Science of the Total Environment 481 (2014) 274–279

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Amines and amine-related compounds in surface waters: A review of sources, concentrations and aquatic toxicity Amanda E. Poste ⁎, Merete Grung, Richard F. Wright Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, 0349 Oslo, Norway

H I G H L I G H T S • • • • •

We review amine concentrations in surface waters and their potential sources. Amine concentrations were often below detection and rarely exceeded 10 μg/L. Available information does not suggest amines toxicity risk in surface waters. Use of amine-based carbon capture technologies may increase amine emissions. This may be of concern, since amines can form toxic nitrosamines and nitramines.

a r t i c l e

i n f o

Article history: Received 19 December 2013 Received in revised form 16 February 2014 Accepted 16 February 2014 Available online 4 March 2014 Keywords: Amines CO2 capture Surface waters Nitrosamines Nitramines Toxicity

a b s t r a c t This review compiles available information on the concentrations, sources, fate and toxicity of amines and aminerelated compounds in surface waters, including rivers, lakes, reservoirs, wetlands and seawater. There is a strong need for this information, especially given the emergence of amine-based post-combustion CO2 capture technologies, which may represent a new and significant source of amines to the environment. We identify a broad range of anthropogenic and natural sources of amines, nitrosamines and nitramines to the aquatic environment, and identify some key fate and degradation pathways of these compounds. There were very few data available on amines in surface waters, with reported concentrations often below detection and only rarely exceeding 10 μg/L. Reported concentrations for seawater and reservoirs were below detection or very low, while for lakes and rivers, concentrations spanned several orders of magnitude. The most prevalent and commonly detected amines were methylamine (MA), dimethylamine (DMA), ethylamine (EA), diethylamine (DEA) and monoethanolamine (MEAT). The paucity of data may reflect the analytical challenges posed by determination of amines in complex environmental matrices at ambient levels. We provide an overview of available aquatic toxicological data for amines and conclude that at current environmental concentrations, amines are not likely to be of toxicological concern to the aquatic environment, however, the potential for amines to act as precursors in the formation of nitrosamines and nitramines may represent a risk of contamination of drinking water supplies by these often carcinogenic compounds. More research on the prevalence and toxicity of amines, nitrosamines and nitramines in natural waters is necessary before the environmental impact of new point sources from carbon capture facilities can be adequately quantified. © 2014 Elsevier B.V. All rights reserved.

1. Introduction 1.1. Background on amines

Abbreviations: AMP–2, amino-2-methylpropoanol; CL-20, 2,4,6,8,10,12-hexanitro2,4,6,8,10,12-hexaazaisowurtzitane; DEA, diethylamine; DMA, dimethylamine; EA, ethylamine; MA, methylamine; MDEA, methyldiethanolamine; MEA, monoethanolamine; Mor, morpholine; NDMA, N-nitrosodimethylamine; PCC, post-combustion capture; PIP, piperazine. ⁎ Corresponding author. Tel.: +47 982 15 479; fax: +47 22 18 52 00. E-mail address: [email protected] (A.E. Poste).

http://dx.doi.org/10.1016/j.scitotenv.2014.02.066 0048-9697/© 2014 Elsevier B.V. All rights reserved.

Amines are organic compounds containing a basic N atom with a lone pair of electrons (Fig. 1a; McMurry, 1992). They are closely related to ammonia, but differ in that one or more of the H atoms is substituted with an alkyl or aryl group. The number of substituents bonded to the N atom in place of H determines whether the compound is a primary, secondary or tertiary amine. Quaternary ammonium cations are positively charged ions with a structure of NR+ 4 , and are permanently charged and therefore occur as salts. There are hundreds of important amine

A.E. Poste et al. / Science of the Total Environment 481 (2014) 274–279

a)

b)

275

c)

Fig. 1. Generalized chemical structure for a. amines (a generalized primary amine is shown), b. nitrosamines, and c. nitramines.

