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Conservation - Scientific Papers

Brazil Matias Offline
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Gaia 2.0
Timothy M. Lenton, Bruno Latour
Science  14 Sep 2018:
Vol. 361, Issue 6407, pp. 1066-1068
DOI: 10.1126/science.aau0427

According to Lovelock and Margulis's Gaia hypothesis, living things are part of a planetary-scale self-regulating system that has maintained habitable conditions for the past 3.5 billion years (1, 2). Gaia has operated without foresight or planning on the part of organisms, but the evolution of humans and their technology are changing that. Earth has now entered a new epoch called the Anthropocene (3), and humans are beginning to become aware of the global consequences of their actions. As a result, deliberate self-regulation—from personal action to global geoengineering schemes—is either happening or imminently possible. Making such conscious choices to operate within Gaia constitutes a fundamental new state of Gaia, which we call Gaia 2.0. By emphasizing the agency of life-forms and their ability to set goals, Gaia 2.0 may be an effective framework for fostering global sustainability...

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Production of methane and ethylene from plastic in the environment
  • Sarah-Jeanne Royer,
  • Sara Ferrón,
  • Samuel T. Wilson,
  • David M. Karl  

*This image is copyright of its original author
  • Published: August 1, 2018
Abstract

Mass production of plastics started nearly 70 years ago and the production rate is expected to double over the next two decades. While serving many applications because of their durability, stability and low cost, plastics have deleterious effects on the environment. Plastic is known to release a variety of chemicals during degradation, which has a negative impact on biota. Here, we show that the most commonly used plastics produce two greenhouse gases, methane and ethylene, when exposed to ambient solar radiation. Polyethylene, which is the most produced and discarded synthetic polymer globally, is the most prolific emitter of both gases. We demonstrate that the production of trace gases from virgin low-density polyethylene increase with time, with rates at the end of a 212-day incubation of 5.8 nmol g-1 d-1 of methane, 14.5 nmol g-1 d-1 of ethylene, 3.9 nmol g-1 d-1 of ethane and 9.7 nmol g-1 d-1 of propylene. Environmentally aged plastics incubated in water for at least 152 days also produced hydrocarbon gases. In addition, low-density polyethylene emits these gases when incubated in air at rates ~2 times and ~76 times higher than when incubated in water for methane and ethylene, respectively. Our results show that plastics represent a heretofore unrecognized source of climate-relevant trace gases that are expected to increase as more plastic is produced and accumulated in the environment.

Introduction
Over the past 50 years, polymer manufacturing has accelerated, from 2x106 metric tonnes (Mt) per year in 1950 to 381x106 Mt per year in 2015, and is expected to double in the next 20 years [1]. The total global production of plastics to date is estimated at 8300x106 Mt, with polyethylene being the most common polymer [2,3], accounting for approximately 36% of all plastic types [1]. In the environment, plastics are vulnerable to weathering and degradation processes, caused by environmental factors such as light, heat, moisture, chemical oxidation and biological activity that are responsible for physical and chemical changes in the structure of the polymer [4].

Polyethylene, like other plastics, is not inert and is known to release additives and other degradation products into the environment throughout its lifetime. For example, the additive bisphenol-A used in the manufacture of many plastic products [5] is leached as plastics age, and hydrocarbon gases are produced during high-temperature decomposition (>202°C) [6]. These chemicals vary amongst different types of plastic and, once released, some can be toxic and have adverse effects on the environment and human health [79]. Degradation processes not only affect the chemical integrity of the plastic but also ultimately results in the fragmentation of the polymer into smaller units increasing the surface area exposed to the elements.

Most plastic is synthesized from natural gases [10] and leaching is expected to occur during the aging processes. However, to the best of our knowledge, no previous study has reported hydrocarbon gas emissions from plastics under natural conditions. This study seeks to investigate this phenomenon and its potential environmental consequences.

Our research investigated the production of hydrocarbon gases from polyethylene and other plastics at ambient temperature, with an emphasis on methane (CH4), one of the most potent atmospheric greenhouse gases [1113] and ethylene (C2H4), which reacts with OH in the atmosphere and increases carbon monoxide concentrations [14,15]. Given the substantial rise in plastic production worldwide, understanding the extent of CH4 and C2H4 emissions from plastic is essential. In addition, we report production rates of ethane (C2H6), the second most abundant hydrocarbon in the atmosphere after CH4, known to enhance the level of tropospheric ozone and carbon monoxide [14,16], and propylene (C3H6), also a hydrocarbon pollutant in the atmosphere [17]. Since plastics come in different compositions and morphologies, we conducted a series of experiments to evaluate gas production under a variety of environmental conditions. We show that solar radiation initiates the production of these gases for the polymers tested.

