Propiedades químicas de los suelos

Coastal eutrophication has not only been observed in Chinese seas, but also in many other coastal waters of the world (Diaz & Rosenberg 2008; Garnier et al. 2010; UNEP 2016). Many events of harmful algal blooms have been reported in coastal waters of the Americas, Europe, and South Asia (Diaz & Rosenberg 2008). The Global NEWS-2 model is a widely used tool for global and regional analyses as I indicated in Section 7.2.1. To my knowledge, 35 studies have used the model since 2010 (Figure 7.4). Most of these are for regional analyses in China, Indonesia, the Bay of Bengal, Europe, North and South America and Africa (Figure 7.4). I contributed to approximately one-third of these global and regional analyses (Figures 7.4 and 7.5).

Figure 7.5 distinguishes between four types of Global NEWS-2 studies. The first type is typically studies that used the original version of Global NEWS-2. In 2010, this version was published with applications of MEA scenarios for future projections (Mayorga et al. 2010; Seitzinger et al. 2010). This version was used in around 20 studies for different regions (Figure 7.5). Half of these studies developed alternative scenarios to MEA. These studies belong to the second type in Figure 7.5 and are for different regions. They focus on different aspects such as effects of alternative agricultural scenarios including energy crops on coastal eutrophication or how people experience coastal eutrophication (the lived experience) (Table 7.4).

The third type includes the studies that developed new formulations of Global NEWS-2 since 2010. For example, for Indonesia new model formulations have been developed for dams (Suwarno et al. 2014b) and for direct sewage inputs to rivers (Suwarno et al. 2014a). For the Bay of Bengal, new model formulations are developed for open defecation (Nurul et al. under review) and aquaculture (Sattar et al. 2014). Two global

179 studies include new formulations; the first is a version of Global NEWS-2 that includes seasonality for DIN (McCrackin et al. 2014) and the second includes soil P dynamics (Strokal & de Vries 2012). But these formulations for global analyses are not integrated into one new model system (Table 7.4). The fourth type includes the development of a new model. This is what I did: I developed a new MARINA model for China based on Global NEWS-2 (this PhD thesis). I consider this as a new model because it differs more from Global NEWS-2 in terms of model inputs and formulations than any of the other studies. In particular, it differs with respect to the spatial scale (sub-basin), aquatic retentions and sources of nutrients in rivers (see Section 7.2).

The results of applying the models (both original and improved) reveal similarities and differences between China and other regions (see Table 7.4 for examples). Similarities are mainly associated with trends in river export of nutrients since 1970 and the effects of these trends on coastal eutrophication. For example, the overall conclusion of the studies from Table 7.4 is that nutrient export by many world rivers has been increasing since 1970 (Mayorga et al. 2010), resulting in coastal eutrophication. This holds particularly true for rivers in North America (McCrackin et al. 2013), Europe (Blaas & Kroeze 2016; Strokal & Kroeze 2013), Asia (Sattar et al. 2014; Strokal et al. 2014b; Suwarno et al. 2013) and for some rivers in South America (Van der Struijk & Kroeze 2010), according to the original Global NEWS-2 model. Similar conclusions can be drawn for Chines rivers (Qu & Kroeze 2010; Strokal et al. 2014b).

However, there are differences in nutrient pollution levels between the original and improved versions of Global NEWS-2. For example, new model formulations for the Bay of Bengal (Nurul et al. under review), Indonesia (Suwarno et al. 2014a), and the MARINA model for China (this PhD thesis) suggest higher levels of nutrients in their rivers than the original Global NEWS-2. This has to do with missing sources of nutrients in the original model (e.g., Section 7.3.1 for China). Furthermore, the original Global NEWS-2 was found to underestimate the effects of dams on nutrient export by Indonesian rivers. Similar conclusions are drawn in this PhD thesis for Chinese rivers.

