Gaps in the local nutrient cycle

Eva writes*

In June 2019, the Dutch government set the goal of having as much of a circular agricultural system as possible by 2030. European Union regulations state that objectives of organic agriculture include that distribution channels should be kept short, and that one should aim for a local approach. This means that closing the agricultural cycle should happen at the most local level possible [pdf]. With the current division of agricultural practices in the Netherlands, however, that will be a challenge.

To take an example, farmers in the region of West Zeeuws-Vlaanderen lack local supplies of manure. Therefore, a gap in the nutrient cycle appears: the rate of nutrients taken from the soil is higher than the rate of nutrients returned to this soil. Currently, farmers in the region close the gap with chemical fertilizers and manure imported from Noord-Brabant.

Because chemical fertilizers harm the environment, organic farmers try to  minimize the use of chemical fertilizers, meaning greater imports of manure from Brabant. However, the cattle farmers in Brabant often import their cattle feed from far away (Africa, Asia, and the Americas). How sustainable is this organic farming?

Current non-organic, non-circular agriculture

This example shows why it is so important to close the local cycle when we want organic agriculture to actually be a more sustainable option. The issue is that, with current practices, an unclosed local nutrient cycle is unavoidable. That is because of one consistent factor taking nutrients out of the cycle: human consumption. By consuming, we take nutrients out of the cycle, which end up in by-products: food waste, by-products of food processing and, well, our fecal matter. These nutrients are never returned to the soil, which is why manure needs to be imported to fill the gap. However, importing means that there will always be a gap somewhere in the world. Local solutions are needed!

The first steps towards a minimized gap in the local cycle should be the prevention of food waste. This still does not completely close the cycle: full recycling of all by-products is needed, including human excreta. Currently, human fecal matter is still seen as something we would rather dispose of. Nevertheless, seeing that a fully organic agricultural system with locally closed cycles is the goal for 2030, its recycling might be unavoidable. Other options include using legumes for nitrogen fixation. Nitrogen, however, is the only main nutrient that is present in the atmosphere: a fixation process cannot be applied for other main nutrients, like phosphorus and potassium. Therefore, it might become very difficult to find alternatives for all nutrients.

That is why it will probably be beneficial to consider the option of using human fecal matter. Current research shows that there are still some issues with emissions during storage and after spreading, and that human excreta contain contaminants of concern that need to be filtered out first: the development of a proper management system and additional research is clearly necessary. With the ‘local approach’ goal and the unavoidable gap caused by human consumption in mind, however, I would argue that investment in this research is definitely worth it.

Bottom line: By not recycling all by-products of human consumption, there will always be an unavoidable gap in the nutrient cycle. With organic farming being focused on a local circular approach, a way must be found to close this gap locally. Of the many possible strategies, the most obvious one is using our poop!


* Please help my Environmental Economics students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice :).

Eating meat: choice or constraint?

Edde writes*

A high consumption of meat – and animal-based products in general – is a common practice all over the world [pdf] and over the past decades, global meat production has been rising. Whereas it is generally recommended for a person to eat not more than 70 grams a day, individuals in countries such as for example Argentina and Luxembourg consumed in 2013 on average 293.8 and 270 grams a day, respectively.

Understanding what induces meat consumption is important, as high meat consumption can negatively affect the long-term well-being of our ecosystems (a “market failure”).

Many factors influence meat consumption. These include, but are not limited to, an individual’s living situation, social identity, knowledge and skills, and one’s cultural and political norms and values. Although these factors determine to a certain extent why people consume meat, it is not always clear whether this is really a voluntary choice, or a choice encouraged by economic incentives.

Except for the factors above associated with individual dietary choices, a look at meat consumption from a national level can show how  “market dynamics” can increase meat consumption.

Meat producers respond to meat consumption. Economically speaking, the choice to consume meat can be seen as a vote to produce meat, which can explain record global meat production (see figure below). Higher consumption spurs investment in production (and subsequently sunk costs in capital and machinery) in the meat industry, which makes it easier to increase economies of scale, thereby making meat cheaper and meat alternatives relatively more expensive. Following the law of demand, a lower meat price – ceteris paribus – will lead to a higher quantity demanded. Furthermore, this will also likely reduce demand for substitute goods, such as more-sustainable meat alternatives. Consequently, this can engender a rather path-dependent process in which more meat is consumed and produced, thereby encouraging less-sustainable meat eating.

