Growing hypoxic zones reduce habitat for billfish and tuna

Billfish and tuna, important commercial and recreational fish species, may be more vulnerable to fishing pressure because of shrinking habitat, according to a new study published by scientists from NOAA, The Billfish Foundation, and University of Miami Rosenstiel School of Marine and Atmospheric Science.
An expanding zone of low oxygen, known as a hypoxic zone, in the Atlantic Ocean is encroaching upon these species' preferred oxygen-abundant habitat, forcing them into shallower waters where they are more likely to be caught.
During the study, published recently in the journal Fisheries Oceanography, scientists tagged 79 sailfish and blue marlin with satellite tracking devices in the western North Atlantic, off south Florida and the Caribbean; and eastern tropical Atlantic, off the coast of West Africa. The pop off archival satellite tags monitored horizontal and vertical movement patterns. Researchers confirmed that billfish prefer oxygen rich waters closer to the surface and will actively avoid waters low in oxygen.

Leaking underground CO2 storage could contaminate drinking water

Leaks from carbon dioxide injected deep underground to help fight climate change could bubble up into drinking water aquifers near the surface, driving up levels of contaminants in the water tenfold or more in some places, according to a study by Duke University scientists.
Based on a year-long analysis of core samples from four drinking water aquifers, "We found the potential for contamination is real, but there are ways to avoid or reduce the risk," says Robert B. Jackson, Nicholas Professor of Global Environmental Change and professor of biology at Duke.
"Geologic criteria that we identified in the study can help identify locations around the country that should be monitored or avoided," he says. "By no means would all sites be susceptible to problems of water quality."

Assessing arsenic and cadmium susceptibility

BANGLADESH is a developing country where fisheries and aquaculture remain very important as a source to supplement animal origin nutrition, employment generation, improving environmental condition and earning revenue in foreign exchange. Environmental pollution now-a-days poses a great threat to human beings as well as to animal kingdom over the world. Water resource, being the prominent component of the environment, is getting polluted over the decades. Contamination of water environment with various pollutants has increased considerably in resent years in many parts of the world. Various heavy metal ions such as As, Cd, Zn, Cu, Cr, Ni, Pb, Hg etc. are entering into environment through various processes.

Health Risks in a Bangladeshi Population due to Arsenic Exposure

Researchers of Columbia University conducted a population-based prevalence survey in Araihazar, Bangladesh, to describe the distribution of arsenic exposure in a rural Bangladeshi population and to assess the population’s awareness to this problem as well as to possible remediation options. Water samples from 5,967 contiguous tube wells in a defined geographic area were tested using laboratory-based methods.
Additionally, for each well, the owner/caretaker (or a close relative) was interviewed regarding his or her awareness of the health consequences of as exposure. Arsenic exposure data and demographic characteristics for the 65,876 users of these wells were also collected from the 5,967 respondents.

Solutions of Arsenic groundwater poisoning in southern Asia

An estimated 60 million people in Bangladesh are exposed to unsafe levels of naturally occurring arsenic in their drinking water, dramatically raising their risk for cancer and other serious diseases, according to the World Health Organization (WHO). Because most of the contaminated water is near the surface, many people in Bangladesh have installed deep wells to tap into groundwater that’s relatively free of arsenic.
In recent years, however, farmers have begun using the deep, uncontaminated aquifers for irrigation – a practice that could compromise access to clean drinking water across the country, according to a report in the May 27 issue of the journal Science. The report is co-authored by groundwater experts Scott Fendorf (Stanford University), Holly A. Michael (University of Delaware) and Alexander van Geen (Columbia University).
“Every effort should be made to prevent irrigation by pumping from deeper aquifers that are low in arsenic,” the authors wrote. “This precious resource must be preserved for drinking.”

Karnafully River Water of Bangladesh is under pollution

The Karnafully is one of the most important River of Bangladesh. It is called the mother of Chittagong city because it feeding the city in many ways and also contents the all kinds of garbage of that city and it play an important role in the communication system of the whole region. From the beginning the importance of the river was very much and increasing day by day. But at present that river is under pollution.
In a recent study show that due to industrial wastes, municipality sewage and agricultural runoff on the river water she is nearly facing Biological death. Standard temperature for sustaining aquatic life is 20-30 (0C) where as current temperature is 230C.

Source of Arsenic Contamination of Drinking Water in Bangladesh

Arsenic is a deadly poison with a history of use in intrigue and assassination.But the element and its derivatives are also used in many industries, such as metal smelting and as a component in products ranging from insecticide to micro-chips.And unfortunately, it is also found in abundance in the soil and rock in Bangladesh. It's leached up through the water table in tens of millions of water wells across the country.The source of arsenic in soil water is still a controversial issue and yet to be resolved.So what is the cause of Arsenic Pollution in Bangladesh?

• Scientists say that sedimentation with arsenic laden soils began in this region about 25,000-80,000 years back in the Quaternary era which was most popularly known as the Younger Deltaic Deposition or YDD.

ARSENIC POLLUTION IN BANGLADESH

In Bangladesh over 18 millions people are drinking arsenic poisoned water daily

Arsenic is a slow killer that accumulates in the body resulting in nails rotting, dark spots, bleeding sores, swelling, large warts and a form of gangrene. It is carcinogen increasing the risk of skin cancer and tumors of the bladder, kidney, liver and lungs.
Arsenic is naturally occurring in pyrite bedrock underlying much of West Bengal. The poisoning began to occur as millions of kiloliters of water was being pumped out from deep within underground reservoirs. As a result the water level dropped and exposed the arsenic-bearing pyrite to air leading to oxidisation, a reaction which flushed arsenic into the remaining water.

Villagers in Jampukkur, first noticed something was wrong in the 1970’s when dark spots spread across their bodies. They finally learned they were drinking arsenic contaminated water in 1993 when official tests showed 95% of the village wells were contaminated.

Pollution and waste management in Dhaka

A study recently conducted by the Institute of Water Modeling, with the support of the World Bank, has revealed that the water being supplied in certain points of Dhaka has “extremely high organic pollution.” The same report also mentions the high concentration of dissolved solidschlorides, sulphates, ammonia, cadmium and the heavy metal chromium. It has also been pointed out that in some localities like Hazaribagh and Tarabo, near the Buriganga, the concentration of some chemicals is higher than elsewhere. The tanneries in these areas have been identified as the polluters.
Some Wasa officials, on condition of anonymity, have admitted that the water in these rivers are so polluted that, even after treatment with required chemicals, it is not completely free of ammonia. The presence of other elements reduces the transparency of the water and sometimes gives it an undesirable smell. Experts have indicated that drinking such polluted water for a long time increases the risk of different diseases, and definitely affects the liver. There is also heightened possibility of jaundice.

Heightened concern over river pollution

We are gratified to see that when it comes to the issue of combating river pollution, the pressure does not seem to be letting up, and that the issue continues to dominate the people's agenda.
This is as it should be, as there is no more pressing concern for the government of the day, and if it does not act swiftly and with efficiency and effectiveness, then soon the damage to our environment might become irreversible.
This issue has long been one that environmental organisations such as BELA and BPA have attempted to bring to the fore-front of people's consciousness, and of late, The Daily Star has led the charge on the issue with serialised front page coverage of the toxic river pollution.

Polluted rivers and risky water in Bangladesh

The water of Buriganga, Balu, Sitalakhya and Turag are severely polluted. No biological survival can occur there as oxygen is depleted and might have reached nearly O level! Oxygen level in fresh river water is 9mg/l at 20ºc and 7.6mg/l at 30ºc (Summer).
BOD5 (consumption of oxygen for decomposition of microbs) indicates organic pollution. River Buriganga receives the following types of sewage.
Nature of Sewage BOD5, mg/l
Strong Sewage 450-550
Average Sewage 350-400
The sewage of 400 mg/l, and higher BODs shows mixing of industrial effluent with domestic sewage. Untreated industrial effluent is discharged from the dispersed and cluster of industries. Most industries do not have in-house treatment plants, and even if some of them had it, they would not use it perhaps to save operation cost in blatant violation of environmental rules without any concern for pollution of the rivers.
Industrial waste should not be allowed to enter the domestic sewage network as it interferers with treatment plants. In fact there is only one sewage treatment plant at Pagla for treating domestic wastes, operated by WASA with capacity of 0.12x106m3/d. Industries should be responsible for treating their own waste in-house. The city may have up to a dozen or more such domestic sewage treatment plants.

Pollution makes river of Bangladesh waters hard to treat

Water of the Buriganga and Shitalakhya rivers has become difficult to treat due to high level of pollution, said Dr MA Taher Khandker, director general of Bangladesh Haor and Wetland Development Board at a seminar.
“Water in the Buriganga and Turag rivers have literally turned into poison,” said Khandker in his presentation at the seminar titled 'Pollution of Rivers around Capital Dhaka: Mitigation Options' at Water Development Board (WDB) office.
Dissolved Oxygen (DO) level, an indicator of measuring river health and aquatic life in its water, stands at zero milligram (per litre) at different points of Buriganga, Turag, Tongi Khal and Balu during dry season, he said.

Water pollution in Buriganga

The capital of bangladesh Dhaka situated on the bank of the river Buriganga.The water of Buriganga is polluting by Industial waste and capital sewage which cause her to become biologically dead.

Tannery west mainly contaminating the river.Around 20,000 cubic meters of untreated highly toxic liquid waste flow in to the Buriganga through canals on a recent report.