An important difference between China and other regions is in causes of water pollution (Table 7.4 as an example). For China the large contribution of manure point sources may be unique, but in other regions, this source could be unimportant. This pollution is largely from industrial farms with inadequate manure management (Chapter 4, Sections 7.2.3 and 7.3.1). Animal production has also been industrializing in other world regions such as North America and Europe (e.g., Herrero et al. 2013; Steinfeld et al. 2006). However, management of animal manure in those regions is apparently more effective than in China. For example, discharges of manure to water bodies are strictly controlled by permits in North America (Hribar 2010) and recycling of manure is regulated in

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are often ineffective for nutrient removal, yet require considerable energy for aeration and produce a lot of sludge that needs proper management (see Jin et al. (2014) for an overview). Today, advanced technologies are able to remove most of N and P from waste during treatment and produce less sludge at the lower cost for energy (e.g., Kartal et al. 2010; Khiewwijit 2016). Combining them with technologies that allow nutrient recovery and recycling can facilitate to close nutrient cycles (e.g., Cai et al. 2013; Jaffer et al. 2002; Tervahauta et al. 2014).

In optimistic futures for China, we need implementation of best available today technologies (see examples above). A challenge can be to upscale emerging technologies (e.g., Chen et al. 2015; Tervahauta et al. 2014). Nevertheless, the economy in China develops quickly. This opens up opportunities to explore the implementation of the technologies to reduce water pollution from animal and human waste in the future.

7.3.2 Comparison with Global NEWS-2 studies for other regions

Coastal eutrophication has not only been observed in Chinese seas, but also in many other coastal waters of the world (Diaz & Rosenberg 2008; Garnier et al. 2010; UNEP 2016). Many events of harmful algal blooms have been reported in coastal waters of the Americas, Europe, and South Asia (Diaz & Rosenberg 2008). The Global NEWS-2 model is a widely used tool for global and regional analyses as I indicated in Section 7.2.1. To my knowledge, 35 studies have used the model since 2010 (Figure 7.4). Most of these are for regional analyses in China, Indonesia, the Bay of Bengal, Europe, North and South America and Africa (Figure 7.4). I contributed to approximately one-third of these global and regional analyses (Figures 7.4 and 7.5).

Figure 7.5 distinguishes between four types of Global NEWS-2 studies. The first type is typically studies that used the original version of Global NEWS-2. In 2010, this version was published with applications of MEA scenarios for future projections (Mayorga et al. 2010; Seitzinger et al. 2010). This version was used in around 20 studies for different regions (Figure 7.5). Half of these studies developed alternative scenarios to MEA. These studies belong to the second type in Figure 7.5 and are for different regions. They focus on different aspects such as effects of alternative agricultural scenarios including energy crops on coastal eutrophication or how people experience coastal eutrophication (the lived experience) (Table 7.4).

The third type includes the studies that developed new formulations of Global NEWS-2 since 2010. For example, for Indonesia new model formulations have been developed for dams (Suwarno et al. 2014b) and for direct sewage inputs to rivers (Suwarno et al. 2014a). For the Bay of Bengal, new model formulations are developed for open defecation (Nurul et al. under review) and aquaculture (Sattar et al. 2014). Two global

179 studies include new formulations; the first is a version of Global NEWS-2 that includes seasonality for DIN (McCrackin et al. 2014) and the second includes soil P dynamics (Strokal & de Vries 2012). But these formulations for global analyses are not integrated into one new model system (Table 7.4). The fourth type includes the development of a new model. This is what I did: I developed a new MARINA model for China based on Global NEWS-2 (this PhD thesis). I consider this as a new model because it differs more from Global NEWS-2 in terms of model inputs and formulations than any of the other studies. In particular, it differs with respect to the spatial scale (sub-basin), aquatic retentions and sources of nutrients in rivers (see Section 7.2).

The results of applying the models (both original and improved) reveal similarities and differences between China and other regions (see Table 7.4 for examples). Similarities are mainly associated with trends in river export of nutrients since 1970 and the effects of these trends on coastal eutrophication. For example, the overall conclusion of the studies from Table 7.4 is that nutrient export by many world rivers has been increasing since 1970 (Mayorga et al. 2010), resulting in coastal eutrophication. This holds particularly true for rivers in North America (McCrackin et al. 2013), Europe (Blaas & Kroeze 2016; Strokal & Kroeze 2013), Asia (Sattar et al. 2014; Strokal et al. 2014b; Suwarno et al. 2013) and for some rivers in South America (Van der Struijk & Kroeze 2010), according to the original Global NEWS-2 model. Similar conclusions can be drawn for Chines rivers (Qu & Kroeze 2010; Strokal et al. 2014b).