compounds, including both biogenic amines as well as synthesized compounds with diverse industrial, pharmaceutical and commercial applications. The broad range of anthropogenic uses of amines and amine-related compounds and the associated risk for release of these compounds to the aquatic environment make it particularly important to understand the concentrations, sources and processes related to amines in aquatic systems. In particular, secondary and tertiary amines, as well as quaternary amine salts, can act as precursors for the formation of several potentially toxic compounds, including nitrosamines (or N-nitrosamines; Fig. 1b) and nitramines (or N-nitramines; Fig. 1c) (Ma et al., 2012). 1.2. CO2 capture context Technologies designed to capture and store CO2 from combustion flue gasses (post combustion capture: PCC) are increasingly being considered for use in reducing CO2 emissions, particularly at sites where electricity is being produced using fossil fuels. Aqueous amines are the most common solvents for PCC and have long been used as solvents in CO2 removal (“sweetening”) processes for natural gas (Reynolds et al., 2012). PCC activities result in loss of amines from the absorber column, and represent a potential source of amines and amine degradation products (including nitrosamines and nitramines) to the environment (Nielsen et al., 2012; Reynolds et al., 2012). These can potentially have toxic effects on aquatic ecosystems (Brooks and Wright, 2008; Veltman et al., 2010) and could pose a risk for drinking water supplies (Richardson et al., 2007). Monoethanolamine (MEA, a primary amine) is the most commonly used solvent in these processes, however, there are many other amines that are used (or that have been suggested for use) in CO2 capture, including secondary and tertiary amines (Reynolds et al., 2012). The amines chosen for PCC activities will have important implications with respect to the potential for production of toxic nitrosamines and nitramines both in the capture facility and in the atmosphere (Nielsen et al., 2011, 2012). Nitrosamines are mostly derived from secondary and tertiary amines, since nitrosamines formed from primary amines rapidly isomerize and react with O2 to form imines (Nielsen et al., 2012). 2. Sources and sinks of amines and amine-related compounds 2.1. Sources of amines to the aquatic environment Amines are widespread in the environment and have many natural as well as industrial sources. Biogenic amines can be formed through decarboxylation of amino acids (often through microbial processes), or by amination of ketones and aldehydes (Santos, 1996). The strong tastes and smells associated with certain plants or with decomposing organisms are often attributable to amines. In fungi and flowers, volatile amines are often used to attract insects or other species (Smith, 1970); while the smell given off by decaying fish is due to the release of trimethylamine due to the breakdown of amino acids in the protein rich tissue. In the freshwater environment, 1,4-diaminobutane (putrescine) and phenethylamine can occur in phytoplankton (Kanazawa et al., 1966; Steiner and Hartmann, 1968). There are also several natural amines with important biological functions, including many

