Saturday, October 27, 2007

Groundwater, Mountains and Media

An article in India Today, gave me this opportunity to write about geology. I don't write about it enough, but then the media doesn't cover it enough :-)

The October 15th issue of India Today had an article about Dr. Ritesh Arya, a hydrogeologist, who has turned to drilling for groundwater at very high altitudes in the Himalayas. India Today reporter Ramesh Vinayak interviewed him. Dr. Arya has caused quite a sensation by drilling successfully for groundwater at fifteen thousand feet. The Army and the locals are pleased with him. Villages and army posts which had to bring water by tankers, now have flowing water through bore wells. Hurray for Dr. Arya and his geological skills. Mr. Vinayak's reporting on geology is another matter. Here is what he writes about Dr. Arya's research thesis. "At the heart of his ground-breaking thesis is the finding that groundwater resources in the Himalayan region depend on the type of rocks and structural parameters like folds, fissures and fault-line in the rock strata. I am sure Dr. Arya very skillfully interpreted the geology, but I don't see any ground-breaking revelations here. The parameters that control groundwater occurrence and movement are pretty much the same everywhere, no matter what the altitude, i.e. geological properties of rocks and structural features such as fractures, joints, faults. Then Mr Vinayak writes something bizarre," The mountains have groundwater just like the plains but the water movement at high-altitude is controlled by principles of gravity and iso-stacy (wherein the water level is itself up)". Wow! That must have been the physics class I missed in school. I had no idea water responds to gravity differently in the mountains than in the plains. And what is this iso-stacy? The term is isostacy and it is a concept used to explain why topography exists on a continental scale. The lithosphere, which is the rigid outer shell comprising the earth's tectonic plates rides on a plastic asthenosphere. Plastic in the sense that the material deforms by plastic flow. Imagine a block of wood floating in water. The height of the wooden block above water-level is determined by its density and thickness. The lithosphere similarly rides upon the asthenosphere at a height depending upon its density and thickness. As you must have guessed by now, it has nothing whatsoever to do with groundwater. Here's a suggestion for reporters who are blank about science. Why not ask the scientist being interviewed to write a couple of paragraphs?

Okay, enough harassing the media. On to more geology. Groundwater high in the mountains reminded me of my trekking days in college. Where I live in Pune, the popular places to trek were the Sahyadri mountains, and particularly the various 16th century forts strategically placed along the western ghat escarpments. Many of these forts have fresh water wells. People are often surprised to learn that there is groundwater so high up. The popular thinking is that water will just flow down the slope or through cracks and find the lowest level such as adjoining valleys or plains to accumulate. But there can be plenty of groundwater in these western ghats. These are not orogenic mountains like the Himalayas, but were formed during and after the Deccan Trap volcanic eruptions by a combination of the processes of magmatic underplating and denudational uplift. Magmatic underplating refers to the process whereby much of the melt produced in the mantle during such large magmatic events such as the Deccan Traps does not reach the surface but sticks to the underside of the lithosphere. All this hot stuff makes the lithosphere buoyant causing uplift. Most of the uplift is however thought to be denudational uplift (evidence summarized in Sheth 2007) which refers to the process whereby the lithosphere which has been depressed by the weight of the thick volcanic pile rebounds upon removal of the material by erosion causing uplift. This may take place millions of years after the volcanic event. This is analogous to an iceberg floating in water. If you shave off some ice from the top, the iceberg will rise by a proportional amount. Iso-stacy or rather isostacy is in action in the Deccan Traps as well. The Sahyadris are formed of two main types of basalts which occur as alternating layers; amygdaloidal basalt which solidified from more viscous lava and generally forms gentler erosional slopes and compact basalt which solidified from more fluid lava and forms steeper slopes as seen in image below.

Groundwater systems can occur in both types of basalt. My friend Dr. Himanshu Kulkarni has studied these basalt groundwater systems extensively. After two decades of research, some general principles are emerging. Basalts are crystalline rocks with an interlocking fabric of crystals. So, water in these rocks is stored and flows along cracks, joints and fractures. Both, horizontal sheet joints and vertical joints serve as conduits for water flow. Amgdaloidal basalt is generally the more capacious in water storage and high yielding aquifers are those where a layer of amygdaloidal basalt is underlain by the more impermeable compact basalt (Kulkarni et. al. 2000). The figure below illustrates these concepts of basalt hydrogeology.

