Co-exposure levels of volatile organic compounds and metals/metalloids in children: Implications for E-waste recycling activity prediction.

Identifying informal e-waste recycling activity is crucial for preventing health hazards caused by e-waste pollution. This study attempted to build a prediction model for e-waste recycling activity based on the differential exposure biomarkers of the populations between the e-waste recycling area (ER) and non-ER. This study recruited children in ER and non-ER and conducted a quasi-experiment among the adult investigators to screen differential exposure or effect biomarkers by measuring urinary 25 volatile organic compound (VOC) metabolites, 18 metals/metalloids, and 8-hydroxy-2'-deoxyguanosine (8-OHdG). Compared with children of the non-ER, the ER children had higher metal/metalloid (e.g., manganese [Mn], lead [Pb], antimony [Sb], tin [Sn], and copper [Cu]) and VOC exposure (e.g., carbon-disulfide, acrolein, and 1-bromopropane) levels, oxidative DNA damage, and non-carcinogenic risks. Individually added 8-OHdG, VOC metabolites, and metals/metalloids to the support vector machine (SVM) classifier could obtain similar classification effects, with the area under curve (AUC) ranging from 0.741 to 0.819. The combined inclusion of 8-OHdG and differential VOC metabolites, metals/metalloids, and mixed indexes (e.g., product items or ratios of different metals/metalloids) in the SVM classifier showed the highest performance in predicting e-waste recycling activity, with an AUC of 0.914 and prediction accuracy of 83.3 %. "Sb × Mn", followed by "Sn × Pb/Cu", "Sb × Mn/Cu", and "Sn × Pb", were the top four important features in the models. Compared with non-ER children, the levels of urinary Mn, Pb, Sb, Sn, and Cu in ER children were 1.2 to 2.4 times higher, while the levels of "Sb × Mn", "Sn × Pb/Cu", "Sb × Mn/Cu", and "Sn × Pb" were 3.5 to 4.7 times higher, suggesting that these mixed indexes could amplify the differences between e-waste exposed and non-e-waste exposed populations. With the continued inclusion of new biomarkers of e-waste pollution in the future, our prediction model is promising for screening informal e-waste recycling sites.

[Heavy Metal Pollution Characteristics and Risk Assessment of Golden Snub-nosed Monkey (Rhinopithecus roxellana) Habitat in Shennongjia Mountains].

The golden snub-nosed monkey is one of the most endangered animal species endemic to China. In order to explore the characteristics and health risks of golden snub-nosed monkeys exposed to heavy metals, we collected the plant food sources, soil, and water samples from the golden snub-nosed monkey habitat in the Shennongjia Mountains; examined the contents of seven heavy metals (Cu, Zn, Pb, Cd, Cr, Ni, and As); and adopted the comprehensive pollution index, potential ecological risk index, and Nemerow index to evaluate pollutants in the water, soil, and food plants. At the same time, the Target Hazard Quotient method was used to assess heavy metals in the food plants. The results showed that the heavy metal concentration of the habitat water was 0.004-1.220 µg·L-1. The water comprehensive pollution index showed that the habitat water was safe. In addition, the ω(Cd)(0.162-0.822 mg·kg-1) in the soil was 2.71 times the background value of the soil in Hubei province, indicating a moderate risk of ecological harm. The over-standard rates of Pb, Cd, Cr, and Ni in food plants were 29%, 29%, 18%, and 35%, respectively; the pollution indexes of lichen and bark were 6.038 and 7.709, which were at a heavy pollution level; and the pollution indexes of Abies fragesii and Vicia cracca were 2.716 and 2.034, which indicated a moderately polluted level. The rest of the plants were at a safe level. Our health risk analysis showed that the risk of lichen and bark were higher than that of leaves, followed by fruits. Among the seven metals, As most threatened the health of the golden snub-nosed monkeys (THQ>1). In general, heavy metals had polluted the habitats of the golden snub-nosed monkeys in the Shennongjia Mountains, and we are certain that the heavy metal pollution was associated with human activities. Thus, human activities in the Shennongjia Mountains should be reasonably restricted in the future. Our results can provide scientific support for the population conservation of golden snub-nosed monkeys in China and provide research samples in the health risk valuation of heavy metals in endangered animals through food plants.

Lichen as a Biomonitor for Vehicular Emission of Metals: A Risk Assessment of Lichen Consumption by the Sichuan Snub-Nosed Monkey (Rhinopithecus roxellana).