However, there are differences in nutrient pollution levels between the original and improved versions of Global NEWS-2. For example, new model formulations for the Bay of Bengal (Nurul et al. under review), Indonesia (Suwarno et al. 2014a), and the MARINA model for China (this PhD thesis) suggest higher levels of nutrients in their rivers than the original Global NEWS-2. This has to do with missing sources of nutrients in the original model (e.g., Section 7.3.1 for China). Furthermore, the original Global NEWS-2 was found to underestimate the effects of dams on nutrient export by Indonesian rivers. Similar conclusions are drawn in this PhD thesis for Chinese rivers.

An important difference between China and other regions is in causes of water pollution (Table 7.4 as an example). For China the large contribution of manure point sources may be unique, but in other regions, this source could be unimportant. This pollution is largely from industrial farms with inadequate manure management (Chapter 4, Sections 7.2.3 and 7.3.1). Animal production has also been industrializing in other world regions such as North America and Europe (e.g., Herrero et al. 2013; Steinfeld et al. 2006). However, management of animal manure in those regions is apparently more effective than in China. For example, discharges of manure to water bodies are strictly controlled by permits in North America (Hribar 2010) and recycling of manure is regulated in

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Europe (Oenema et al. 2007). In China, new environmental policies for animal production have been recently introduced but require time and efforts for their effective implementation (Section 7.3.1).

In contrast, open defecation is probably not an important source of water pollution in China, but it may be for other Asian rivers, e.g. draining into the Bay of Bengal (Nurul et al. under review) and the Java Sea (Suwarno et al. 2014a). This is because in China less than five percent of the human population practiced open defecation in 2000 (WHO/UNICEF 2014). This is not the case for countries including India, Bangladesh and Pakistan which contain rivers draining into the Bay of Bengal. This holds especially for rural populations in those countries as over two-thirds, half and one-fifth of rural populations in India, Pakistan and Bangladesh practice open defecation, respectively (WHO/UNICEF 2014). For Indonesia, this number was one-fifth, but for the urban population in 2000 (Suwarno et al. 2014a). As a result, open defecation became a large contributor to nutrient pollution in rivers of those countries. This also contributes to coastal eutrophication (Nurul et al. under review; Suwarno et al. 2014a).

Urban waste is today an important source of P in Chinese rivers especially in urbanized deltas with large cities such as Shanghai (Yangtze river delta), Shenzhen and Guangzhou (Pearl river delta). Sewage from the urban population is also an important driver of P pollution in many other world rivers (Harrison et al. 2010; Mayorga et al. 2010; Strokal & de Vries 2012). However, for the rivers of Indonesia this source may be one of the most important causes of N and P pollution in the future (Suwarno et al. 2014a). For example, Suwarno et al. (2014a) calculated a factor of 20-40 increase in nutrient inputs to Indonesian rivers between 2000 and 2050 using the improved version of Global NEWS-2. This increase is a result of rising urban population connected to sewage systems with relatively low nutrient removal efficiencies.

Future trends in river export of nutrients differ among regions and depend on scenarios (Figure 7.5 and Table 7.4). In general, MEA scenarios with globalized socio-economic trends and with a reactive approach for environmental management (the GO scenario) project higher exports of dissolved nutrients by world rivers in the coming years (Seitzinger et al. 2010). However, these trends still differ among the regions. The difference is especially visible between Europe and Asia. European rivers may become cleaner in the future as a result of effective environmental policies. In contrast, Asian rivers may be more polluted due to a lack of environmental policies based on the GO scenario. Examples are rivers in China (this PhD thesis), Indonesia (Suwarno et al. 2013) and Bay of Bengal (Sattar et al. 2014).