Source: Advanced Center for Water Resources Development and Management

Such conditions for the formation of a groundwater system are met at many of the high-altitude forts. At Sinhagad, one of the most popular forts near Pune, there are several fresh water wells and storage tanks that have exploited such structural zones of groundwater flow.

In image the brown arrows point to horizontal sheet joints developed at the junction of two lava flows. Such joints among other joint systems form a zone of groundwater flow (blue arrows). The well indicated by the pink arrow captures this flow. The circular green spots are additional water storage tanks.

Groundwater exploration "consultants" have got a bad reputation, sometimes richly deserved, in my part of the country in the state of Maharashtra. People now have smartened up but in the bad old days there were scamsters walking around with a magnetic compass claiming to locate water, and then those who dabbled in dowsing. It was great to read that Dr. Arya relies on sound geological principles for his explorations. In any case, dowsing in the mountains can be dangerous.

What I would like to know is if the principles of dowsing are any different in the mountains than in the plains.

References:

H. Kulkarni, S. B. Deolankar, A. Lalwani, B. Joseph, S. Pawar, 2000; Hydrogeological framework of the Deccan basalt groundwater systems, west-central India; Hydrogeology Journal; Volume 8, Number 4, p. 368-378.

Hetu C. Sheth 2007; Plume-related regional pre-volcanic uplift in the Deccan Traps: Absence of evidence, evidence of absence; Hetu C. Sheth; In www.MantlePlumes.org

Monday, October 22, 2007

How we think about Race and Intelligence

Media articles and the blogosphere has been abuzz about James Watson's latest indiscretion, stating that Africans are less intellectually endowed than people of European descent. He has been rightly chastised for his really insensitive and unsubstantiated remarks, but that made me think about some other articles and reports about race and intelligence and our reaction to it.

In his book, Guns Germs and Steel, Jared Diamond stresses the genetic equality of humans and explains why Europeans got a head start in achieving technological prowess, leading to their military domination over other cultures. The reasons are to be found in unique combinations of geography, climate, availability of plants that could be cultivated and animals that could be domesticated. Diamond is so mortified about starting a controversy related to group differences that he stays away from even exploring whether culture and religion could have played a role. But here is what he has to say about New Guineans " That is, natural selection promoting genes for intelligence has probably been far more ruthless in New Guinea than in more densely populated, politically more complex societies, where natural selection for body chemistry was instead more potent......That is in mental ability New Guineans are probably genetically superior to Westerners, and they surely are superior in escaping the devastating developmental disadvantages under which most children in industrialized societies now grow up". So, Diamond has no problems accepting that in principle evolution can make one group more intelligent that some other group. Not only that but according to him, at least as far as child rearing goes, New Guinean culture is superior to Western culture. Why was this not met with accusations of racism? Was it because New Guineans and other hunter gatherer societies have been persecuted and any suggestion that they could actually be more intelligent than industrialized people make us feel a little less guilty? Is it okay to say that traditional hunter gather societies are more intelligent than urban societies but not the other way around?

A 2006 study on European Jews (Ashkenazim) settled in the U.S. by Gregory Cochran, Jason Hardy, and Henry Harpending proposed that the high average IQ shown by this group resulted due to occupational constraints imposed on Jews in Medieval times. Jews were forced into trades that required computational skills such as trading and money-lending. This resulted in selection for verbal and mathematical intelligence. A follow up study by David, H. and Lynn, R. compared IQ's of European Jews with Oriental Jews in Israel and found that European Jews have an IQ 14 points higher than Oriental Jews. This according to the authors supported the earlier evolutionary explanation, since Oriental Jews "were permitted to engage in a much wider range of occupations and hence did not come under the selection pressure to develop the high verbal and mathematical intelligence that was present for Ashkenazim". Both the original study and the follow up have received attention and criticism but no howls of protests for example from Oriental Jews or for that matter any other community that they have been racially targeted.

