Nitrogen is an essential nutrient for plant growth, and nitrogen fertilization and is often used in agriculture in the developing world and in organic process farming in wealthy countries. But organic farmers have to worry about yield also, and that has led to overuse and misuse that has resulted in the accumulation of surplus nitrogen in soil and its eventual migration to soil layers and groundwater.

It's no secret that the organic growing process is harder on the environment, with more toxic pesticides, less efficient use of the land, and lower yields, but some practices are exceptionally harmful, like growing crops in organic (peat) soil. 

When organic soils are drained and cultivated the organic matter in the soil will decompose which leads to emissions of greenhouse gases, finds a study in Denmark, and that makes up as much as 6 percent of Denmark's total greenhouse gas emissions.

In the 1980s, the recycling debate was all the rage, with arguments for and against government doing it. The argument against government doing it was predictable; government is inefficient and expensive and the landfills waiting for a recycling list that would grow with every environmental lobbying effort would be the size of regular landfills.

Government recycling won and now there are giant landfills of recycling material that can never actually be recycled - all those glossy magazine pages with perfume on them, for example. Most of California recycling is actually done in China, after being shipped there in emissions-belching boats.

Hydraulic fracturing is an important technological advance in the extraction of natural gas and petroleum from black shales, but wastewater produced along with shale gas and petroleum following fracking is extremely saline and contains high concentrations of barium.

A pesticide called heptachlor epoxide and used in 1970s was found in milk at that time - and it being linked to Parkinson's disease now, in a paper in Neurology.

Early life exposures to toxic chemicals such as PCBs and DDT dampen an infant's response to the tuberculosis vaccine, according to a new study.

DDT? Banned over 40 years ago but so safe the United States EPA creates guidelines for other countries to spray it inside homes? 

It's that pesky 'persistent pollutant' designation which, like endocrine disruptor, is invoked when nothing else is available. Todd Jusko, Ph.D., an assistant professor in epidemiology at the University of Rocheste, lead author of the paper, also says PCBs - banned in the 1970s - are still impacting babies and, in case that doesn't get environmental activist fundraiser juices flowing, that thousand of other pollutants similar to PCBs and DDT have "unknown health implications."

Though 99.9999% of species that have gone extinct have never actually been identified, it is common to read claims that we are facing a catastrophic species extinction crisis.

It's best to take such talk with a grain of salt, because conservationists are only now discovering that cities are better at preserving species than pristine wilderness environments. A recent study looked at the distributions of 1,643 protected species in Australia, and counted up the number of these species that occurred in square-kilometer units across the continent. They found that, on average, urban environments contain more threatened protected species in a given area than rural environments.

A carbon tax of just $11 would offset the CO2 emissions from tourism, according to a paper in the Journal of Sustainable Tourism.

Every time people go on vacation, or journalists go off to climate conferences like the one in Paris, they are using fossil fuel energy. The total emissions from vacations like that would be the sixth largest emitter of CO2 if it were a country - five percent of total human-made emissions of CO2.   

The extinction of one carnivore species can trigger the demise of fellow predators - a phenomenon called horizontal extinction cascades, where extinctions of carnivore species can have a ripple effect across species triggering further unexpected extinctions of other carnivores.

Using insects, the research team Frank van Veen, Dirk Sanders and Rachel Kehoe from the Centre for Ecology and Conservation at the University's Penryn campus in Cornwall, set up experimental communities with complex food webs in 40 four-square metre outdoor field-cages which they observed over a spring and summer season. These communities consisted of several species of aphids and their natural enemies, parasitoid wasps.