There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. 
The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. 
The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. 
The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

Influence of Diet On the Distribtion of Nitrogen Isotopes in Animals

The science of the total environment

A review of soil heavy metal pollution from mines in China: pollution and health risk assessment.

Health risks of heavy metals in contaminated soils and food crops irrigated with wastewater in Beijing, China

Rivers are major pathways for a variety of materials to flow in and out of reservoirs. Impounding rivers changes the characteristics of a water body from “rivers’’ to “reservoirs”, affecting not only their hydrology but also their physical, chemical, and biological characteristics. To understand the influence of damming on the distribution and methylation of Hg within a river-reservoir ecosystem, this chapter illustrates the spatial and temporal distributions of Hg species in the inflow–outflow rivers of the six cascade reservoirs in Wujiang River Basin, Southwest China. Furthermore, the influence of cascade reservoirs on the distributions of Hg species in rivers of Wujiang River Basin is elucidated as well.

Mercury in Inflow/Outflow Rivers of Reservoirs

Interaction of selenium and mercury in soil-plant system in mercury mining areas and their combined exposure and risk

Utilization of desulfurization gypsum potentially impairs the efforts for reducing Hg emissions from coal-fired power plants in China

Reservoirs play a complicated role in the transportation of mercury (Hg) the river reservoir ecosystems. Under different environmental conditions, reservoirs can be a sink for Hg to the outflow river, a source of Hg to the inflow river, or a place for Hg to transform from inorganic Hg (IHg) to methylmercury (MeHg). The different pathways for regulation and operation in the reservoir lead to distinct water exchange frequencies and residence times as well as distinct source-sink characteristics for the reservoir. In this chapter, we (1) estimated the input/output fluxes of Hg species (THg and MeHg) in a reservoir and (2) assessed the role of different reservoir stages on the source/sink of Hg in the transportation and transformation of Hg in a river reservoir ecosystem.

Mercury Mass Balance in Reservoirs with Different Ages

Emissions from coal-fired power plants (CFPPs) have a negative impact on the environment and metals are one of the categories of substances that have received considerable attention. In the present study, atmospheric zinc (Zn) emissions from eight CFPPs with different kinds of boilers and air pollution control devices (APCDs) in Guizhou Province, Southwest China, were investigated as well as the partitioning of this metal among boilers and APCDs. During the investigation of a CFPP, samples were taken of input and output materials during the same period. Our results give a Zn content of 32–165 mg kg−1 for feed coal, 52–237 mg kg−1 for bottom ash, 108–725 mg kg−1 for fly ash, 1.2–6.0 mg kg−1 for limestone, 1.6–7.3 mg kg−1 for gypsum, and 1.39–7.06 μg Nm−3 for stack gas. Most of the zinc content in the feed coal goes with the flue gas after combustion and amounts to 94.2–96.1% and 60.5–78.1% for pulverized coal-fired boilers (PC) and circulating fluidized bed boilers (CFB), respectively. Based on input Zn, a larger share (80.8–96.4%) ends up the captured fly ash of PC boilers than the case of CFB boilers (66.1–73.6%). In turn, a minor portion is captured into the flue gas desulfurization gypsum, while we found a maximum of 0.05‰ is emitted into the atmosphere. The atmospheric emission factors (EMFs) of Zn for the eight CFPPs are 7.55–57.22 mg ton−1 coal, 4.17–22.75 μg (kWh)−1, or 0.39–2.36 g TJ−1 using different benchmarks. Overall, the calculated emission factors here are distinctively low with the upgrading of APCDs in recent years. An estimation of 1276 ± 1047 kg year−1 (range: 498–3777 kg year−1) of Zn is emitted into the atmosphere from the CFPPs of Guizhou Province in 2017 by coupling the EMFs obtained from this study and the coal consumption by this category of power plants.

Xinbin Feng

Papers

Mercury in Inflow/Outflow Rivers of Reservoirs

Interaction of selenium and mercury in soil-plant system in mercury mining areas and their combined exposure and risk

Utilization of desulfurization gypsum potentially impairs the efforts for reducing Hg emissions from coal-fired power plants in China

Mercury Mass Balance in Reservoirs with Different Ages

Partitioning behaviors of zinc in eight coal-fired power plants with different fueled coals and air pollution control devices