181 However, the results of alternative scenarios differ from the results of the MEA scenarios and among regions (Figure 7.5 and Table 7.4). For example, in European seas, the potential for coastal eutrophication may become higher in the future if large-scale production of micro-algae for biodiesel increases in European countries, according to Blaas and Kroeze (2014). This is a result of nutrient losses to water systems during micro-algae production on land. Strokal et al. (2014c) showed that increasing nutrient removal during treatment is more effective to reduce coastal eutrophication in the southern Black Sea and increasing nutrient efficiencies in agriculture is more effective to reduce coastal eutrophication in the northern Black Sea. Biogas production may be a solution to reduce water pollution in Indonesian rivers by reducing losses of human waste (Suwarno 2015). Zinia and Kroeze (2015) analyzed expectations of people to future changes and their lived experience in Bangladesh draining into the Bay of Bengal. For China, I developed different alternative scenarios with the focus on optimistic perspectives. I also explored the effectiveness of the recent environmental policy on reducing water pollution. I discuss and present the results of my scenarios in Sections 7.3.1 and 7.4.2.

Figure 7.4. Relevant studies on river export of nutrients that used the original Global

NEWS-2 model or the MARINA model since 2010. Details and references are given in Figure 7.5. Asia includes rivers draining into the Bay of Bengal and Indonesia. Europe includes rivers draining into the Black Sea and other European Seas such as the Mediterranean, Baltic and North seas. N and S stand for North and South.

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Europe (Oenema et al. 2007). In China, new environmental policies for animal production have been recently introduced but require time and efforts for their effective implementation (Section 7.3.1).

In contrast, open defecation is probably not an important source of water pollution in China, but it may be for other Asian rivers, e.g. draining into the Bay of Bengal (Nurul et al. under review) and the Java Sea (Suwarno et al. 2014a). This is because in China less than five percent of the human population practiced open defecation in 2000 (WHO/UNICEF 2014). This is not the case for countries including India, Bangladesh and Pakistan which contain rivers draining into the Bay of Bengal. This holds especially for rural populations in those countries as over two-thirds, half and one-fifth of rural populations in India, Pakistan and Bangladesh practice open defecation, respectively (WHO/UNICEF 2014). For Indonesia, this number was one-fifth, but for the urban population in 2000 (Suwarno et al. 2014a). As a result, open defecation became a large contributor to nutrient pollution in rivers of those countries. This also contributes to coastal eutrophication (Nurul et al. under review; Suwarno et al. 2014a).

Urban waste is today an important source of P in Chinese rivers especially in urbanized deltas with large cities such as Shanghai (Yangtze river delta), Shenzhen and Guangzhou (Pearl river delta). Sewage from the urban population is also an important driver of P pollution in many other world rivers (Harrison et al. 2010; Mayorga et al. 2010; Strokal & de Vries 2012). However, for the rivers of Indonesia this source may be one of the most important causes of N and P pollution in the future (Suwarno et al. 2014a). For example, Suwarno et al. (2014a) calculated a factor of 20-40 increase in nutrient inputs to Indonesian rivers between 2000 and 2050 using the improved version of Global NEWS-2. This increase is a result of rising urban population connected to sewage systems with relatively low nutrient removal efficiencies.

Future trends in river export of nutrients differ among regions and depend on scenarios (Figure 7.5 and Table 7.4). In general, MEA scenarios with globalized socio-economic trends and with a reactive approach for environmental management (the GO scenario) project higher exports of dissolved nutrients by world rivers in the coming years (Seitzinger et al. 2010). However, these trends still differ among the regions. The difference is especially visible between Europe and Asia. European rivers may become cleaner in the future as a result of effective environmental policies. In contrast, Asian rivers may be more polluted due to a lack of environmental policies based on the GO scenario. Examples are rivers in China (this PhD thesis), Indonesia (Suwarno et al. 2013) and Bay of Bengal (Sattar et al. 2014).