neurotransmitters (such as epinephrine, norepinephrine, dopamine, serotonin and histamine). Many aquatic organisms are capable of producing and releasing amines (both primary amines as well as more complex compounds) to the water. Studies in marine systems have indicated that aliphatic amines (such as methylamine (MA), dimethylamine (DMA) and diethylamine (DEA)) often originate from biological sources (Facchini et al., 2008; Müller et al., 2009). These compounds can play an important role in the carbon and nitrogen cycles of remote marine environments (Wheeler and Hellebust, 1981; Facchini et al., 2008; Müller et al., 2009). Many precursors to amines are released by aquatic organisms while alive, or during decomposition (Wang and Lee, 1994). For example, MEA is an important degradation product of a phospholipid found in mammalian and bacterial cell membranes (Garsin, 2010), and several amines can be formed through the decarboxylation of amino acids. These processes are likely to represent an important in situ source of amines to aquatic ecosystems. Amines and amine precursors are an important component of soil organic nitrogen (Schulten and Schnitzer, 1998; Yu et al., 2002), and can be delivered from terrestrial catchment to aquatic systems. Substantial photochemical formation of primary amines from terrestriallyderived humic matter occurs in coastal waters (Bushaw-Newton and Moran, 1999). In a recent survey of amine concentrations in 21 Norwegian lakes, elevated concentrations of several amines were found in lakes with high total organic carbon concentrations, suggesting a possible link between delivery of dissolved organic matter to these lakes and eventual amine concentrations (Poste et al., in preparation). Other potential natural sources of amines (and amine precursors) to freshwaters include sea birds and other migratory wildlife. These organisms could deliver amine and amine-related compounds to aquatic ecosystems through their feces and urine both directly to the water and indirectly through the catchment. Furthermore, these organisms may be sources of both nitrates and nitrites, which may be of importance with respect to nitrosamine and nitramine formation. Secondary (and tertiary) amines can be formed through the degradation of proteins and N-containing compounds in domestic wastewater (Ma et al., 2012). Secondary amines are also used in large quantities as intermediates in chemical, pesticide and pharmaceutical synthesis (Sacher et al., 1997; Ma et al., 2012). Post-combustion CO2 capture activities may become a significant industrial source of amines to the environment, due to the losses of solvent amines (such as MEA) through evaporation and entrainment from the CO2 absorber column (Reynolds et al., 2012). CO2 removal from natural gas can also results in the release of amines to the environment (Karadas et al., 2010). In addition to being present in several environmental media, both primary and secondary amines are also common in many natural and processed animal and plant-based food items such as vegetables, preserves, cheeses, fish and meats (Neurath et al., 1977; Köse, 2010). 2.2. Sources of amine-related compounds to the aquatic environment 2.2.1. Nitrosamines Nitrosamines (or N-nitrosamines) are formed through the nitrosation of secondary and higher degree amines and have a basic structure of R1R2N-NO (Landsman et al., 2007; Fig. 1b). Nitrosamines are often

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present in industrial and domestic discharges and can be formed in several industrial processes, including rubber manufacture, leather tanning, metal casting and food processing (Landsman et al., 2007; Ma et al., 2012). Urine also appears to be an important source of nitrosamines, and high concentrations have been observed in sewage (Ma et al., 2012). Nitrosamines can also be formed during amine-based CO2 capture processes in the stack or subsequently in the atmosphere (Nielsen et al., 2012; Reynolds et al., 2012). Many pharmaceuticals (for both human and livestock) and pesticides are secondary or tertiary amines (Le Roux et al., 2011), and these compounds may act as precursors for nitrosamine formation in the environment and in water treatment processes. In particular, amine-based herbicides, which are often applied along with nitrogen fertilizers, may be particularly vulnerable to nitrosation (Wolfe et al., 1976). Nitrosamines can also be present as impurities in nitrogenous pesticides (Fishbein, 1978). A great deal of research has been carried out on the inadvertent formation of nitrosamines during wastewater treatment and drinking water disinfection processes (particularly chloramination; Nawrocki and Andrzejewski, 2011). Several nitrosamines are formed in these water treatment processes, including N-nitrosodimethylamine (NDMA), which is the most extensively studied nitrosamine in freshwater. Little is known about the specific precursors in water that are particularly relevant for the formation of nitrosamines, but it has been suggested that the high concentrations of NDMA in waters influenced by municipal wastewaters may be due to the prevalence of quaternary amine salts in consumer products such as shampoos, detergents and fabric softeners (Kemper et al., 2010). In general, the disinfection byproducts formed are dependent on the amine precursors that are present, with primary amines tending to act as precursors for halonitriles, haloamides and halonitroalkanes and secondary amines, tertiary amines and quaternary amine salts acting as important precursors of nitrosamines (Shah and Mitch, 2012). Although quaternary amine salts are not particularly reactive with oxidants, high loading of these compounds may result to substantial nitrosamine formation, even where nitrosamine yields are low (Shah and Mitch, 2012). Organic nitrogen compounds associated with human waste, as well as bacterial and algal exudates, may be a source of precursors for compounds such as nitrosamines, especially in waters impacted by wastewater inputs and/or high phytoplankton biomass (Shah and Mitch, 2012). High concentrations of nitrosamines can occur in chlorinated swimming pools and hot tubs (Walse and Mitch, 2008) and are present in metal working fluids (Fadlallah et al., 1997). There may also be an environmental health risk associated with the presence of tobaccospecific nitrosamines in surface waters (Andra and Makris, 2011). These compounds are excreted in the urine of tobacco consumers, and seem to be excreted at higher rates by people that use smokeless tobacco products, such as snus (which is commonly used in Scandinavia) (Andra and Makris, 2011). Given that wastewater treatment and drinking water treatment efficiencies for these tobacco specific nitrosamines are unknown, there is concern that this may represent a source of nitrosamine exposure for humans (Andra and Makris, 2011). Although primary amines used in CO2 capture do not give rise to nitrosamines, there are often secondary and tertiary amines present as impurities in primary amine solvents, which can form nitrosamines in the presence of nitrosating agents (Reynolds et al., 2012).

