An area near the city of Chihuahua has been traditionally irrigated with wastewater to grow forage crops. It has been hypothesized that metal levels could be found in these soils high enough to cause potential health problems to the population. The objective of this study was to determine heavy metal concentrations in different soils due to irrigation practices. Four soil types were evaluated; a soil with a past and present history of wastewater irrigation (S1), a soil with a history of wastewater irrigation until 2003 (S2), a soil with no irrigation history (S3), and a soil similar to S1 and adjacent to the river where the wastewater is transported (S11). Three soil depths were evaluated; 0–15, 15–30 and 30–50 cm. Consequently, a total of 150 soil samples were analyzed evaluating pH, EC, OM and the following elements; Na, K, Cd, Pb, Ni, Cr, Cu and Fe. The pH (P=0.000) and EC (P=0.000) were different for each soil type but no differences were noted for soil depth and the interaction. Maximum pH levels were noted in S3 with a value of 8.74 while maximum EC was observed in S1 with a value of 0.850 dSm−1. The OM level was different for soil type (P=0.000), soil depth (P=0.005) and the interaction (P=0.014). S1 and S11 obtained maximum levels of OM while minimum levels were noted in S3. Maximum OM levels were observed at the 0–15 cm depth followed by the 15–30 cm depth and finally at the 30–50 cm depth. The highest concentration of metals was as follows: K in S1 (359.3 mg kg−1); Cd in S1 (4.48 mg kg−1); Pb in S11 (155.83 mg kg−1); Ni in S1 (10.74 mg kg−1); Cu in S1 (51.36 mg kg−1); B in S3 (41.5 mg kg−1); Fe in S3 (20,313.0 mg kg−1), Cr in S3 (44.26 mg kg−1) and Na in S3 (203.0 mg kg−1). The conclusion is that some metals are present in the soils due to anthropogenic activities but others are present in natural forms.
The hydraulic Conchos Watershed is essential for the inhabitants of the state of Chihuahua, Mexico. Nevertheless, evidence shows that the water that flows in the Conchos River is contaminated. The objective was to determine if Vanadium (V) and Lithium (Li) were present in the water of the Conchos River.
Given some things, what's prior: those things taken individually or those things taken collectively? Is each of them prior to them, or are they prior to every one of them? Is each thing prior to the things, or are the things themselves prior to each thing itself?This is, at a very rough first pass, the general question at the heart of a neglected debate in foundational ontology, the debate over the relative ontological priority of individuality and collectivity.What's prior, each of some entities or those very entities? Are some objects taken separately prior to those objects taken together, or are the objects taken together prior to the objects taken separately?Using a common piece of jargon: given some things, what's prior, every single such thing or the plurality of them?¹ The question ought not to be confused with others that have interested metaphysicians both across history and in more recent years. For instance, what's at issue is not the relative priority of some entities and a further entity that's somehow made out of those entities (a mereological fusion of them, a class or set of them, a fact or proposition about them, and so forth). That concerns the relative priority of some things (whether taken individually or collectively) and a somehow composite thing to which they bear some sort of intimate, constitutive relation (parthood, membership, etc.). The question is instead over the relative priority of each of some objects and those very objects-the focus is on individuality and collectivity proper, not on compositeness and componency.
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