Source

On the other hand, sustainable eating can also reflect incentives rather than choices. Considering that meat can be too expensive or not accessible, populations may be (financially/economically) incentivized to consume little meat. This may be better for animal welfare and ecosystems, yet it does not guarantee a more prosperous and equitable society. In poor countries, consumption of protein is low, yet it would be better for health and well-being (and thus economic prosperity) if these populations included more protein – such as meat – in their diet.

Therefore, when talking about meat consumption and sustainability through an economic lens, it is important to consider the impact of consumer choices on our environment as well as underlying mechanisms affecting those choices. To improve the long-term well-being of our ecosystems and economies, national and global economic policies need to consider all the factors encouraging (and discouraging) meat consumption.


* Please help my Environmental Economics students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice :).

Your tourists or your life

Frank writes*

A flight from Eindhoven to Berlin: 50 euros.
The extra revenue for Berlin’s economy: 300 euros.
Climate change caused by the plane’s emissions [pdf]: 5 euros.
That picture of you, with the Brandenburger Tor: priceless.

Or is it?

Direct emissions from aviation are responsible for roughly 3% of the total carbon dioxide emissions in the European Union. Compared to other forms of public transport [pdf], air travel is one of the most carbon intensive methods of movement. Meanwhile, according to the International Civil Aviation Organization, the number of flights and the total emissions by the industry are only projected to grow in the near future.

Photo by dsleeter_2000 via climatevisuals.org

In the light of climate change, this has led some to oppose flying, such as flight shaming. According to a survey by the European Investment Bank, a majority of EU citizens favor a ban on short-distance flights. Dutch politicians prefer a European tax on flying, which will result in higher prices that will reduce demand for flights.

European tax legislation is notoriously hard to pass, requiring unanimous approval by all 28 members. Therefore, the Netherlands are planning to introduce a national flight tax. However, a national flight tax introduces its own unique downsides, with the main concerns regarding capital flight (pun intended) from the aviation and tourism industries.

Academics like William Nordhaus, recipient of the 2018 Nobel Memorial Prize in Economic Sciences, argue that we must not “[burn] down the village to save it”. They assert that while the impacts from climate change may be grave, we should also consider the impacts of those measures which we take against it, which can impact the same groups as climate change. According to research by TU Delft, CO2 reductions may not be as large as some proponents boast, but economic damage might also be smaller than opponents fear.

Bottom line: We should not blindly pick one option, but rationally weigh the range of alternatives which we can choose from. This brings about a whole other range of concerns regarding sensitivity to assumptions and decisions on parameters like discount rates, but these fall outside the scope of this blogpost. We may choose to face the full cost of flying to Berlin, and potentially stay home instead, or we may choose a selfie with the Brandenburger Tor. But choose, we must.


* Please help my Environmental Economics students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice :).

The importance of whale poo

Marina writes*

One of the more important actors in the carbon cycle of the world are phytoplankton. Thinking on a global scale, two big carbon sinks stand out. Namely, vegetation and the oceans. Phytoplankton are responsible for most of the transfer of carbon dioxide from the atmosphere and into the oceans, via photosynthesis that produces half the oxygen on Earth.

Phytoplankton also form the foundation of many aquatic food webs. They are food for zooplankton, crustaceans, small sharks, whales and other big fish and mammals indirectly Unfortunately, phytoplankton are disappearing. Research shows that there is a 40 percent reduction in the global phytoplankton population since the 1950s. The rise in global sea temperatures is thought of as the main driver of decline. But much more research is needed to understand the reductions of these populations.

Whales, similarly, act their part in the carbon cycle. This is also referred to as the ‘biological pump’, or the ‘whale pump’. This process removes carbon and nitrogen from the sunlit zone of the sea and sends those elements downwards through a downward flux of aggregates, feces, and vertical migration on invertebrates and fish. Whales, in the process of foraging deep in the oceans and coming up for air to breathe, release nitrogenous nutrients through their urea (pee) and fecal plumes (poo). That process means more nutrients for primary producers such as phytoplankton. Additionally, when whales die, they sink to the bottom of the ocean, taking all that accumulated carbon with them. The whale carcasses also act as a host to a variety of species, such as snails, mollusks and bacteria that live on the bottom of the ocean.