We readily accept that we are more intelligent than our remote ancestors living say a few hundred thousand years ago. That would mean our cognitive evolution was being fueled by selection on existing variability in genes for intelligence. Would there not be such variability in modern populations and did conditions exist in the recent past such that there are discrete differences between groups? Is it even legitimate to research whether groups differ in their intellectual capabilities? In a hysterical editorial the Times of India doesn't think so. They say that some topics such as group differences are best left to sociologists (now that should solve all our problems). According to the Times the job of a scientist is to observe, test and report, which to me is exactly what Cochran et. al. did in their study of Ashkenazim Jews. Their hypothesis has not yet been validated, but there is a clear test available. This will be based on a comparison of IQ's of sibling pairs (to control for environmental differences), one of whom carries the genes that Cochran et. al. have identified as the candidate "intelligence gene" and the other who is a non-carrier. If the carrier is not smarter than the non-carrier, then the hypothesis is wrong. To date, no such specific hypothesis has been presented about innate differences in cognitive abilities between Africans and Europeans. It is reasonable to suppose that any differences are due to social and other environmental factors and the genetic component to the differences measured is negligible. But with the explosion in human genomic data the day might come when someone does present a genetic explanation. Will we be mature enough to let science do the talking?

Some News About My Blogs

I started blogging recently. One reason was that I like writing about science. Another was to point out errors in science reporting especially in the Indian media in the very faint hope that some feedback might reach the media. I send my criticisms directly to newspapers, but the usual trend is that if my article is generally supportive of the media report it has a higher chance of being published. I cannot prove this (I plan to start collecting statistics), but just a trend I have noticed. My post on the editorial in Times of India on Junk DNA was not published in the letters section of the newspaper but received quite a bit of support from the blogosphere. It also caught the attention of the Online Centre for Media Studies, who have posted a synopsis of my post and a link to my blog. It's good to know some feedback is reaching would be and working journalists.

Another piece of news, although somewhat dated. My posts on the Ram Sethu controversy, Adams Bridge and Ram Sethu: A Dummies Guide, received a lot of attention. Again the reaction was mostly supportive, although one memorable comment - either written in jest or due seriousness I am not sure- stands out. I was invited to write an article by the Indian National Interest Review, an online magazine. You can download my article on the Palk Strait here.

Monday, October 15, 2007

Media and Nobel Peace Prize

Spot which one of these newspaper headlines and captions are from Indian newspapers:

Gore Shares Peace Prize for Climate Change Work

PM congratulates Gore for peace prize

2007 Nobel Peace prize awarded to Pachauri's IPCC, Al Gore

Pachauri and Gore share prize for raising awareness on climate change

Gore and U.N. Panel Share Peace Prize

Chidanand Rajghatta had a fine essay in the Times of India about the desperate lengths the Indian media goes to claim an Indian success story. Indian newspapers have been gushing about Pachauri the "man who put emotion into hard science", Pachauri the "efficient administrator and enabler", and Pachauri who stood up to Gore when the two had a brief disagreement in 2002 when Pachauri was elected to head the Inter Governmental Panel for Climate Change (IPCC). Strangely, not one Indian newspaper has tried to find out, even as a matter of curiosity, what Pachauri has contributed to the science of climate change. I agree that his main job was administrative but isn't the media even curious? Wasn't it the research done by hundred's of scientists that enabled the IPCC to take the strong position it did about the urgency of dealing with climate change? Or is the Indian media under the delusion that somehow it was Pachauri heroically fighting opposition who convinced everybody to start acting responsibly on this issue?

In an earlier post I had written about this peculiar mentality of claiming an Indian connection to everything. In the hoopla over Pachauri's "achievement" there was one headline that was particularly revealing about the way we seem to think and link status, success and expertise.

Rajendra Pachauri backed N-deal - Hindustan Times

Now that Pachauri has "won the nobel" let's start asking his expert opinion on just about every subject under the sun. But expertise in one field does not translate into authority in another. Our media just doesn't seem to understand that.

Friday, October 12, 2007

Orissa and Hexavalent Chromium

A list of the most polluted places on earth prepared by Blacksmith Institute, an environmental group appeared in the Times of India, a few days ago. Not surprisingly it included two sites from India; Vapi in Gujarath state and Sukinda in Orissa state. Pollution in Vapi was mostly due to the chemical industry while that in Sukinda has a geological origin, the mining of chromite deposits. Sukinda mines account for a staggering 97% of discovered chromium ore deposits in India. Why is Orissa so unusually blessed or cursed some would say with chromite?