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Anthropogenic contamination of tap water, beer, and sea salt
  • Mary Kosuth  ,
  • Sherri A. Mason ,
  • Elizabeth V. Wattenberg  

*This image is copyright of its original author
  • Published: April 11, 2018
Abstract

Plastic pollution has been well documented in natural environments, including the open waters and sediments within lakes and rivers, the open ocean and even the air, but less attention has been paid to synthetic polymers in human consumables. Since multiple toxicity studies indicate risks to human health when plastic particles are ingested, more needs to be known about the presence and abundance of anthropogenic particles in human foods and beverages. This study investigates the presence of anthropogenic particles in 159 samples of globally sourced tap water, 12 brands of Laurentian Great Lakes beer, and 12 brands of commercial sea salt. Of the tap water samples analyzed, 81% were found to contain anthropogenic particles. The majority of these particles were fibers (98.3%) between 0.1–5 mm in length. The range was 0 to 61 particles/L, with an overall mean of 5.45 particles/L. Anthropogenic debris was found in each brand of beer and salt. Of the extracted particles, over 99% were fibers. After adjusting for particles found in lab blanks for both salt and beer, the average number of particles found in beer was 4.05 particles/L with a range of 0 to 14.3 particles/L and the average number of particles found in each brand of salt was 212 particles/kg with a range of 46.7 to 806 particles/kg. Based on consumer guidelines, our results indicate the average person ingests over 5,800 particles of synthetic debris from these three sources annually, with the largest contribution coming from tap water (88%).

Introduction
The first peer-reviewed papers to document plastic pollution in the natural world were published over 45 years ago [1,2]. Since then, a robust body of work has accumulated, and the ubiquity of synthetic polymers in the environment is now undisputed. From abandoned gillnets hundreds of meters in length to plankton sized fragments, synthetic polymers have been extracted from remote corners of the Earth’s biosphere. Plastics have been quantified in marine environments [3] that include segments of the pelagic biome [4] coastal habitats [5], deep sea sediments [6, 7], as well as freshwater lakes [8,9] and associated tributaries [10]. Particles have also turned up in Arctic sea ice [11], ambient air [12], and a plethora of biota such as seabirds [13, 14], aquatic mammals [15], fish [16], and benthic invertebrates [17].

The last 45 years have also seen a commensurate increase in plastic production as the total global output of 30 million tons in 1970 climbed to 322 million tons in 2015 [18]. Hopes of closing the loop on the plastic waste stream depend on overall recycling rates, which vary widely across the globe, even among developed nations with well-established recycling infrastructure. Europe, for example, recycled 26% of disposable plastics in 2012, while the United States (US) reported rates as low as 8.8% in the same year [19].

The heterogeneous nature of microplastics make them a challenge to study. Although they are referred to in the literature as synthetic polymers derived from petrochemicals that are less than 5 mm in length, a universally accepted definition does not exist. Plastics in general represent a wide range of materials, each with unique physical characteristics and chemical compositions. Roughly 90% of plastic produced globally, however, falls into one of six categories: HDPE, LDPE, PP, PVC, PS, and PET [20].

Plastics are hydrophobic and have been known to adsorb chemicals from the environment such as PCBs, PBDEs, and PAHs [21], some of which are known reproductive toxicants and carcinogens [22, 23, 24]. Plastic can also adsorb metals [25] and bacteria [26], sometimes at concentrations many times higher than their immediate surroundings [27]. Furthermore, there is evidence that once ingested some of these organic chemicals can desorb in the guts of animals [28]. Plastics can also leach synthetic additives, such as phthalates, alkylphenols, and bisphenol A [29]. A more recent study indicates that plastics can be cytotoxic to human cells [30]. Finally, plastic debris can serve as a unique microhabitat for marine organisms [31, 32] and aid in the transport of invasive species [33]. These known issues highlight why microplastics are considered a contaminant of emerging concern [34, 35, 36].

While evidence of plastic pollution in the natural world quickly mounts, few studies focus on synthetic polymer contamination in human consumables. A 2014 publication reported synthetic polymers in 24 brands of German beer [37]. Another study published the following year found microplastics in 15 brands of Chinese commercial salt sourced from lakes, mines, and coastal seas [38]. Two more studies of salt emerged in 2017; one reported the presence of plastic particles in globally sourced commercial salt [39] while the other found plastic particles in Spanish table salt [40]. Anthropogenic debris was also found in both fish and bivalves that were purchased in markets, intended for human consumption [35]. The known accumulation of anthropogenic debris in global water bodies makes contamination of human consumables sourced from those water bodies very likely. This study and others that predate it, seek to provide evidence of this contamination.

Our study focused on three common human consumables: beer, sea salt, and tap water. One objective of this study was to determine if the findings from previous studies [32, 33, 34, 35] regarding beer and salt are regional anomalies or pieces of a larger, global food and beverage contamination issue. For this reason, we analyzed contamination of beer and salt products purchased within the US [33, 34, 35]. We specifically analyzed beers brewed from water sourced from the Laurentian Great Lakes because of the known prominence of plastic pollution within those bodies of water. Internationally sourced salts purchased in the city of Minneapolis were chosen because when it comes to products such as salt, local markets often sell globally sourced products.

Another major objective of this study was to begin surveying contamination of drinking water. To the authors’ knowledge, no survey of anthropogenic debris in tap water has ever been published. We analyzed 159 water samples collected from fourteen countries. The samples, provided by Orb Media, span seven geographical regions from five continents. Approximately half of the samples came from developed countries and the other half from developing countries. The samples, representing both rural and urban communities, were subjected to different filtering methods and were used for different purposes. This broad survey provides an indication of whether the levels of contamination differ between developing and developed nations, and serves as a foundation for future studies that can focus on more specific questions regarding tap water contamination.

Anthropogenic contamination of tap water, beer, and sea salt
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