This nutrient cycling has important implications for policy makers, as healthy whale populations can potentially slow or stabilize the decline of phytoplankton and other species. The real-world implications of slow but irreversible ecosystem changes are difficult to predict. Thus, humans should be extra cautious about the ways in which they interact with their environment.

Bottom line: The example of human impacts on whale and phytoplankton populations shows that we do not fully understand the complexities of ecosystems and our impacts on them.


* Please help my Environmental Economics students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice :).

The cities of tomorrow

Alina writes*

Cities have become the hubs of human settlement, development, and economic growth over the last two centuries. Globally, urban spaces occupy 1-3% of terrestrial land, yet in 2018, cities accommodated 55% of the world’s population. The percentage is expected to rise to 68% by 2050. Additionally, urban based-economic activities generate an estimated 55%, 73%, and 85% of gross national product in low-, middle-, and high-income nations [pdf] respectively. From these statistics, it is evident that urban environments have become detrimental to natural environments, consuming 78% of the world’s energy and producing 60% of global greenhouse gases. It is critical to make urban landscapes environmentally sustainable in order to mitigate and prevent projected environmental catastrophes.

Eco-cities are a recent urban phenomenon entailing a city built from scratch with a fundamental focus on sustainability embedded in its design, operation, and management.

One example is the Songdo eco-city, which is actually a district within Incheon, South Korea. At its heart, Songdo strives to have a substantially smaller carbon footprint than traditional cities and to be highly energy and resource efficient. Sustainable elements include, but not limited to:

These sustainable aspects sound great on paper. However, it is worth evaluating the extent to which an eco-city is more sustainable than a traditional city.

A major shortcoming of Songdo and other eco-cities is that building an entire city or urban district from scratch is incredibly challenging. It requires a large chunk of empty land which is suitable for urban development and hefty upfront investment costs. Songdo’s capital cost was worth $40 billion making it one of the most expensive private developments in the world.

Additionally, the majority of the cities in the world are already built, meaning they have locked-in unsustainable infrastructure, and are unlikely to be torn down and rebuilt sustainably. Thus, it could perhaps be more beneficial to optimise existing cities by implementing sustainable elements into them rather than creating eco-cities from scratch.

Bottom line: Songdo could be the blueprint of future eco-cities; however, it is still just a pilot version. Eco-cities have considerable potential to solve urban environmental problems, but most cities – which are traditional and non-sustainably designed – will continue to operate unsustainably due to infrastructural lock-ins.


* Please help my Environmental Economics students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice :).

The safest country in the world?

Emil writes*

The Netherlands is famed for its water management prowess. This is not for nothing, from the construction of the Afsluitdijk after the Zuiderzeevloed in 1916, to the Delta works after the Watersnoodramp in 1953, water is, and always has been, a genuine threat to livelihood in the Netherlands. Through this decorated history of water management, the Netherlands has built up a complex network of governmental institutions that divide the responsibilities of domestic water management. An important responsibility of this network is flood management. The relevant institutions use a multilayer safety framework, in which flood prevention takes priority over spatial design (tailored to flood damage curtailment) and crisis management (in case of flooding).

In 2017, the norms of flood prevention were updated through the adoption of the new Waterwet (Water Law). Flood management must now be assessed based on risk, which is defined both by the probability of a flood occurring, and the consequences that flooding entails. Based on this, the probability of flooding must be low in places where the consequences would be great in order to minimize risk. Risk is calculated per dike trajectory, of which the Netherlands has 255. (A “dike trajectory” is a set of dikes for organisational and management purposes in the larger institutional framework. A trajectory ranges from 0.2 km to 47 km in length.)

