Stream contamination by trace elements: biota incorporation and phytoremediation

In this review, we present information about the presence of trace elements on streams and the consequences related to the increase of these chemical elements on aquatic systems. Although several studies on trace elements contamination in aquatic environments are conducted on point sources, non-point sources also have a high potential to contaminate water bodies. Some trace elements are important for the development of an organism. However, even essential elements, in high concentrations, may be toxic to aquatic organisms. In some cases, trace elements may accumulate and be transferred along food webs, generating changes in the structure and functioning of terrestrial ecosystems. The phytoremediation techniques could be an important tool in reducing the problems generated by trace elements. Thus, understanding the effects generated by the increase of trace elements concentrations on aquatic ecosystems becomes important to help public managers to apply solutions for the mitigation of this chemical pollution on natural resources.

Genes Indicative of Zoonotic and Swine Pathogens Are Persistent in Stream Water and Sediment following a Swine Manure Spill

ABSTRACTManure spills into streams are relatively frequent, but no studies have characterized stream contamination with zoonotic and veterinary pathogens, or fecal chemicals, following a spill. We tested stream water and sediment over 25 days and downstream for 7.6 km for the following: fecal indicator bacteria (FIB), the fecal indicator chemicals cholesterol and coprostanol, 20 genes for zoonotic and swine-specific bacterial pathogens by presence/absence PCR for viable cells, one swine-specificEscherichia colitoxin gene (STII gene) by quantitative PCR (qPCR), and nine human and animal viruses by qPCR or reverse transcription-qPCR. Twelve days postspill, and 4.2 km downstream, water concentrations of FIB, cholesterol, and coprostanol were 1 to 2 orders of magnitude greater than those detected before, or above, the spill, and genes indicating viable zoonotic or swine-infectiousEscherichia coliwere detected in water or sediment. STII gene levels increased from undetectable before or above the spill to 105copies/100 ml of water 12 days postspill. Thirteen of 14 water (8/9 sediment) samples had viable STII-carrying cells postspill. Eighteen days postspill, porcine adenovirus and teschovirus were detected 5.6 km downstream. FIB concentrations (per gram [wet weight]) in sediment were greater than in water, and sediment was a continuous reservoir of genes and chemicals postspill. Constituent concentrations were much lower, and detections less frequent, in a runoff event (200 days postspill) following manure application, although the swine-associated STII andstx2egenes were detected. Manure spills are an underappreciated pathway for livestock-derived contaminants to enter streams, with persistent environmental outcomes and the potential for human and veterinary health consequences.