2.2.2. Nitramines In the atmosphere, secondary or tertiary amines can react with hydroxyl radicals to form N-based radicals which in turn react with NO2 to form nitramines. Nitramines tend to be more stable than their corresponding nitrosamines (Låg et al., 2011). Nitramine formation depends strongly on both types of amines present as well as environmental conditions (e.g. temperature and pH), and requires a higher

activation energy than the corresponding nitrosamine formation reaction (Cooney et al., 1987). The primary direct anthropogenic source of nitramines to the environment is weapons manufacturing activities, as many military (and other) explosives contain nitramines (Douglas et al., 2009). Military sites and ammunition factories may be heavily contaminated with nitramines (Levsen et al., 1993; Douglas et al., 2009). As for nitrosamines, nitramines can be formed during amine-based CO2 capture, particularly where secondary amines (such as piperazine) are being used as solvents, or where secondary or tertiary amines are present as impurities in primary amine solvents (Reynolds et al., 2012). 2.3. Fate and degradation in the aquatic environment Low molecular weight amines are typically water soluble, but solubility decreases as the hydrocarbon chains in the substituents lengthen. Given the hydrophilicity of most amines, they may be expected to remain in solution rather than partitioning into other phases (including sediments or animal tissues). Although some primary amines, such as methylamine, can be taken up by phytoplankton in the absence of NH+ 4 (Balch, 1985), and may play a role in eukaryotic osmosis; for example, methylamines are used in marine cartilaginous fishes as osmolytic solutes (Hazon et al., 2003). MEA can be taken up by both bacteria and some phytoplankton (Choi et al., 2012; Garsin, 2010), with enhancement of cell growth observed in the green alga Scenedesmus sp. at MEA concentrations up to 300 mg/L. Like amines, both nitrosamines and nitramines are hydrophilic and are likely to stay in solution rather than partitioning into the sediment or biotic phase. Photolysis is a particularly important pathway for the degradation of nitrosamines (Lee et al., 2005), while microbial degradation appears to be an important loss pathway for many nitramines (Douglas et al., 2009; Schaefer et al., 2007). 3. Concentrations in surface waters 3.1. Reported concentrations There are few data available for amine concentrations in surface waters (summarized in Tables 1 and S1), and most of these data are for polluted rivers, making it difficult to assess the range of amine concentrations present in natural aquatic systems. Existing data include values from rivers in Germany (Neurath et al., 1977; Sacher et al., 1997), Turkey (Akyüz and Ata, 2006), Poland (Anrzejewski et al., 2011), Iran (Farajzadeh and Nouri, 2013), China (Wang et al., 2011; Ma et al., 2012) and USA (Chen and Valentine, 2007). Data are also available for reservoirs (Gerecke and Sedlak, 2003; Mitch et al., 2003), wetlands (Neurath et al., 1977), and seawater (Poste et al., in preparation; Akyüz and Ata, 2006). To our knowledge, with the exception of a heavily impacted urban lake in China (Cai et al., 2003; Fu et al., 2012) and two American lakes (Gerecke and Sedlak, 2003; Mitch et al., 2003), a recent survey of 21 Norwegian lakes (Poste et al., in preparation, Tables 1 and S1) represents the only data available for amine concentrations in lake water, and indeed the only data available that has been paired with information on the physical and chemical characteristics of sampled sites. Reported concentrations of amines in surface waters are often below detection and only rarely exceed 10 μg/L (Tables 1, S1). Reported amine concentrations for seawater (two samples only) were b1 μg/L. For rivers, lakes, reservoirs and wetlands observed concentrations spanned several orders of magnitude, with a large amount of intra-site variability in amine concentrations as well as the types of amines present. The highest concentrations encountered are generally at sites that are likely heavily influenced by human activity (e.g. 21–70 μg/L in East Lake, China; Cai et al., 2003). The amines that were most prevalent and commonly detected were MEA, DMA, EA, DEA, and MA, with concentrations ranging from below detection (generally b0.1 μg/L) to 70 μg/L