The accepted probability of a flood occurring is calculated based on two different methods: Local Individual Risk (LIR) and Societal Cost Benefit Analysis (SCBA). LIR refers to the probability of death by flooding and must be ≤0.00001 death per year. Mortality is a constant between zero and one, determined on a neighborhood scale. It represents the average mortality by flooding based on historical data. The highest mortality value within an area behind a dike trajectory determines the mortality constant for the whole trajectory. The evacuation fraction is the estimated proportion of the human population behind a single dike trajectory that can be evacuated preventatively. With these equation terms, the flooding probability for a dike trajectory can be calculated as:

LIR = Flooding probability * Mortality * (1 – Evacuation fraction)

Just like LIR, the SCBA [pdf] calculates flooding probability per dike trajectory, but based on economic value. It is a very complex cost benefit analysis, but notable factors include a discount rate of 5.5% and “value of a statistical life” of € 6.7 million.

For each dike trajectory, the lowest probability calculated, by either LIR or SCBA, is used for the entire dike trajectory. Whether a dike trajectory meets the required safety norm is determined through annual inspection but can change over time. Land subsidence or sea level rise could alter the flooding probability. With the determined flooding probability, it is possible to calculate the economically optimal time to initiate flood defense construction. The flooding probability sharply decreases after the construction of new defense works, after which it increases slowly for the aforementioned reasons. The flooding probability follows a downward trend over time because of increasing population and economic value behind the dikes, which therefore increases the risk of flooding.

The Netherlands’ flood defense management seems impeccable, but the costs of defending against sea level rise of 45 cm to 85 cm by 2085 may be steep.

Bottom Line: Facing a 1/100000 chance of dying in a flood, every year, may seem terrifying, but it’s subjective and should make you grateful for being born here and not in another low-lying, coastal area.


* Please help my Environmental Economics students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice :).

A labyrinth of poor choices

Miqui writes*

The shoes are recycled, upcycled, organic, vegan, made in the EU, and come with a promise to plant two trees! The fashion industry is pushing our buttons and pulling our levers to temp us to purchase new shoes, without guilt. The green movement has become trendy and hip as it’s expanded beyond hippies. In Green consumption: the Global rise of Eco-chic, Bart Barendregt argues that green lifestyles are now part of capitalist society. Now elites combine their environmentalism with taste and personal wellness.

It is, however, the question whether this green movement is actually helping in achieving our environmental goals. Genuine pro-environmental behaviour is severely limited by bounded rationality. With bounded rationality people strive consciously to attain certain goals they have in mind but are also strongly limited in making an optimal choice by things like information gaps, information asymmetries, heuristics and a range of biases.

This bounded rationality is gratefully abused by some parts of the fashion industry. In this, companies make “unwarranted or overblown claims of sustainability or environmental friendliness in an attempt to gain market share”. Because of our bounded rationality people are not well equipped to stand strong against this greenwashing and consequently end up buying products that do not deliver the environmental-friendly result that the ad or label promised.

One thing is clear, sustainable consumption is an oxymoron. Consumption of products practically always involves the use of resources and the production of waste which in an overpopulated earth inevitably harms the environment. Sustainable consumption is no consumption.

Nevertheless, we can reduce our footprint by buying recycled, upcycled, organic, vegan, second-hand and offset emissions. As explained above, we are very limited in making a choice with an optimal environmental result.

For example, the promise of a shoe brand to plant two trees if you buy their product sounds like a great deal for an environmentalist, but do most people know whether these two trees actually compensate in any significant way? It does for your consumer shame but with regard to the environment it is a complicated question. The image of two large, full-grown trees and a pair of shoes probably comforts you with regard to the CO2 emissions. Perhaps those trees actually do compensate for the CO2 emissions but the production and sale of shoes involves much more than the CO2 emissions.

A Life Cycle Assessment (LCA) on footwear tells us that the use of energy, and the raising of cattle in the case of leather shoes, indeed has a huge impact on global warming. However, what this LCA also shows is that there is a striking impact in the solid waste management phase and that cattle raising also results in significant acidification and eutrophication of environments. An important factor in this assessment is the studied production area which considerable affects the impact of production. What this means is that offsetting CO2 by planting two trees does not compensate the wide range of environmental impacts.

