Arsenic speciation in polychaetes (Annelida) and sediments from the intertidal mudflat of Sundarban mangrove wetland, India

This paper documents the concentration of total arsenic and individual arsenic species in four soft-bottom benthic polychaetes (Perenereis cultifera, Ganganereis sootai, Lumbrinereis notocirrata and Dendronereis arborifera) along with host sediments from Sundarban mangrove wetland, India. An additional six sites were considered exclusively for surface sediments for this purpose. Polychaetes were collected along with the host sediments and measured for their total arsenic content using inductively coupled plasma mass spectrometry. Arsenic concentrations in polychaete body tissues varied greatly, suggesting species-specific characteristics and inherent peculiarities in arsenic metabolism. Arsenic was generally present in polychaetes as arsenate (As^V ranges from 0.16 to 0.50 mg kg^?1) or arsenite (As^III ranges from 0.10 to 0.41 mg kg^?1) (30–53 % as inorganic As) and dimethylarsinic acid (DMA^V <1–25 %). Arsenobetaine (AB < 16 %), and PO₄-arsenoriboside (8–48 %) were also detected as minor constituents, whilst monomethylarsonic acid (MA^V) was not detected in any of the polychaetes. The highest total As (14.7 mg kg^?1 dry wt) was observed in the polychaete D. arborifera collected from the vicinity of a sewage outfall in which the majority of As was present as an uncharacterised compound (10.3 mg kg^?1 dry wt) eluted prior to AB. Host sediments ranged from 2.5 to 10.4 mg kg^?1 of total As. This work supports the importance of speciation analysis of As, because of the ubiquitous occurrence of this metalloid in the environment, and its variable toxicity depending on chemical form. It is also the first work to report the composition of As species in polychaetes from the Indian Sundarban wetlands.     

Between economics and ecology: some historical and philosophical considerations for modelers of natural capital

Natural capital models attempt to remediate the relationship between economics and ecology either by conjoining models and theories from each discipline or by finding a type of phenomena that can be meaningfully measured by both fields. The developmentof a widely accepted model which integrates economics and ecologyhas eluded researchers since the early 1970s. This paper offers an historical and philosophical perspective on some of the conceptual problems or obstacles that hinder the development ofnatural capital models. In particular, the disciplinary assumptions of economic science and ecological science are examined and it is argued that these assumptions are antithetical. Hence, the development of an effective and acceptednatural capital model will require that economics and ecology reconsider their self-conceptions as sciences. For the purposesof theoretical research and practical policy, the paper cautionsagainst confusing the issue of whether or not economic models accord with ecological models with the issue of whether or not economic activities accord with ecological realities.     

大气汞均相和非均相化学反应过程研究进展

作为环境中汞传输的最重要通道,大气在汞的全球生物地球化学循环和传输扩散中起着极其关键的作用.大气环境成分复杂,汞在随大气环境传递过程中会经历复杂的化学反应,并导致不同形态之间相互转化,这也成为影响大气汞远距离传输尺度的关键因素.本文主要对大气汞在不同相界面之间的分配过程和主要影响因素(包括相界面的物理化学性质和外部环境条件等)进行了总结;对大气Hg0主要氧化反应过程(卤族元素氧化和O_3、OH·氧化)进行了阐述;对大气Hg~(2+)还原反应过程,尤其是光致还原反应等进行了梳理.如何综合运用野外监测分析和室内模拟等,利用微观分子表面分析等新技术明确大气汞均相、非均相反应过程,并将反应机理与大气汞传输过程模拟系统融合,将是未来大气汞研究的重要内容之一.     

Changes in weather and climate extremes: State of knowledge relevant to air and water quality in the United States

Air and water quality are impacted by extreme weather and climate events on time scales ranging from minutes to many months. This review paper discusses the state of knowledge of how and why extreme events are changing and are projected to change in the future. These events include heat waves, cold waves, floods, droughts, hurricanes, strong extratropical cyclones such as nor'easters, heavy rain, and major snowfalls. Some of these events, such as heat waves, are projected to increase, while others, with cold waves being a good example, will decrease in intensity in our warming world. Each extreme's impact on air or water quality can be complex and can even vary over the course of the event.

