Tuesday, March 27, 2007

DIY Water Treatment, Part II

This post is the second of three discussing possibilities for self-reliance in water treatment using charcoal filtration. The first installment provided a general primer on the downsides of chemical pesticide application in industrial agriculture. In this installment I summarize the results of our investigation into the particular agrochemicals of concern in northern Thailand. In the next post I’ll describe our work designing a drinking water treatment system.

DIY Water Filtration
Part II: Agrochemicals of concern

In order to have some idea of what contaminants might be in the canal water, we first had to come up with a list of particular agrochemical products commonly used in the region and in Thailand in general. We used three strategies to identify these suspect substances: (1) interviewing local farmers and the proprietors of local feed shops where the chemicals are purchased; (2) literature research via the web on the most prevalent imported agrochemicals in Thailand; and (3) investigating refuse (trash piles, garbage bins, etc.) in and around nearby fields and orchards.

Our pesticide detective work revealed the following:

Out of the twenty-nine agrochemical products we identified…
…sixteen are moderately to highly acutely toxic to humans
…eight are possible human carcinogens and three are known human carcinogens
…nine are cholinesterase inhibitors – neurotoxins, in other words
…eight are suspected endocrine disruptors
…five are reproductive or developmental toxins
…nine are classified as “Bad Actors” by the Pesticide Action Network
…and thirteen represent significant threats to groundwater contamination.

OK, so are you ready to go organic yet?

Chemical warfare, over-the-counter

An informal survey of local farmers and the staff of local feed shops (where agrochemicals are purchased by local farmers) identified several chemicals applied widely and liberally throughout the region that may constitute a threat to drinking water supplies. Of this list of seventeen pesticide products, nine are classified by the Pesticide Action Network (PAN) as “Bad Actors.” Bad Actors are chemicals that exhibit one or more of the following properties: high acutely toxicity, cholinesterase inhibition (neurotoxicity), known or probable carcinogenicity, known reproductive or developmental toxicity, or are known to constitute a groundwater pollution threat. Furthermore, PAN identifies propiconazole, tebuconazole, metalaxyl, mefenoxam and fluazifop as potential groundwater contaminants.

A wide variety of agrochemical products are available at a shop in nearby Ban Pajee.

In addition to surveying the products at the local feed stores, our research of the literature on pesticides in Thailand revealed that out of the ten most prevalent agrochemicals imported to Thailand, six are classified as PAN Bad Actors and seven constitute threats to groundwater contamination. These seven are: methyl parathion, methamidophos, methomyl, 2,4 D, atrazine, ametryn, and paraquat.

Biocides in our backyard

As the hot-and-dry season got hotter and drier, the grasses and trees in and around Pun Pun responded by turning a golden color and shedding their leaves. This seasonal transition gives the contrasting emerald green hue of the neighbor’s conventionally farmed orange grove and almost cartoony quality. Despite the examples set for successful organic gardening and permaculture by Pun Pun and the adjacent Panya Project, the absentee owner is practicing the unfortunately typical style of inefficient and chemical intensive farming.

These methods are inefficient because they depend on big inputs of capital, energy and materials that would be unnecessary under organic conditions. For example, instead of enriching the soil with organic matter, synthetic fertilizers are applied to provide nutrients to the trees. And instead of cultivating a diverse mixture of species that provide pest deterrence for one another, synthetic pesticides are applied in staggering quantities. Well, fertilizer causes everything to grow, including the weeds, which then necessitates either the application of herbicides or mechanical removal (i.e. mowing, weed-whacking).

The orange grove viewed from Pun Pun. The road leads up the hill to the cooking school at You Sabai. The thatch roof in the lower let corner is my house. Note the fishpond just below.

When you stand back and look at the orange grove, what’s remarkable is that there’s all this green grass growing up between the trees. Everywhere else the grass is a nice gold color – dry – hanging out and waiting for the rains to come. But in the orange grove they have a real grass problem. The watering system is really inefficient – the sprinklers spray water everywhere: up into the air and onto the leaves of the trees where a lot of it evaporates before it even hits the ground. The sprinklers often spray water onto the road, which causes washouts and makes it hard to get up to You Sabai with the motorbike. The fertilizer is applied to make the orange trees grow, but the grass competes for it as well. So the owner is spending all this money buying chemicals and pumping water, most of which never make it to his cash crop and instead cause this lush green grass to grow, for which there’s no use so he’s got to hire some guys to go out there twice a week and mow all the grass down with gas powered weed eaters – and there’s more money and energy spent that perpetuates the self-stoking cycle of inefficiency that characterizes conventional agriculture.

And the dunderheadedness of this is not even the worst part. The truly bad news is that the orange grove is up-gradient from the water canal and Pun Pun’s several ponds – ponds stocked with fish to eat and to store water for showering and irrigation of our gardens. Within a landscape, ponds are hotbeds of ecological diversity and thus are critical features in permaculture design. But it turns out most agrochemicals wreak all kinds of havoc on aquatic ecosystems. So there’s serious concern about what’s being applied to those orange trees and what it will do once it reaches the ponds – an undoubted eventuality

Looking back at Pun Pun from above the orange grove. Pun Pun has several ponds in the low-lying area below the grove. Our water is pumped from the lowest pond – visible at the right edge of the photograph.

It’s pretty easy to work out which chemicals are applied in Thai farm fields because, sadly, it’s fairly common practice to toss empty containers in the weeds and leave half-empty bottles of chemicals lying about. The orange grove proved to be no exception in this aspect of agricultural intransigence. Our investigation of discarded agrochemical packaging and empty containers we found lying around the perimeter of the orange grove revealed that ethyl hydrogen phosphonate, chlorpyrifos, propiconazole, and dimethoate are among the pesticide chemicals being used. Thus far we haven’t found significant toxicological data for ethyl hydrogen phosphonate; however, chlorpyrifos, propiconazole, and dimethoate are all classified by PAN as Bad Actors, exhibit moderate to high acute toxicity to humans upon exposure, and are moderately toxic to very highly toxic to aquatic species.

Some discarded agrochemical product containers found in the weeds around the perimeter of the citrus grove and adjacent to the Pun Pun community.

Chlorpyrifos is a suspected endocrine disruptor. Both chlorpyrifos and dimethoate are associated with cholinesterase inhibition, an indicator of neurotoxicity, and can be absorbed through the skin. Propiconazole and dimethoate are possible human carcinogens as well as developmental or reproductive toxins, and are identified by PAN as potential groundwater contaminants.

A photo indicating the proximity of the discarded pesticide containers to one of Pun Pun’s fish ponds.

Back to the lab

When I signed up to learn about organic farming, seed saving and earthen building at Pun Pun, I had no idea that the experience would end up taking me back to the chemistry lab. In fact, I came to Thailand expressly to break my association with academic science and all its abstractions and frequent irrelevance to the “real world.”

But now I have a list of thirteen chemicals that are terribly destructive to the environment and stupendously poisonous to human beings and are in all likelihood leaching into groundwater supplies all over northern Thailand. And I want to know if an impossibly humble material – homemade charcoal – can effectively scrub these nightmarish substances out of our drinking water. So a trip back to the laboratory seems unavoidable…

Ideally, we could design some experiments to determine the adsorptive capacity of our homemade charcoal for the contaminants of concern. This will take some time though, and of course requires chemical reagents and analytical equipment not readily available in rural northern Thailand. But luckily I have some friends at universities around the US who are keen to help out. At the moment, we’re packing up samples to send to an environmental engineering professor who’s offered to run some analyses on the quality of our charcoal. We’ve also been trying to make inroads with Thai universities to see what collaborations may be possible. And I’m looking into potential sources of funding support. But for the moment, despite the lack of specific data I believe it’s possible to design a system around a general set of parameters and make conservative estimates regarding its capacity for contaminant removal. I’ll discuss this design strategy in the next post.

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