Two lichen species, Usnea aciculifera and Usnea luridorufa, were used as biomonitors for the deposition of traffic-related metals in China's Shennongjia National Nature Reserve. The suitability of the two lichen species for use as biomonitors was compared. The health threat to the Sichuan snub-nosed (aka golden) monkey (Rhinopithecus roxellana) from consuming lichen with elevated metal concentrations due to vehicular traffic was then assessed. Lichens, with large surface areas and neither roots nor stomata, efficiently absorb both particulate and gaseous air pollutants. The resulting data was used to assess the effect of heavy metal accumulation on the lichens as well as the health risk imposed on the monkeys as lichen is a primary food source. Lichen samples were collected in the core area of the reserve at three locations of varying traffic intensity. A forth site in the reserve, with no proximate traffic, was used as the control. Results show: (1) lichen from high traffic sites has significantly higher concentrations of Fe, Cd, Pb Zn, and Cr than lichen collected from the control site; (2) vehicular traffic is the primary source of metals in lichen; (3) U. luridorufa collected at high traffic sites displayed decreased photosynthetic efficiency, an indication of stress; (4) intake of Cd and Pb from vehicle emissions in the Shennongjia National Nature Reserve could adversely affect snub-nosed monkey health. This research advances the science of biomonitoring, contributes to environmental protection efforts in China's nature reserves and helps improve food safety for Sichuan snub-nosed monkey, a national treasure of China.

Effect of starter culture on microbiological, physiochemical and nutrition quality of Xiangxi sausage.

Fermented sausages have a long tradition originating from China. In this study, three starter microorganisms including Pediococcus pentosaceus (P), Staphylococcus xylosus (S), and a combination of P. pentosaceus and S. xylosus (P + S) were conducted for the manufacture of traditional Xiangxi (a city in China) fermented sausages. The physicochemical changes of the above three kinds of sausages during fermentation were studied and discussed, and also compared with these properties on the natural fermented sausage (N, i.e., control). The results revealed that five kinds of bacterial phases were existed at different fermentation stages in N, P, S and P + S fermented sausages, respectively. The microbiological data showed that an initial enterobacteria count of approximately 5.3 log CFU/g for all four batches of sausages. The enterobacteria count in the inoculated sausages of P and P + S groups decreased significantly to about 1 log CFU/g whereas group N and S had a count of about 3.3 log CFU/g after fermentation. In the early stages of fermentation, the pH rapidly decreased below 5.3. FAA and FFA were significantly increased in all groups and TBARS value in group P was higher than that of the other three groups. In conclusion, starter cultures can be used to improve the hygiene level of Xiangxi sausages without significant effects on pH, AW, and nitrite residue.

Thalli Growth, Propagule Survival, and Integrated Physiological Response to Nitrogen Stress of Ramalina calicaris var. japonica in Shennongjia Mountain (China).

In this study, effects of nitrogen (N) availability on growth, survival of Ramalina calicaris var. japonica, and whether it respond nitrogen stress in an integrated physiological way was evaluated. Thalli growth and propagule survival, thalli N and phosphorus (P) content, and activity of phosphomonoesterase (PME) of R. calicaris var. japonica were determined in a field experiment. Its differentiate adsorption in ammonia and nitrate, the activity of glutamine synthetase (GSA) and nitrate reductase (NRA) also were investigated in a series of indoor experiments. The results showed that N deposition significantly decreased the growth and survival of this lichen, and the N sensitivity threshold was suggested at 6.0 kg N⋅ha-1⋅y-1. When the N deposition increased from 8.59 kg N⋅ha-1⋅y-1 to 14.24, 20.49, 32.99 and 57.99 kg N⋅ha-1⋅y-1, the growth rates of lichen thalli decreased by 26.47, 39.01, 52.18 and 60.3%, respectively; Whereas the survival rate of the lichen propagules decreased from 92.8% of control (0.0 kg N⋅ha-1⋅y-1) to 10.7% of 50.0 kg N⋅ha-1⋅y-1, when they were treated with 0.00, 6.25, 12.5, 25.0, and 50.0 kg N⋅ha-1⋅y-1 deposition. Compared with an adequate adsorption of ammonium N, no nitrate adsorption occurred when thalli was submerged in solution lower than 0.4 mM. Our results also suggested that thalli total nitrogen, N:P ratio increased with N availability, and the activity of PME was significantly correlated with thalli total nitrogen. These all indicated that phosphorus limitation occurred when R. calicaris var. japonica treated with higher nitrogen deposition. Compared with slightly effects of NRA, GSA of R. calicaris var. japonica responded nitrogen availability significantly; In addition, GSA and NRA negatively correlated with thalli growth rate and propagule survival significantly. These results indicated that nitrogen stress do decrease growth and survival of R. calicaris var. japonica, and lichen would be impacted by excess nitrogen in a integrated, not a fragmentary way, including nitrogen uptake, assimilation, even nutrient balance of nitrogen and phosphorous.

[Soil heterotrophic respiration and its sensitivity to soil temperature and moisture in Liquidambar formosana and Pinus massoniana forests in hilly areas of southeast Hubei Province, China].