181 However, the results of alternative scenarios differ from the results of the MEA scenarios and among regions (Figure 7.5 and Table 7.4). For example, in European seas, the potential for coastal eutrophication may become higher in the future if large-scale production of micro-algae for biodiesel increases in European countries, according to Blaas and Kroeze (2014). This is a result of nutrient losses to water systems during micro-algae production on land. Strokal et al. (2014c) showed that increasing nutrient removal during treatment is more effective to reduce coastal eutrophication in the southern Black Sea and increasing nutrient efficiencies in agriculture is more effective to reduce coastal eutrophication in the northern Black Sea. Biogas production may be a solution to reduce water pollution in Indonesian rivers by reducing losses of human waste (Suwarno 2015). Zinia and Kroeze (2015) analyzed expectations of people to future changes and their lived experience in Bangladesh draining into the Bay of Bengal. For China, I developed different alternative scenarios with the focus on optimistic perspectives. I also explored the effectiveness of the recent environmental policy on reducing water pollution. I discuss and present the results of my scenarios in Sections 7.3.1 and 7.4.2.

Figure 7.4. Relevant studies on river export of nutrients that used the original Global

NEWS-2 model or the MARINA model since 2010. Details and references are given in Figure 7.5. Asia includes rivers draining into the Bay of Bengal and Indonesia. Europe includes rivers draining into the Black Sea and other European Seas such as the Mediterranean, Baltic and North seas. N and S stand for North and South.

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Figure 7.5. Details on Global NEWS-2 and MARINA shown in Figure 7.4. See Table 7.4 for

aspects that new model formulations differ from the original Global NEWS-2 model and for alternative scenarios. MEA = Millennium Ecosystem Assessment.

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Table 7.4. Comparison of selected studies using Global NEWS-2 and MARINA.

Region New developments and alternative _scenarios Dominant sources of _{nutrients in rivers} References

China oMARINA (new model), differs

from Global NEWS-2 in:

- sub-basin scale

- dams and P accumulation in

rivers

- manure point sources

- uncollected human waste

oAlternative optimistic scenarios

oPoint inputs of

manure for N and P

oSewage for P in

urbanized areas

This study, Chapters 2-6

Asia: The Bay of Bengal

oNew model formulations for:

- open defecation

- aquaculture

oAnalysis of lived experience of

future trends

oOpen defecation for

N and P

oAgriculture for N

Zinia and Kroeze (2015) Nurul et al. (under review)

Sattar et al. (2014) Indonesia oNew model formulation for:

- dams

- direct inputs of sewage

oAlternative scenarios for biogas

oDirect sewage inputs

for N and P Suwarno et al. (2014a) _{Suwarno et al. (2014b)}

Europe: The Black Sea

oOriginal Global NEWS-2

oAlternative scenarios for sewage

and agriculture

oAgriculture in the

north

oSewage in the south

Strokal and Kroeze (2013)

Strokal et al. (2014c) European

seas

oOriginal Global NEWS-2(a)

oAlternative scenarios for

biodiesel

oAgriculture or

sewage depending on limiting nutrient

Blaas and Kroeze (2016) Blaas and Kroeze (2014) North

America

oOriginal Global NEWS-2(b)

oOriginal MEA scenarios

oAgriculture N

(fertilizers, manure and crop N fixation)

McCrackin et al. (2013) South

America

oOriginal Global NEWS-2

oOriginal MEA scenarios

oAgriculture for DIN(f)

oSewage for DIP(f)

oLeaching of organic

matter for DON and

DOP(f)

Van der Struijk and Kroeze (2010)

Africa oOriginal Global NEWS-2

oOriginal MEA scenarios

oAgriculture,

especially manure for N

oSewage for P

Yasin et al. (2010)

Global oNew model formulations(c) for:

- P soil dynamics(d)

- DIN seasonality(e)

oSewage for P globally

oAgriculture for N

globally

oVary among regions

Strokal and de Vries (2012)

McCrackin et al. (2014)

(a)The study area includes 48 rivers draining into the North Sea, Mediterranean Sea, Black Sea, Baltic Sea, Atlantic

In document Directivos Directivos (página 68-71)