With this in mind, is it possible for a mainstream consumer to make a well-intended choice with an optimal environmental result? Arguably not. Most people simply do not have the time, resources and capability to come to such a result. According to Thomas P. Lyon, a business professor at the University of Michigan, says that “the ideal system for regulating green marketing claims would entail comprehensive labeling and certification requirements”. Whether labeling and certifications are helpful in promoting environmental behavior is not clear. Lyon compares it with making right decision in relation to healthy food as he argues that “there’s not a lot of evidence that those nutrition labels have changed America’s eating habits.”

Bottom line: The green movement is turning trendy. More people are developing environmental awareness, and pro-environmental choices are going mainstream. We are on the right track, even if we’re a bit distracted as to what it means.


* Please help my Environmental Economics students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice :).

Valuing tigers and humans

Shivalika writes*

The Sundarbans — the world’s largest mangrove ecosystem — is shared between India and Bangladesh. With the global mangrove biome increasingly under threat from human exploitation, how India and Bangladesh choose to manage and conserve the Sundarbans could be the difference between preserving these crucial and biodiverse habitats or letting them disappear in 100 years. But the two countries are struggling to manage this resource effectively. A necessary first step is forming a cooperative alliance to collectively manage the resource.

The Sundarbans provide many crucial ecosystem services. They are, for example, the last remaining stronghold for the endangered Royal Bengal Tiger and host several species of mangrove trees that have an intrinsic value of their own. The livelihood of roughly 3.5 million coastal residents depends on the forest. Due to climate change and resulting sea-level rise, the mangroves provide essential flood protection and reduced mortality from floods, tsunamis, and cyclones that are common in the area.

Photo by Deshakalyan Chowdhury, AFP.

One can, by this point, draw the conclusion that the Sundarbans need to be protected, at all costs. But what are these costs exactly? It is the environmental economist’s duty to quantify the benefits of action and the costs of inaction to inform policy. One simply cannot put “all costs” into one cause.

A cost-benefit analysis is thus called for to make credible policy suggestions to the Indian and Bangladeshi governments in regard to the protection of the Sundarbans. About a quarter of the Indian Sundarbans [pdf] is currently a core protected area – allowing no human activity whatsoever. In the Bangladeshi Sundarbans, 23% of the area is declared protected.

What would the area look like if the entirety of it was protected? This policy appeals to advocates of strong sustainability or preservationists, but there are economic, social, and political consequences to consider.

Take the example of Bengal tiger protection alone. Here, there are economic costs for enforcement and monitoring, social costs because of the tiger-human conflict in the surrounding villages, and political implications of any policy that would effectively be perceived as a prioritisation of the lives of tigers over the lives of people that depend on extractive industries in the Sundarbans or have been hurt or killed by tigers. The intrinsic value of the tiger, or extrinsic value of the ecosystem of which it is a part, are the benefits of this proposed policy. And tigers are only a small part of the Sundarbans. A bigger picture analysis would need to include a host of different factors to consider and monetise.

Bottom line: These costs and benefits are, if at all possible, not easy to monetise. But even a humble attempt at doing so will add to the understanding of the complex nature of the Sundarbans, and the ever more complex consequences of any policy for their conservation.

 


* Please help my Environmental Economics students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice :).

True costs of 5G

Marieke writes*

The wireless network has become an indispensable part of our society, the 5th generation will soon be implemented. The implementation of the 5G network in the Netherlands is planned in Amsterdam by 2020, and from 2025 onwards all European cities have to be covered according to the Dutch news provider.

What does 5G actually entail? Technically speaking, 5G enables a much faster connection (up until 20 Gbps, which means 20 times faster Wi-Fi and 30 times faster data) and it used a much bigger bandwidth of the mobile broadband, which will generate a bigger capacity and coverage for all network-users. Next to providing the possibility of using the wireless network with a massively increased speed, the 5G network will also enable the following possibilities:

  • Internet of things, e.g., smart heating-systems, self-ordering fridges, etc.
  • Self-driving cars
  • Smart cities, e.g., parking lots with sensors or automatic streetlamps
  • Industrialized automation, e.g., scheduling maintenance from a distance
  • Voice commands via devices such as Siri, Alexa and Google

For 5G internet many more, but smaller antennas are needed than for 4G. Volkskrant says that to cover an entire city with internet, an antenna is needed on every corner of the street.

