Human exposure to methylmercury from crayfish (Procambarus clarkii) in China

Methylmercury (MeHg) accumulation in aquatic food raises global concerns about human exposure to MeHg. Crayfish is the world’s third largest farmed crustacean species and a favorite aquatic food in many countries. However, human health hazard due to MeHg exposure via crayfish consumption is unclear, partly because appropriate survey data are lacking. We report on mercury concentrations and speciation in edible tail muscle of crayfish collected from restaurants in 23 Chinese cities. On average, MeHg constituted 99.1 % of mercury in tail muscle, and MeHg concentrations were comparable with those reported for fish in China. Variation in MeHg concentrations was not attributable to broad geographic region (i.e., provinces) or tail length. For different populations, potential health risk (characterized by hazard quotient or HQ) of MeHg exposure through crayfish consumption depended largely on crayfish consumption rates. In particular, a health hazard (HQ > 1) was found for high-rate consumers (i.e., 95 %ile or higher) in some cities in the middle and lower reaches of the Yangtze River (MLYR), during the peak consumption season. Our results suggest that more attention should be paid to dietary MeHg intake via crayfish consumption in China, particularly for communities with high consumption in MLYR.

     

A 21st-Century perspective on snow drought in the Upper Colorado River Basin

In the Upper Colorado River Basin (UCRB), there is a deep reliance on seasonal snowpack for maintenance of water resources. The term “snow drought” has recently emerged to describe periods of anomalously low snowpack. Unique seasonal patterns in precipitation and temperature that drive snow drought can have distinct hydrologic signatures, and these relationships have not been carefully studied in the UCRB. Here we examine snow drought with a new classification scheme using peak snow water equivalent (SWE) and the ratio of basin-wide modeled peak SWE to accumulated (onset to peak) precipitation (SWE/P) that clusters snow drought years into three distinct groups—“warm,” “dry,” and “warm & dry”—that minimize within-group variance. Over the period 1916–2018, we identify 14 warm years ($\overline{P}$ = 160 mm; $\overline{\mathrm{SWE}/P}$ = 0.24), 24 dry years ($\overline{P}$ = 117 mm; $\overline{\mathrm{SWE}/P}$ = 0.35), and 21 warm & dry years ($\overline{P}$ = 94 mm; $\overline{\mathrm{SWE}/P}$ = 0.23). An elevation-based analysis reveals two distinct patterns: warm snow droughts see severe SWE reductions primarily at lower (<2600 m) elevations (65% at lower elevations, 37% overall), whereas “dry” scenarios exhibit a consistent reduction across all elevations (39% overall). Using naturalized streamflow data, we also differentiate snow droughts by their earlier streamflow timing and decreased peakedness (warm: 7 days, 2%; dry: 7 days, 2%; warm & dry: 13 days, 5%). This research provides new insights into snow drought patterns relevant for regional water management.     

Field demonstration of surfactant-enhanced solubilization of DNAPL at Dover Air Force Base, Delaware

This study reports on a surfactant-based flood for tetrachloroethylene (PCE) removal from a control test cell at the Dover National Test Site. The surfactant formulation (sodium dihexyl sulfosuccinate (Aerosol-MA or AMA), isopropanol and calcium chloride) was able to achieve a high concentration of PCE in swollen micelles (supersolubilization) without vertical PCE migration. The hydraulic system included eight screened wells that were operated in both vertical circulation and line drive configurations. After 10 pore volumes of flushing, the overall PCE removal was 68% (65% of which corresponded to the surfactant flooding alone). In addition, the residual PCE saturation was reduced from 0.7% to 0.2%, and the concentration of PCE in the groundwater was reduced from 37-190 mg/L before the flushing to 7.3 mg/L after flooding. Recycling the surfactant solution reduced the required surfactant mass (and thus cost, and waste) by 90%. Close to 80% of the total PCE removal was obtained during the first five pore volumes which were operated in an upward vertical circulation flow scheme. No free oil phase was observed during the test. Further analysis of multilevel sampler data suggests that most of the trapped oil remaining in the cell was likely localized in secluded regions of the aquifer, which helps explain the lower PCE groundwater concentration after remedial activities. In summary, this field study demonstrated the feasibility of surfactant-enhanced remediation to reduce the mass in the source zone and significantly reduce the PCE aqueous concentration and therefore the risk associated with the contaminant plume.     