Chromite deposits form by a process of concentration by crystallization in magmas. But not just any magmas. Chromites are almost exclusively restricted to ultramafics, magmas rich in magnesium and iron. Chromite deposits occur in two varieties known as stratiform and podiform. As the terms imply, stratiform means layers of concentrated chromite within the ultramafic rocks, while podiform chromite occurs as lenses or pods of concentrated chromite within the ultramafics. The Sukinda chromites are stratiform. During the late Archean- early Proterozoic period around 2.5 to 2 billion years ago geologists estimate, massive amounts of ultramafic magmas originating in the mantle were injected into the crust in the area that is now Orissa. But why is chromium so concentrated in ultramafic magmas? Chromium is a refractory metal i.e. a metal with a melting point higher than iron and cobalt. It takes a large amount of melting in the mantle to release significant amounts of chromium in to the liquid phase. But large amounts of melting also make the magmas rich in magnesium and iron. So the connection of chromium and chromite deposits with ultramafic rocks.

Stratiform and podiform chromite deposits occur in distinctive tectonic settings. Stratiform deposits occur mostly within ultramafic intrusions in stable continental crust, while most podiform deposits originated in oceanic settings, either within ultramafic rocks associated with mid-oceanic spreading centres or in subduction zone associated back-arc spreading centres. Later, plate tectonic movements have obducted or thrust up these chromite bearing ultramafics to form sections of spectacular mountain belts. The best example in India are the podiform chromites in Ladakh (Karmalkar N.R. et al. 2000), which originated in the oceanic crust between the Indian and Asian continents in the Mesozoic period, and were subsequently thrust up to form the early Himalayan mountains as the Indian plate collided with the Asian plate.

Chromite deposits show an interesting age distribution indicative of the thermal and tectonic evolution of the earth.

Image Source : Stowe (1994). Stratiform deposits occur almost exclusively in the late Archean-early Proterozoic period (2.8 - 1.8 billion years ago), while podiform deposits occur almost exclusively in the Mesozoic and Tertiary periods beginning around 200 million years ago (there are some podiform chromites in late Proterozoic orogenic belts around 800 million years old). Anyone familiar with the geological time scale with readily appreciate that biological evolution has imparted a temporal uniqueness to the sedimentary rock record, enabling geologists to subdivide geologic history into different periods. What is less appreciated is that the thermal and tectonic evolution of the earth has also produced a distinctive rock record (a good idea for a post series). Chromite deposits are one good example. The mid late Archean-early Proterozoic was a period of intense continental crust building. Owing to the high geothermal gradients in the Archean (the interior of the earth was hotter then), there were periods of copious amounts of melting in the upper mantle and lower parts of earlier formed crust. So, were formed large ultramafic complexes and associated chromites. Over time, the earth cooled and large scale melting of the mantle became localized to plate boundaries. The breakup of supercontinent Pangea beginning in the early Mesozoic led to significant worldwide development of subduction zones and associated back-arc spreading centres and the origin of ultramafic hosted chromite. This activity culminated in intense amounts of mountain building activity in the mid-Mesozoic and early Cenozoic. So, podiform chromites occur mainly within tectonically emplaced slices of oceanic rock sequences in this age group. The gap between around 800 million years to 200 million years is one of geology's unresolved problems.

Chromium from Sukinda mines is present as air-borne dust and is also being leached into the groundwater and nearby streams in the form of hexavalent chromium (+6 oxidation state).

In image, the Sukinda syncline is clearly seen. In the core of the syncline the arrow points to the open pit Sukinda chromite mines. The rust color is due to oxidation of the ore. When ingested either through air-borne dust or through water, hexavalent chromium is reduced in our cells to pentavalent and trivalent chromium. This leads to a variety of health problems, including increased risk of cancer. An estimated two hundred and seventy thousand people around Sukinda are at risk or are suffering from chromium related poisoning. The Orissa Pollution Control Board have pleaded impotence, saying “It is unique, it is gigantic and it is beyond the means and purview of the (Orissa Pollution Control) Board to solve the problem,”. In effect they have questioned the rationale for their own existence. The board chairman L.N. Patnaik has predictably rubbished the report, saying that any mining activity will lead to some air pollution, apparently forgetting that chromium is getting into the water supply in massive quantities.

Hexavalent chromium gained recognition because of the movie Erin Brockovic, in which the character played by Julia Roberts campaigned successfully against a polluting industry. In India, maybe this lady on the left can help :-)


References:
Karmalkar N.R., A. G. Dessai and R. A. Duraiswami: Alteration of Chromite from the Dunites of Indus Ophiolite Belt, Ladakh 27-34, Himalaya, India, Gondwana Geological Magazine; V. 15 (1)- June 2000

Stowe, C. W. 1994. Compositions and tectonic settings of chromite deposits through time. Econ. Geol. 89:528 – 546

Wednesday, October 10, 2007

Climate and Point of No Return

The science section of the Times of India has a rather alarming article on global warming. According to Australian scientist Tim Flannery, we may have already emitted greenhouse gases to a threshold value that may cause "irreversible climate change". Flannery remarks that the Intergovernmental Panel on Climate Change (IPCC) report due in November will show that greenhouse gas level by mid 2005 have reached around 455 parts per million, a level not expected until a decade later. The Times of India calls Flannery a "world recognized climate change scientist". I looked up his credentials and found that he is a palaeontologist, an expert on mammals who over the course of his research I am sure has acquired a good knowledge of climate change. But he is not a climate scientist. Don't Indian science reporters ever do any background checks? He may well be right about greenhouse gases already passing some threshold, but with or without immediate thresholds, isn't climate change irreversible on the time scale of the next few hundred years anyway? Owing to the long residence time of CO2 in the atmosphere there is always going to be a lag between our reducing emissions and its effects to be felt in terms of stabilizing the temperature.

This press release reminded me of a cartoon I saw some time back.

Cartoon Creator: Mike Adams; Source: www.NewsTarget.com

Flannery's fears may be well founded. We should be doing better than this.

Saturday, October 6, 2007

Tiny Frogs and Fault Rocks

Two news items that caught my eye in the last week or so.

Tiny Frog is India's smallest land vertebrate:
Biologist S D Biju of Delhi University working in the western ghat forests in Kerala discovered a new species of leaf frog which they named Nyctibatrachus minimus. Adult males are barely 10 mm in length and can fit inside a 5 rupee coin (Image source Delhi Univ).

The pleasant surprise was that a press release from an Indian university was picked up by a major science news portal, in this case Science Daily. Indian universities do not have well organized proactive press offices. News of research rarely filters out even in Indian newspapers. Indian scientists for their part have remained largely invisible to the public. We meet them not through their books or articles or on radio and TV talk shows, but only on that tiresome "science day" when hordes of bored school children are made to walk through science exhibits in some government institution. There a government scientist will tell you how fulfilling a career option science is. Despite their best efforts, science as an activity doesn't register among young Indians as something exciting.

Fresh from within the San Andreas Fault:
In 2004, the San Andreas Fault Observatory at Depth, a monumental project to drill right into the world's most famous fault zone began. The San Andreas fault zone marks the boundary between the Pacific plate and the North American plate. The goal was to set up a deep monitoring system to analyse the movements of rocks along the fault zone. After drilling about 2 miles, geologists have recovered about a ton of rock from within the fault zone itself.

It is a magnesium aluminium rich silicate rock known as serpentinite (Image source: Earthscope). Its composition and physical structure will be invaluable in understanding the conditions at depth, and how this major plate boundary behaves and how earthquakes work. In time geologists using this deep monitoring system hope to refine earthquake prediction methods.

Tuesday, October 2, 2007

Diets, Consumption and Global Warming

Part 6 of the six part series on Pune pollution and environment.

Sometime back a blogger left a comment on one of my earlier blogs, suggesting a number of ways to reduce pollution. Among the many was, "don't drive, walk as much as possible", the rationale obviously being that using less fuel is good for the environment. In these times, when global warming is one of the big talking points, walking is the healthy and responsible way forward. But is it?

A few weeks ago I read a strange article in the Times of London, where a calculation was presented. Apparently if a person walks to the store and around the neighbourhood for errands, let's say around 3 miles or 4.8 km, then providing that person with enough calories to replace those burnt, emits more CO2 than if the person had driven to the store. Driving to the store and back according to the calculation will emit around 0.9 kg of CO2. On the other hand, walking to the store will burn around 180 calories. To replace that with a mostly beef diet will result in 3.6 kg of CO2 emissions. With a straight face the report says “The troubling fact is that taking a lot of exercise and then eating a bit more food is not good for the global atmosphere. Eating less and driving to save energy would be better.” This says a lot about how energy intensive the meat food production chain has become in developed countries. But not just the meat. If you try to replace those 180 burnt calories with milk, it will result in 1.2 kg of CO2 emissions, still more than driving. In 2002, in the United States, the food production system accounted for around 17% of fossil fuel use. Going vegetarian or "vegan"will reduce this burden. Another study has calculated that the difference in greenhouse gas emissions due to shifting to a veggie diet is as much as that achieved by shifting from an SUV to a standard car, a reduction of about 1.4 tons CO2 per person per year. Cutting meat altogether from our diet seems very unpopular at present. Recently, Michael O'Leary, the boss of budget airline Ryanair, came under heavy criticism when he remarked that global warming can be eliminated by slaughtering the world's livestock. Off course going veggie alone doesn't help as illustrated by this cartoon.

I walk a lot in Pune, so do I actually contribute more to global warming by walking and not driving. Suppose following the U.K example I walk around 4.8 km per day and burn about 200 calories. My diet these days is almost entirely vegetarian. Based on a Ford Foundation study on energy intensity of Indian agriculture I calculated that producing 1 kg of food will result in about 2 kg of CO2 emissions. This includes energy required for the entire food production chain including fertilizers and transportation. If I burn 200 calories, eating healthy I would have to eat about 300 grams of various vegetables to make up those burnt calories resulting in about 0.6 kg of CO2 emissions. Much less than the person walking in U.K. and gorging on beef later. Energy intensity of Indian agriculture is still much less than the industrialized food production of the west. If I drive those 4.8 km in my Fiat (that old beast still chugs along) this will result in about 1.15 Kg of CO2 being emitted. But if a person zips around on a two wheeler, driving 4.8 km to the store and back will emit around 0.19 kg of CO2. In Pune, walking over short distances is better than driving a car, but not better than driving a two wheeler when it comes to replacing burnt calories and emitting greenhouse gases.

This will work as long the person maintains a particular weight. If a person starts overeating then all those extra calories represents extra emissions of CO2. This is likely to be a problem in urban India with all the new found prosperity. Trends of weight increase in urban Indians suggest that 40 to 50 million Indians have become overweight over the last few years and it could get worse. To gain one pound a week one has to eat 500 calories extra per day. That is a total of 3500 extra calories. Urban Indians are becoming fat not by eating huge amount of healthy veggies, but by stuffing themselves with calorie rich foods like sweets and oil rich fried stuff. That would mean they will require about 900 - 1000 grams of extra food to put on 1 pound of weight or 20 kg of extra food to gain 10 kg weight. The energy intensity of producing smaller amount of sweets and oil is probably the same as consuming larger amount of veggies. Going by this assumption, that would mean additional emissions of about 230 kg CO2 for every 10 kg of weight increase. If 50 million Indians become overweight by 10 kg that will result in additional emissions of 11.5 million tons of CO2. The figure will be much more if they start eating more chicken, since poultry industry is becoming very energy intensive, western style. My calculations are probably off by some amounts but the intent is to show that obesity and consumption has unexpected consequences.

How are urban Indians doing when it comes to personal lifestyles and the contribution thereof to global warming? Why not find out? Use the personal CO2 calculators I have listen below to calculate how much you contribute to global warming.

Carbon Counter
Conservation Fund Calculator
Carbon Footprint Calculator

To help you out here is a conversion list:

1 Dollar ~ Rs 40
1 gallon = 3.37 litres
1 kg = 2.2 lbs
One unit on your MSEB electricity bill ~ 1 kwhr.
1 cylinder of cooking gas (Propane) ~ 16.5 litres
Fuel Economy: 1km/lit = 2.35 miles/gallon
1000 kg = 1 ton

Compare your emissions with those of households of other nations given below.
CO2 Household Emissions by Country:
Australia - 14 tons/yr
China - 2.4 tons/yr
U.K- 9.8 tons/yr
U.S.- 19.06 tons/yr.

In the interest of full disclosure, I emit about 4 tons per year, a little more I suspect than many Puneites, primarily due to international travel.

This has been a fun series to write. I will be writing on and off about Pune so watch this space.

Part1. Idling and Pollution
Part2. PMT buses and Pollution
Part3. Rickshaws and Pollution
Part 4. Urban Forests and Clean Air
Part 5. Sensing Corruption Remotely