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Table 1 Concentrations of amines in surface waters. Concentrations are reported in μg/L and compounds are identified as follows: MEA: monoethanolamine, DMA: dimethylamine, EA: ethylamine, DEA: diethylamine, MA: methylamine, Mor: morpholine, and PIP: piperazine. Data for several additional amines (including piperidine, pyrrolidine, n-propylamine, n-butylamine, n-pentylamine, n-hexylamine, 2-amino-2-methyl propanol (AMP), methylethylamine, and diphenylamine) are found in Table S1. CAS numbers and chemical structures for these compounds are found in Table S2. Site type and location

MEA

Rivers Germany (n = 6) Germany (n = 2) Turkey (n = 1) United States (n = 1) Poland (n = 1) China (n = 12) China (n = 57) Iran (n = 1) Lakes China (n = 1) United States (n = 2) United States (n = 1) China (n = 1) Norway (n = 21)

DMA

EA

DEA

MA

0.1–11.9 ~2–3 0.008 0.5 5–6 b0.1–3.9 0.2–7.2

1–37.1 b0.1 0.002

0.5–9

1–20.6 ~1 0.0002

21 b0.18 b0.1 0.2–1.86

Reservoirs United States (n = 2) United States (n = 1)

0.18–3.22

b0.1–2.4 0.2–1.5 b0.6

b2.6

70

48

b0.09 b0.02

0.04–0.35

PIP

0.230

0.067

b0.1–0.1 0.1–2.5

b0.1–0.3

5.6 0.05–0.89

0.16–0.6

b0.18 b0.1

Wetlands Germany (n = 1) w Turkey (n = 1) Norway (n = 1)

0.060

Mor

0.013 0.92

Neurath et al., 1977 Sacher et al., 1997 Akyüz and Ata, 2006; a Chen and Valentine, 2007 Anrzejewski et al., 2011 Wang et al., 2011 Ma et al., 2012 Farajzadeh and Nouri, 2013

Cai et al., 2003 Gerecke and Sedlak, 2003 Mitch et al., 2003 Fu et al., 2012 Poste et al. in preparation

Gerecke and Sedlak, 2003 Mitch et al., 2003

0.6

0.6

Reference

0.002 b0.02

6.2

0.002 0.04

0.001 0.33

Neurath et al., 1977

0.016

0.007 0.38

Akyüz and Ata, 2006; a Poste et al. in preperation

a These values represent mean concentrations (calculated from two samples, one from summer and one from winter) determined using back extraction as described by Akyüz and Ata (2006).