Dominance, not kinship, determines individual position within the communal roosts of a cooperatively breeding bird

Kin selection has played an important role in the evolution and maintenance of cooperative breeding behaviour in many bird species. However, although relatedness has been shown to affect the investment decisions of helpers in such systems, less is known about the role that kin discrimination plays in other contexts, such as communal roosting. Individuals that roost communally benefit from reduced overnight heat loss, but the exact benefit derived depends on an individual's position in the roost which in turn is likely to be influenced by its position in its flock's dominance hierarchy. We studied the effects of kinship and other factors (sex, age, body size and flock sex ratio) on an individual's roosting position and dominance status in captive flocks of cooperatively breeding long-tailed tits Aegithalos caudatus. We found that overall, kinship had little influence on either variable tested; kinship had no effect on a bird's position in its flock's dominance hierarchy and the effect of kinship on roosting position was dependent on the bird's size. Males were generally dominant over females and birds were more likely to occupy preferred roosting positions if they were male, old and of high status. In this context, the effect of kinship on social interactions appears to be less important than the effects of other factors, possibly due to the complex kin structure of winter flocks compared to breeding groups.     

Natural radioactive nuclides in some Tunisian thermo-mineral springs

Radioactivity in some Tunisian thermo-mineral springs (11 hot mineral springs and one cold spring) has been determined for the first time in Tunisia using radiochemical separation procedures. The obtained results show that 238U activity concentrations vary between 1.5 and about 43 mBq/l. The measured activities of 234U and 226Ra range from 1.1 to about 82.2 mBq/l and 34-3,900 mBq/l. respectively. The radioactive disequilibria in these waters are in excess of concentration of 234U compared to that of 238U. The 226Ra/234U activity ratios are high and in the range of 9.0-691.0). U, Th and Ra activities are similar to those published for other non-polluted regions of the world. Radioactivity in the only cold mineral water from A?n Oktor is very low, and thus health hazards due to the consumption of this water are not expected.     

Trends in food production and nitrous oxide emissions from the agriculture sector in India: environmental implications

We studied trends in food production and nitrous oxide emissions from India's agricultural sector between 1961 and 2000. Data from Food and Agricultural Statistics (FAO) have been gathered covering production, consumption, fertilizer use and livestock details. IPCC 1996 revised guidelines were followed in studying the variations in N₂O-N emissions. Results suggest that total N₂O-N emissions (direct, animal waste and indirect sources) increased ~6.1 times from ~0.048 to ~0.294 Tg N₂O-N, over 40 years. Source-wise breakdown of emissions from 1961–2000 indicated that during 1961 most of the N₂O-N inputs were from crop residues (61%) and biological nitrogen fixation (25%), while during 2000 the main sources were synthetic fertilizer (~48%) and crop residues (19%). Direct emissions increased from ~0.031 to ~0.183 Tg. It is estimated that ~3.1% of global N₂O-N emissions comes from India. Trends in food production, primarily cereals (rice, wheat and coarse grains) and pulses, and fertilizer consumption from 1961–2000 suggest that food production (cereals and pulses) increased only 3.7 times, while nitrogenous fertilizer consumption increased ~43 times over this period, leading to extensive release of nitrogen to the atmosphere. From this study, we infer that the challenge for Indian agriculture lies not only in increasing production but also in achieving production stability while minimizing the impact to the environment, through various management and mitigation options.     

African land ecology: opportunities and constraints for agricultural development

Compared to other continents, the economic growth performance of Sub-Saharan Africa has been poor over the last four decades. Likewise, progress in agricultural development has been limited and the Green Revolution left Africa almost untouched. The question raised in the literature is whether the poor performance is a question of poor policies or of an unfavorable biophysical environment (policy versus destiny). This paper, with a broad perspective, analyzes adaptation of current land use to environmental conditions in Africa and compares the physical resource base of Africa with Asia. In doing so, we search for unifying principles that can have operational consequences for agricultural development. We argue that some specificities of the natural resource base, namely local homogeneity and spatial diversity of the predominant Basement Complex soils, imply that simple fertilizer strategies may not produce the yield increases obtained elsewhere.     

