Reblog:New scientific study on plastic entering the ocean

February 13, 2015

Reblog from Algalita Blog

How much plastic is entering the ocean?

An important article has come out in Science Magazine. This is the first scientific study to systematically estimate the amount of plastic going into the ocean from land. It also highlights the geographies that contribute the most and provides insights into the relative impact of different mitigation strategies.

ballona-creekOne thing we have learned from this article is the estimated amount of plastic going into the ocean is far greater than most previous estimates. Yet, overwhelming amount of plastic going into the ocean today pales in comparison to what scientists estimate for the future. I have been studying this area for 15 years and it’s gone up by two orders of magnitude – it is approximately one hundred times worse than what I measured in 1999. This article is stating they expect an increase of ten in the next ten years.

Habitats are normally damaged by removing valuables from them, such as animals, plants and minerals. In a complete turnaround, we are destroying our ocean habitat by inserting our valuable polymer plastics. This leads us to a clear understanding of why the status quo HAS to change by adopting a zero waste circular economy—if we don’t, it will be ten times worse than it is now, or a thousand times worse than I found it in 1999.

Plastic consumption in developing countries is increasing and because many of these countries do not have sufficient waste collection, more plastic is entering our ocean each day. We keep hearing Mismanaged Waste. That implies that burning waste in an incineration or burying it in a landfill is properly managed waste, but it’s not. We believe in Zero Waste. This so-called managed waste is composed of precious resources that need to be recovered.

algalita-global-estimate-plastic-pollutionThe quantity of plastic in the global ocean’s five accumulator gyres has reached a level that is destroying their fragile ecosystems. It is reasonable that plastic manufacturers, who profit from externalizing the cost of dealing with their products that become waste, take some responsibility for the destruction of gyre habitat and help remove some of the tonnage of plastic causing the damage. Additionally, this would incentivize manufacturers of plastic products to design them to be easy to recycle and help create the infrastructure to process the collected plastics.

In 2013 International Coastal Cleanup Day had 648,015 volunteers from 92 countries combing coastlines around the world. In one day they gathered about 12.3 million pounds (about 6,000 tons) of trash, much of which was plastic. Even if it was all plastic, it would only be a third of what goes into the ocean each day, based on a mid-range estimate from the Jenna study. We would have to have a worldwide clean up 3 times a day, every day of the year to clean up what is ending up in the ocean, although much of the world’s coastal areas were not covered by the volunteers.


In the North Pacific Gyre this summer, Algalita researchers took plankton samples from 10 meters below the surface. In our lab, we found that every spoonful of plankton looked at under a microscope had tiny plastic fibers in it. Gyres were pristine areas where virtually nothing floated for long. The creatures there think anything floating is something to eat. The plastic is being consumed in high quantities, has no nutritional value, and is toxic. On top of all this, floating garbage in the pristine ocean is UGLY and constitutes an aesthetic. An ugly world, poisoned by our waste, is not a world we want to live in, and bequeath to our progeny.

What can we do? Single use disposables are the biggest culprit. Targeting waste from “use once and toss” plastics is the key. We can’t solve the ocean plastic problem at scale without addressing waste management in developing countries. We can change habits and behavior. People are rational if they are given rational reasons for changing their habits.

As members of the Trash Free Seas Alliance, Algalita is happy to see that this information has been made available through Science Magazine. This is an important study and we must act on the information it provides, or we will see the status quo based prediction of exponential increase in marine plastic pollution by 2025 come true.

Read the article here.

Homemade sea water for testing an ROV

March 16, 2014

Our GHCHS Algilata OpenROV project is not located near the ocean.   The OpenROV community has found that salt water operation can be flakey compared to fresh water due to low resistance between the salt water and  external wires that connect the battery tubes and the motors.     This post deals with making simulated sea water for testing the OpenROV in the lab.

Sea water conducts electricity due to the dissolved salts that produce ions for transporting charge between conductors submerged into the water.   Typical sea water has 35 parts per thousand  by weight of salt in water.    Since water at standard conditions weighs 1000 grams/liter then we can say that sea water has 35g of salt per liter.

I wanted to use just a cup measure to make a batch of sea water.     So I weighed one cup some Himalayan salt and found that it weighed 8 oz.  So we can estimate the weight of salt using this ratio…about 1  avoirdupois oz weight per 1  fluid oz .   Of course this will vary with the granularity of the salt due to variations in packing density but it should be good enough for conductivity testing.

