A 5.3 m sediment core and soil samples were taken from Diss Mere and its catchment. The sediment core was dated and Hg analysed on the sediment and soil samples. The Hg record of the sediment core shows that Diss Mere has been contaminated for the past thousand years and the historical trends in sediment contamination are in good agreement with the development of the weaving industry in Diss and hemp cultivation in the region. Mercury contamination in Diss Mere has been significant and reached a peak in the mid-19th century with sediment Hg concentrations over 50 μg g−1. Elevated Hg concentrations were also found in contemporary soils in residential areas with former industrial land use. Although local hemp cultivation and the traditional weaving industry were abandoned a hundred years ago, Hg contamination caused by these activities still exists in the catchment, and affects the lake. 相似文献
Wastewater produced from a metal plating is a major environmental problem. Industrial auditing revealed that the main source
of pollution mainly originated from rinsing water. The characterization of final effluent showed that it is highly contaminated
with hazardous heavy metals and cyanide. The concentration of copper, hexavalent chromium, nickel, and cyanide in the rinsing
water of metal plating department was 14.8, 40.9, 13.3, and 19 mg/l, respectively. The concentration of cyanide and zinc from
the galvanizing department reached 60 and 80 mg/l. The remediation scheme included the application of in-plant control measures
via changing the rinsing process followed by the destruction of cyanide and reduction of hexavalent chromium bearing wastes.
The pretreated wastes were then mixed with other industrial wastes prior to a combined chemical coagulation-sedimentation
using lime and/or lime in combination with ferric chloride. The results indicated that, after applying the waste minimization
measures alone at the source, prior to final treatment of industrial waste, removal rates of cyanide, copper, nickel, and
chromium concentrations were 23.2%, 14.9%, 32.3%, and 55.3%, respectively in the rinse water from metal plating department.
Furthermore, the removal rates of cyanide and zinc in the galvanizing department reached 59.7% and 24.3. The integrated control
measures and treatment scheme led to more than 99% removal of copper, nickel, chromium, and zinc, while the complete removal
of cyanide was achieved in the final effluent. 相似文献
The status of wild capture fisheries has induced many fisheries and conservation scientists to express concerns about the
concept of using forage fish after reduction to fishmeal and fish oil, as feed for farmed animals, particularly in aquaculture.
However, a very large quantity of forage fish is being also used untransformed (fresh or frozen) globally for other purposes,
such as the pet food industry. So far, no attempts have been made to estimate this quantum, and have been omitted in previous
fishmeal and fish oil exploitation surveys. On the basis of recently released data on the Australian importation of fresh
or frozen fish for the canned cat food industry, here we show that the estimated amount of raw fishery products directly utilized
by the cat food industry equates to 2.48 million metric tonnes per year. This estimate, plus the previously reported global
fishmeal consumption for the production of dry pet food suggest that 13.5% of the total 39.0 million tonnes of wild caught
forage fish is used for purposes other than human food production. This study attempts to bring forth information on the direct
use of fresh or frozen forage fish in the pet food sector that appears to have received little attention to this date and
that needs to be considered in the global debate on the ethical nature of current practices on the use of forage fish, a limited
biological resource. 相似文献
While the presence of lead in urban soils from residential lead paint and leaded gasoline is well documented, the relative contribution of lead from area historical industrial activities is not. This study examined the connection between historical industrial sources of lead in Portland, Maine, USA from 1860 to 1970 to current, spatial distributions of soil lead. Collecting 1859 surface and 122 sub-surface soil samples in accordance with USEPA's Lead Safe Yard Protocols, lead concentrations varied from 9 mg/kg to >100,000 mg/kg with most of the samples greater than USEPA's critical value for lead (400 mg/kg). Using historical documents, probable sources of lead were mapped. In comparing two datasets, no clear relationship emerged. Findings were hampered by inability to sample under large areas of impervious surfaces and private properties. Because of lead's immobility in soil, one would expect decreasing concentration with depth, but lead concentrations varied with depth and location. The haphazard dumping of lead-contaminated industrial waste and the relocation of contaminated fill are likely factors. These findings suggest that in urban areas where multiple historical sources of lead existed, surface sampling to determine presence of lead may not be sufficient to protect public health. 相似文献
In all tanning technology operations wastes are generated. These reach the environment as residual waters, solid and liquid waste as well as atmospheric emissions and odours.
This study tests an alternative method to the traditional tanning method at an industrial level. The new method is based on tanning without float and by significantly increasing the temperature at the end of the tanning process. The properties of the leathers obtained using the two methods have been compared and the results indicate that those leathers have similar physical, chemical, and organoleptic properties. However, the differences existing from the environmental point of view are significant. It is not necessary to use clean water for this tanning. Moreover, there is a 75% reduction of the residual float, a 91% reduction of the chrome discharged, and a 94% reduction of the chlorides discharged. A financial assessment was carried out to demonstrate that the newly proposed system is 32% more economic than the traditional one. 相似文献