Developing the Ethical Delphi

A number of EU institutions and government committees across Europe have expressed interest in developing methods and decision-support tools to facilitate consideration of the ethical dimensions of biotechnology assessment. As part of the work conducted in the EC supported project on ethical tools (Ethical Bio-TA Tools), a number of ethical frameworks with the potential to support the work of public policy decision-makers has been characterized and evaluated. One of these potential tools is the Delphi method. The Delphi method was originally developed to assess variables that are intangible and/or shrouded in uncertainty by drawing on the knowledge and abilities of a diverse group of experts through a form of anonymous and iterative consultation. The method has hitherto been used by a diversity of practitioners to explore issues such as technology assessment, environmental planning, and public health measures. From the original (classical) Delphi, a family of Delphi-related processes has emerged. As a result of the evaluation of the various Delphi processes, it is proposed that the classical method can be further developed and applied as a form of ethical framework to assist policy-makers. Through a series of exercises and trials, an Ethical Delphi has been developed as a potential approach for characterizing ethical issues raised by the use of novel biotechnologies. Advantages and disadvantages of the method are discussed. Further work is needed to develop the procedural aspects of the Ethical Delphi method and to test its use in different cultural contexts. However, utilizing an ethical framework of this type combines the advantages of a methodical approach to capture ethical aspects with the democratic virtues of transparency and openness to criticism. Ethical frameworks such as the Ethical Delphi should contribute to better understanding of and decision-making on issues that involve decisive ethical dimensions.     

Endocannabinoid 2-arachidonoylglycerol protects inflammatory insults from sulfur dioxide inhalation via cannabinoid receptors in the brain

Sulfur dioxide(SO_2) pollution in the atmospheric environment causes brain inflammatory insult and inflammatory-related microvasculature dysfunction.However,there are currently no effective medications targeting the harmful outcomes from chemical inhalation.Endocannabinoids(eCBs) are involved in neuronal protection against inflammation-induced neuronal injury.The 2-arachidonoylglycerol(2-AG),the most abundant eCBs and a full agonist for cannabinoid receptors(CB1 and CB2),is also capable of suppressing proinflammatory stimuli and improving microvasculature dysfunction.Here,we indicated that endogenous 2-AG protected against neuroinflammation in response to SO_2 inhalation by inhibiting the activation of microglia and astrocytes and attenuating the overexpression of inflammatory cytokines,including tumor necrosis factor alpha(TNF-a),interleukin(IL)-1β,and inducible nitric oxide synthase(iNOS).In addition,endogenous 2-AG prevented cerebral vasculature dysfunction following SO_2 inhalation by inhibiting endothelin 1(ET-1),vascular cell adhesion molecule-1(VCAM-1) and intercellular adhesion molecule 1(ICAM-1) expression,elevating endothelial nitric oxide synthase(eNOS) level,and restoring the imbalance between thromboxane A2(TXA2) and prostaglandin 12(PGI2).In addition,the action of endogenous 2-AG on the suppression of inflammatory insult and inflammatory-related microvasculature dysfunction appeared to be mainly mediated by CB1 and CB2 receptors.Our results provided a mechanistic basis for the development of new therapeutic approaches for protecting brain injuries from SO_2 inhalation.     

Particulate matter (PM2.5) exposure season-dependently induces neuronal apoptosis and synaptic injuries

Epidemiological studies have shown that particulate matter 2.5 (PM_2.5) not only increases the incidence of cardiopulmonary illnesses but also relates to the development of neurodegenerative diseases. Considering that PM_2.5 is highly heterogeneous with regional disparity and seasonal variation, we investigated whether PM_2.5 exposure induced neuronal apoptosis and synaptic injuries in a season-dependent manner. The results indicated that PM_2.5 altered the expression of apoptosis-related proteins (mainly bax and bcl-2), activated caspase-3 and caused neuronal apoptosis. Additionally, PM_2.5 decreased the levels of synaptic structural protein postsynaptic density (PSD-95) and synaptic functional protein N-methyl-D-aspartate (NMDA) receptor subunit (NR2B) expression. These effects occurred in a season-dependent manner, and PM_2.5 collected from the winter showed the strongest changes. Furthermore, the effect was coupled with the inhibition of phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) and phosphorylated cAMP-response element binding protein (p-CREB). Based on the findings, we analyzed the correlations between the chemical composition of PM_2.5 samples and the biological effects, and confirmed that winter PM_2.5 played a major role in causing neuronal apoptosis and synaptic injuries among different season samples.