentina, in a period between April 2005 and March 2009, to assess the concentration levels, spatial and seasonal distribution, and putative input sources of 18 selected organochlorine pesticides (OCs), following UNEP-IAEA procedures. Average concentration levels in sediments ranged between 3.54 and 63.79 ng g^???1, d.w. (mean = 15.99 ng g^???1, d.w.), for ??OCs, and from nondetectable to 8.03 ng g^???1, d.w. (mean = 2.16 ng g^???1, d.w.), and from nondetectable to 3.20 ng g^???1 (mean = 0.97 ng g^???1, d.w.) for hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs), respectively. Principal component analysis allowed the classification of sampling sites according to the main OCs inputs over the estuary. In comparison to other worldwide locations and to the world coastal sediment concentrations range, sediment DDTs and HCHs levels were in the low range; on the opposite, ??OCs average was in the medium range. OCs seasonal distribution was found to be highly correlated with the precipitations seasonality and sowing seasons in the adjacent agriculture fields. In addition, an ecotoxicological risk assessment pointed industrial and agriculture catchment zones with intermediate probability of adverse effects to biota, while the city sewage outfall was classified with none indication of an immediate threat. Data indicated that the estuary sediments were functioning as a sink for persistent OC pesticides (either in use or banned), however, it was found a declining trend on their environmental burden.     

Nitrogen and phosphorus budgets for the Yucat��n littoral: An approach for groundwater management

Human activities have altered the balance of ecosystems to the detriment of natural environments. Eutrophication is a serious risk in Yucatán, a state in the eastern peninsula of México where groundwater supplies the only freshwater to a karst shelf environment. While economic development in Yucatán is increasing, environmental awareness is lagging, and efficient waste treatment systems are lacking. To assess potential nitrogen and phosphorus inputs into the coastal zone of Yucatán, we analyzed government reports and the chemical composition of groundwater and aquaculture wastewater. Swine, poultry, and tourism are revealed as the main continental nutrient sources, while groundwater with high nitrate concentrations is the principal coastal nutrient source, a pattern similar to other river discharges around the world. This study demonstrates that environmental risk management practices must be implemented in the Yucatán region to protect groundwater quality.     

Comparing the Number of Ozone Exceedances in Different Seasons of the Year in Mexico City

Ozone air pollution is a serious problem in several cities of the world. Hence, to analyse the behaviour of this pollutant is a very important issue. One problem of interest is to study the behaviour of the inter-occurrences times between two ozone exceedances, i.e. between two days in which the pollutant’s measurement surpasses a given threshold. Another interest resides in comparing the behaviour of ozone measurements in different seasons of the year. In this paper we use some Poisson models to analyse this problem. The time interval at which the ozone measurements were taken is split into subintervals corresponding roughly to the seasons of the year. We consider three parametric forms for the mean of the Poisson model, and consequently for the mean of the inter-occurrences times. In each model, the parameters describing its mean are estimated using Bayesian inference via Markov chain Monte Carlo methods. The models are applied to the ozone measurements provided by the Mexico City monitoring network. Theoretical results suggest that an increase has occurred in the mean inter-exceedances times and this is corroborated by the observed data. Differences between the behaviour of the pollutant during different seasons of the year are also detected as well as similarities in the same season in different years. Besides estimating the mean of the Poisson models, inference for the possible presence and location of change-points indicating change of parameters of the model is also performed.     

Adsorptive and photocatalytic activity of Fe3O4-functionalized multilayer graphene oxide in the treatment of industrial textile wastewater

Environmental Science and Pollution Research - Multilayer graphene oxide (mGO) was synthesized and functionalized via co-precipitation method to produce magnetic Fe3O4-functionalized multilayer...     

Mercury and selenium concentrations in the crab Callinectes arcuatus from three coastal lagoons of NW Mexico

Environmental Science and Pollution Research - Mercury and selenium concentrations and Se:Hg molar ratio in edible muscle and hepatopancreas of the crab Callinectes arcuatus from coastal lagoons of...