http://earthworm.co.za/wp-content/uploads/2009/04/influence-humic-acid-vc-on-plant-growth.pdf

The influence of humic acids derived from earthworm-processed organic wastes on plant growth.

Mining and smelting are important economic activities. However, mining-related industries are also some of the largest sources of environmental pollution from heavy metals. China is one of the largest producers and consumers of lead and zinc in the world. A large amount of lead, zinc, and related elements, such as cadmium, have been released into the environment due to mineral processing activities and have impacted water resources, soils, vegetables, and crops. In some areas, this pollution is hazardous to human health. This article reviews studies published in the past 10 years (2000-2009), on the environmental and human health consequences of lead/zinc mineral exploitation in China. Polluted areas are concentrated in the following areas: the junction of Yunnan, Guizhou and Sichuan provinces, west-central Hunan province, central Guangxi province, northern Guangdong, northwestern Henan province, the border between Shanxi and Gansu provinces, and the region of Liaoning province near Bohai. Lead (Pb) and cadmium (Cd) are the main pollutants and are associated with human health effects such as high lead blood levels in children, arthralgia, osteomalacia, and excessive cadmium in urine.

Impacts of lead/zinc mining and smelting on the environment and human health in China

Phytoremediation is an emerging technology for the remediation of mine tailings, a global problem for which conventional remediation technologies are costly. There are two approaches to phytoremediation of mine tailings, phytoextraction and phytostabilization. Phytoextraction involves translocation of heavy metals from mine tailings to the plant shoot biomass followed by plant harvest, while phytostabilization focuses on establishing a vegetative cap that does not shoot accumulate metals but rather immobilizes metals within the tailings. Phytoextraction is currently limited by low rates of metal removal which is a combination of low biomass production and insufficiently high metal uptake into plant tissue. Phytostabilization is currently limited by a lack of knowledge of the minimum amendments required (e.g., compost, irrigation) to support long-term plant establishment. This review addresses both strategies within the context of two specific climate types: temperate and arid. In temperate environments, mine tailings are a source of metal leachates and acid mine drainage that contaminate nearby waterways. Mine tailings in arid regions are subject to eolian dispersion and water erosion. Examples of phytoremediation within each of these environments are discussed. Current research suggests that phytoextraction, due to high implementation costs and long time frames, will be limited to sites that have high land values and for which metal removal is required. Phytostabilization, due to lower costs and easier implementation, will be a more commonly used approach. Complete restoration of mining sites is an unlikely outcome for either approach.

Phytoremediation of mine tailings in temperate and arid environments

Composted materials as organic fertilizers

Heavy metal accumulation and tolerance in plants from mine tailings of the semiarid Cartagena-La Unión mining district (SE Spain).

It is widely known that anthropogenic activities strongly contributed to heavy metals contamination of the environment. For this reason, distribution of heavy metals in soils and plants around urban and industrial point sources have been the object of extensive studies. Lesser attention has been given to accumulation of heavy metals in animals bred in these polluted environments, and relatively few works are concerned with the accumulation of heavy metals through the food chain. The aim of this work is to examine the distribution of heavy metals in two contaminated environments, a smelter-refinery and a mine area situated in S.W. Sardinia. The first sampling area is located near one of the most important Pb and Zn smelting-refineries of Europe, and the second near abandoned and working mines. In this study, target organs of sheep and lamb were considered for their heavy metals accumulation. Samples of vegetation were collected throughout the vegetative period and analyzed for their Pb, Zn and Cd content. Winter forage and soil were also sampled.

Heavy metal bioaccumulation in lamb and sheep bred in smelting and mining areas of S.W. Sardinia (Italy).

Sorption of atrazine and trifluralin in relation to the physio-chemical characteristics of selected soils

The humification index (HI) values of three different manures and earthworm casts were calculated for three different extractant solutions (0.5M sodium hydroxide, 0.1M sodium pyrophosphate pH 7 and 0.1M sodium pyrophosphate plus 0.1M NaOH). The alkaline sodium pyrophosphate solution was found to be the most suitable because of both its extraction efficiency and the quality of the organic matter extracted which allows a good characterization of the stabilization degree attained by composting. Neutral sodium pyrophosphate extracts also show characteristic HI values for different samples but lower extraction efficiencies. The HI values for sodium hydroxide extracts show only little differences between manures and composts. The good correspondence found between HI data and isoelectric focusing (IEF) patterns confirmed on one side that humification indexes give a quantitative measure of the humification degree, on the other side that IEF is a suitable technique in order to obtain qualitative informations on organic matter stabilization in earthworm casts.

Characterization of organic matter from animal manures after digestion by earthworms

Samples of soils and vegetation from the mining area of South-West Sardinia (Italy) were analyzed for Pb, Zn, Cd, and Cu content. The area (more than 100 km2) is inhabited by many thousands of people; land utilization includes mainly grapes on some small plains and permanent sheep pasture on the hills. The levels of Pb, Zn, and Cd were found to be exceptionally high in most samples. Lead concentration was up to 71000 μg g−1 in the soils and 4000 jig g−1 in vegetation; Cd concentration was found up to 665 μg g−1 in soils and 26.5 μg g−1 in vegetation. The heavy metal content of some soil samples was highly variable. Data show that Pb is easily absorbed by plant roots and translocated to foliage. In spite of the high heavy metal level, no signs of toxicity were apparent in vegetation.

P. Sequi

Papers

Heavy metal bioaccumulation in lamb and sheep bred in smelting and mining areas of S.W. Sardinia (Italy).

Sorption of atrazine and trifluralin in relation to the physio-chemical characteristics of selected soils

Characterization of organic matter from animal manures after digestion by earthworms

Anomalous contents of heavy metals in soils and vegetation of a mine area in S.W. Sardinia, Italy

Contribution of agricultural land in the Po Valley to coastal eutrophication of the Adriatic Sea