Implications:

Because extreme weather and climate events impact air and water quality, understanding how the various extremes are changing and are projected to change in the future has ramifications on air and water quality management.     

Modulatory effects of Punica granatum L juice against 2115 MHz (3G) radiation-induced reproductive toxicity in male Wistar rat

Environmental Science and Pollution Research - Advancements in telecommunication sector result in increasing exposure to electromagnetic (EM) radiation, which has been correlated with incidence of...     

Exceptionally high levels of multiple mating in an army ant

Most species of social insects have singly mated queens, although there are notable exceptions. Competing hypotheses have been proposed to explain the evolution of high levels of multiple mating, but this issue is far from resolved. Here we use microsatellites to investigate mating frequency in the army ant Eciton burchellii and show that queens mate with an exceptionally large number of males, eclipsing all but one other social insect species for which data are available. In addition we present evidence that suggests that mating is serial, continuing throughout the lifetime of the queen. This is the first demonstration of serial mating among social hymenoptera. We propose that high paternity within colonies is most likely to have evolved to increase genetic diversity and to counter high pathogen and parasite loads.     

Passive acoustic monitoring of the decline of Mexico's critically endangered vaquita

The vaquita (Phocoena sinus) is the world's most endangered marine mammal with approximately 245 individuals remaining in 2008. This species of porpoise is endemic to the northern Gulf of California, Mexico, and historically the population has declined because of unsustainable bycatch in gillnets. An illegal gillnet fishery for an endangered fish, the totoaba (Totoaba macdonaldi), has recently resurged throughout the vaquita's range. The secretive but lucrative wildlife trade with China for totoaba swim bladders has probably increased vaquita bycatch mortality by an unknown amount. Precise population monitoring by visual surveys is difficult because vaquitas are inherently hard to see and have now become so rare that sighting rates are very low. However, their echolocation clicks can be identified readily on specialized acoustic detectors. Acoustic detections on an array of 46 moored detectors indicated vaquita acoustic activity declined by 80% between 2011 and 2015 in the central part of the species’ range. Statistical models estimated an annual rate of decline of 34% (95% Bayesian credible interval –48% to –21%). Based on results from 2011 to 2014, the government of Mexico enacted and is enforcing an emergency 2‐year ban on gillnets throughout the species’ range to prevent extinction, at a cost of US$74 million to compensate fishers. Developing precise acoustic monitoring methods proved critical to exposing the severity of vaquitas’ decline and emphasizes the need for continual monitoring to effectively manage critically endangered species.     

Why is the coral-reef fish Valenciennea strigata (Gobiidae) monogamous?

Parental-investment theory predicts that monogamy should be rare, and empirical evidence supports this prediction. Monogamy has generally been explained by either (1) a need for biparental care, or (2) a uniform distribution of limiting resources. By contrast, monogamy has evolved in several coral-reef fishes without biparental care, and many coral-reef fishes may not be limited by resources. Monogamy in these fishes might be explained by either (3) a low population density that favors mate fidelity, or (4) an abundance of resources that allows all males to breed and thus lowers the cost-benefit ratio for females that mate guard. We tested predictions of these hypotheses in the coral-reef fish, Valenciennea strigata, except that (1) biparental care had previously been rejected. We found no evidence of resource limitation (2a): food densities within territories did not differ from the density of food in unused habitat adjacent to territories; potential nest sites also existed in this unused habitat. Similarly, (2b) if resources limit the population, territory defense might require the coordinated efforts of a pair; however, widowed fish maintained their territories and (3) remated rapidly. Finally, (4) all males maintained a nest, both sexes enforced monogamy by mate guarding, and females benefited from guarding a high-quality (large) mate. Females mated to large males fed more than when they paired with small males. The results support the hypothesis that abundant and uniformly distributed resources can lead to monogamy by lowering the cost of guarding a mate when mate guarding provides benefits. Received: 25 November 1997 / Accepted after revision: 29 December 1997