Field monitoring was conducted to study the annual dynamics of soil heterotrophic respiration and soil temperature and moisture in Liquidambar formosana and Pinus massoniana forests in hilly areas of southeast Hubei Province, China. At the same time, laboratory experiment was performed to study the heterotrophic respiration rate along soil profile, and the sensitivity of surface soil (0-5 cm) heterotrophic respiration to soil temperature and moisture. Then, a model was established to valuate the potential effects of warming change on the soil heterotrophic respiration in study area. In L. formosana and P. massoniana forests, the soil heterotrophic respiration rate in 0-5 cm layer was 2.39 and 2.62 times, and 2.01 and 2.94 times of that in 5-10 cm and 10-20 cm layers, respectively, illustrating that soil heterotrophic respiration mainly occurred in 0-5 cm surface layer. The temperature sensitivity factor (Q10) of soil heterotrophic respiration in 0-5 cm, 5-10 cm, and 10-20 cm layers was 2.10, 1.86, and 1.78 in L. formosana forest, and 1.86, 1.77, and 1.44 in P. massoniana forest, respectively. The relationship between surface soil heterotrophic respiration and temperature (T) well fitted exponential function R = alphaexp (beta3T), and that between surface soil heterotrophic respiration and moisture (W) well fitted quadratic function R = a+bW+cW2. Therefore, the relationship of surface soil heterotrophic respiration with soil temperature and moisture could be described by the model lnR = a+bW+cW2 +dT+eT2, which suggested that the response of soil heterotrophic respiration to soil moisture was depended on soil temperature, i.e., the sensitivity decreased with decreasing soil temperature. The calculation of the annual soil heterotrophic respiration rate in the two forests with the established model showed that the calculated respiration rate was a slightly higher in L. formosana forest but close to the measured one in P. massoniana forest, illustrating the applied importance of the model. Our results suggested that the soil heterotrophic respiration in the L. formosana and P. massoniana forests in hilly areas of southeast Hubei Province would have an obvious increase under the background of global warming.

[Effects of eutrophic nitrogen nutrition on carbon balance capacity of Liquidambar formosana seedlings under low light].

To investigate the effects of atmospheric nitrogen deposition on the seedlings regeneration of Liquidambar formosana, a greenhouse experiment was conducted, in which, the low light- and nitrogen supplies were controlled similar to those in typical L. formosana secondary forests, with the effects of different light- and nitrogen supply on the L. formosana seedlings survival, leaf functional traits, biomass allocation, and gas exchange studied. The whole plant light compensation point (LCP(whoIe-plant)) of the seedlings was estimated with a whole plant carbon balance model, and then compared with the understory photosynthetic active radiance (PAR) of the typical secondary forests. Under 3.0% and 6.0% of full sunlight, eutrophic nitrogen supply led to a decrease of seedlings survival (shade tolerance) and specific leaf area (SLA), but had no obvious effects on the seedlings biomass allocation. At eutrophic nitrogen supply, light intensity had significant effects on the leaf area based maximum assimilation rate, whereas increasing nitrogen supply under low light induced the increase of leaf mass based dark respiration rate. Both light intensity and nitrogen supply had significant effects on the mass based leaf respiration rate, and the interaction of light and nitrogen had significant effects on the mass based stem respiration rate. Increasing nitrogen supply increased the LCP(wholeplant), under 3.0%, 6.0%, and 12.0% of full sunlight, but decreased the LCP(whoIe-plant) under 25.0% of full sunlight. The decrease of the seedlings shade tolerance induced by the increasing nitrogen supply under low light was correlated with the variations of the seedlings carbon balance capacity. Under the background of elevated atmospheric nitrogen deposition, the maintenance of L. formosana populations in China would more depend on disturbances and gap regeneration, and the population dynamics would be deeply affected.

[Effects of waterlogging on ecophysiological characteristics of Salix variegate seedlings].

Salix variegate, a widely distributed species along the riverbank in Three Gorges Reservoir area, plays an important role in soil conservation and riverbank stabilization. Waterlogging from April to May was simulated in 2006 to test the adapting ability and mechanism of S. variegate seedlings to water environment change resulted from the construction of Three Gorges Project. The results showed that under waterlogging, all of the S. variegate seedlings could survive, but their maximum photosynthesis (Pmax), transpiration rate (Tr), water use efficiency (WUE), and stomatal conductance (Gs) decreased significantly with the prolongation of waterlogging. In the early period of waterlogging (20 days), these indices changed little, with the Pmax and Tr decreased by 18.5% and 2.2%, respectively, compared with the control. After 30 days, Pmax and Tr decreased by 53.4% and 23.7%, respectively, and then, kept stable. The contents of chlorophyll and carotenoid and their ratio decreased significantly with the prolongation of waterlogging, while the ratio of chlorophyll a to b increased significantly. The ratio of chlorophyll to carotenoid ranged in 4.873-6.883, and that of chlorophyll a to b ranged in 2.855-3.912. Adventitious roots were developed after waterlogging, which would benefit the oxygen supply for the plants. It was suggested that S. variegate had good adaptability to waterlogging, and could be used as a pioneer species in the restoration of degraded water-level fluctuation zone.