Given that there are 28.3 grams per avoirdupois oz and  33.8 fluid oz per liter the sea water concentration of 35 gm per liter converts to  1.24 avoirdupois oz per 33.8 fluid oz or

1 avoirdupois oz per 27.2 fluid oz.

Since 1 cup (8 fl oz) of Himalayan salt weighed 8 avoirdupois oz then I would need to mix this with 217.6 fluid oz of water or 27.2 cups of water (1.7 gallons)

So I now have a simple rule of thumb for adding granulated salt to water using a volume measure:

volume ratio salt:water  1 : 27.2 

Other useful equivalents:   5.7 oz salt per gallon of water

                                              1/4 cup salt to 6 3/4  cup water

                                             1 tablespoon  salt to  1.7 cups water

Measuring salinity using conductivity:

Scientist often use conductivity to estimate salinity.   Standard units of conductivity are Siemans/meter  (S/m).    The electrical conductivity of 35 ppt salt water at a temperature of 15 °C is 42.9 mS/cm  (ref).   Thus 35 ppt equates to 42.9 mS/cm.


Taken from wikipedia

Conductivity measurements assume that there are two parallel electrical plates of area A in water at a distance L apart.   If a voltage (V) is put across the plates and the current flow (I) measured then the conductivity  k = I/V*L/A =  L/(R*A)  where R is the resistance V/I.    Under ideal conditions the conductivity between the ROV wires and the water should be very low (high resistivity) but if a small area of copper is exposed  then conduction can occur. eg  some OpenROV forum members are finding resistance on the order of kiloohms rather than megohms.

Practically, if you put two probes from an ohm meter into water, the measured resistance will depend upon the area of the probe submerged and the distance between them.   You can use this as a reference to test your simulated sea water at home.

conductivity plug testerI made a simple  crude conductivity  instrument out of a two prong to three prong electrical plug adapter.   The plug prongs are separated by 1 cm and the exposed area between the prongs is almost exactly 1 sq sm.  I covered the non-facing sides with tape or you  could use paint or nail polish to insulate the surfaces from water.   See photo.

In the field,  dip the plug tester prongs into the water and measure the resistance between them.  Note the temperature since conductivity varies a lot with temperature.

Theoretical  plug conductivity prediction for sea water.

k = L/(R*A)  = 1/R            S/cm

= 1000/R    mS/cm

Typically sea water resistance in ohms for this homemade instrument  at 15 deg C would be

R_ohms = L/(A*k)= 1cm/(1cm ^2)/(42.9 mS/cm) = 1000/42.9 = 23.3 ohms

When creating your simulated sea water at  home you would like to have similar conditions.   You would add salt to your water tank/tub until the resistance level matched.


I did a quick conductivity test by dissolving 1 tablespoon of Himalayan sea salt in 1 3/4 cups of water.   The measured resistance  using my plug conductivity tester was around 3 kohms with a VOM meter and using the voltage / current method the resistance was 230 ohms.     So it is reading much higher than the theory.    The test was done at 70F (21C).   Temperature changes the conductivity about 2% per degree.  The measurement was 6 deg C higher so at most we would expect a 12%  increase over the 15 C reference.

The absolute measurements can vary too much with conductivity so I would recommend just using the 35g/kg  salt/water mixing method or just doing relative conductivity measurements..i.e.  matching field conductivity to home conductivity under similar conditions.

Making Fat Shark FPV goggles work with OPENROV ($7 solution ?)

March 7, 2014

Robodox ROV team is building an OPENROV 2.5 kit for Algalita Research Foundation to take on their July 2014 Pacific Gyre expedition.    The ORV catamaran , named Alguita, will take a team of scientist to sample and analyze the effects of plastic in the ocean on marine species.    To help extend their capability to locate plastic concentrations they are utilizing a variety of sensors.   One is a Phantom quadcopter drone equipped with a Fat Shark Predator V2 FPV system.

IMG_7776The Predator V2 uses two LCD screens to display video in goggles show below.


The Predator specifications are shown here.   Pictures are sent from an aerial camera platform to the goggles in real time over a 5GHz wireless link.

openrov 2.4The underwater ROV that Robodox is building will do a similar function by transmitting HD camera video to a topside Laptop computer over a two wire tether.    It would be desirable if the Fat Shark video goggles could also display the Laptop video sent by the ROV.    Unfortunately the video formats are not compatible without a VGA to composite video converter.   I did a little research into how this could be accomplished.

Here is the plan:

1) purchase a Tmart $3  VGA to A/V RCA converter.  03m-VGA-to-SVIDEO-and-RCA-Female-Cable_320x320

2) Purchase an $3.50 Allelectronics 3.5mm  A/V  to RCA cable with 6 ft  extension to allow freedom of movement between the laptop and the goggles.

3) Plug the VGA converter into the laptop VGA output port and then plug the 3.5mm A/V cable into the Fat Shark video input port via the extension.   Turn off the Fat Shark wireless receiver.

Seems like this would work…yet to be tested.

Wireless Connection to the Fat Shark

The transmitter side of the Fat Shark FPV system involves a small 600 TVL camera that plugs into a transmitter compatible with the receiver in the goggles.

Fat Shark tranmitter

If the transmitter is available on the boat (ie a spare that is used for the Phantom drone) then the output of the converter could be used in place of the camera output that plugs into the transmitter.   This way the goggles could be free from any wires. There would be another plug adapter to mate the composite video RCA plug to the plug on the xmitter.

Robodox 599 Algalita 2014 Youth Summit Video Submission

October 30, 2013

Note 6 BBB: Creating OPENROV image with Virtualbox (problems still)

October 28, 2013

I followed the procedure   to use the Virtualbox /Vagrant approach to generate an OPENROV image.   I am really enthusiastic about the fact that I can run Linux easily on my Toshiba Win 7 machine.

Fixing the number of processors

The first problem I ran into was the Vagrantfile in the openrov-image-master GIT repository has a default of 2 cpu’s for the Virtualbox.    My Toshiba Satellite L655 intel processor doesn’t have hardware virtualization (VT-x) capability available in the bios.   The default value of 2 processors  requires VT-x.   I fixed this by editing the Vagrantfile to use 1 cpu and at least got ubuntu installed.  Here is the new Vagrantfile:


# -*- mode: ruby -*- # vi: set ft=ruby :

Vagrant.configure(“2”) do |config|  

# All Vagrant configuration is done here. The most common configuration  

# options are documented and commented below. For a complete reference,  

# please see the online documentation at = “ubuntu-12.04-32bit”   config.vm.box_url = “”   config.vm.provision :shell, :path => “”

config.vm.provider :virtualbox do |vb|          

vb.customize [“modifyvm”, :id, “–ioapic”, “on”]     

vb.customize [“modifyvm”, :id, “–memory”, “2048”]     

# you cannot use more than one cpu unless you have hardware virtualization. So for my Toshiba laptop I have no VT-x in BIOS   

vb.customize [“modifyvm”, :id, “–hwvirtex”, “off”]     

#vb.customize [“modifyvm”, :id, “–cpus”, “2”]



end code:

Use Chrome over IE

Problem with IE downloading ubuntu-saucy-console-armhf-2013-09-26.tar.xz  .   Apparently IE creates a tar out of this that must be unzipped.   PEA zip gave an index out off range error and I could not unzip the file.   Used google Chrome and worked ok.     I added the file to the Vagrantfile.

Logging in

I used putty to SSH into the Virtualbox.

User: vagrant

Password: vagrant    (It took me a while to discover this!!)

When ubuntu boots it goes to the home directory.

First thing is to change the directory to  /vagrant and list the directory since this has the build script.

Welcome to your Vagrant-built virtual machine.
Last login: Fri Sep 14 06:22:31 2012 from
vagrant@precise32:~$ cd /vagrant
vagrant@precise32:/vagrant$ ls
]             lib      putty info 10.24.txt    ubuntu-saucy-console-armhf-2013-09-26.tar.xz
contrib       Vagrantfile

I list the directory using “ls” command and then copy the long name of the .tar.xz file and use it in the build command
vagrant@precise32:/vagrant$ sudo ./ ubuntu-saucy-console-armhf-2013-09-26.tar.xz –black

When running be sure to add the processor type  as a second argument.  For me this is “–black”.

Updating Ubuntu

The next error was the need to install some missing tool packages.  I  wrote a shell script that is called in the Vagrantfile to load boot tools, git, nodejs,npm qemu-user-static,cross compiler etc.  Here is the script


echo “updating ubuntu with nodejs,crosscompilers ,git,qemu-static etc”

sudo apt-get update

sudo apt-get install -y dosfstools git-core kpartx u-boot-tools wget

sudo apt-get install -y nodejs nodejs-dev npm

sudo apt-get install -y debootstrap qemu-user-static qemu-system git

sudo apt-get install -y g++-4.6-arm-linux-gnueabihf

#end script is called in the Vagrantfile by adding a provisioner statement

config.vm.provision :shell, :path => “” 

Build Errors

Currently I still am getting some build errors related to unsuccessful mounts and failure to make some directories:

mount: wrong fs type, bad option, bad superblock on /dev/mapper/loop0p1,


mount: mount point /vagrant/root/dev/ does not exist

mount: mount point /vagrant/root/proc/ does not exist

mount: mount point /vagrant/root/sys/ does not exist

mount: mount point /vagrant/root/run/ does not exist

mount: mount point /vagrant/root/etc/resolv.conf does not exist

cp: cannot create regular file `/vagrant/root/usr/bin/’: No such file or directory

mkdir: cannot create directory `/vagrant/root/tmp/work/’: No such file or directory

Here are more complete debug files

installation debug printout

dmesg and partd printouts

Anyone have some ideas??

Proposed Towed Ocean Debris Location and Evaluation Robot (TODLER)

May 22, 2013

Algalita has an informal sensor working group to help them define requirements for a 2014 voyage to sample plastic debris in the Eastern Pacific ocean.    I had proposed using robotics to assist them in some way such as a ROV or possibly R/C boat or helicopter with cameras.     These are local aids but the general problem of mapping the ocean debris remains largely unsolved due to inadequate sensors.   I began thinking there would be a need for a coarse debris ocean plastic sampler that could be towed by any ship or research vessel in the ocean including the Liquid Robotics Wave Glider which would be cheap, reliable and easily deployed.     So I wanted to start a requirements study for a proposed Towed Ocean Debris Location and Evaluation Robot (TODLER)

Why TODLERTotal debris weight data can be useful in estimating plastic content:  The plastic in the ocean is now reaching weights that are 6 to 40 + times more than the  dry biomass floating in the ocean.   E.g.  Algalita reported in 2001 that the plastic to plankton dry weight of the  was 6.1:1.   Subsequent voyages found much larger ratios… nearer to 40:1.   The ratio is increasing every year due to the influx of plastic from the rivers, ship dumping and natural disasters such as the Japanese tsunami.    Although we are interested in the amount of plastic in the ocean… measuring the total debris weight would give a reasonably accurate assessment due to the large plastic to biomass weight ratios.    It would avoid the tedious job of carefully separating biomass and plastic in the lab and give many more opportunities to collect samples world-wide.  The samples would measure the weight of wet biomass plus the debis so the ratios would be slightly lower than those mentioned above.

A total debris sample might have one additional data point… the difference between the dry and wet weight of the sample.   This could give an indication of the amount of biomass present.    The usefulness of this would vary depending upon the ratio of plastic to biomass.   On tows that do not sample a lot of plastic one could reduce the error in the plastic weight estimate by about 16% (in 6:1 ratio sample) but this would be of little use in a 40:1 .    The wet/dry ration would require some type of air or centrifugal water extraction device.   A tradeoff study would determine the cost effectiveness of the wet-dry weighing.

Concept:  This is a small towed robotic vehicle that contains  a mini  Manta plankton trawl net capability which can collect a debris surface sample, weigh the contents , record and transmit data to the towing vessel and then clean the net for another sample.   The sample time would be programmable and be based upon a flow sensor to ensure that the ocean area covered is consistent for each sample.  The total debris weight would be used to estimate the plastic debris weight.

There would be several versions of the system each with different capabilities. The baseline version would sample only the surface at <5 knots and be towable by small craft say less than 50 ft.  Follow-on versions would be capable of  sampling at greater depths and at higher speeds.   The higher speeds would allow TODLER to operate during normal ocean cruising speeds for small yachts or research vessels.  This could allow a large  amount of data to be taken by volunteers willing to tow the robot.  Automatic data logging would be a useful feature to simplify the tasks of the volunteer.     If proven successful, it might be adapted later for large cargo ships  to take data during normal voyages.     These added capabilities would change the design significantly due to the weight and stress on the towing tether.  However, possibly adding an intermediate small craft like pontoon boat/raft which had the main tether load attached to it could mean the TODLER would have a uniform interface for all its tow boats.

Prototype design driving requirements:


I.1)Towable by a  Wave Glider which can patrol the oceans at speeds from .4 to 1.5 knots using the power of the waves.   The Wave Glider weighs about 200 lbs and displaces a maximum 300 lbs.  If we assume that the drag is proportional to the displacement and we don’t want the Wave Glider to slow down too much.. then perhaps we should keep the TODDS at 30 lb limit and require it to have an aerodynamic shape.

I.2)Portable enough to fit on the Algalita  25ft x50ft ORV .  Perhaps a volume of a large duffel bag including its tow ropes and electronics.

I.3)Max off-board sensor power  13.3v at 3 amps or 40 watts. (Wave Glider driven)


II.1) Initial tow speed capability: 5 knots

II.2)Final tow speed capability TBD knots:   near the maximum speed of the Algalita ORV. (although Manta nets are typically towed at a maximum speed of 2.5 kts we would want the capability to collect plastic on outward and inward journeys without slowing down.  This could drive biomass into the mesh possibly making the scrubbing process more complex.)

II.3)  Net area:  TBD   I would like this to be small to make cleaning easier and to keep the robot volume small.   If it was 10% of the area of a Manta Trawl (209 sqin) this would make it around 20 sqin or the area of a 5 in diameter circle.  To match the ocean area of a manta trawl the tow distance would have to be increased from  about .7 km to 7 km.  If towed by a Wave Glider there could be a series of circular tows made during a voyage that would allow the sample taken to be constrained to a 1 sqkm area.

II.4 Net samples before replacement:

Prototype 40 samples

Wave Glider improvement:  Last 6 months (180 days x 6 samples per day)    ~1000 samples

This might involve having spare nets that can be changed periodically.

II.5  Measure only the wet weight of the sample.

More later:

Is this a viable thing to do??  Your comments are welcome.

Examination of the B-240 plastic to oil system for cleaning up the oceans

October 29, 2012


b-240-3g  Updated brochure.

This system fascinates me and I wanted to do a back of the envelope calculation with respect to its cost per kilo of cleaning up the plastic and how many of these you would need to have going to keep up with the plastic in the ocean.

Ok, lets summarize what it claims:

Throuput: 2.7 gal (.0643 barrels)  per hr  from 22 lbs (10 kg)  of plastic.

Per day this produces about 1.5 barrels of oil from 240 kg of plastic.

We can look at this in terms of energy:  Assume density of HHV bio-oil 4.55kg/gal and 17.9 MJ/kg then 2. 7 gal/hr equates to 220 MJ/hr .   The price of bio-oil is running around 6 Euro/GJ so the value of the oil produced is about  1.3 Euro/hr (1.69 $US).

Energy use:   Stated as 7 kw per hr.   Not sure how to intrepret this since it is a power per hour rather than energy per hr.     Energy units are usually kwhr.  If we ignore the per hr and assume it consumes  7kw  then the machine would use 7kwh per hr .   Residential electricity costs about 10 cents per kwhr however on a ship it is probably much higher.   But even at 10 cents per hr it would cost about a $1/hr just for electricity.

Plastic density:

Plastic density varies considerably in the ocean.  For example, sampling in the North western Atlantic showed an avg might be .1 kg/per sqkm up to a max of about 1.4 kg per sq km

Suppose for convience, we assume a plastic density in surface waters to be  1 kg per sq km .  So we would need 10 sq km per hr of ocean clean up to keep this machine going .

How can we get that kind of input stream?  Lets consider two conceptual ways both involving what I call Sea Kites the are flown in the ocean.  Boyan Slat Marine Litter Extraction Array (MLEA) is fixed and the Ralph Schneider Floating Horizon is propelled by the waves.

MLEA concept:

Lets suppose that the sampling is done with a fixed boom that filters sea water out like Boyan Slat’s Sea kites.   The average current assumed in a 5 year gyre rotation is about .2 km per hr so this leads to a boom length of  10 sq km per hr/.2 km per hr  = 50km.

So it appears that with the 1 kg/km plastic density about 1 Sea Kite of 50km would be required to keep this machine busy.

Floating Horizon:

The basic sweep width is 7 m x  2 km/hr = 14 000 sq m/hr   = .014 sq km/hr

To sweep 10 sq km/hr one would need about 700 units and some how be able to consolidate the collection for processing.    Ralph had proposed about 4000 units to clean the entire ocean area with 570 units per service ship.   Thus, one of the machines could be assigned to a service ship.

Cost of Machine and Solar arrays:

B-240   $200,000 ??

Marine quality solar arrays  $8/watt*5000 watt = $40,000

Probably need a plastic shredder , rinser, oil collector, conveyors ..  $300,000

More later: