外文翻譯---- 砷在環(huán)境中的生化特性

1、 1外文文獻： 外文文獻： Arsenic in the environment: Biology and ChemistryAbstract：Arsenic (As) distribution and toxicology in the environment is a serious issue, with millions of individuals worldwide being affected by As tox

2、icosis. Sources of As contamination are both natural and anthropogenic and the scale of contamination ranges from local to regional.There are many areas of research that are being actively pursued to address the As conta

3、mination problem. These include new methods of screening for As in the field, determining the epidemiology of As in humans, and identifying the risk of As uptake in agriculture.Remediation of As-affected water supplies i

4、s important and research includes assessing natural remediation potential as well as phytoremediation. Another area of active research is on the microbially mediated biogeochemical interactions of As in the environment.I

5、n 2005, a conference was convened to bring together scientists involved in many of the different areas of As research. In this paper, we present a synthesis of the As issues in the light of long-standing research and wit

6、h regards to the new findings presented at this conference. This contribution provides a backdrop to the issues raised at the conference together with an overview of contemporary and historical issues of As contamination

7、 and health impacts.Crown Copyright . 2007 Published by Elsevier B.V. All rights reserved.1. Introduction1.1. Location and scale of problemArsenic (As) has been detected in groundwater in several countries of the world,

8、with concentration levels exceeding the WHO drinking water guideline value of 10 μg/L (WHO, 2001) as well as the national regulatory standards (e.g. 50 μg/L in India and Bangladesh, Ahmedet al., 2004; Mukherjee et al., 2

9、006). Arsenic in groundwater is often associated with geologic sources, but in some locations anthropogenic inputs can be extremely important. Ingestion of geogenic As from groundwater sources is manifested as chronic he

10、alth disorders in most of the affected regions of the world (BGS Bhattacharya et al.,2002a,b; Smedley and Kinniburgh, 2002; Welch and 3raising community awareness about the health problems related to chronic As exposure

11、 from drinking water. An overall risk assessment including a component of mitigation for As contamination should be based on accurate determination of As levels in TW water using economically viable methods for As screen

12、ing. Field test kits offer a more practical tool than laboratory measurements within the time frame and financial resources available for screening and assessment of the As-contaminated wells as well as their monitoring.

13、 Simple, low-cost methods for As determination, such as the field test kits have proved to be most suitable for performing the TW screening quickly. Several commercial field test kits are available for determination of A

14、s in TW water (Rahman et al., 2002; Khandaker, 2004; Deshpande and Pande, 2005; van Geen et al., 2005; Steinmaus et al., 2006). Field kits provide semiquantitative results and the reliability of several field kits are qu

15、estioned because of poor accuracy (Rahman et al., 2002). Thus, there is a need for further evaluation of the screening results by the field kit, prior to its recommendation for wide scale use in Bangladesh and elsewhere

16、in the world.1.3. EpidemiologyIngestion of groundwater with elevated As concentrations and the associated human health effects are prevalent in several regions across the world. Arsenic toxicity and chronic arsenicosis i

17、s of an alarming magnitude particularly in South Asia and is a major environmental health disaster (Chakraborti et al., 2004;Kapaj et al., 2006). Arsenic is perhaps the only human carcinogen for which there is adequate e

18、vidence ofcarcinogenic risk by both inhalation and ingestion (Centeno et al., 2002; Chen and Ahsan, 2004). Most ofthe ingested As is rapidly excreted via the kidney within a few days (Tam et al., 1979; Buchet et al., 198

19、1; Vahter, 1994). However, high levels of As are retained for longer periods of time in the bone, skin, hair, and nails of exposed humans (Karagas et al., 2000; Mandal et al., 2003). Studies of As speciation in the urine

20、 of exposed humans indicate that the metabolites comprise 10–15% inorganic As (iAs) and monomethylarsonic acid (MMAV) and a major proportion (60–80%) of dimethylarsenic acid (DMAV) (Tam et al., 1979; Vahter et al., 1995;

21、 Hopenhayn-Rich et al., 1996). Recent studies have found monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII) in trace quantities in human urine (Aposhian et al., 2000; Del Razo et al., 2001; Mandal et al.