When reading into the literature (both academic, peer reviewed sources, newspaper articles and websites of pro-5G stakeholders), it becomes clear that 5G is mainly presented as economically profitable, firstly because of the insane number of new products that can be brought onto the market or other uses of products that can be optimized, but also because it is said to be more energy efficient than 4G networks. T-mobile for example emphasizes that industrialized automation will save a lot of costs that are a result of current inefficiencies in the production process of many products and services.

However, what remains undiscussed in these sources, are the negative  externalities. For example:

  • Energy costs: even though 5G uses less energy per operation, the overall use of internet will increase, because more devices will be connected to the wireless system. Next to this, 5G requires the production of new devices and infrastructure to replace 4G devices and systems, increasing energy consumption and CO2 emissions [pdf].
  • Impact of radiation on mental health: it is argued that the addition of the high frequency 5G radiation to an already complex mix of lower frequencies (prior generations), will contribute to a negative public health outcome. It is stressed that the effects are still too unclear to draw any long-term conclusions. Additionally, the effects are hard to measure, since there is no control group anymore (everyone is exposed to the radiation). It is emphasized that these effects need to be studied before 5G is brought to the market
  • Lastly, the current generation of wireless connection, is already proven to negatively impact mental health, when assessing the impact of smartphone and social media use. The question arises if this would increase with the introduction to 5G.

Bottom line: For my essay I want to research the costs of these externalities and compare them to the economic benefits of the implementation of the 5G network.


* Please help my Environmental Economics students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice :).

Educating girls: Two birds, one stone

Jasmijn writes*

It is commonly assumed that solutions to climate change are to be found in the realm of the natural environment. It is intuitive that decisionmakers and individuals focus on interventions such as the development of renewable energy sources, plant-based diets and the recycling of plastic in the process of adopting climate change mitigation strategies or more sustainable life styles. As a result, policies that have traditionally been labeled as part of the social equality and development discourse are rarely considered.

An example of a rather surprising but highly influential climate policy is the promotion of education for girls. This policy kills two birds with one stone and addresses three of the Sustainable Development Goals: quality education, gender equality and climate action. To put it into more economic terms, it appears that increasing education for girls might have positive externalities that we are unaware of. If these environmental benefits are quantified, funding could be provided by environmental governmental departments and NGOs and thereby supplement the resources already available through development aid. More resources available means a higher chance of a successful policy.

One of the most obvious advantageous characteristics of a society with more educated women is a reduced rate of population growth, because better education women tend to have less children. Classic authors such as Malthus (1798) [pdf] and Erlich (1968) have highlighted that our increasing human population will ultimately lead to the degradation of the natural environment. Hence, a stabilized rate of population growth will result in a quantifiable reduction of human pressure on the environment, for example by a reduction in carbon emissions, land use change rates and pollution.

Secondly, educated women will have skills that enable them to participate in the decision-making process and resource management. In the global South, women are largely responsible for the collection of raw materials such as fuelwood and play a central role agricultural production due to the persistence of traditional gender roles. Decisionmakers will miss out on gendered knowledge about these resources by excluding women from the decision-making process and thereby reduce the effectiveness of mitigation policies. Moreover, management strategies proposed by women might be more sustainable, as women’s needs are generally more closely related to the preservation of nature. For example, the conservation of forests is essential for the collection of fuel wood.

Nevertheless, the relationship between education, women’s representation in decision-making bodies and environmental sustainability is complex. Patriarchal norms are resilient in many societies and even if chances to participate increase by education, women’s voices may not be heard [pdf]. Additionally, one should keep in mind that women are not a homogenous group. Other factors such as class and race also come at play, and it is unclear how women’s education interacts with those variables. Therefore, it is challenging to quantify the role of increased women’s education in effective and sustainable resource governance.

Bottom line: Education of girls does not only affect social equality, but also has a positive impact on the state of the natural environment. Two important dimensions of these positive environmental externalities are a decrease in carbon emission due to reduction of population growth, and resource management that is more focused on conservation. However, social norms about gender are powerful, which might decrease the effectiveness and benefits of this policy.


* Please help my Environmental Economics students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice :).