10-Jun-2019: Massive 8,000-mile 'dead zone' could be one of the gulf's largest
Just off the coast of Louisiana and Texas where the Mississippi River empties, the ocean is dying. The cyclical event known as the dead zone occurs every year, but scientists predict that this year's could be one of the largest in recorded history.
Annual spring rains wash the nutrients used in fertilizers and sewage into the Mississippi. That fresh water, less dense than ocean water, sits on top of the ocean, preventing oxygen from mixing through the water column. Eventually those freshwater nutrients can spur a burst of algal growth, which consumes oxygen as the plants decompose.
The resulting patch of low-oxygen waters leads to a condition called hypoxia, where animals in the area suffocate and die. Scientists estimate that this year the dead zone in the Gulf of Mexico will spread for just over or just under 8,000 square miles across the continental shelf situated off the coast.
When the oxygen is below two parts per million, any shrimp, crabs, and fish that can swim away, will swim away. The animals in the sediment [that can't swim away] can be close to annihilated. Animals like shrimp will often search for more oxygen in shallower waters closer to the shore. Shrimp subjected to hypoxic waters are smaller, their growth stunted by pollution.
Dead zones are not unique to the Gulf of the Mexico, though the gulf's is estimated to be the world's second largest. In the world's largest dead zone, in the Baltic Sea, low oxygen devastated fisheries, and most marine animals can no longer survive there.
Off the West Coast of the United States, California and Oregon crab and oyster industries have reported profit losses since the early 21st century, saying the annual wave of low oxygen ocean water has destroyed many of the animals they normally fish from the sediment.
Dead zone causes: Much of the Midwest saw unprecedented rainfall this spring, leading to a large increase in the amount of runoff washing into the sea. Many farmers were so affected by the intense rains that they were unable to plant crops like corn and soybean, meaning all the nitrogen and phosphorus-rich fertilizer they had spread washed into the Mississippi. Scientists are predicting that a warming climate could lead to more extreme rainfall in the region and ultimately make it more difficult to control fertilizer runoff.
The best way to solve the issue is to limit the nutrients at their source. Once they're in the river, there's no good way to reduce them. Better management practices could reduce the size, and suggested maintaining soil health by rotating crops, using less fertilizer, and using crop covers to keep soil in place.
Other than agricultural runoff, sewage water and weather also impact the size of the dead zone.
Farmers are already adopting practices to reduce nutrient runoff. Precision farming and artificial intelligence are both helping farmers reduce the amount of fertilizer they need to use on crops. High costs and a steep learning curve are making it difficult for the sustainable technologies to be adopted by all farmers.
Warm water is less capable of carrying oxygen, and a study published last year noted stretches of low-oxygen water thousands of miles across the ocean. Climate change is also expected to cause more intense precipitation and flooding in the Midwest, which will contribute to the amount of chemical fertilizer washed into the ocean.
6-May-2019: Traces of banned bisphenol A found in baby bottles
Despite the use of bisphenol-A (BPA) being prohibited in feeding bottles for babies, the toxic chemical continues to be found in some bottles and cups for babies sold in the Indian market, and is leaching into baby foods, found a recent study conducted by Toxics Link.
BPA is an endocrine-disrupting chemical that has been accepted as the “chemical of concern” globally, and countries have taken action to phase it out from products. The toxic chemical is known to mimic a hormone in the body which activates the progression of cancer and interferes with the development of the reproductive system.
Epidemiological studies of children indicate correlations between BPA exposure and heart diseases, liver toxicity, and metabolic syndrome (diabetes obesity). As per the current Bureau of Indian Standard (BIS) regulations, the use of BPA is prohibited, but the current study observed the migration of BPA in baby feeding bottle samples.
A set of 20 samples of baby feeding bottles and sippy cups were randomly collected from eight states: Gujarat, Rajasthan, Kerala, Andhra Pradesh, Jharkhand, Maharashtra, Manipur and Delhi. The samples were sent to the Indian Institute of Technology, Guwahati, for the study titled Bottles can be Toxic- Part II.
The collected samples included both branded and local feeding bottles as well as sippy cups of different brands. Ten (seven bottles and three sippy cups) of them were labelled ‘BPA-free’ or zero per cent BPA.
It was observed that all 20 samples showed release of BPA between 0.9 ppb and 10.5 ppb (parts per billion) in its first extraction and 0.008 ppb and 3.46 ppb in second extraction from the same containers (migration was analysed two times).
Only one sample of baby feeding bottles showed no level of BPA migration in its second extraction; the same sample showed the lowest concentration in the first extraction.
The results suggest that there is a chance that the containers have more BPA. In the earlier studies, the total BPA level was detected between 0.1 and 98.4 ppm (parts per million) in baby feeding bottle, while in sippy cups it was detected between below detectable level to 14.9 ppm.
Earlier the baby feeding bottles and sippy cups were manufactured with polycarbonate in which BPA was the main constituent (BPA is the building block for polycarbonate). However, after the prohibition of BPA, it is quite surprising that traces of BPA are still being found in the bottles. Similarly, traces of BPA were also detected in the sippy cups. Hence, it raises questions on the material being used in baby feeding bottles and sippy cups.
Toxics Link had undertaken the first study in India in 2014 on the presence of BPA in baby feeding bottles, and found high presence of BPA in the samples tested. Subsequently BIS revised the standard for baby feeding bottles in 2015 as per IS 14625:2015, and prohibited the use of BPA in baby feeding bottles.
Further, the Ministry of Women and Child Development had said that the material used for plastic feeding bottles and accessories, excluding teats, shall be of polypropylene conforming to IS 10910 or polyethersulfone (PES) or any other olefin based polymer, co-polyester material or other raw material. The materials used should not pose any health risk to babies and shall not contain BPA.
The polycarbonate-based baby feeding bottles are still available in the Indian market, even though they have been prohibited since 2015 as per BIS. Hence, it needs stricter monitoring.
5-Oct-2018: Reusable water-treatment particles developed to effectively eliminate BPA
Micron-sized spheres created in the lab of Rice environmental engineer Pedro Alvarez are built to catch and destroy bisphenol A (BPA), a synthetic chemical used to make plastics.
BPA is commonly used to coat the insides of food cans, bottle tops and water supply lines, and was once a component of baby bottles. While BPA that seeps into food and drink is considered safe in low doses, prolonged exposure is suspected of affecting the health of children and contributing to high blood pressure.
The good news is that reactive oxygen species (ROS) -- in this case, hydroxyl radicals -- are bad news for BPA. Inexpensive titanium dioxide releases ROS when triggered by ultraviolet light. But because oxidizing molecules fade quickly, BPA has to be close enough to attack.
That's where the trap comes in.
Close up, the spheres reveal themselves as flower-like collections of titanium dioxide petals. The supple petals provide plenty of surface area for the Rice researchers to anchor cyclodextrin molecules.
Cyclodextrin is a benign sugar-based molecule often used in food and drugs. It has a two-faced structure, with a hydrophobic (water-avoiding) cavity and a hydrophilic (water-attracting) outer surface. BPA is also hydrophobic and naturally attracted to the cavity. Once trapped, ROS produced by the spheres degrades BPA into harmless chemicals.
In the lab, the researchers determined that 200 milligrams of the spheres per liter of contaminated water degraded 90 percent of BPA in an hour, a process that would take more than twice as long with unenhanced titanium dioxide.
The work fits into technologies developed by the Rice-based and National Science Foundation-supported Center for Nanotechnology-Enabled Water Treatment because the spheres self-assemble from titanium dioxide nanosheets.
The size of the particles is less than 100 nanometers. Because of their very small size, they're very difficult to recover from suspension in water. The Rice particles are much larger. Where a 100-nanometer particle is 1,000 times smaller than a human hair, the enhanced titanium dioxide is between 3 and 5 microns, only about 20 times smaller than the same hair. That means we can use low-pressure microfiltration with a membrane to get these particles back for reuse. It saves a lot of energy.
Because ROS also wears down cyclodextrin, the spheres begin to lose their trapping ability after about 400 hours of continued ultraviolet exposure. But once recovered, they can be easily recharged.
This new material helps overcome two significant technological barriers for photocatalytic water treatment. First, it enhances treatment efficiency by minimizing scavenging of ROS by non-target constituents in water. Here, the ROS are mainly used to destroy BPA.
Second, it enables low-cost separation and reuse of the catalyst, contributing to lower treatment cost. This is an example of how advanced materials can help convert academic hypes into feasible processes that enhance water security.
5-Oct-2018: Reusable water-treatment particles developed to effectively eliminate BPA
Micron-sized spheres created in the lab of Rice environmental engineer Pedro Alvarez are built to catch and destroy bisphenol A (BPA), a synthetic chemical used to make plastics.
BPA is commonly used to coat the insides of food cans, bottle tops and water supply lines, and was once a component of baby bottles. While BPA that seeps into food and drink is considered safe in low doses, prolonged exposure is suspected of affecting the health of children and contributing to high blood pressure.
The good news is that reactive oxygen species (ROS) -- in this case, hydroxyl radicals -- are bad news for BPA. Inexpensive titanium dioxide releases ROS when triggered by ultraviolet light. But because oxidizing molecules fade quickly, BPA has to be close enough to attack.
That's where the trap comes in.
Close up, the spheres reveal themselves as flower-like collections of titanium dioxide petals. The supple petals provide plenty of surface area for the Rice researchers to anchor cyclodextrin molecules.
Cyclodextrin is a benign sugar-based molecule often used in food and drugs. It has a two-faced structure, with a hydrophobic (water-avoiding) cavity and a hydrophilic (water-attracting) outer surface. BPA is also hydrophobic and naturally attracted to the cavity. Once trapped, ROS produced by the spheres degrades BPA into harmless chemicals.
In the lab, the researchers determined that 200 milligrams of the spheres per liter of contaminated water degraded 90 percent of BPA in an hour, a process that would take more than twice as long with unenhanced titanium dioxide.
The work fits into technologies developed by the Rice-based and National Science Foundation-supported Center for Nanotechnology-Enabled Water Treatment because the spheres self-assemble from titanium dioxide nanosheets.
The size of the particles is less than 100 nanometers. Because of their very small size, they're very difficult to recover from suspension in water. The Rice particles are much larger. Where a 100-nanometer particle is 1,000 times smaller than a human hair, the enhanced titanium dioxide is between 3 and 5 microns, only about 20 times smaller than the same hair. That means we can use low-pressure microfiltration with a membrane to get these particles back for reuse. It saves a lot of energy.
Because ROS also wears down cyclodextrin, the spheres begin to lose their trapping ability after about 400 hours of continued ultraviolet exposure. But once recovered, they can be easily recharged.
This new material helps overcome two significant technological barriers for photocatalytic water treatment. First, it enhances treatment efficiency by minimizing scavenging of ROS by non-target constituents in water. Here, the ROS are mainly used to destroy BPA.
Second, it enables low-cost separation and reuse of the catalyst, contributing to lower treatment cost. This is an example of how advanced materials can help convert academic hypes into feasible processes that enhance water security.
22-May-2019: Coral bleaching observed near Mandapam, Keezhakkarai, Palk Bay
The National Centre for Coastal Research, an institute under the Ministry of Earth Sciences, in India, has a field research station in the Gulf of Mannar region, and researchers led by Dr. Shanmugaraj have found an alarming pattern of bleaching in the reefs in Mandapam, Keezhakkarai and Palk Bay. They have found that sea surface temperature ranged from 28.7°C to 31°C in the August 2018-February 2019 period and there was no bleaching seen then. However, when the temperatures rose to between 32°C and 36°C between March 2019 and May 2019, researchers observed a pattern of bleaching in corals, which was different at different layers within the sea.
About 12% of coral species observed at depths between 0 m and 2 m such as Porites solida, Poritis lutea, Montipora digitate, Acropora hyacinthus were completely bleached. About 5% of species observed at depths between 2 m and 4 m such as Acropora formosa, Acropora hyacinthus, Montipora digitata, Montipora foliosa, Pocillopora damicornis, Goniastrea retiformis, Platygyra sinensis, Dipsastrea favus, Dipsastrea speciosa were partially bleached. Porites species observed in Palk Bay region were completely bleached at depths from zero to 4 metres. Corals at depths over 5 m did not face bleaching.
In some sites the massive corals such as Porites species were completely bleached but branching corals such as Montipora digitata and Acropora species, were not bleached.
Coral reefs are important hotspots of biodiversity in the ocean. Corals are animals in the same class (Cnidaria) as jellyfish and anemones. They consist of individual polyps that get together and build reefs. Coral reefs support a wide range of species and maintain the quality of the coastal biosphere. Corals control the level of carbon dioxide in the water by converting it into a limestone shell. If this process does not take place, the amount of carbon dioxide in the ocean water would increase significantly and affect ecological niches.
Coral reefs are threatened by climate change. When the sea surface temperature increases beyond a tolerable limit, they undergo a process of bleaching. Basically bleaching is when the corals expel a certain algae known as zooxanthellae, which lives in the tissues of the coral in a symbiotic relationship. About 90% of the energy of the coral is provided by the zooxanthellae which are endowed with chlorophyll and other pigments. They are responsible for the yellow or reddish brown colours of the host coral. In addition the zooxanthellae can live as endosymbionts with jellyfish also.
When a coral bleaches, it does not die but comes pretty close to it. Some of the corals may survive the experience and recover once the sea surface temperature returns to normal levels.