depending on amine and site (Tables 1, S1). Amines with generally lower concentrations (b 0.1–9 μg/L) included morpholine, piperazine, piperidine, pyrrolidine, n-propylamine, n-butylamine and methylethylamine, again depending on amine and site. Concentrations of n-pentylamine, n-hexylamine, AMP and diphenylamine were always below detection. Data on nitrosamine and nitramine concentrations in surface waters are similarly limited. Nitrosamine concentrations (particularly NDMA) are more widely reported, given their strong carcinogenicity, and the known potential for nitrosamine formation during drinking water treatment processes. However, nitrosamine concentrations reported in the literature are primarily for finished drinking water and municipal wastewater effluent. Some studies report nitrosamine concentrations in raw water, but often do not specify the source of this water. Reported NDMA concentrations for surface waters include values for a Turkish lake and its tributaries (b 2–1648 ng/L; Aydin et al., 2012), for a Japanese river system with substantial industrial inputs (up to 2100 ng/L) as well as several other rivers in Japan (n.d. to 32 ng/L; Schreiber and Mitch, 2006; Asami et al., 2009), and for several Chinese rivers (up to 334.9 ng/L; Wang et al., 2011; Ma et al., 2012). Wang et al. (2011) measured nine different nitrosamines and report total concentrations ranging from non-detectable to 42.4 ng/L. Reported nitramine concentrations are mostly for industrial effluent and surface waters near ammunition factories and focus on concentrations of nitramine explosives such as TNT and RDX, with reported concentrations in surface waters ranging from 0.1 (Small and Rosenblatt, 1974) to 109 μg/L (Ryon et al., 1984). 3.2. Analytical approaches and challenges Several analytical approaches for the detection of amines are reported in the literature, and are predominantly based on chemical derivatization followed by extraction of derivatives and detection (e.g. Sacher et al., 1997; Cai et al., 2003; Chang et al., 2012; Fu et al., 2012). The diverse set of methods based on this generalized approach

use a variety of derivatizing reagents, as well as several different methods for extraction (e.g. chemical or solid phase extraction), separation (e.g. gas chromatography (GC), liquid chromatography (LC) or electrophoresis) and detection (e.g. mass spectrometry (MS), fluorescence or laser-induced fluorescence). The chemical analysis of amines in environmental samples poses unique challenges, including low environmental concentrations, high volatility, low molecular weight, high polarity, instability and lack of chromophores (Chang et al., 2012). These analytical challenges and the ongoing process of developing more sensitive and robust methods for amine detection are an important reason for the lack of data on amines in complex environmental matrices, including surface waters.

4. Aquatic toxicology of amines and amine-related compounds Existing toxicological data are limited, but seem to indicate that most amines are practically nontoxic to fish and invertebrates in acute tests (Brooks and Wright, 2008), although some amines show slight to moderate acute toxicity to phytoplankton and bacteria. In tests of acute toxicity of MEA to fish, zebra fish eggs (Danio danio) exhibited the most sensitive response, with a 96 h LC50 of 60.3 mg/L (Groth et al., 1993), while 96 h LC50 values for adult fish ranged from 167 to 338 mg/L (as reviewed by Brooks and Wright (2008)). For Daphnia magna (an aquatic invertebrate), acute toxicity tests revealed a 24 h LC50 of 83.6–16.5 mg/L (Bringmann and Kuhn, 1977) for MEA, while 48 h LC50s generally exceeded 100 mg/L for other amines (Brooks and Wright, 2008). For algae, LC50 concentrations for MEA ranged from 70 to 733 mg/L, while LC50 values for algae exposed to other amines for which acute toxicity data are available (AMP, MDEA, PIP) ranged from 119 to 472 mg/L. The aquatic bacterium Vibrio fischeri was found to be sensitive to acute exposure to amines for which data were available (MEA, AMP, MDEA, PIP), with LC50 values ranging from 6 mg/L (for MEA; Libralato et al., 2008) to 36 mg/L (for MDEA) (Brooks and Wright, 2008).

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Very few chronic exposure data are available for amines. However previous studies have reported lowest observable effect concentrations (LOECs) of 0.5 mg/L for methyldiethanolamine (DMEA) and 0.75 mg/L for MEA in tests of chronic exposure with fish (Bieniarz et al., 1996) and algae (Bringmann and Kuhn, 1978), respectively. Based on acute and chronic toxicity data, the concentrations of amines for which data are available where toxicological effects can be expected (e.g. LC50 and LOEC concentrations) are generally several orders of magnitude higher than the values reported for even the most polluted surface waters (Tables 1, S1). The few available toxicological data for nitrosamines and nitramines point to a higher toxicity to aquatic organisms of these compounds (Brooks and Wright, 2008). Moderate acute toxicity was observed for both fish and algae between 3.2 and 5.85 mg/L (Hovvater et al., 1997; US EPA, 1978 and Bentley et al., 1977). For nitrosamines the most toxic effect reported was a LOEC of 25 μg/L of N-nitrosodimethylamine (NDMA) for algae under chronic exposure (Bringmann and Kuhn, 1980). For nitramines the highest reported toxicity was 50% growth inhibition (growth IC50) concentration of 200 μg/L for the nitramine CL-20 for chronic exposure of fish (Haley et al., 2002). Despite this, the environmental risk is considered low since these concentrations are generally several orders of magnitude higher than those reported in surface waters. The foremost environmental concern associated with amine-based CO2 capture is the risk of contamination of drinking water supplies by nitrosamines and nitramines (Karl et al., 2011; Zhang et al., 2014). Approximately 90% of nitrosamines are believed to be carcinogenic (Nawrocki and Andrzejewski, 2011). Although some nitramines are known to be carcinogenic (Cooney et al., 1987), there are few data available regarding the toxicity (and carcinogenicity) of these compounds (Richardson et al., 2007; Låg et al., 2011). A review of the occurrence and carcinogenicity of nitrosamines and nitramines can be found in Richardson et al. (2007). Regulatory standards for NDMA in drinking water are based on an increase in risk for cancer of 10−6 and are 10 ng/L in California, USA (California Environmental Protection Agency, 2006), 9 ng/L in Ontario, Canada (Government of Ontario, 2002). The Norwegian Institute for Public Health has recommended a limit of 4 ng/L (sum of all nitrosamines and nitramines) for drinking water in Norway (Låg et al., 2011).

5. Final considerations Our review reveals very few data on the concentrations of amines in surface waters and on the toxicity of these compounds. In particular, there are apparently only a few measurements of amines in unpolluted rivers and lakes. This is surprising, given that amines are widely used in various industrial, pharmaceutical and chemical applications and present in wastewaters. The analytical difficulty of determining the concentrations of these compounds at ambient levels in the environment may explain the paucity of data. There is a remarkably broad and complex range of amine sources to the environment, including both natural and anthropogenic sources. Amines are discharged into both the atmosphere and recipient waters as a result of human activities, while both terrestrial and aquatic organisms can act as natural sources of amines to surface waters. Little is known about the spatial and temporal patterns of amine concentrations in surface waters, nor the factors that influence the prevalence of these compounds in surface waters; recent studies of Norwegian lakes provide the only comprehensive information available. Emission of amines to the atmosphere, transport and deposition (wet and dry) from future amine-based carbon capture facilities will represent a new external source of amines to surface waters. Natural sources will complicate the detection and quantification of the contribution of carbon capture sources to amine concentrations in surface waters.

The major risk of adverse environmental or health effects of amines in surface waters is not from the amines themselves, but rather due to the potential for aqueous phase formation of toxic compounds such as nitrosamines through reactions between precursor amines and oxidants such as nitrite (NO− 2 ). Of particular concern is drinking water source protection, as many of these compounds are carcinogenic at low concentrations. Carbon capture from existing large point sources is considered to be a promising approach for reducing global emissions of greenhouse gasses, and amine-based technology may be widely applied in the future. More information on the natural levels of amines in surface waters, spatial and temporal patterns, and the factors influencing the concentrations is needed, as is more information on aquatic toxicity and the formation of reaction products such as nitrosamines and nitramines in the natural environment. Such studies will be required before the full environmental impacts of amine-based carbon capture facilities can be quantified. Acknowledgments This work was supported through a grant to NIVA from the Norwegian Research Council's CLIMIT program and through funding from NIVA's strategic institute program. Appendix A. Supplementary data Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.scitotenv.2014.02.066. References Akyüz M, Ata S. Simultaneous determination of aliphatic and aromatic amines in water and sediment samples by ion-pair extraction and gas chromatography–mass spectrometry. J Chromatogr A 2006;1129:88–94. Andra SS, Makris KC. Tobacco-specific nitrosamines in water: an unexplored environmental health risk. Environ Int 2011;37:412–7. Anrzejewski P, Dabrowska A, Fijolek L, Szweda F. Dimethylamine as a precursor to N-nitrosodimethylamine and formaldehyde in water. Ochrona Srodowiska 2011;33:25–8. Asami M, Oya M, Kosaka K. A nationwide survey of NDMA in raw and drinking water in Japan. Sci Total Environ 2009;407:3540–5. Aydin E, Yaman FB, Ates Genceli E, Topuz E, Erdim E, Gurel M, et al. Occurrence of THM and NDMA precursors in a watershed: effect of seasons and anthropogenic pollution. J Hazard Mater 2012;221–222:86–91. Balch WM. Lack of an effect of light on methylamine uptake by phytoplankton. Limnol Oceanogr 1985;30:665–74. Bentley RE, LeBlank GA, Hollister TA, Sleight BH. Acute toxicity of 1,3,5,7-tetranitrooctahydro1,3,5,7-tetrazocine (HMX) to aquatic organisms. Defense technical information center OAI-PMH repository (US); 1977. Bieniarz K, Epler P, Kime D, Sokolowska-Mikolajczyk M, Popek W, Mikolajczyk T. Effects of N, N-dimethylnitrosamine (DMNA) on in vitro oocyte maturation and embryonic development of fertilized eggs of carp (Cyprinus carpio L.) kept in eutrophied ponds. J Appl Toxicol 1996;16:153–6. Bringmann G, Kuhn R. The effects of water pollutants on Daphnia magna. WasserAbwasser-Forsch 1977;10:161–6. Bringmann G, Kuhn R. Testing of substances for their toxicity threshold: model organisms Microcystis (Diplocystis) aeruginosa and Scenedesmus quadricauda. Mitt Int Ver Theor Angew Limnol 1978;21:275–84. Bringmann G, Kuhn R. Comparison of the toxicity thresholds of water pollutants to bacteria, algae, and protozoa in the cell multiplication inhibition test. Water Res 1980;14:231–41. Brooks S, Wright RF. The toxicity of selected amines and secondary products to aquatic organisms: a review. Norwegian institute for water research, report 5698; 2008. Bushaw-Newton KL, Moran MA. Photochemical formation of biologically available nitrogen from dissolved humic substances in coastal marine systems. Aquat Microb Ecol 1999;18:285–92. Cai L, Zhao Y, Gong S, Dong L, Wu C. Use of a novel sol–gel dibenzo-18-crown-6 solid-phase microextraction fiber and a new derivatizing reagent for determination of aliphatic amines in lake water and human urine. Chromatographia 2003;58: 615–21. California Environmental Protection Agency. Public health goal for N-nitrosodimethylamine in drinking water. California Environmental Protection AgencyCalifornia Environmental Protection Agency; 2006. Chang W-Y, Wang C-Y, Jan J-L, Lo Y-S, Wu C-H. Vortex-assisted liquid–liquid microextraction coupled with derivatization for the fluorometric determination of aliphatic amines. J Chromatogr A 2012;1248:41–7.

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